* Sync with the trunk.

45 files changed, 930 insertions, 684 deletions

diff --git a/configure.ac b/configure.ac
index 876e0a862ee8..0443fe49205a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -5,42 +5,42 @@ AM_INIT_AUTOMAKE([dist-bzip2 foreign])
 
 AC_DEFINE_UNQUOTED(NIX_VERSION, ["$VERSION"], [Nix version.])
 
-AC_CANONICAL_HOST
-
+AC_PROG_SED
 
 # Construct a Nix system name (like "i686-linux").
+AC_CANONICAL_HOST
 AC_MSG_CHECKING([for the canonical Nix system name])
-cpu_name=$(uname -p | tr 'ABCDEFGHIJKLMNOPQRSTUVWXYZ ' 'abcdefghijklmnopqrstuvwxyz_')
-machine_name=$(uname -m | tr 'ABCDEFGHIJKLMNOPQRSTUVWXYZ ' 'abcdefghijklmnopqrstuvwxyz_')
-
-case $machine_name in
-    i*86)
-        machine_name=i686
-        ;;
-    x86_64)
-        machine_name=x86_64
-        ;;
-    ppc)
-        machine_name=powerpc
-        ;;
-    *)
-        if test "$cpu_name" != "unknown"; then
-            machine_name=$cpu_name
-        fi
-        ;;
-esac
 
-sys_name=$(uname -s | tr 'ABCDEFGHIJKLMNOPQRSTUVWXYZ ' 'abcdefghijklmnopqrstuvwxyz_')
+AC_ARG_WITH(system, AC_HELP_STRING([--with-system=SYSTEM],
+  [Platform identifier (e.g., `i686-linux').]),
+  [system=$withval],
+  [case "$host_cpu" in
+     i*86)
+        machine_name="i686";;
+     amd64)
+        machine_name="x86_64";;
+     *)
+        machine_name="$host_cpu";;
+   esac
+
+   case "$host_os" in
+     linux-gnu*)
+	# For backward compatibility, strip the `-gnu' part.
+	system="$machine_name-linux";;
+     *)
+        # Strip the version number from names such as `gnu0.3',
+        # `darwin10.2.0', etc.
+	system="$machine_name-`echo $host_os | "$SED" -e's/@<:@0-9.@:>@*$//g'`";;
+   esac])
+
+sys_name=$(uname -s | tr 'A-Z ' 'a-z_')
 
 case $sys_name in
     cygwin*)
         sys_name=cygwin
         ;;
 esac
-
-AC_ARG_WITH(system, AC_HELP_STRING([--with-system=SYSTEM],
-  [Platform identifier (e.g., `i686-linux').]),
-  system=$withval, system="${machine_name}-${sys_name}")
+   
 AC_MSG_RESULT($system)
 AC_SUBST(system)
 AC_DEFINE_UNQUOTED(SYSTEM, ["$system"], [platform identifier (`cpu-os')])
@@ -62,7 +62,7 @@ fi
 
 
 # Solaris-specific stuff.
-if test "$sys_name" = "sunos"; then
+if test "$sys_name" = sunos; then
     # Solaris requires -lsocket -lnsl for network functions
     LIBS="-lsocket -lnsl $LIBS"
 fi
@@ -255,7 +255,7 @@ AC_ARG_WITH(sqlite, AC_HELP_STRING([--with-sqlite=PATH],
   [prefix of SQLite]),
   sqlite=$withval, sqlite=)
 AM_CONDITIONAL(HAVE_SQLITE, test -n "$sqlite")
-SQLITE_VERSION=3070701
+SQLITE_VERSION=3070900
 AC_SUBST(SQLITE_VERSION)
 if test -z "$sqlite"; then
   sqlite_lib='${top_builddir}/externals/sqlite-autoconf-$(SQLITE_VERSION)/libsqlite3.la'
diff --git a/doc/manual/nix-copy-closure.xml b/doc/manual/nix-copy-closure.xml
index 584e713f14e0..45cfc0f34245 100644
--- a/doc/manual/nix-copy-closure.xml
+++ b/doc/manual/nix-copy-closure.xml
@@ -24,8 +24,11 @@
     </group>
     <arg><option>--sign</option></arg>
     <arg><option>--gzip</option></arg>
+    <arg><option>--bzip2</option></arg>
+    <arg><option>--xz</option></arg>
+    <arg><option>--include-outputs</option></arg>
     <arg choice='plain'>
-      <arg><replaceable>user@</replaceable></arg><replaceable>machine</replaceable>
+      <replaceable>user@</replaceable><replaceable>machine</replaceable>
     </arg>
     <arg choice='plain'><replaceable>paths</replaceable></arg>
   </cmdsynopsis>
@@ -84,25 +87,36 @@ those paths.  If this bothers you, use
 
     <listitem><para>Let the sending machine cryptographically sign the
     dump of each path with the key in
-    <filename>/nix/etc/nix/signing-key.sec</filename>.  If the user on
-    the target machine does not have direct access to the Nix store
-    (i.e., if the target machine has a multi-user Nix installation),
-    then the target machine will check the dump against
-    <filename>/nix/etc/nix/signing-key.pub</filename> before unpacking
-    it in its Nix store.  This allows secure sharing of store paths
-    between untrusted users on two machines, provided that there is a
-    trust relation between the Nix installations on both machines
-    (namely, they have matching public/secret keys).</para></listitem>
+    <filename><replaceable>sysconfdir</replaceable>/nix/signing-key.sec</filename>.
+    If the user on the target machine does not have direct access to
+    the Nix store (i.e., if the target machine has a multi-user Nix
+    installation), then the target machine will check the dump against
+    <filename><replaceable>sysconfdir</replaceable>/nix/signing-key.pub</filename>
+    before unpacking it in its Nix store.  This allows secure sharing
+    of store paths between untrusted users on two machines, provided
+    that there is a trust relation between the Nix installations on
+    both machines (namely, they have matching public/secret
+    keys).</para></listitem>
 
   </varlistentry>
 
-  <varlistentry><term><option>--gzip</option></term>
+  <varlistentry><term><option>--gzip</option> / <option>--bzip2</option> / <option>--xz</option></term>
 
-    <listitem><para>Compress the dump of each path with
-    <command>gzip</command> before sending it.</para></listitem>
+    <listitem><para>Compress the dump of each path with respectively
+    <command>gzip</command>, <command>bzip2</command> or
+    <command>xz</command> before sending it.  The corresponding
+    decompression program must be installed on the target
+    machine.</para></listitem>
 
   </varlistentry>
 
+  <varlistentry><term><option>--include-outputs</option></term>
+  
+  <listitem><para>Also copy the outputs of store derivations included
+  in the closure.</para></listitem>
+  
+  </varlistentry>
+
 </variablelist>
 
 </refsection>
diff --git a/doc/manual/nix-env.xml b/doc/manual/nix-env.xml
index 403ab267827d..a03afaf5c007 100644
--- a/doc/manual/nix-env.xml
+++ b/doc/manual/nix-env.xml
@@ -2,7 +2,7 @@
           xmlns:xlink="http://www.w3.org/1999/xlink"
           xmlns:xi="http://www.w3.org/2001/XInclude"
           xml:id="sec-nix-env">
-  
+
 <refmeta>
   <refentrytitle>nix-env</refentrytitle>
   <manvolnum>1</manvolnum>
@@ -60,7 +60,7 @@ environments.</para>
 <para><command>nix-env</command> takes exactly one
 <emphasis>operation</emphasis> flag which indicates the subcommand to
 be performed.  These are documented below.</para>
-    
+
 </refsection>
 
 
@@ -78,19 +78,19 @@ linkend="sec-common-options" />.</para>
 
   <varlistentry><term><option>--file</option></term>
     <term><option>-f</option></term>
-  
+
     <listitem><para>Specifies the Nix expression (designated below as
     the <emphasis>active Nix expression</emphasis>) used by the
     <option>--install</option>, <option>--upgrade</option>, and
     <option>--query --available</option> operations to obtain
     derivations.  The default is
     <filename>~/.nix-defexpr</filename>.</para></listitem>
-    
+
   </varlistentry>
-      
+
   <varlistentry><term><option>--profile</option></term>
     <term><option>-p</option></term>
-  
+
     <listitem><para>Specifies the profile to be used by those
     operations that operate on a profile (designated below as the
     <emphasis>active profile</emphasis>).  A profile is sequence of
@@ -98,11 +98,11 @@ linkend="sec-common-options" />.</para>
     which is the <emphasis>current generation</emphasis>.  The default
     profile is the target of the symbolic link
     <filename>~/.nix-profile</filename> (see below).</para></listitem>
-    
+
   </varlistentry>
-      
+
   <varlistentry><term><option>--dry-run</option></term>
-  
+
     <listitem><para>For the <option>--install</option>,
     <option>--upgrade</option>, <option>--uninstall</option>,
     <option>--switch-generation</option> and
@@ -117,23 +117,23 @@ linkend="sec-common-options" />.</para>
     substitute is available).</para></listitem>
 
   </varlistentry>
-      
+
   <varlistentry><term><option>--system-filter</option> <replaceable>system</replaceable></term>
-  
+
     <listitem><para>By default, operations such as <option>--query
     --available</option> only include derivations matching the current
     platform.  This option allows you to use derivations for the
     specified platform <replaceable>system</replaceable>.  The special
     value <literal>*</literal> causes derivations for any platform to
     be included.</para></listitem>
-    
+
   </varlistentry>
 
 </variablelist>
 
 </refsection>
 
-  
+
 
 <!--######################################################################-->
 
@@ -170,25 +170,25 @@ linkend="sec-common-options" />.</para>
     this directory.</para>
 
     </listitem>
-    
+
   </varlistentry>
 
   <varlistentry><term><filename>~/.nix-profile</filename></term>
-  
+
     <listitem><para>A symbolic link to the user's current profile.  By
     default, this symlink points to
     <filename><replaceable>prefix</replaceable>/var/nix/profiles/default</filename>.
     The <envar>PATH</envar> environment variable should include
     <filename>~/.nix-profile/bin</filename> for the user environment
     to be visible to the user.</para></listitem>
-    
+
   </varlistentry>
 
 </variablelist>
-        
+
 </refsection>
 
-  
+
 
 <!--######################################################################-->
 
@@ -214,7 +214,7 @@ linkend="sec-common-options" />.</para>
 
 
 <refsection><title>Description</title>
-            
+
 <para>The install operation creates a new user environment, based on
 the current generation of the active profile, to which a set of store
 paths described by <replaceable>args</replaceable> is added.  The
@@ -256,7 +256,7 @@ number of possible ways:
   <emphasis>attribute paths</emphasis> that select attributes from the
   top-level Nix expression.  This is faster than using derivation
   names and unambiguous.  To find out the attribute paths of available
-  packages, use <literal>nix-env -qaA '*'</literal>.</para></listitem>
+  packages, use <literal>nix-env -qaP '*'</literal>.</para></listitem>
 
   <listitem><para>If <option>--from-profile</option>
   <replaceable>path</replaceable> is given,
@@ -306,20 +306,20 @@ number of possible ways:
 
   <varlistentry><term><option>--preserve-installed</option></term>
     <term><option>-P</option></term>
-  
+
     <listitem><para>Do not remove derivations with a name matching one
     of the derivations being installed.  Usually, trying to have two
     versions of the same package installed in the same generation of a
     profile will lead to an error in building the generation, due to
     file name clashes between the two versions.  However, this is not
     the case for all packages.</para></listitem>
-    
+
   </varlistentry>
 
 </variablelist>
 
 </refsection>
-            
+
 
 <refsection xml:id='refsec-nix-env-install-examples'><title>Examples</title>
 
@@ -327,7 +327,7 @@ number of possible ways:
 active Nix expression:
 
 <screen>
-$ nix-env --install gcc-3.3.2 
+$ nix-env --install gcc-3.3.2
 installing `gcc-3.3.2'
 uninstalling `gcc-3.1'</screen>
 
@@ -408,15 +408,15 @@ the following paths will be substituted:
   /nix/store/8zbipvm4gp9jfqh9nnk1n3bary1a37gs-perl-XML-Parser-2.34
   /nix/store/b8a2bg7gnyvvvjjibp4axg9x1hzkw36c-mono-1.1.4
   <replaceable>...</replaceable></screen>
-  
+
 </para>
 
 </refsection>
-    
+
 </refsection>
 
 
-  
+
 <!--######################################################################-->
 
 <refsection xml:id="rsec-nix-env-upgrade"><title>Operation <option>--upgrade</option></title>
@@ -442,7 +442,7 @@ the following paths will be substituted:
 </refsection>
 
 <refsection><title>Description</title>
-            
+
 <para>The upgrade operation creates a new user environment, based on
 the current generation of the active profile, in which all store paths
 are replaced for which there are newer versions in the set of paths
@@ -459,47 +459,47 @@ the same symbolic name, only the one with the highest version is
 installed.</para>
 
 </refsection>
-            
+
 <refsection><title>Flags</title>
 
 <variablelist>
 
   <varlistentry><term><option>--lt</option></term>
-  
+
     <listitem><para>Only upgrade a derivation to newer versions.  This
     is the default.</para></listitem>
-    
+
   </varlistentry>
 
   <varlistentry><term><option>--leq</option></term>
-  
+
     <listitem><para>In addition to upgrading to newer versions, also
     “upgrade” to derivations that have the same version.  Version are
     not a unique identification of a derivation, so there may be many
     derivations that have the same version.  This flag may be useful
     to force “synchronisation” between the installed and available
     derivations.</para></listitem>
-    
+
   </varlistentry>
 
   <varlistentry><term><option>--eq</option></term>
-  
+
     <listitem><para><emphasis>Only</emphasis> “upgrade” to derivations
     that have the same version.  This may not seem very useful, but it
     actually is, e.g., when there is a new release of Nixpkgs and you
     want to replace installed applications with the same versions
     built against newer dependencies (to reduce the number of
     dependencies floating around on your system).</para></listitem>
-    
+
   </varlistentry>
 
   <varlistentry><term><option>--always</option></term>
-  
+
     <listitem><para>In addition to upgrading to newer versions, also
     “upgrade” to derivations that have the same or a lower version.
     I.e., derivations may actually be downgraded depending on what is
     available in the active Nix expression.</para></listitem>
-    
+
   </varlistentry>
 
 </variablelist>
@@ -523,10 +523,10 @@ $ nix-env --upgrade pan
 
 $ nix-env -u '*' <lineannotation>(try to upgrade everything)</lineannotation>
 upgrading `hello-2.1.2' to `hello-2.1.3'
-upgrading `mozilla-1.2' to `mozilla-1.4'</screen>        
+upgrading `mozilla-1.2' to `mozilla-1.4'</screen>
 
 </refsection>
-    
+
 <refsection xml:id="ssec-version-comparisons"><title>Versions</title>
 
 <para>The upgrade operation determines whether a derivation
@@ -570,14 +570,14 @@ lexicographically (i.e., using case-sensitive string comparison).</para>
 2.3a &lt; 2.3c
 2.3pre1 &lt; 2.3c
 2.3pre1 &lt; 2.3q</screen>
-        
+
 </para>
 
 </refsection>
-            
+
 </refsection>
 
-  
+
 
 <!--######################################################################-->
 
@@ -596,14 +596,14 @@ lexicographically (i.e., using case-sensitive string comparison).</para>
 </refsection>
 
 <refsection><title>Description</title>
-            
+
 <para>The uninstall operation creates a new user environment, based on
 the current generation of the active profile, from which the store
 paths designated by the symbolic names
 <replaceable>names</replaceable> are removed.</para>
 
 </refsection>
-            
+
 <refsection><title>Examples</title>
 
 <screen>
@@ -611,11 +611,11 @@ $ nix-env --uninstall gcc
 $ nix-env -e '*' <lineannotation>(remove everything)</lineannotation></screen>
 
 </refsection>
-    
+
 </refsection>
 
 
-  
+
 <!--######################################################################-->
 
 <refsection xml:id="rsec-nix-env-set-flag"><title>Operation <option>--set-flag</option></title>
@@ -632,7 +632,7 @@ $ nix-env -e '*' <lineannotation>(remove everything)</lineannotation></screen>
 </refsection>
 
 <refsection><title>Description</title>
-            
+
 <para>The <option>--set-flag</option> operation allows meta attributes
 of installed packages to be modified.  There are several attributes
 that can be usefully modified, because they affect the behaviour of
@@ -670,7 +670,7 @@ script:
 </para>
 
 </refsection>
-            
+
 <refsection><title>Examples</title>
 
 <para>To prevent the currently installed Firefox from being upgraded:
@@ -716,13 +716,13 @@ $ nix-env --set-flag priority 10 gcc</screen>
 </para>
 
 </refsection>
-    
+
 </refsection>
 
 
-  
+
 <!--######################################################################-->
-  
+
 <refsection><title>Operation <option>--query</option></title>
 
 <refsection><title>Synopsis</title>
@@ -738,9 +738,9 @@ $ nix-env --set-flag priority 10 gcc</screen>
     <arg choice='plain'><option>--available</option></arg>
     <arg choice='plain'><option>-a</option></arg>
   </group>
-  
+
   <sbr />
-  
+
   <arg>
     <group choice='req'>
       <arg choice='plain'><option>--status</option></arg>
@@ -785,7 +785,7 @@ $ nix-env --set-flag priority 10 gcc</screen>
   </arg>
 
   <sbr />
-  
+
   <arg choice='plain' rep='repeat'><replaceable>names</replaceable></arg>
 </cmdsynopsis>
 
@@ -793,7 +793,7 @@ $ nix-env --set-flag priority 10 gcc</screen>
 
 
 <refsection><title>Description</title>
-            
+
 <para>The query operation displays information about either the store
 paths that are installed in the current generation of the active
 profile (<option>--installed</option>), or the derivations that are
@@ -817,23 +817,23 @@ operates.</para>
 <variablelist>
 
   <varlistentry><term><option>--installed</option></term>
-  
+
     <listitem><para>The query operates on the store paths that are
     installed in the current generation of the active profile.  This
     is the default.</para></listitem>
-    
+
   </varlistentry>
 
   <varlistentry><term><option>--available</option></term>
     <term><option>-a</option></term>
-  
+
     <listitem><para>The query operates on the derivations that are
     available in the active Nix expression.</para></listitem>
-    
+
   </varlistentry>
 
 </variablelist>
-            
+
 </refsection>
 
 
@@ -874,7 +874,7 @@ user environment elements, etc. -->
 
   <varlistentry><term><option>--status</option></term>
     <term><option>-s</option></term>
-  
+
     <listitem><para>Print the <emphasis>status</emphasis> of the
     derivation.  The status consists of three characters.  The first
     is <literal>I</literal> or <literal>-</literal>, indicating
@@ -888,7 +888,7 @@ user environment elements, etc. -->
     third is <literal>S</literal> or <literal>-</literal>, indicating
     whether a substitute is available for the
     derivation.</para></listitem>
-    
+
   </varlistentry>
 
   <varlistentry><term><option>--attr-path</option></term>
@@ -901,17 +901,17 @@ user environment elements, etc. -->
     <literal>nix-env --install</literal>.</para></listitem>
 
   </varlistentry>
-  
+
   <varlistentry><term><option>--no-name</option></term>
-  
+
     <listitem><para>Suppress printing of the <literal>name</literal>
     attribute of each derivation.</para></listitem>
-    
+
   </varlistentry>
 
   <varlistentry><term><option>--compare-versions</option> /
   <option>-c</option></term>
-  
+
     <listitem><para>Compare installed versions to available versions,
     or vice versa (if <option>--available</option> is given).  This is
     useful for quickly seeing whether upgrades for installed
@@ -926,21 +926,21 @@ user environment elements, etc. -->
         or installed.</para></listitem>
 
       </varlistentry>
-      
+
       <varlistentry><term><literal>=</literal> <replaceable>version</replaceable></term>
 
         <listitem><para>At most the same version of the package is
         available or installed.</para></listitem>
 
       </varlistentry>
-      
+
       <varlistentry><term><literal>></literal> <replaceable>version</replaceable></term>
 
         <listitem><para>Only older versions of the package are
         available or installed.</para></listitem>
 
       </varlistentry>
-      
+
       <varlistentry><term><literal>- ?</literal></term>
 
         <listitem><para>No version of the package is available or
@@ -951,45 +951,45 @@ user environment elements, etc. -->
     </variablelist>
 
     </para></listitem>
-    
+
   </varlistentry>
 
   <varlistentry><term><option>--system</option></term>
-  
+
     <listitem><para>Print the <literal>system</literal> attribute of
     the derivation.</para></listitem>
-    
+
   </varlistentry>
 
   <varlistentry><term><option>--drv-path</option></term>
-  
+
     <listitem><para>Print the path of the store
     derivation.</para></listitem>
-    
+
   </varlistentry>
 
   <varlistentry><term><option>--out-path</option></term>
-  
+
     <listitem><para>Print the output path of the
     derivation.</para></listitem>
-    
+
   </varlistentry>
 
   <varlistentry><term><option>--description</option></term>
-  
+
     <listitem><para>Print a short (one-line) description of the
     derivation, if available.  The description is taken from the
     <literal>meta.description</literal> attribute of the
     derivation.</para></listitem>
-    
+
   </varlistentry>
 
   <varlistentry><term><option>--meta</option></term>
-  
+
     <listitem><para>Print all of the meta-attributes of the
     derivation.  This option is only available with
     <option>--xml</option>.</para></listitem>
-    
+
   </varlistentry>
 
 </variablelist>
@@ -1023,7 +1023,7 @@ IP- ORBit2-2.8.3    <lineannotation>(installed and by definition present)</linea
 ...
 
 <lineannotation>(show available derivations in the Nix expression <!-- !!! <filename>-->foo.nix<!-- </filename> -->)</lineannotation>
-$ nix-env -f ./foo.nix -qa '*' 
+$ nix-env -f ./foo.nix -qa '*'
 foo-1.2.3
 
 $ nix-env -qc '*' <lineannotation>(compare installed versions to what’s available)</lineannotation>
@@ -1034,7 +1034,7 @@ firefox-1.0.4      &lt; 1.0.7  <lineannotation>(a more recent version is availab
 <replaceable>...</replaceable>
 
 <lineannotation>(show info about a specific package, in XML)</lineannotation>
-$ nix-env -qa --xml --description firefox 
+$ nix-env -qa --xml --description firefox
 <![CDATA[<?xml version='1.0' encoding='utf-8'?>
 <items>
   <item attrPath="0.0.firefoxWrapper"
@@ -1045,8 +1045,8 @@ $ nix-env -qa --xml --description firefox
 </refsection>
 
 </refsection>
-  
-    
+
+
 
 <!--######################################################################-->
 
@@ -1067,25 +1067,25 @@ $ nix-env -qa --xml --description firefox
 
 
 <refsection><title>Description</title>
-            
+
 <para>This operation makes <replaceable>path</replaceable> the current
 profile for the user.  That is, the symlink
 <filename>~/.nix-profile</filename> is made to point to
 <replaceable>path</replaceable>.</para>
 
 </refsection>
-            
+
 <refsection><title>Examples</title>
 
 <screen>
 $ nix-env -S ~/my-profile</screen>
 
 </refsection>
-    
+
 </refsection>
 
 
-  
+
 <!--######################################################################-->
 
 <refsection><title>Operation <option>--list-generations</option></title>
@@ -1101,7 +1101,7 @@ $ nix-env -S ~/my-profile</screen>
 
 
 <refsection><title>Description</title>
-            
+
 <para>This operation print a list of all the currently existing
 generations for the active profile.  These may be switched to using
 the <option>--switch-generation</option> operation.  It also prints
@@ -1121,11 +1121,11 @@ $ nix-env --list-generations
   98   2004-02-06 16:24:33   (current)</screen>
 
 </refsection>
-    
+
 </refsection>
 
 
-  
+
 <!--######################################################################-->
 
 <refsection><title>Operation <option>--delete-generations</option></title>
@@ -1142,7 +1142,7 @@ $ nix-env --list-generations
 
 
 <refsection><title>Description</title>
-            
+
 <para>This operation deletes the specified generations of the current
 profile.  The generations can be a list of generation numbers, or the
 special value <literal>old</literal> to delete all non-current
@@ -1150,7 +1150,7 @@ generations.  Periodically deleting old generations is important to
 make garbage collection effective.</para>
 
 </refsection>
-            
+
 <refsection><title>Examples</title>
 
 <screen>
@@ -1159,11 +1159,11 @@ $ nix-env --delete-generations 3 4 8
 $ nix-env -p other_profile --delete-generations old</screen>
 
 </refsection>
-    
+
 </refsection>
 
 
-  
+
 <!--######################################################################-->
 
 <refsection><title>Operation <option>--switch-generation</option></title>
@@ -1183,7 +1183,7 @@ $ nix-env -p other_profile --delete-generations old</screen>
 
 
 <refsection><title>Description</title>
-            
+
 <para>This operation makes generation number
 <replaceable>generation</replaceable> the current generation of the
 active profile.  That is, if the
@@ -1207,11 +1207,11 @@ $ nix-env -G 42
 switching from generation 50 to 42</screen>
 
 </refsection>
-    
+
 </refsection>
 
 
-  
+
 <!--######################################################################-->
 
 <refsection><title>Operation <option>--rollback</option></title>
@@ -1226,7 +1226,7 @@ switching from generation 50 to 42</screen>
 </refsection>
 
 <refsection><title>Description</title>
-            
+
 <para>This operation switches to the “previous” generation of the
 active profile, that is, the highest numbered generation lower than
 the current generation, if it exists.  It is just a convenience
@@ -1246,9 +1246,9 @@ $ nix-env --rolback
 error: no generation older than the current (91) exists</screen>
 
 </refsection>
-    
+
 </refsection>
 
 
-  
+
 </refentry>
diff --git a/perl/Makefile.am b/perl/Makefile.am
index eded469f924b..ccb08b447b1f 100644
--- a/perl/Makefile.am
+++ b/perl/Makefile.am
@@ -2,10 +2,12 @@ perlversion := $(shell perl -e 'use Config; print $$Config{version};')
 perlarchname := $(shell perl -e 'use Config; print $$Config{archname};')
 perllibdir = $(libdir)/perl5/site_perl/$(perlversion)/$(perlarchname)
 
-PERL_MODULES = lib/Nix/Store.pm lib/Nix/Manifest.pm lib/Nix/GeneratePatches.pm lib/Nix/SSH.pm lib/Nix/Config.pm.in
+PERL_MODULES = lib/Nix/Store.pm lib/Nix/Manifest.pm lib/Nix/GeneratePatches.pm lib/Nix/SSH.pm lib/Nix/CopyClosure.pm lib/Nix/Config.pm.in
 
+# Hack required by "make check".
 all: $(PERL_MODULES:.in=)
-	ln -sfn $(abs_builddir)/.libs/libNixStore.so lib/Store.so
+	mkdir -p lib/auto/Nix/Store
+	ln -sfn $(abs_builddir)/.libs/libNixStore.so lib/auto/Nix/Store/Store.so
 
 install-exec-local: $(PERL_MODULES:.in=)
 	$(INSTALL) -d $(DESTDIR)$(perllibdir)/Nix
diff --git a/perl/lib/Nix/Config.pm.in b/perl/lib/Nix/Config.pm.in
index 658305fd9783..b657683be3f8 100644
--- a/perl/lib/Nix/Config.pm.in
+++ b/perl/lib/Nix/Config.pm.in
@@ -4,6 +4,7 @@ $binDir = $ENV{"NIX_BIN_DIR"} || "@bindir@";
 $libexecDir = $ENV{"NIX_LIBEXEC_DIR"} || "@libexecdir@";
 $manifestDir = $ENV{"NIX_MANIFESTS_DIR"} || "@localstatedir@/nix/manifests";
 $logDir = $ENV{"NIX_LOG_DIR"} || "@localstatedir@/log/nix";
+$confDir = $ENV{"NIX_CONF_DIR"} || "@sysconfdir@/nix";
 
 $bzip2 = $ENV{"NIX_BZIP2"} || "@bzip2@";
 $curl = "@curl@";
diff --git a/perl/lib/Nix/CopyClosure.pm b/perl/lib/Nix/CopyClosure.pm
new file mode 100644
index 000000000000..045f6bfaf156
--- /dev/null
+++ b/perl/lib/Nix/CopyClosure.pm
@@ -0,0 +1,46 @@
+package Nix::CopyClosure;
+
+use strict;
+use Nix::Config;
+use Nix::Store;
+
+
+sub copyTo {
+    my ($sshHost, $sshOpts, $storePaths, $compressor, $decompressor, $includeOutputs, $dryRun, $sign) = @_;
+
+    $compressor = "$compressor |" if $compressor ne "";
+    $decompressor = "$decompressor |" if $decompressor ne "";
+    
+    # Get the closure of this path.
+    my @closure = reverse(topoSortPaths(computeFSClosure(0, $includeOutputs,
+        map { followLinksToStorePath $_ } @{$storePaths})));
+
+    # Ask the remote host which paths are invalid.  Because of limits
+    # to the command line length, do this in chunks.  Eventually,
+    # we'll want to use ‘--from-stdin’, but we can't rely on the
+    # target having this option yet.
+    my @missing = ();
+    while (scalar(@closure) > 0) {
+        my @ps = splice(@closure, 0, 1500);
+        open(READ, "set -f; ssh $sshHost @{$sshOpts} nix-store --check-validity --print-invalid @ps|");
+        while (<READ>) {
+            chomp;
+            push @missing, $_;
+        }
+        close READ or die;
+    }
+
+    # Export the store paths and import them on the remote machine.
+    if (scalar @missing > 0) {
+        print STDERR "copying ", scalar @missing, " missing paths to ‘$sshHost’...\n";
+        #print STDERR "  $_\n" foreach @missing;
+        unless ($dryRun) {
+            open SSH, "| $compressor ssh $sshHost @{$sshOpts} '$decompressor nix-store --import'" or die;
+            exportPaths(fileno(SSH), $sign, @missing);
+            close SSH or die "copying store paths to remote machine `$sshHost' failed: $?";
+        }
+    }
+}
+
+
+1;
diff --git a/perl/lib/Nix/Manifest.pm b/perl/lib/Nix/Manifest.pm
index 7790cfe3b98c..d1717a0a8ebd 100644
--- a/perl/lib/Nix/Manifest.pm
+++ b/perl/lib/Nix/Manifest.pm
@@ -53,8 +53,14 @@ sub addPatch {
 sub readManifest_ {
     my ($manifest, $addNAR, $addPatch) = @_;
 
-    open MANIFEST, "<$manifest"
-        or die "cannot open `$manifest': $!";
+    # Decompress the manifest if necessary.
+    if ($manifest =~ /\.bz2$/) {
+        open MANIFEST, "$Nix::Config::bzip2 -d < $manifest |"
+            or die "cannot decompress `$manifest': $!";
+    } else {
+        open MANIFEST, "<$manifest"
+            or die "cannot open `$manifest': $!";
+    }
 
     my $inside = 0;
     my $type;
@@ -120,7 +126,6 @@ sub readManifest_ {
             elsif (/^\s*Hash:\s*(\S+)\s*$/) { $hash = $1; }
             elsif (/^\s*URL:\s*(\S+)\s*$/) { $url = $1; }
             elsif (/^\s*Size:\s*(\d+)\s*$/) { $size = $1; }
-            elsif (/^\s*SuccOf:\s*(\/\S+)\s*$/) { } # obsolete
             elsif (/^\s*BasePath:\s*(\/\S+)\s*$/) { $basePath = $1; }
             elsif (/^\s*BaseHash:\s*(\S+)\s*$/) { $baseHash = $1; }
             elsif (/^\s*Type:\s*(\S+)\s*$/) { $patchType = $1; }
@@ -286,14 +291,22 @@ EOF
     open MAINLOCK, ">>$lockFile" or die "unable to acquire lock ‘$lockFile’: $!\n";
     flock(MAINLOCK, LOCK_EX) or die;
 
+    our $insertNAR = $dbh->prepare(
+        "insert into NARs(manifest, storePath, url, hash, size, narHash, " .
+        "narSize, refs, deriver, system) values (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)") or die;
+
+    our $insertPatch = $dbh->prepare(
+        "insert into Patches(manifest, storePath, basePath, baseHash, url, hash, " .
+        "size, narHash, narSize, patchType) values (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)");
+
     $dbh->begin_work;
 
     # Read each manifest in $manifestDir and add it to the database,
     # unless we've already done so on a previous run.
     my %seen;
     
-    for my $manifest (glob "$manifestDir/*.nixmanifest") {
-        $manifest = Cwd::abs_path($manifest);
+    for my $manifestLink (glob "$manifestDir/*.nixmanifest") {
+        my $manifest = Cwd::abs_path($manifestLink);
         my $timestamp = lstat($manifest)->mtime;
         $seen{$manifest} = 1;
 
@@ -312,20 +325,16 @@ EOF
 
         sub addNARToDB {
             my ($storePath, $narFile) = @_;
-            $dbh->do(
-                "insert into NARs(manifest, storePath, url, hash, size, narHash, " .
-                "narSize, refs, deriver, system) values (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)",
-                {}, $id, $storePath, $narFile->{url}, $narFile->{hash}, $narFile->{size},
+            $insertNAR->execute(
+                $id, $storePath, $narFile->{url}, $narFile->{hash}, $narFile->{size},
                 $narFile->{narHash}, $narFile->{narSize}, $narFile->{references},
                 $narFile->{deriver}, $narFile->{system});
         };
         
         sub addPatchToDB {
             my ($storePath, $patch) = @_;
-            $dbh->do(
-                "insert into Patches(manifest, storePath, basePath, baseHash, url, hash, " .
-                "size, narHash, narSize, patchType) values (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)",
-                {}, $id, $storePath, $patch->{basePath}, $patch->{baseHash}, $patch->{url},
+            $insertPatch->execute(
+                $id, $storePath, $patch->{basePath}, $patch->{baseHash}, $patch->{url},
                 $patch->{hash}, $patch->{size}, $patch->{narHash}, $patch->{narSize},
                 $patch->{patchType});
         };
@@ -333,10 +342,10 @@ EOF
         my $version = readManifest_($manifest, \&addNARToDB, \&addPatchToDB);
         
         if ($version < 3) {
-            die "you have an old-style manifest `$manifest'; please delete it";
+            die "you have an old-style or corrupt manifest `$manifestLink'; please delete it";
         }
         if ($version >= 10) {
-            die "manifest `$manifest' is too new; please delete it or upgrade Nix";
+            die "manifest `$manifestLink' is too new; please delete it or upgrade Nix";
         }
     }
 
diff --git a/perl/lib/Nix/Store.pm b/perl/lib/Nix/Store.pm
index bef6e7460ca7..4283e77a45af 100644
--- a/perl/lib/Nix/Store.pm
+++ b/perl/lib/Nix/Store.pm
@@ -1,6 +1,5 @@
 package Nix::Store;
 
-use 5.010001;
 use strict;
 use warnings;
 
@@ -12,7 +11,12 @@ our %EXPORT_TAGS = ( 'all' => [ qw( ) ] );
 
 our @EXPORT_OK = ( @{ $EXPORT_TAGS{'all'} } );
 
-our @EXPORT = qw(isValidPath topoSortPaths computeFSClosure followLinksToStorePath);
+our @EXPORT = qw(
+    isValidPath queryReferences queryPathInfo queryDeriver queryPathHash
+    topoSortPaths computeFSClosure followLinksToStorePath exportPaths
+    hashPath hashFile hashString
+    addToStore makeFixedOutputPath
+);
 
 our $VERSION = '0.15';
 
diff --git a/perl/lib/Nix/Store.xs b/perl/lib/Nix/Store.xs
index af71ad955c4f..f8a577fce8fd 100644
--- a/perl/lib/Nix/Store.xs
+++ b/perl/lib/Nix/Store.xs
@@ -18,10 +18,8 @@ using namespace nix;
 void doInit() 
 {
     if (!store) {
-        nixStore = canonPath(getEnv("NIX_STORE_DIR", getEnv("NIX_STORE", "/nix/store")));
-        nixStateDir = canonPath(getEnv("NIX_STATE_DIR", "/nix/var/nix"));
-        nixDBPath = getEnv("NIX_DB_DIR", nixStateDir + "/db");
         try {
+            setDefaultsFromEnvironment();
             store = openStore();
         } catch (Error & e) {
             croak(e.what());
@@ -69,7 +67,7 @@ SV * queryPathHash(char * path)
         try {
             doInit();
             Hash hash = store->queryPathHash(path);
-            string s = "sha256:" + printHash(hash);
+            string s = "sha256:" + printHash32(hash);
             XPUSHs(sv_2mortal(newSVpv(s.c_str(), 0)));
         } catch (Error & e) {
             croak(e.what());
@@ -148,3 +146,73 @@ SV * followLinksToStorePath(char * path)
         }
     OUTPUT:
         RETVAL
+
+
+void exportPaths(int fd, int sign, ...)
+    PPCODE:
+        try {
+            doInit();
+            Paths paths;
+            for (int n = 2; n < items; ++n) paths.push_back(SvPV_nolen(ST(n)));
+            FdSink sink(fd);
+            exportPaths(*store, paths, sign, sink);
+        } catch (Error & e) {
+            croak(e.what());
+        }
+
+
+SV * hashPath(char * algo, int base32, char * path)
+    PPCODE:
+        try {
+            Hash h = hashPath(parseHashType(algo), path).first;
+            string s = base32 ? printHash32(h) : printHash(h);
+            XPUSHs(sv_2mortal(newSVpv(s.c_str(), 0)));
+        } catch (Error & e) {
+            croak(e.what());
+        }
+
+
+SV * hashFile(char * algo, int base32, char * path)
+    PPCODE:
+        try {
+            Hash h = hashFile(parseHashType(algo), path);
+            string s = base32 ? printHash32(h) : printHash(h);
+            XPUSHs(sv_2mortal(newSVpv(s.c_str(), 0)));
+        } catch (Error & e) {
+            croak(e.what());
+        }
+
+
+SV * hashString(char * algo, int base32, char * s)
+    PPCODE:
+        try {
+            Hash h = hashString(parseHashType(algo), s);
+            string s = base32 ? printHash32(h) : printHash(h);
+            XPUSHs(sv_2mortal(newSVpv(s.c_str(), 0)));
+        } catch (Error & e) {
+            croak(e.what());
+        }
+
+
+SV * addToStore(char * srcPath, int recursive, char * algo)
+    PPCODE:
+        try {
+            doInit();
+            Path path = store->addToStore(srcPath, recursive, parseHashType(algo));
+            XPUSHs(sv_2mortal(newSVpv(path.c_str(), 0)));
+        } catch (Error & e) {
+            croak(e.what());
+        }
+
+
+SV * makeFixedOutputPath(int recursive, char * algo, char * hash, char * name)
+    PPCODE:
+        try {
+            doInit();
+            HashType ht = parseHashType(algo);
+            Path path = makeFixedOutputPath(recursive, ht,
+                parseHash16or32(ht, hash), name);
+            XPUSHs(sv_2mortal(newSVpv(path.c_str(), 0)));
+        } catch (Error & e) {
+            croak(e.what());
+        }
diff --git a/scripts/build-remote.pl.in b/scripts/build-remote.pl.in
index e8c76086dae2..c805d6740ef3 100755
--- a/scripts/build-remote.pl.in
+++ b/scripts/build-remote.pl.in
@@ -3,7 +3,9 @@
 use Fcntl ':flock';
 use English '-no_match_vars';
 use IO::Handle;
+use Nix::Config;
 use Nix::SSH qw/sshOpts openSSHConnection/;
+use Nix::CopyClosure;
 no warnings('once');
 
 
@@ -208,7 +210,7 @@ print STDERR "@ build-remote $drvPath $hostName\n" if $printBuildTrace;
 
 
 my $maybeSign = "";
-$maybeSign = "--sign" if -e "/nix/etc/nix/signing-key.sec";
+$maybeSign = "--sign" if -e "$Nix::Config::confDir/signing-key.sec";
 
 
 # Register the derivation as a temporary GC root.  Note that $PPID is
@@ -224,8 +226,7 @@ sub removeRoots {
 
 
 # Copy the derivation and its dependencies to the build machine.
-system("NIX_SSHOPTS=\"@sshOpts\" @bindir@/nix-copy-closure $hostName $maybeSign $drvPath @inputs") == 0
-    or die "cannot copy inputs to $hostName: $?";
+Nix::CopyClosure::copyTo($hostName, [ @sshOpts ], [ $drvPath, @inputs ], "", "", 0, 0, $maybeSign ne "");
 
 
 # Perform the build.
@@ -239,7 +240,7 @@ my $buildFlags = "--max-silent-time $maxSilentTime --fallback --add-root $rootsD
 # in which case every child receives SIGHUP; however, `-tt' doesn't
 # work on some platforms when connection sharing is used.)
 pipe STDIN, DUMMY; # make sure we have a readable STDIN
-if (system("ssh $hostName @sshOpts '(read; kill -INT -\$\$) <&0 & nix-store -r $drvPath $buildFlags > /dev/null' 2>&4") != 0) {
+if (system("exec ssh $hostName @sshOpts '(read; kill -INT -\$\$) <&0 & nix-store -r $drvPath $buildFlags > /dev/null' 2>&4") != 0) {
     # Note that if we get exit code 100 from `nix-store -r', it
     # denotes a permanent build failure (as opposed to an SSH problem
     # or a temporary Nix problem).  We propagate this to the caller to
@@ -259,7 +260,7 @@ foreach my $output (@outputs) {
     my $maybeSignRemote = "";
     $maybeSignRemote = "--sign" if $UID != 0;
     
-    system("ssh $hostName @sshOpts 'nix-store --export $maybeSignRemote $output'" .
+    system("exec ssh $hostName @sshOpts 'nix-store --export $maybeSignRemote $output'" .
            "| NIX_HELD_LOCKS=$output @bindir@/nix-store --import > /dev/null") == 0
 	or die "cannot copy $output from $hostName: $?";
 }
diff --git a/scripts/download-using-manifests.pl.in b/scripts/download-using-manifests.pl.in
index a827a995f919..ef663dabb1ef 100755
--- a/scripts/download-using-manifests.pl.in
+++ b/scripts/download-using-manifests.pl.in
@@ -3,6 +3,7 @@
 use strict;
 use Nix::Config;
 use Nix::Manifest;
+use Nix::Store;
 use POSIX qw(strftime);
 use File::Temp qw(tempdir);
 
@@ -19,14 +20,8 @@ my $fast = 1;
 my $dbh = updateManifestDB();
 
 
-sub isValidPath {
-    my $p = shift;
-    if ($fast) {
-        return -e $p;
-    } else {
-        return system("$Nix::Config::binDir/nix-store --check-validity '$p' 2> /dev/null") == 0;
-    }
-}
+# $hashCache->{$algo}->{$path} yields the $algo-hash of $path.
+my $hashCache;
 
 
 sub parseHash {
@@ -101,15 +96,17 @@ sub computeSmallestDownload {
             
             foreach my $patch (@{$patchList}) {
                 if (isValidPath($patch->{basePath})) {
-                    # !!! this should be cached
                     my ($baseHashAlgo, $baseHash) = parseHash $patch->{baseHash};
-                    my $format = "--base32";
-                    $format = "" if $baseHashAlgo eq "md5";
-                    my $hash = $fast && $baseHashAlgo eq "sha256"
-                        ? `$Nix::Config::binDir/nix-store -q --hash "$patch->{basePath}"`
-                        : `$Nix::Config::binDir/nix-hash --type '$baseHashAlgo' $format "$patch->{basePath}"`;
-                    chomp $hash;
-                    $hash =~ s/.*://;
+
+                    my $hash = $hashCache->{$baseHashAlgo}->{$patch->{basePath}};
+                    if (!defined $hash) {
+                        $hash = $fast && $baseHashAlgo eq "sha256"
+                            ? queryPathHash($patch->{basePath})
+                            : hashPath($baseHashAlgo, $baseHashAlgo ne "md5", $patch->{basePath});
+                        $hash =~ s/.*://;
+                        $hashCache->{$baseHashAlgo}->{$patch->{basePath}} = $hash;
+                    }
+                    
                     next if $hash ne $baseHash;
                 }
                 push @queue, $patch->{basePath};
@@ -257,7 +254,7 @@ open LOGFILE, ">>$logFile" or die "cannot open log file $logFile";
 my $date = strftime ("%F %H:%M:%S UTC", gmtime (time));
 print LOGFILE "$$ get $targetPath $date\n";
 
-print "\n*** Trying to download/patch `$targetPath'\n";
+print STDERR "\n*** Trying to download/patch `$targetPath'\n";
 
 
 # Compute the shortest path.
@@ -281,7 +278,7 @@ sub downloadFile {
     $ENV{"PRINT_PATH"} = 1;
     $ENV{"QUIET"} = 1;
     my ($hash, $path) = `$Nix::Config::binDir/nix-prefetch-url '$url'`;
-    die "download of `$url' failed" . ($! ? ": $!" : "") unless $? == 0;
+    die "download of `$url' failed" . ($! ? ": $!" : "") . "\n" unless $? == 0;
     chomp $path;
     return $path;
 }
@@ -293,17 +290,17 @@ while (scalar @path > 0) {
     my $u = $edge->{start};
     my $v = $edge->{end};
 
-    print "\n*** Step $curStep/$maxStep: ";
+    print STDERR "\n*** Step $curStep/$maxStep: ";
 
     if ($edge->{type} eq "present") {
-        print "using already present path `$v'\n";
+        print STDERR "using already present path `$v'\n";
         print LOGFILE "$$ present $v\n";
 
         if ($curStep < $maxStep) {
             # Since this is not the last step, the path will be used
             # as a base to one or more patches.  So turn the base path
             # into a NAR archive, to which we can apply the patch.
-            print "  packing base path...\n";
+            print STDERR "  packing base path...\n";
             system("$Nix::Config::binDir/nix-store --dump $v > $tmpNar") == 0
                 or die "cannot dump `$v'";
         }
@@ -311,17 +308,17 @@ while (scalar @path > 0) {
 
     elsif ($edge->{type} eq "patch") {
         my $patch = $edge->{info};
-        print "applying patch `$patch->{url}' to `$u' to create `$v'\n";
+        print STDERR "applying patch `$patch->{url}' to `$u' to create `$v'\n";
 
         print LOGFILE "$$ patch $patch->{url} $patch->{size} $patch->{baseHash} $u $v\n";
 
         # Download the patch.
-        print "  downloading patch...\n";
+        print STDERR "  downloading patch...\n";
         my $patchPath = downloadFile "$patch->{url}";
 
         # Apply the patch to the NAR archive produced in step 1 (for
         # the already present path) or a later step (for patch sequences).
-        print "  applying patch...\n";
+        print STDERR "  applying patch...\n";
         system("$Nix::Config::libexecDir/bspatch $tmpNar $tmpNar2 $patchPath") == 0
             or die "cannot apply patch `$patchPath' to $tmpNar";
 
@@ -331,7 +328,7 @@ while (scalar @path > 0) {
         } else {
             # This was the last patch.  Unpack the final NAR archive
             # into the target path.
-            print "  unpacking patched archive...\n";
+            print STDERR "  unpacking patched archive...\n";
             system("$Nix::Config::binDir/nix-store --restore $v < $tmpNar2") == 0
                 or die "cannot unpack $tmpNar2 into `$v'";
         }
@@ -341,13 +338,13 @@ while (scalar @path > 0) {
 
     elsif ($edge->{type} eq "narfile") {
         my $narFile = $edge->{info};
-        print "downloading `$narFile->{url}' into `$v'\n";
+        print STDERR "downloading `$narFile->{url}' into `$v'\n";
 
         my $size = $narFile->{size} || -1;
         print LOGFILE "$$ narfile $narFile->{url} $size $v\n";
         
         # Download the archive.
-        print "  downloading archive...\n";
+        print STDERR "  downloading archive...\n";
         my $narFilePath = downloadFile "$narFile->{url}";
 
         if ($curStep < $maxStep) {
@@ -356,7 +353,7 @@ while (scalar @path > 0) {
                 or die "cannot unpack `$narFilePath' into `$v'";
         } else {
             # Unpack the archive into the target path.
-            print "  unpacking archive...\n";
+            print STDERR "  unpacking archive...\n";
             system("$Nix::Config::bzip2 -d < '$narFilePath' | $Nix::Config::binDir/nix-store --restore '$v'") == 0
                 or die "cannot unpack `$narFilePath' into `$v'";
         }
@@ -376,20 +373,15 @@ if (defined $finalNarHash) {
 
     # The hash in the manifest can be either in base-16 or base-32.
     # Handle both.
-    my $extraFlag =
-        ($hashAlgo eq "sha256" && length($hash) != 64)
-        ? "--base32" : "";
-    
-    my $hash2 = `$Nix::Config::binDir/nix-hash --type $hashAlgo $extraFlag $targetPath`
-        or die "cannot compute hash of path `$targetPath'";
-    chomp $hash2;
+    my $hash2 = hashPath($hashAlgo, $hashAlgo eq "sha256" && length($hash) != 64, $targetPath);
     
-    die "hash mismatch in downloaded path $targetPath; expected $hash, got $hash2"
+    die "hash mismatch in downloaded path $targetPath; expected $hash, got $hash2\n"
         if $hash ne $hash2;
 } else {
-    die "cannot check integrity of the downloaded path since its hash is not known";
+    die "cannot check integrity of the downloaded path since its hash is not known\n";
 }
 
 
+print STDERR "\n";
 print LOGFILE "$$ success\n";
 close LOGFILE;
diff --git a/scripts/nix-copy-closure.in b/scripts/nix-copy-closure.in
index 172acd9e7da2..8bb60e920ef2 100755
--- a/scripts/nix-copy-closure.in
+++ b/scripts/nix-copy-closure.in
@@ -3,11 +3,12 @@
 use Nix::SSH;
 use Nix::Config;
 use Nix::Store;
+use Nix::CopyClosure;
 
 
 if (scalar @ARGV < 1) {
     print STDERR <<EOF
-Usage: nix-copy-closure [--from | --to] HOSTNAME [--sign] [--gzip] PATHS...
+Usage: nix-copy-closure [--from | --to] HOSTNAME [--sign] [--gzip] [--bzip2] [--xz] PATHS...
 EOF
     ;
     exit 1;
@@ -39,8 +40,16 @@ while (@ARGV) {
         $sign = 1;
     }
     elsif ($arg eq "--gzip") {
-        $compressor = "| gzip";
-        $decompressor = "gunzip |";
+        $compressor = "gzip";
+        $decompressor = "gunzip";
+    }
+    elsif ($arg eq "--bzip2") {
+        $compressor = "bzip2";
+        $decompressor = "bunzip2";
+    }
+    elsif ($arg eq "--xz") {
+        $compressor = "xz";
+        $decompressor = "xz -d";
     }
     elsif ($arg eq "--from") {
         $toMode = 0;
@@ -67,30 +76,7 @@ openSSHConnection $sshHost or die "$0: unable to start SSH\n";
 
 
 if ($toMode) { # Copy TO the remote machine.
-
-    # Get the closure of this path.
-    my @allStorePaths = reverse(topoSortPaths(computeFSClosure(0, $includeOutputs, map { followLinksToStorePath $_ } @storePaths)));
-
-    # Ask the remote host which paths are invalid.
-    open(READ, "set -f; ssh $sshHost @sshOpts nix-store --check-validity --print-invalid @allStorePaths|");
-    my @missing = ();
-    while (<READ>) {
-        chomp;
-        push @missing, $_;
-    }
-    close READ or die;
-
-    # Export the store paths and import them on the remote machine.
-    if (scalar @missing > 0) {
-        print STDERR "copying these missing paths:\n";
-        print STDERR "  $_\n" foreach @missing;
-        unless ($dryRun) {
-            my $extraOpts = $sign ? "--sign" : "";
-            system("set -f; nix-store --export $extraOpts @missing $compressor | ssh $sshHost @sshOpts '$decompressor nix-store --import'") == 0
-                or die "copying store paths to remote machine `$sshHost' failed: $?";
-        }
-    }
-
+    Nix::CopyClosure::copyTo($sshHost, [ @sshOpts ], [ @storePaths ], $compressor, $decompressor, $includeOutputs, $dryRun, $sign);
 }
 
 else { # Copy FROM the remote machine.
@@ -110,10 +96,12 @@ else { # Copy FROM the remote machine.
 
     close READ or die "nix-store on remote machine `$sshHost' failed: $?";
 
-    # Export the store paths on the remote machine and import them on locally.
+    # Export the store paths on the remote machine and import them locally.
     if (scalar @missing > 0) {
-        print STDERR "copying these missing paths:\n";
-        print STDERR "  $_\n" foreach @missing;
+        print STDERR "copying ", scalar @missing, " missing paths from ‘$sshHost’...\n";
+        #print STDERR "  $_\n" foreach @missing;
+        $compressor = "| $compressor" if $compressor ne "";
+        $decompressor = "$decompressor |" if $decompressor ne "";
         unless ($dryRun) {
             my $extraOpts = $sign ? "--sign" : "";
             system("set -f; ssh $sshHost @sshOpts 'nix-store --export $extraOpts @missing $compressor' | $decompressor $Nix::Config::binDir/nix-store --import") == 0
diff --git a/scripts/nix-prefetch-url.in b/scripts/nix-prefetch-url.in
index 45bad75f3e9f..eea2b814b733 100755
--- a/scripts/nix-prefetch-url.in
+++ b/scripts/nix-prefetch-url.in
@@ -1,165 +1,128 @@
-#! @shell@ -e
-
-url=$1
-expHash=$2
-
-binDir=@bindir@
-if [ -n "$NIX_BIN_DIR" ]; then binDir="$NIX_BIN_DIR"; fi
+#! @perl@ -w @perlFlags@
+
+use strict;
+use File::Basename;
+use File::Temp qw(tempdir);
+use File::stat;
+use Nix::Store;
+use Nix::Config;
+
+my $url = shift;
+my $expHash = shift;
+my $hashType = $ENV{'NIX_HASH_ALGO'} || "sha256";
+my $cacheDir = $ENV{'NIX_DOWNLOAD_CACHE'};
+
+if (!defined $url || $url eq "") {
+    print STDERR <<EOF
+Usage: nix-prefetch-url URL [EXPECTED-HASH]
+EOF
+    ;
+    exit 1;
+}
 
-# needed to make it work on NixOS
-export PATH=$PATH:@coreutils@
+sub writeFile {
+    my ($fn, $s) = @_;
+    open TMP, ">$fn" or die;
+    print TMP "$s" or die;
+    close TMP or die;
+}
 
-hashType=$NIX_HASH_ALGO
-if test -z "$hashType"; then
-    hashType=sha256
-fi
+sub readFile {
+    local $/ = undef;
+    my ($fn) = @_;
+    open TMP, "<$fn" or die;
+    my $s = <TMP>;
+    close TMP or die;
+    return $s;
+}
 
-hashFormat=
-if test "$hashType" != "md5"; then
-    hashFormat=--base32
-fi
+my $tmpDir = tempdir("nix-prefetch-url.XXXXXX", CLEANUP => 1, TMPDIR => 1)
+    or die "cannot create a temporary directory";
 
-if test -z "$url"; then
-    echo "syntax: nix-prefetch-url URL [EXPECTED-HASH]" >&2
-    exit 1
-fi
+# Hack to support the mirror:// scheme from Nixpkgs.
+if ($url =~ /^mirror:\/\//) {
+    system("$Nix::Config::binDir/nix-build '<nixpkgs>' -A resolveMirrorURLs --argstr url '$url' -o $tmpDir/urls > /dev/null") == 0
+        or die "$0: nix-build failed; maybe \$NIX_PATH is not set properly\n";
+    my @expanded = split ' ', readFile("$tmpDir/urls");
+    die "$0: cannot resolve ‘$url’" unless scalar @expanded > 0;
+    print STDERR "$url expands to $expanded[0]\n";
+    $url = $expanded[0];
+}
 
 # Handle escaped characters in the URI.  `+', `=' and `?' are the only
 # characters that are valid in Nix store path names but have a special
 # meaning in URIs.
-name=$(basename "$url" | @sed@ -e 's/%2b/+/g' -e 's/%3d/=/g' -e 's/%3f/\?/g')
-if test -z "$name"; then echo "invalid url"; exit 1; fi
+my $name = basename $url;
+die "cannot figure out file name for ‘$url’\n" if $name eq ""; 
+$name =~ s/%2b/+/g;
+$name =~ s/%3d/=/g;
+$name =~ s/%3f/?/g;
 
+my $finalPath;
+my $hash;
 
 # If the hash was given, a file with that hash may already be in the
 # store.
-if test -n "$expHash"; then
-    finalPath=$($binDir/nix-store --print-fixed-path "$hashType" "$expHash" "$name")
-    if ! $bindir/nix-store --check-validity "$finalPath" 2> /dev/null; then
-        finalPath=
-    fi
-    hash=$expHash
-fi
-
-
-mkTempDir() {
-    if test -n "$tmpPath"; then return; fi
-    local i=0
-    while true; do
-        if test -z "$TMPDIR"; then TMPDIR=/tmp; fi
-        tmpPath=$TMPDIR/nix-prefetch-url-$$-$i
-        if mkdir "$tmpPath"; then break; fi
-        # !!! to bad we can't check for ENOENT in mkdir, so this check
-        # is slightly racy (it bombs out if somebody just removed
-        # $tmpPath...).
-        if ! test -e "$tmpPath"; then exit 1; fi
-        i=$((i + 1))
-    done
-    trap removeTempDir EXIT SIGINT SIGQUIT
+if (defined $expHash) {
+    $finalPath = makeFixedOutputPath(0, $hashType, $expHash, $name);
+    if (isValidPath($finalPath)) { $hash = $expHash; } else { $finalPath = undef; }
 }
 
-removeTempDir() {
-    if test -n "$tmpPath"; then
-        rm -rf "$tmpPath" || true
-    fi
-}
-
-
-doDownload() {
-    @curl@ $cacheFlags --fail --location --max-redirs 20 --disable-epsv \
-        --cookie-jar $tmpPath/cookies "$url" -o $tmpFile
-}
-
-
-# Hack to support the mirror:// scheme from Nixpkgs.
-if test "${url:0:9}" = "mirror://"; then
-    if test -z "$NIXPKGS_ALL"; then
-        echo "Resolving mirror:// URLs requires Nixpkgs.  Please point \$NIXPKGS_ALL at a Nixpkgs tree." >&2
-        exit 1
-    fi
-
-    mkTempDir
-    nix-build "$NIXPKGS_ALL" -A resolveMirrorURLs --argstr url "$url" -o $tmpPath/urls > /dev/null
-
-    expanded=($(cat $tmpPath/urls))
-    if test "${#expanded[*]}" = 0; then
-        echo "$0: cannot resolve $url." >&2
-        exit 1
-    fi
-
-    echo "$url expands to ${expanded[*]} (using ${expanded[0]})" >&2
-    url="${expanded[0]}"
-fi
-
-
 # If we don't know the hash or a file with that hash doesn't exist,
 # download the file and add it to the store.
-if test -z "$finalPath"; then
-
-    mkTempDir
-    tmpFile=$tmpPath/$name
+if (!defined $finalPath) {
 
+    my $tmpFile = "$tmpDir/$name";
+    
     # Optionally do timestamp-based caching of the download.
     # Actually, the only thing that we cache in $NIX_DOWNLOAD_CACHE is
     # the hash and the timestamp of the file at $url.  The caching of
     # the file *contents* is done in Nix store, where it can be
     # garbage-collected independently.
-    if test -n "$NIX_DOWNLOAD_CACHE"; then
-        echo -n "$url" > $tmpPath/url
-        urlHash=$($binDir/nix-hash --type sha256 --base32 --flat $tmpPath/url)
-        echo "$url" > "$NIX_DOWNLOAD_CACHE/$urlHash.url"
-        cachedHashFN="$NIX_DOWNLOAD_CACHE/$urlHash.$hashType"
-        cachedTimestampFN="$NIX_DOWNLOAD_CACHE/$urlHash.stamp"
-        cacheFlags="--remote-time"
-        if test -e "$cachedTimestampFN" -a -e "$cachedHashFN"; then
-            # Only download the file if it is newer than the cached version.
-            cacheFlags="$cacheFlags --time-cond $cachedTimestampFN"
-        fi
-    fi
-
+    my ($cachedTimestampFN, $cachedHashFN, @cacheFlags);
+    if (defined $cacheDir) {
+        my $urlHash = hashString("sha256", 1, $url);
+        writeFile "$cacheDir/$urlHash.url", $url;
+        $cachedHashFN = "$cacheDir/$urlHash.$hashType";
+        $cachedTimestampFN = "$cacheDir/$urlHash.stamp";
+        @cacheFlags = ("--time-cond", $cachedTimestampFN) if -f $cachedHashFN && -f $cachedTimestampFN;
+    }
+    
     # Perform the download.
-    doDownload
+    my @curlFlags = ("curl", $url, "-o", $tmpFile, "--fail", "--location", "--max-redirs", "20", "--disable-epsv", "--cookie-jar", "$tmpDir/cookies", "--remote-time", (split " ", ($ENV{NIX_CURL_FLAGS} || "")));
+    (system $Nix::Config::curl @curlFlags, @cacheFlags) == 0 or die "$0: download of ‘$url’ failed\n";
 
-    if test -n "$NIX_DOWNLOAD_CACHE" -a ! -e $tmpFile; then
+    if (defined $cacheDir && ! -e $tmpFile) {
         # Curl didn't create $tmpFile, so apparently there's no newer
         # file on the server.
-        hash=$(cat $cachedHashFN)
-        finalPath=$($binDir/nix-store --print-fixed-path "$hashType" "$hash" "$name") 
-        if ! $binDir/nix-store --check-validity "$finalPath" 2> /dev/null; then
-            echo "cached contents of \`$url' disappeared, redownloading..." >&2
-            finalPath=
-            cacheFlags="--remote-time"
-            doDownload
-        fi
-    fi
-
-    if test -z "$finalPath"; then
-
+        $hash = readFile $cachedHashFN or die;
+        $finalPath = makeFixedOutputPath(0, $hashType, $hash, $name);
+        unless (isValidPath $finalPath) {
+            print STDERR "cached contents of ‘$url’ disappeared, redownloading...\n";
+            $finalPath = undef;
+            (system $Nix::Config::curl @curlFlags) == 0 or die "$0: download of ‘$url’ failed\n";
+        }
+    }
+
+    if (!defined $finalPath) {
+        
         # Compute the hash.
-        hash=$($binDir/nix-hash --type "$hashType" $hashFormat --flat $tmpFile)
-        if ! test -n "$QUIET"; then echo "hash is $hash" >&2; fi
-
-        if test -n "$NIX_DOWNLOAD_CACHE"; then
-            echo $hash > $cachedHashFN
-            touch -r $tmpFile $cachedTimestampFN
-        fi
-
+        $hash = hashFile($hashType, $hashType ne "md5", $tmpFile);
+
+        if (defined $cacheDir) {
+            writeFile $cachedHashFN, $hash;
+            my $st = stat($tmpFile) or die;
+            open STAMP, ">$cachedTimestampFN" or die; close STAMP;
+            utime($st->atime, $st->mtime, $cachedTimestampFN) or die;
+        }
+    
         # Add the downloaded file to the Nix store.
-        finalPath=$($binDir/nix-store --add-fixed "$hashType" $tmpFile)
-
-        if test -n "$expHash" -a "$expHash" != "$hash"; then
-            echo "hash mismatch for URL \`$url'" >&2
-            exit 1
-        fi
-        
-    fi
-fi
+        $finalPath = addToStore($tmpFile, 0, $hashType);
+    }
 
+    die "$0: hash mismatch for ‘$url’\n" if defined $expHash && $expHash ne $hash;
+}
 
-if ! test -n "$QUIET"; then echo "path is $finalPath" >&2; fi
-
-echo $hash
-
-if test -n "$PRINT_PATH"; then
-    echo $finalPath
-fi
+print STDERR "path is ‘$finalPath’\n" unless $ENV{'QUIET'};
+print "$hash\n";
+print "$finalPath\n" if $ENV{'PRINT_PATH'};
diff --git a/scripts/nix-pull.in b/scripts/nix-pull.in
index f3cba0c02619..74545a35004c 100755
--- a/scripts/nix-pull.in
+++ b/scripts/nix-pull.in
@@ -33,10 +33,6 @@ if (! -l $manifestDirLink) {
 
 
 # Process the URLs specified on the command line.
-my %narFiles;
-my %patches;
-
-my $skipWrongStore = 0;
 
 sub downloadFile {
     my $url = shift;
@@ -59,16 +55,7 @@ sub processURL {
     # First see if a bzipped manifest is available.
     if (system("$Nix::Config::curl --fail --silent --head '$url'.bz2 > /dev/null") == 0) {
         print "fetching list of Nix archives at `$url.bz2'...\n";
-        my $bzipped = downloadFile "$url.bz2";
-
-        $manifest = "$tmpDir/MANIFEST";
-
-        system("$Nix::Config::bzip2 -d < $bzipped > $manifest") == 0
-            or die "cannot decompress manifest";
-
-        $manifest = (`$Nix::Config::binDir/nix-store --add $manifest`
-                     or die "cannot copy $manifest to the store");
-        chomp $manifest;
+        $manifest = downloadFile "$url.bz2";
     }
 
     # Otherwise, just get the uncompressed manifest.
@@ -77,20 +64,6 @@ sub processURL {
         $manifest = downloadFile $url;
     }
 
-    my $version = readManifest($manifest, \%narFiles, \%patches);
-    
-    die "`$url' is not a manifest or it is too old (i.e., for Nix <= 0.7)\n" if $version < 3;
-    die "manifest `$url' is too new\n" if $version >= 5;
-
-    if ($skipWrongStore) {
-        foreach my $path (keys %narFiles) {
-            if (substr($path, 0, length($storeDir) + 1) ne "$storeDir/") {
-                print STDERR "warning: manifest `$url' assumes a Nix store at a different location than $storeDir, skipping...\n";
-                exit 0;
-            }
-        }
-    }
-
     my $baseName = "unnamed";
     if ($url =~ /\/([^\/]+)\/[^\/]+$/) { # get the forelast component
         $baseName = $1;
@@ -129,12 +102,12 @@ sub processURL {
 while (@ARGV) {
     my $url = shift @ARGV;
     if ($url eq "--skip-wrong-store") {
-        $skipWrongStore = 1;
+        # No-op, no longer supported.
     } else {
         processURL $url;
     }
 }
 
 
-my $size = scalar (keys %narFiles);
-print "$size store paths in manifest\n";
+# Update the cache.
+updateManifestDB();
diff --git a/scripts/nix-push.in b/scripts/nix-push.in
index dcdad5721265..cf46d00dfb06 100755
--- a/scripts/nix-push.in
+++ b/scripts/nix-push.in
@@ -198,8 +198,8 @@ for (my $n = 0; $n < scalar @storePaths; $n++) {
     # In some exceptional cases (such as VM tests that use the Nix
     # store of the host), the database doesn't contain the hash.  So
     # compute it.
-    if ($narHash eq "sha256:0000000000000000000000000000000000000000000000000000") {
-        $narHash = `$binDir/nix-hash --type sha256 '$storePath'`;
+    if ($narHash =~ /^sha256:0*$/) {
+        $narHash = `$binDir/nix-hash --type sha256 --base32 '$storePath'`;
         die "cannot hash `$storePath'" if $? != 0;
         chomp $narHash;
         $narHash = "sha256:$narHash";
diff --git a/src/libexpr/common-opts.cc b/src/libexpr/common-opts.cc
index d029d2ec35b9..e0865d9fcc25 100644
--- a/src/libexpr/common-opts.cc
+++ b/src/libexpr/common-opts.cc
@@ -44,4 +44,15 @@ bool parseSearchPathArg(const string & arg, Strings::iterator & i,
 }
 
 
+Path lookupFileArg(EvalState & state, string s)
+{
+    if (s.size() > 2 && s.at(0) == '<' && s.at(s.size() - 1) == '>') {
+        Path p = state.findFile(s.substr(1, s.size() - 2));
+        if (p == "") throw Error(format("file `%1%' was not found in the Nix search path (add it using $NIX_PATH or -I)") % p);
+        return p;
+    } else
+        return absPath(s);
+}
+
+
 }
diff --git a/src/libexpr/common-opts.hh b/src/libexpr/common-opts.hh
index 6b7247fc3d89..c28641e9015d 100644
--- a/src/libexpr/common-opts.hh
+++ b/src/libexpr/common-opts.hh
@@ -14,6 +14,8 @@ bool parseOptionArg(const string & arg, Strings::iterator & i,
 bool parseSearchPathArg(const string & arg, Strings::iterator & i,
     const Strings::iterator & argsEnd, EvalState & state);
 
+Path lookupFileArg(EvalState & state, string s);
+
 }
 
 
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index b11562baa436..dc361c043f67 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -363,9 +363,8 @@ static void prim_derivationStrict(EvalState & state, Value * * args, Value & v)
             foreach (PathSet::iterator, j, refs) {
                 drv.inputSrcs.insert(*j);
                 if (isDerivation(*j))
-                    drv.inputDrvs[*j] = store -> queryDerivationOutputNames(*j);
+                    drv.inputDrvs[*j] = store->queryDerivationOutputNames(*j);
             }
-
             explicitlyPassed = true;
         } else if (path.at(0) == '!') {
             size_t index;
@@ -387,7 +386,7 @@ static void prim_derivationStrict(EvalState & state, Value * * args, Value & v)
         debug(format("derivation uses `%1%'") % path);
         if (!useDrvAsSrc && isDerivation(path))
             if (explicitlyPassed)
-                drv.inputDrvs[path] = store -> queryDerivationOutputNames(path);
+                drv.inputDrvs[path] = store->queryDerivationOutputNames(path);
             else if (drv.inputDrvs.find(path) == drv.inputDrvs.end())
                 drv.inputDrvs[path] = singleton<StringSet>(output);
             else
@@ -416,17 +415,7 @@ static void prim_derivationStrict(EvalState & state, Value * * args, Value & v)
         HashType ht = parseHashType(outputHashAlgo);
         if (ht == htUnknown)
             throw EvalError(format("unknown hash algorithm `%1%'") % outputHashAlgo);
-        Hash h(ht);
-        if (outputHash.size() == h.hashSize * 2)
-            /* hexadecimal representation */
-            h = parseHash(ht, outputHash);
-        else if (outputHash.size() == hashLength32(h))
-            /* base-32 representation */
-            h = parseHash32(ht, outputHash);
-        else
-            throw Error(format("hash `%1%' has wrong length for hash type `%2%'")
-                % outputHash % outputHashAlgo);
-        string s = outputHash;
+        Hash h = parseHash16or32(ht, outputHash);
         outputHash = printHash(h);
         if (outputHashRecursive) outputHashAlgo = "r:" + outputHashAlgo;
         
diff --git a/src/libmain/Makefile.am b/src/libmain/Makefile.am
index ababc3595968..404353c62922 100644
--- a/src/libmain/Makefile.am
+++ b/src/libmain/Makefile.am
@@ -7,13 +7,6 @@ libmain_la_LIBADD = ../libstore/libstore.la @BDW_GC_LIBS@
 pkginclude_HEADERS = shared.hh
 
 AM_CXXFLAGS = \
- -DNIX_STORE_DIR=\"$(storedir)\" \
- -DNIX_DATA_DIR=\"$(datadir)\" \
- -DNIX_STATE_DIR=\"$(localstatedir)/nix\" \
- -DNIX_LOG_DIR=\"$(localstatedir)/log/nix\" \
- -DNIX_CONF_DIR=\"$(sysconfdir)/nix\" \
- -DNIX_LIBEXEC_DIR=\"$(libexecdir)\" \
- -DNIX_BIN_DIR=\"$(bindir)\" \
  -DNIX_VERSION=\"$(VERSION)\" \
  -I$(srcdir)/.. -I$(srcdir)/../libutil \
  -I$(srcdir)/../libstore
diff --git a/src/libmain/shared.cc b/src/libmain/shared.cc
index 8532cdaadcab..d3b73f8fd5a3 100644
--- a/src/libmain/shared.cc
+++ b/src/libmain/shared.cc
@@ -65,7 +65,7 @@ void printMissing(StoreAPI & store, const PathSet & paths)
     }
 
     if (!willSubstitute.empty()) {
-        printMsg(lvlInfo, format("these paths will be downloaded/copied (%.2f MiB download, %.2f MiB unpacked):")
+        printMsg(lvlInfo, format("these paths will be fetched (%.2f MiB download, %.2f MiB unpacked):")
             % (downloadSize / (1024.0 * 1024.0))
             % (narSize / (1024.0 * 1024.0)));
         foreach (PathSet::iterator, i, willSubstitute)
@@ -90,23 +90,6 @@ static void setLogType(string lt)
 }
 
 
-static void closeStore()
-{
-    try {
-        throw;
-    } catch (std::exception & e) {
-        printMsg(lvlError,
-            format("FATAL: unexpected exception (closing store and aborting): %1%") % e.what());
-    }
-    try {
-        store.reset((StoreAPI *) 0);
-    } catch (...) {
-        ignoreException();
-    }
-    abort();
-}
-
-
 RemoveTempRoots::~RemoveTempRoots()
 {
     removeTempRoots();
@@ -120,30 +103,8 @@ static bool showTrace = false;
    processor. */
 static void initAndRun(int argc, char * * argv)
 {
-    /* Setup Nix paths. */
-    nixStore = canonPath(getEnv("NIX_STORE_DIR", getEnv("NIX_STORE", NIX_STORE_DIR)));
-    nixDataDir = canonPath(getEnv("NIX_DATA_DIR", NIX_DATA_DIR));
-    nixLogDir = canonPath(getEnv("NIX_LOG_DIR", NIX_LOG_DIR));
-    nixStateDir = canonPath(getEnv("NIX_STATE_DIR", NIX_STATE_DIR));
-    nixDBPath = getEnv("NIX_DB_DIR", nixStateDir + "/db");
-    nixConfDir = canonPath(getEnv("NIX_CONF_DIR", NIX_CONF_DIR));
-    nixLibexecDir = canonPath(getEnv("NIX_LIBEXEC_DIR", NIX_LIBEXEC_DIR));
-    nixBinDir = canonPath(getEnv("NIX_BIN_DIR", NIX_BIN_DIR));
-
-    string subs = getEnv("NIX_SUBSTITUTERS", "default");
-    if (subs == "default") {
-        substituters.push_back(nixLibexecDir + "/nix/substituters/copy-from-other-stores.pl");
-        substituters.push_back(nixLibexecDir + "/nix/substituters/download-using-manifests.pl");
-    } else
-        substituters = tokenizeString(subs, ":");
-
-    /* Get some settings from the configuration file. */
-    thisSystem = querySetting("system", SYSTEM);
-    maxBuildJobs = queryIntSetting("build-max-jobs", 1);
-    buildCores = queryIntSetting("build-cores", 1);
-    maxSilentTime = queryIntSetting("build-max-silent-time", 0);
-    buildTimeout = queryIntSetting("build-timeout", 0);
-
+    setDefaultsFromEnvironment();
+    
     /* Catch SIGINT. */
     struct sigaction act;
     act.sa_handler = sigintHandler;
@@ -260,12 +221,6 @@ static void initAndRun(int argc, char * * argv)
        exit. */
     RemoveTempRoots removeTempRoots __attribute__((unused));
 
-    /* Make sure that the database gets closed properly, even if
-       terminate() is called (which happens sometimes due to bugs in
-       destructor/exceptions interaction, but that needn't preclude a
-       clean shutdown of the database). */
-    std::set_terminate(closeStore);
-    
     run(remaining);
 
     /* Close the Nix database. */
diff --git a/src/libstore/Makefile.am b/src/libstore/Makefile.am
index e19256b925ea..39a61233b4a7 100644
--- a/src/libstore/Makefile.am
+++ b/src/libstore/Makefile.am
@@ -15,7 +15,16 @@ libstore_la_LIBADD = ../libutil/libutil.la ../boost/format/libformat.la ${aterm_
 EXTRA_DIST = schema.sql
 
 AM_CXXFLAGS = -Wall \
- ${sqlite_include} -I$(srcdir)/.. -I$(srcdir)/../libutil
+ ${sqlite_include} -I$(srcdir)/.. -I$(srcdir)/../libutil \
+ -DNIX_STORE_DIR=\"$(storedir)\" \
+ -DNIX_DATA_DIR=\"$(datadir)\" \
+ -DNIX_STATE_DIR=\"$(localstatedir)/nix\" \
+ -DNIX_LOG_DIR=\"$(localstatedir)/log/nix\" \
+ -DNIX_CONF_DIR=\"$(sysconfdir)/nix\" \
+ -DNIX_LIBEXEC_DIR=\"$(libexecdir)\" \
+ -DNIX_BIN_DIR=\"$(bindir)\" \
+ -I$(srcdir)/.. -I$(srcdir)/../libutil \
+ -I$(srcdir)/../libstore
 
 local-store.lo: schema.sql.hh
 
diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index d12f41d66941..a8ef9b23efaf 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -1650,6 +1650,9 @@ void DerivationGoal::startBuilder()
             (format("nixbld:!:%1%:\n")
                 % (buildUser.enabled() ? buildUser.getGID() : getgid())).str());
 
+        /* Create /etc/hosts with localhost entry. */
+        writeFile(chrootRootDir + "/etc/hosts", "127.0.0.1 localhost\n");
+
         /* Bind-mount a user-configurable set of directories from the
            host file system.  The `/dev/pts' directory must be mounted
            separately so that newly-created pseudo-terminals show
@@ -2199,9 +2202,7 @@ void SubstitutionGoal::tryNext()
     if (subs.size() == 0) {
         /* None left.  Terminate this goal and let someone else deal
            with it. */
-        printMsg(lvlError,
-            format("path `%1%' is required, but there is no substituter that can build it")
-            % storePath);
+        debug(format("path `%1%' is required, but there is no substituter that can build it") % storePath);
         amDone(ecFailed);
         return;
     }
@@ -2232,8 +2233,7 @@ void SubstitutionGoal::referencesValid()
     trace("all references realised");
 
     if (nrFailed > 0) {
-        printMsg(lvlError,
-            format("some references of path `%1%' could not be realised") % storePath);
+        debug(format("some references of path `%1%' could not be realised") % storePath);
         amDone(ecFailed);
         return;
     }
@@ -2286,9 +2286,7 @@ void SubstitutionGoal::tryToRun()
         return;
     }
 
-    printMsg(lvlInfo,
-        format("substituting path `%1%' using substituter `%2%'")
-        % storePath % sub);
+    printMsg(lvlInfo, format("fetching path `%1%'...") % storePath);
     
     logPipe.create();
 
@@ -2364,19 +2362,15 @@ void SubstitutionGoal::finished()
     try {
         
         if (!statusOk(status))
-            throw SubstError(format("builder for `%1%' %2%")
+            throw SubstError(format("fetching path `%1%' %2%")
                 % storePath % statusToString(status));
 
         if (!pathExists(storePath))
-            throw SubstError(
-                format("substitute did not produce path `%1%'")
-                % storePath);
+            throw SubstError(format("substitute did not produce path `%1%'") % storePath);
         
     } catch (SubstError & e) {
 
-        printMsg(lvlInfo,
-            format("substitution of path `%1%' using substituter `%2%' failed: %3%")
-            % storePath % sub % e.msg());
+        printMsg(lvlInfo, e.msg());
         
         if (printBuildTrace) {
             printMsg(lvlError, format("@ substituter-failed %1% %2% %3%")
diff --git a/src/libstore/globals.cc b/src/libstore/globals.cc
index 2e9dc88237d1..5c22f1406649 100644
--- a/src/libstore/globals.cc
+++ b/src/libstore/globals.cc
@@ -1,3 +1,5 @@
+#include "config.h"
+
 #include "globals.hh"
 #include "util.hh"
 
@@ -138,5 +140,33 @@ void reloadSettings()
     settings.clear();
 }
 
+
+void setDefaultsFromEnvironment()
+{
+    /* Setup Nix paths. */
+    nixStore = canonPath(getEnv("NIX_STORE_DIR", getEnv("NIX_STORE", NIX_STORE_DIR)));
+    nixDataDir = canonPath(getEnv("NIX_DATA_DIR", NIX_DATA_DIR));
+    nixLogDir = canonPath(getEnv("NIX_LOG_DIR", NIX_LOG_DIR));
+    nixStateDir = canonPath(getEnv("NIX_STATE_DIR", NIX_STATE_DIR));
+    nixDBPath = getEnv("NIX_DB_DIR", nixStateDir + "/db");
+    nixConfDir = canonPath(getEnv("NIX_CONF_DIR", NIX_CONF_DIR));
+    nixLibexecDir = canonPath(getEnv("NIX_LIBEXEC_DIR", NIX_LIBEXEC_DIR));
+    nixBinDir = canonPath(getEnv("NIX_BIN_DIR", NIX_BIN_DIR));
+
+    string subs = getEnv("NIX_SUBSTITUTERS", "default");
+    if (subs == "default") {
+        substituters.push_back(nixLibexecDir + "/nix/substituters/copy-from-other-stores.pl");
+        substituters.push_back(nixLibexecDir + "/nix/substituters/download-using-manifests.pl");
+    } else
+        substituters = tokenizeString(subs, ":");
+
+    /* Get some settings from the configuration file. */
+    thisSystem = querySetting("system", SYSTEM);
+    maxBuildJobs = queryIntSetting("build-max-jobs", 1);
+    buildCores = queryIntSetting("build-cores", 1);
+    maxSilentTime = queryIntSetting("build-max-silent-time", 0);
+    buildTimeout = queryIntSetting("build-timeout", 0);
+}
+
  
 }
diff --git a/src/libstore/globals.hh b/src/libstore/globals.hh
index 231c1f8508ac..12a9b9ca15c0 100644
--- a/src/libstore/globals.hh
+++ b/src/libstore/globals.hh
@@ -114,7 +114,9 @@ void overrideSetting(const string & name, const Strings & value);
 
 void reloadSettings();
 
-    
+void setDefaultsFromEnvironment();
+
+
 }
 
 
diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index 8ca5daa9f171..29817df9d6e8 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -327,10 +327,9 @@ void LocalStore::openDB(bool create)
     if (sqlite3_exec(db, ("pragma synchronous = " + syncMode + ";").c_str(), 0, 0, 0) != SQLITE_OK)
         throwSQLiteError(db, "setting synchronous mode");
 
-    /* Set the SQLite journal mode.  WAL mode is fastest, but doesn't
-       seem entirely stable at the moment (Oct. 2010).  Thus, use
-       truncate mode by default. */
-    string mode = queryBoolSetting("use-sqlite-wal", false) ? "wal" : "truncate";
+    /* Set the SQLite journal mode.  WAL mode is fastest, so it's the
+       default. */
+    string mode = queryBoolSetting("use-sqlite-wal", true) ? "wal" : "truncate";
     string prevMode;
     {
         SQLiteStmt stmt;
@@ -367,7 +366,7 @@ void LocalStore::openDB(bool create)
     stmtRegisterValidPath.create(db,
         "insert into ValidPaths (path, hash, registrationTime, deriver, narSize) values (?, ?, ?, ?, ?);");
     stmtUpdatePathInfo.create(db,
-        "update ValidPaths set narSize = ? where path = ?;");
+        "update ValidPaths set narSize = ?, hash = ? where path = ?;");
     stmtAddReference.create(db,
         "insert or replace into Refs (referrer, reference) values (?, ?);");
     stmtQueryPathInfo.create(db,
@@ -684,7 +683,7 @@ ValidPathInfo LocalStore::queryPathInfo(const Path & path)
 }
 
 
-/* Update path info in the database.  Currently only updated the
+/* Update path info in the database.  Currently only updates the
    narSize field. */
 void LocalStore::updatePathInfo(const ValidPathInfo & info)
 {
@@ -693,6 +692,7 @@ void LocalStore::updatePathInfo(const ValidPathInfo & info)
         stmtUpdatePathInfo.bind64(info.narSize);
     else
         stmtUpdatePathInfo.bind(); // null
+    stmtUpdatePathInfo.bind("sha256:" + printHash(info.hash));
     stmtUpdatePathInfo.bind(info.path);
     if (sqlite3_step(stmtUpdatePathInfo) != SQLITE_DONE)
         throwSQLiteError(db, format("updating info of path `%1%' in database") % info.path);
@@ -1125,16 +1125,14 @@ struct HashAndWriteSink : Sink
     HashAndWriteSink(Sink & writeSink) : writeSink(writeSink), hashSink(htSHA256)
     {
     }
-    virtual void operator ()
-        (const unsigned char * data, unsigned int len)
+    virtual void operator () (const unsigned char * data, size_t len)
     {
         writeSink(data, len);
         hashSink(data, len);
     }
     Hash currentHash()
     {
-        HashSink hashSinkClone(hashSink);
-        return hashSinkClone.finish().first;
+        return hashSink.currentHash().first;
     }
 };
 
@@ -1180,7 +1178,7 @@ void LocalStore::exportPath(const Path & path, bool sign,
     
     PathSet references;
     queryReferences(path, references);
-    writeStringSet(references, hashAndWriteSink);
+    writeStrings(references, hashAndWriteSink);
 
     Path deriver = queryDeriver(path);
     writeString(deriver, hashAndWriteSink);
@@ -1223,11 +1221,11 @@ struct HashAndReadSource : Source
     {
         hashing = true;
     }
-    virtual void operator ()
-        (unsigned char * data, unsigned int len)
+    size_t read(unsigned char * data, size_t len)
     {
-        readSource(data, len);
-        if (hashing) hashSink(data, len);
+        size_t n = readSource.read(data, len);
+        if (hashing) hashSink(data, n);
+        return n;
     }
 };
 
@@ -1267,7 +1265,7 @@ Path LocalStore::importPath(bool requireSignature, Source & source)
 
     Path dstPath = readStorePath(hashAndReadSource);
 
-    PathSet references = readStorePaths(hashAndReadSource);
+    PathSet references = readStorePaths<PathSet>(hashAndReadSource);
 
     Path deriver = readString(hashAndReadSource);
     if (deriver != "") assertStorePath(deriver);
@@ -1278,7 +1276,7 @@ Path LocalStore::importPath(bool requireSignature, Source & source)
     bool haveSignature = readInt(hashAndReadSource) == 1;
 
     if (requireSignature && !haveSignature)
-        throw Error("imported archive lacks a signature");
+        throw Error(format("imported archive of `%1%' lacks a signature") % dstPath);
     
     if (haveSignature) {
         string signature = readString(hashAndReadSource);
@@ -1354,6 +1352,19 @@ Path LocalStore::importPath(bool requireSignature, Source & source)
 }
 
 
+Paths LocalStore::importPaths(bool requireSignature, Source & source)
+{
+    Paths res;
+    while (true) {
+        unsigned long long n = readLongLong(source);
+        if (n == 0) break;
+        if (n != 1) throw Error("input doesn't look like something created by `nix-store --export'");
+        res.push_back(importPath(requireSignature, source));
+    }
+    return res;
+}
+
+
 void LocalStore::deleteFromStore(const Path & path, unsigned long long & bytesFreed,
     unsigned long long & blocksFreed)
 {
@@ -1369,7 +1380,7 @@ void LocalStore::deleteFromStore(const Path & path, unsigned long long & bytesFr
                 PathSet referrers; queryReferrers(path, referrers);
                 referrers.erase(path); /* ignore self-references */
                 if (!referrers.empty())
-                    throw PathInUse(format("cannot delete path `%1%' because it is in use by `%2%'")
+                    throw PathInUse(format("cannot delete path `%1%' because it is in use by %2%")
                         % path % showPaths(referrers));
                 invalidatePath(path);
             }
@@ -1409,6 +1420,8 @@ void LocalStore::verifyStore(bool checkContents)
     if (checkContents) {
         printMsg(lvlInfo, "checking hashes...");
 
+        Hash nullHash(htSHA256);
+
         foreach (PathSet::iterator, i, validPaths) {
             try {
                 ValidPathInfo info = queryPathInfo(*i);
@@ -1417,17 +1430,30 @@ void LocalStore::verifyStore(bool checkContents)
                 printMsg(lvlTalkative, format("checking contents of `%1%'") % *i);
                 HashResult current = hashPath(info.hash.type, *i);
                 
-                if (current.first != info.hash) {
+                if (info.hash != nullHash && info.hash != current.first) {
                     printMsg(lvlError, format("path `%1%' was modified! "
                             "expected hash `%2%', got `%3%'")
                         % *i % printHash(info.hash) % printHash(current.first));
                 } else {
+
+                    bool update = false;
+
+                    /* Fill in missing hashes. */
+                    if (info.hash == nullHash) {
+                        printMsg(lvlError, format("fixing missing hash on `%1%'") % *i);
+                        info.hash = current.first;
+                        update = true;
+                    }
+                    
                     /* Fill in missing narSize fields (from old stores). */
                     if (info.narSize == 0) {
                         printMsg(lvlError, format("updating size field on `%1%' to %2%") % *i % current.second);
                         info.narSize = current.second;
-                        updatePathInfo(info);
+                        update = true;                        
                     }
+
+                    if (update) updatePathInfo(info);
+
                 }
             
             } catch (Error & e) {
diff --git a/src/libstore/local-store.hh b/src/libstore/local-store.hh
index b97e2f406190..2739c4eea69d 100644
--- a/src/libstore/local-store.hh
+++ b/src/libstore/local-store.hh
@@ -148,7 +148,7 @@ public:
     void exportPath(const Path & path, bool sign,
         Sink & sink);
 
-    Path importPath(bool requireSignature, Source & source);
+    Paths importPaths(bool requireSignature, Source & source);
     
     void buildDerivations(const PathSet & drvPaths);
 
@@ -261,6 +261,8 @@ private:
 
     Path createTempDirInStore();
 
+    Path importPath(bool requireSignature, Source & source);
+    
     void checkDerivationOutputs(const Path & drvPath, const Derivation & drv);
 };
 
diff --git a/src/libstore/references.cc b/src/libstore/references.cc
index ade9c9aa20e3..c1f9e3ba7711 100644
--- a/src/libstore/references.cc
+++ b/src/libstore/references.cc
@@ -57,11 +57,11 @@ struct RefScanSink : Sink
 
     RefScanSink() : hashSink(htSHA256) { }
     
-    void operator () (const unsigned char * data, unsigned int len);
+    void operator () (const unsigned char * data, size_t len);
 };
 
 
-void RefScanSink::operator () (const unsigned char * data, unsigned int len)
+void RefScanSink::operator () (const unsigned char * data, size_t len)
 {
     hashSink(data, len);
 
diff --git a/src/libstore/remote-store.cc b/src/libstore/remote-store.cc
index 84c87246f0f0..ce99c205e7d0 100644
--- a/src/libstore/remote-store.cc
+++ b/src/libstore/remote-store.cc
@@ -27,13 +27,15 @@ Path readStorePath(Source & from)
 }
 
 
-PathSet readStorePaths(Source & from)
+template<class T> T readStorePaths(Source & from)
 {
-    PathSet paths = readStringSet(from);
-    foreach (PathSet::iterator, i, paths) assertStorePath(*i);
+    T paths = readStrings<T>(from);
+    foreach (typename T::iterator, i, paths) assertStorePath(*i);
     return paths;
 }
 
+template PathSet readStorePaths(Source & from);
+
 
 RemoteStore::RemoteStore()
 {
@@ -65,6 +67,7 @@ void RemoteStore::openConnection()
     /* Send the magic greeting, check for the reply. */
     try {
         writeInt(WORKER_MAGIC_1, to);
+        to.flush();
         unsigned int magic = readInt(from);
         if (magic != WORKER_MAGIC_2) throw Error("protocol mismatch");
 
@@ -166,6 +169,7 @@ void RemoteStore::connectToDaemon()
 RemoteStore::~RemoteStore()
 {
     try {
+        to.flush();
         fdSocket.close();
         if (child != -1)
             child.wait(true);
@@ -213,7 +217,7 @@ PathSet RemoteStore::queryValidPaths()
     openConnection();
     writeInt(wopQueryValidPaths, to);
     processStderr();
-    return readStorePaths(from);
+    return readStorePaths<PathSet>(from);
 }
 
 
@@ -240,7 +244,7 @@ bool RemoteStore::querySubstitutablePathInfo(const Path & path,
     if (reply == 0) return false;
     info.deriver = readString(from);
     if (info.deriver != "") assertStorePath(info.deriver);
-    info.references = readStorePaths(from);
+    info.references = readStorePaths<PathSet>(from);
     info.downloadSize = readLongLong(from);
     info.narSize = GET_PROTOCOL_MINOR(daemonVersion) >= 7 ? readLongLong(from) : 0;
     return true;
@@ -258,7 +262,7 @@ ValidPathInfo RemoteStore::queryPathInfo(const Path & path)
     info.deriver = readString(from);
     if (info.deriver != "") assertStorePath(info.deriver);
     info.hash = parseHash(htSHA256, readString(from));
-    info.references = readStorePaths(from);
+    info.references = readStorePaths<PathSet>(from);
     info.registrationTime = readInt(from);
     info.narSize = readLongLong(from);
     return info;
@@ -283,7 +287,7 @@ void RemoteStore::queryReferences(const Path & path,
     writeInt(wopQueryReferences, to);
     writeString(path, to);
     processStderr();
-    PathSet references2 = readStorePaths(from);
+    PathSet references2 = readStorePaths<PathSet>(from);
     references.insert(references2.begin(), references2.end());
 }
 
@@ -295,7 +299,7 @@ void RemoteStore::queryReferrers(const Path & path,
     writeInt(wopQueryReferrers, to);
     writeString(path, to);
     processStderr();
-    PathSet referrers2 = readStorePaths(from);
+    PathSet referrers2 = readStorePaths<PathSet>(from);
     referrers.insert(referrers2.begin(), referrers2.end());
 }
 
@@ -318,7 +322,7 @@ PathSet RemoteStore::queryDerivationOutputs(const Path & path)
     writeInt(wopQueryDerivationOutputs, to);
     writeString(path, to);
     processStderr();
-    return readStorePaths(from);
+    return readStorePaths<PathSet>(from);
 }
 
 
@@ -338,7 +342,7 @@ Path RemoteStore::addToStore(const Path & _srcPath,
     openConnection();
     
     Path srcPath(absPath(_srcPath));
-    
+
     writeInt(wopAddToStore, to);
     writeString(baseNameOf(srcPath), to);
     /* backwards compatibility hack */
@@ -358,7 +362,7 @@ Path RemoteStore::addTextToStore(const string & name, const string & s,
     writeInt(wopAddTextToStore, to);
     writeString(name, to);
     writeString(s, to);
-    writeStringSet(references, to);
+    writeStrings(references, to);
     
     processStderr();
     return readStorePath(from);
@@ -377,14 +381,14 @@ void RemoteStore::exportPath(const Path & path, bool sign,
 }
 
 
-Path RemoteStore::importPath(bool requireSignature, Source & source)
+Paths RemoteStore::importPaths(bool requireSignature, Source & source)
 {
     openConnection();
-    writeInt(wopImportPath, to);
+    writeInt(wopImportPaths, to);
     /* We ignore requireSignature, since the worker forces it to true
-       anyway. */    
+       anyway. */
     processStderr(0, &source);
-    return readStorePath(from);
+    return readStorePaths<Paths>(from);
 }
 
 
@@ -392,7 +396,7 @@ void RemoteStore::buildDerivations(const PathSet & drvPaths)
 {
     openConnection();
     writeInt(wopBuildDerivations, to);
-    writeStringSet(drvPaths, to);
+    writeStrings(drvPaths, to);
     processStderr();
     readInt(from);
 }
@@ -459,7 +463,7 @@ void RemoteStore::collectGarbage(const GCOptions & options, GCResults & results)
     
     writeInt(wopCollectGarbage, to);
     writeInt(options.action, to);
-    writeStringSet(options.pathsToDelete, to);
+    writeStrings(options.pathsToDelete, to);
     writeInt(options.ignoreLiveness, to);
     writeLongLong(options.maxFreed, to);
     writeInt(options.maxLinks, to);
@@ -471,7 +475,7 @@ void RemoteStore::collectGarbage(const GCOptions & options, GCResults & results)
     
     processStderr();
     
-    results.paths = readStringSet(from);
+    results.paths = readStrings<PathSet>(from);
     results.bytesFreed = readLongLong(from);
     results.blocksFreed = readLongLong(from);
 }
@@ -482,7 +486,7 @@ PathSet RemoteStore::queryFailedPaths()
     openConnection();
     writeInt(wopQueryFailedPaths, to);
     processStderr();
-    return readStorePaths(from);
+    return readStorePaths<PathSet>(from);
 }
 
 
@@ -490,7 +494,7 @@ void RemoteStore::clearFailedPaths(const PathSet & paths)
 {
     openConnection();
     writeInt(wopClearFailedPaths, to);
-    writeStringSet(paths, to);
+    writeStrings(paths, to);
     processStderr();
     readInt(from);
 }
@@ -498,6 +502,7 @@ void RemoteStore::clearFailedPaths(const PathSet & paths)
 
 void RemoteStore::processStderr(Sink * sink, Source * source)
 {
+    to.flush();
     unsigned int msg;
     while ((msg = readInt(from)) == STDERR_NEXT
         || msg == STDERR_READ || msg == STDERR_WRITE) {
@@ -508,11 +513,11 @@ void RemoteStore::processStderr(Sink * sink, Source * source)
         }
         else if (msg == STDERR_READ) {
             if (!source) throw Error("no source");
-            unsigned int len = readInt(from);
+            size_t len = readInt(from);
             unsigned char * buf = new unsigned char[len];
             AutoDeleteArray<unsigned char> d(buf);
-            (*source)(buf, len);
-            writeString(string((const char *) buf, len), to);
+            writeString(buf, source->read(buf, len), to);
+            to.flush();
         }
         else {
             string s = readString(from);
diff --git a/src/libstore/remote-store.hh b/src/libstore/remote-store.hh
index 3be9e315a219..c5853ef53646 100644
--- a/src/libstore/remote-store.hh
+++ b/src/libstore/remote-store.hh
@@ -58,7 +58,7 @@ public:
     void exportPath(const Path & path, bool sign,
         Sink & sink);
 
-    Path importPath(bool requireSignature, Source & source);
+    Paths importPaths(bool requireSignature, Source & source);
     
     void buildDerivations(const PathSet & drvPaths);
 
diff --git a/src/libstore/store-api.cc b/src/libstore/store-api.cc
index d67ff2c77299..36ade2170876 100644
--- a/src/libstore/store-api.cc
+++ b/src/libstore/store-api.cc
@@ -298,6 +298,17 @@ string showPaths(const PathSet & paths)
 }
 
 
+void exportPaths(StoreAPI & store, const Paths & paths,
+    bool sign, Sink & sink)
+{
+    foreach (Paths::const_iterator, i, paths) {
+        writeInt(1, sink);
+        store.exportPath(*i, sign, sink);
+    }
+    writeInt(0, sink);
+}
+
+
 }
 
 
diff --git a/src/libstore/store-api.hh b/src/libstore/store-api.hh
index 0384657498b5..14890f5225ad 100644
--- a/src/libstore/store-api.hh
+++ b/src/libstore/store-api.hh
@@ -154,9 +154,7 @@ public:
     
     /* Copy the contents of a path to the store and register the
        validity the resulting path.  The resulting path is returned.
-       If `fixed' is true, then the output of a fixed-output
-       derivation is pre-loaded into the Nix store.  The function
-       object `filter' can be used to exclude files (see
+       The function object `filter' can be used to exclude files (see
        libutil/archive.hh). */
     virtual Path addToStore(const Path & srcPath,
         bool recursive = true, HashType hashAlgo = htSHA256,
@@ -174,9 +172,9 @@ public:
     virtual void exportPath(const Path & path, bool sign,
         Sink & sink) = 0;
 
-    /* Import a NAR dump created by exportPath() into the Nix
-       store. */
-    virtual Path importPath(bool requireSignature, Source & source) = 0;
+    /* Import a sequence of NAR dumps created by exportPaths() into
+       the Nix store. */
+    virtual Paths importPaths(bool requireSignature, Source & source) = 0;
 
     /* Ensure that the output paths of the derivation are valid.  If
        they are already valid, this is a no-op.  Otherwise, validity
@@ -345,6 +343,12 @@ ValidPathInfo decodeValidPathInfo(std::istream & str,
     bool hashGiven = false);
 
 
+/* Export multiple paths in the format expected by ‘nix-store
+   --import’. */
+void exportPaths(StoreAPI & store, const Paths & paths,
+    bool sign, Sink & sink);
+
+
 }
 
 
diff --git a/src/libstore/worker-protocol.hh b/src/libstore/worker-protocol.hh
index 576e754d2d7a..ef1e0993df28 100644
--- a/src/libstore/worker-protocol.hh
+++ b/src/libstore/worker-protocol.hh
@@ -8,7 +8,7 @@ namespace nix {
 #define WORKER_MAGIC_1 0x6e697863
 #define WORKER_MAGIC_2 0x6478696f
 
-#define PROTOCOL_VERSION 0x108
+#define PROTOCOL_VERSION 0x109
 #define GET_PROTOCOL_MAJOR(x) ((x) & 0xff00)
 #define GET_PROTOCOL_MINOR(x) ((x) & 0x00ff)
 
@@ -29,7 +29,6 @@ typedef enum {
     wopSyncWithGC = 13,
     wopFindRoots = 14,
     wopExportPath = 16,
-    wopImportPath = 17,
     wopQueryDeriver = 18,
     wopSetOptions = 19,
     wopCollectGarbage = 20,
@@ -39,7 +38,8 @@ typedef enum {
     wopQueryFailedPaths = 24,
     wopClearFailedPaths = 25,
     wopQueryPathInfo = 26,
-    wopQueryDerivationOutputNames = 27,
+    wopImportPaths = 27,
+    wopQueryDerivationOutputNames = 28,
 } WorkerOp;
 
 
@@ -59,7 +59,7 @@ typedef enum {
 
 
 Path readStorePath(Source & from);
-PathSet readStorePaths(Source & from);
+template<class T> T readStorePaths(Source & from);
 
     
 }
diff --git a/src/libutil/hash.cc b/src/libutil/hash.cc
index b9e7846992f6..bbfe7847fd8a 100644
--- a/src/libutil/hash.cc
+++ b/src/libutil/hash.cc
@@ -204,6 +204,22 @@ Hash parseHash32(HashType ht, const string & s)
 }
 
 
+Hash parseHash16or32(HashType ht, const string & s)
+{
+    Hash hash(ht);
+    if (s.size() == hash.hashSize * 2)
+        /* hexadecimal representation */
+        hash = parseHash(ht, s);
+    else if (s.size() == hashLength32(hash))
+        /* base-32 representation */
+        hash = parseHash32(ht, s);
+    else
+        throw Error(format("hash `%1%' has wrong length for hash type `%2%'")
+            % s % printHashType(ht));
+    return hash;
+}
+
+
 bool isHash(const string & s)
 {
     if (s.length() != 32) return false;
@@ -290,21 +306,13 @@ HashSink::HashSink(HashType ht) : ht(ht)
     start(ht, *ctx);
 }
     
-HashSink::HashSink(const HashSink & h)
-{
-    ht = h.ht;
-    bytes = h.bytes;
-    ctx = new Ctx;
-    *ctx = *h.ctx;
-}
-    
 HashSink::~HashSink()
 {
+    bufPos = 0;
     delete ctx;
 }
 
-void HashSink::operator ()
-    (const unsigned char * data, unsigned int len)
+void HashSink::write(const unsigned char * data, size_t len)
 {
     bytes += len;
     update(ht, *ctx, data, len);
@@ -312,11 +320,21 @@ void HashSink::operator ()
 
 HashResult HashSink::finish()
 {
+    flush();
     Hash hash(ht);
     nix::finish(ht, *ctx, hash.hash);
     return HashResult(hash, bytes);
 }
 
+HashResult HashSink::currentHash()
+{
+    flush();
+    Ctx ctx2 = *ctx;
+    Hash hash(ht);
+    nix::finish(ht, ctx2, hash.hash);
+    return HashResult(hash, bytes);
+}
+
 
 HashResult hashPath(
     HashType ht, const Path & path, PathFilter & filter)
diff --git a/src/libutil/hash.hh b/src/libutil/hash.hh
index 13740954d625..e0b6478cc418 100644
--- a/src/libutil/hash.hh
+++ b/src/libutil/hash.hh
@@ -58,6 +58,9 @@ string printHash32(const Hash & hash);
 /* Parse a base-32 representation of a hash code. */
 Hash parseHash32(HashType ht, const string & s);
 
+/* Parse a base-16 or base-32 representation of a hash code. */
+Hash parseHash16or32(HashType ht, const string & s);
+
 /* Verify that the given string is a valid hash code. */
 bool isHash(const string & s);
 
@@ -88,7 +91,7 @@ string printHashType(HashType ht);
 
 union Ctx;
 
-class HashSink : public Sink
+class HashSink : public BufferedSink
 {
 private:
     HashType ht;
@@ -99,8 +102,9 @@ public:
     HashSink(HashType ht);
     HashSink(const HashSink & h);
     ~HashSink();
-    virtual void operator () (const unsigned char * data, unsigned int len);
+    void write(const unsigned char * data, size_t len);
     HashResult finish();
+    HashResult currentHash();
 };
 
 
diff --git a/src/libutil/serialise.cc b/src/libutil/serialise.cc
index 9b422271323f..c4563ffd1212 100644
--- a/src/libutil/serialise.cc
+++ b/src/libutil/serialise.cc
@@ -2,24 +2,117 @@
 #include "util.hh"
 
 #include <cstring>
+#include <cerrno>
 
 
 namespace nix {
 
 
-void FdSink::operator () (const unsigned char * data, unsigned int len)
+BufferedSink::~BufferedSink()
+{
+    /* We can't call flush() here, because C++ for some insane reason
+       doesn't allow you to call virtual methods from a destructor. */
+    assert(!bufPos);
+    if (buffer) delete[] buffer;
+}
+
+    
+void BufferedSink::operator () (const unsigned char * data, size_t len)
+{
+    if (!buffer) buffer = new unsigned char[bufSize];
+    
+    while (len) {
+        /* Optimisation: bypass the buffer if the data exceeds the
+           buffer size. */
+        if (bufPos + len >= bufSize) {
+            flush();
+            write(data, len);
+            break;
+        }
+        /* Otherwise, copy the bytes to the buffer.  Flush the buffer
+           when it's full. */
+        size_t n = bufPos + len > bufSize ? bufSize - bufPos : len;
+        memcpy(buffer + bufPos, data, n);
+        data += n; bufPos += n; len -= n;
+        if (bufPos == bufSize) flush();
+    }
+}
+
+
+void BufferedSink::flush()
+{
+    if (bufPos == 0) return;
+    size_t n = bufPos;
+    bufPos = 0; // don't trigger the assert() in ~BufferedSink()
+    write(buffer, n);
+}
+
+
+FdSink::~FdSink()
+{
+    try { flush(); } catch (...) { ignoreException(); }
+}
+
+
+void FdSink::write(const unsigned char * data, size_t len)
 {
     writeFull(fd, data, len);
 }
 
 
-void FdSource::operator () (unsigned char * data, unsigned int len)
+void Source::operator () (unsigned char * data, size_t len)
+{
+    while (len) {
+        size_t n = read(data, len);
+        data += n; len -= n;
+    }
+}
+
+
+BufferedSource::~BufferedSource()
 {
-    readFull(fd, data, len);
+    if (buffer) delete[] buffer;
 }
 
 
-void writePadding(unsigned int len, Sink & sink)
+size_t BufferedSource::read(unsigned char * data, size_t len)
+{
+    if (!buffer) buffer = new unsigned char[bufSize];
+
+    if (!bufPosIn) bufPosIn = readUnbuffered(buffer, bufSize);
+            
+    /* Copy out the data in the buffer. */
+    size_t n = len > bufPosIn - bufPosOut ? bufPosIn - bufPosOut : len;
+    memcpy(data, buffer + bufPosOut, n);
+    bufPosOut += n;
+    if (bufPosIn == bufPosOut) bufPosIn = bufPosOut = 0;
+    return n;
+}
+
+
+size_t FdSource::readUnbuffered(unsigned char * data, size_t len)
+{
+    ssize_t n;
+    do {
+        checkInterrupt();
+        n = ::read(fd, (char *) data, bufSize);
+    } while (n == -1 && errno == EINTR);
+    if (n == -1) throw SysError("reading from file");
+    if (n == 0) throw EndOfFile("unexpected end-of-file");
+    return n;
+}
+
+
+size_t StringSource::read(unsigned char * data, size_t len)
+{
+    if (pos == s.size()) throw EndOfFile("end of string reached");
+    size_t n = s.copy((char *) data, len, pos);
+    pos += n;
+    return n;
+}
+
+
+void writePadding(size_t len, Sink & sink)
 {
     if (len % 8) {
         unsigned char zero[8];
@@ -56,28 +149,36 @@ void writeLongLong(unsigned long long n, Sink & sink)
 }
 
 
-void writeString(const string & s, Sink & sink)
+void writeString(const unsigned char * buf, size_t len, Sink & sink)
 {
-    unsigned int len = s.length();
     writeInt(len, sink);
-    sink((const unsigned char *) s.c_str(), len);
+    sink(buf, len);
     writePadding(len, sink);
 }
 
 
-void writeStringSet(const StringSet & ss, Sink & sink)
+void writeString(const string & s, Sink & sink)
+{
+    writeString((const unsigned char *) s.c_str(), s.size(), sink);
+}
+
+
+template<class T> void writeStrings(const T & ss, Sink & sink)
 {
     writeInt(ss.size(), sink);
-    for (StringSet::iterator i = ss.begin(); i != ss.end(); ++i)
+    foreach (typename T::const_iterator, i, ss)
         writeString(*i, sink);
 }
 
+template void writeStrings(const Paths & ss, Sink & sink);
+template void writeStrings(const PathSet & ss, Sink & sink);
 
-void readPadding(unsigned int len, Source & source)
+
+void readPadding(size_t len, Source & source)
 {
     if (len % 8) {
         unsigned char zero[8];
-        unsigned int n = 8 - (len % 8);
+        size_t n = 8 - (len % 8);
         source(zero, n);
         for (unsigned int i = 0; i < n; i++)
             if (zero[i]) throw SerialisationError("non-zero padding");
@@ -115,9 +216,19 @@ unsigned long long readLongLong(Source & source)
 }
 
 
+size_t readString(unsigned char * buf, size_t max, Source & source)
+{
+    size_t len = readInt(source);
+    if (len > max) throw Error("string is too long");
+    source(buf, len);
+    readPadding(len, source);
+    return len;
+}
+
+ 
 string readString(Source & source)
 {
-    unsigned int len = readInt(source);
+    size_t len = readInt(source);
     unsigned char * buf = new unsigned char[len];
     AutoDeleteArray<unsigned char> d(buf);
     source(buf, len);
@@ -126,14 +237,17 @@ string readString(Source & source)
 }
 
  
-StringSet readStringSet(Source & source)
+template<class T> T readStrings(Source & source)
 {
     unsigned int count = readInt(source);
-    StringSet ss;
+    T ss;
     while (count--)
-        ss.insert(readString(source));
+        ss.insert(ss.end(), readString(source));
     return ss;
 }
 
+template Paths readStrings(Source & source);
+template PathSet readStrings(Source & source);
+
 
 }
diff --git a/src/libutil/serialise.hh b/src/libutil/serialise.hh
index 0e797d63bca9..ded4b12a046e 100644
--- a/src/libutil/serialise.hh
+++ b/src/libutil/serialise.hh
@@ -11,7 +11,25 @@ namespace nix {
 struct Sink 
 {
     virtual ~Sink() { }
-    virtual void operator () (const unsigned char * data, unsigned int len) = 0;
+    virtual void operator () (const unsigned char * data, size_t len) = 0;
+};
+
+
+/* A buffered abstract sink. */
+struct BufferedSink : Sink
+{
+    size_t bufSize, bufPos;
+    unsigned char * buffer;
+
+    BufferedSink(size_t bufSize = 32 * 1024)
+        : bufSize(bufSize), bufPos(0), buffer(0) { }
+    ~BufferedSink();
+
+    void operator () (const unsigned char * data, size_t len);
+    
+    void flush();
+    
+    virtual void write(const unsigned char * data, size_t len) = 0;
 };
 
 
@@ -20,49 +38,55 @@ struct Source
 {
     virtual ~Source() { }
     
-    /* The callee should store exactly *len bytes in the buffer
-       pointed to by data.  It should block if that much data is not
-       yet available, or throw an error if it is not going to be
-       available. */
-    virtual void operator () (unsigned char * data, unsigned int len) = 0;
+    /* Store exactly ‘len’ bytes in the buffer pointed to by ‘data’.
+       It blocks until all the requested data is available, or throws
+       an error if it is not going to be available.   */
+    void operator () (unsigned char * data, size_t len);
+
+    /* Store up to ‘len’ in the buffer pointed to by ‘data’, and
+       return the number of bytes stored.  If blocks until at least
+       one byte is available. */
+    virtual size_t read(unsigned char * data, size_t len) = 0;
 };
 
 
-/* A sink that writes data to a file descriptor. */
-struct FdSink : Sink
+/* A buffered abstract source. */
+struct BufferedSource : Source
 {
-    int fd;
+    size_t bufSize, bufPosIn, bufPosOut;
+    unsigned char * buffer;
 
-    FdSink()
-    {
-        fd = -1;
-    }
+    BufferedSource(size_t bufSize = 32 * 1024)
+        : bufSize(bufSize), bufPosIn(0), bufPosOut(0), buffer(0) { }
+    ~BufferedSource();
     
-    FdSink(int fd) 
-    {
-        this->fd = fd;
-    }
+    size_t read(unsigned char * data, size_t len);
     
-    void operator () (const unsigned char * data, unsigned int len);
+    /* Underlying read call, to be overriden. */
+    virtual size_t readUnbuffered(unsigned char * data, size_t len) = 0;
 };
 
 
-/* A source that reads data from a file descriptor. */
-struct FdSource : Source
+/* A sink that writes data to a file descriptor. */
+struct FdSink : BufferedSink
 {
     int fd;
 
-    FdSource()
-    {
-        fd = -1;
-    }
+    FdSink() : fd(-1) { }
+    FdSink(int fd) : fd(fd) { }
+    ~FdSink();
     
-    FdSource(int fd) 
-    {
-        this->fd = fd;
-    }
-    
-    void operator () (unsigned char * data, unsigned int len);
+    void write(const unsigned char * data, size_t len);
+};
+
+
+/* A source that reads data from a file descriptor. */
+struct FdSource : BufferedSource
+{
+    int fd;
+    FdSource() : fd(-1) { }
+    FdSource(int fd) : fd(fd) { }
+    size_t readUnbuffered(unsigned char * data, size_t len);
 };
 
 
@@ -70,7 +94,7 @@ struct FdSource : Source
 struct StringSink : Sink
 {
     string s;
-    virtual void operator () (const unsigned char * data, unsigned int len)
+    void operator () (const unsigned char * data, size_t len)
     {
         s.append((const char *) data, len);
     }
@@ -81,29 +105,25 @@ struct StringSink : Sink
 struct StringSource : Source
 {
     const string & s;
-    unsigned int pos;
+    size_t pos;
     StringSource(const string & _s) : s(_s), pos(0) { }
-    virtual void operator () (unsigned char * data, unsigned int len)
-    {
-        s.copy((char *) data, len, pos);
-        pos += len;
-        if (pos > s.size())
-            throw Error("end of string reached");
-    }
+    size_t read(unsigned char * data, size_t len);    
 };
 
 
-void writePadding(unsigned int len, Sink & sink);
+void writePadding(size_t len, Sink & sink);
 void writeInt(unsigned int n, Sink & sink);
 void writeLongLong(unsigned long long n, Sink & sink);
+void writeString(const unsigned char * buf, size_t len, Sink & sink);
 void writeString(const string & s, Sink & sink);
-void writeStringSet(const StringSet & ss, Sink & sink);
+template<class T> void writeStrings(const T & ss, Sink & sink);
 
-void readPadding(unsigned int len, Source & source);
+void readPadding(size_t len, Source & source);
 unsigned int readInt(Source & source);
 unsigned long long readLongLong(Source & source);
+size_t readString(unsigned char * buf, size_t max, Source & source);
 string readString(Source & source);
-StringSet readStringSet(Source & source);
+template<class T> T readStrings(Source & source);
 
 
 MakeError(SerialisationError, Error)
diff --git a/src/nix-env/nix-env.cc b/src/nix-env/nix-env.cc
index 3dfecb2d7313..a8d9076cfb8d 100644
--- a/src/nix-env/nix-env.cc
+++ b/src/nix-env/nix-env.cc
@@ -1270,7 +1270,7 @@ void run(Strings args)
         else if (arg == "--profile" || arg == "-p")
             globals.profile = absPath(needArg(i, args, arg));
         else if (arg == "--file" || arg == "-f")
-            globals.instSource.nixExprPath = absPath(needArg(i, args, arg));
+            globals.instSource.nixExprPath = lookupFileArg(globals.state, needArg(i, args, arg));
         else if (arg == "--switch-profile" || arg == "-S")
             op = opSwitchProfile;
         else if (arg == "--switch-generation" || arg == "-G")
diff --git a/src/nix-hash/nix-hash.cc b/src/nix-hash/nix-hash.cc
index 4867234bffc1..5b35ccd9dae3 100644
--- a/src/nix-hash/nix-hash.cc
+++ b/src/nix-hash/nix-hash.cc
@@ -43,7 +43,7 @@ void run(Strings args)
     }
 
     if (op == opHash) {
-        for (Strings::iterator i = ss.begin(); i != ss.end(); ++i) {
+        foreach (Strings::iterator, i, ss) {
             Hash h = flat ? hashFile(ht, *i) : hashPath(ht, *i).first;
             if (truncate && h.hashSize > 20) h = compressHash(h, 20);
             std::cout << format("%1%\n") %
@@ -52,8 +52,8 @@ void run(Strings args)
     }
 
     else {
-        for (Strings::iterator i = ss.begin(); i != ss.end(); ++i) {
-            Hash h = op == opTo16 ? parseHash32(ht, *i) : parseHash(ht, *i);
+        foreach (Strings::iterator, i, ss) {
+            Hash h = parseHash16or32(ht, *i);
             std::cout << format("%1%\n") %
                 (op == opTo16 ? printHash(h) : printHash32(h));
         }
diff --git a/src/nix-instantiate/nix-instantiate.cc b/src/nix-instantiate/nix-instantiate.cc
index 98eadbd69580..93aa50943450 100644
--- a/src/nix-instantiate/nix-instantiate.cc
+++ b/src/nix-instantiate/nix-instantiate.cc
@@ -138,8 +138,7 @@ void run(Strings args)
     }
 
     foreach (Strings::iterator, i, files) {
-        Path path = absPath(*i);
-        Expr * e = state.parseExprFromFile(path);
+        Expr * e = state.parseExprFromFile(lookupFileArg(state, *i));
         processExpr(state, attrPaths, parseOnly, strict, autoArgs,
             evalOnly, xmlOutput, xmlOutputSourceLocation, e);
     }
diff --git a/src/nix-store/nix-store.cc b/src/nix-store/nix-store.cc
index 371ca54af07c..e92ccb153d12 100644
--- a/src/nix-store/nix-store.cc
+++ b/src/nix-store/nix-store.cc
@@ -133,14 +133,6 @@ static void opAddFixed(Strings opFlags, Strings opArgs)
 }
 
 
-static Hash parseHash16or32(HashType ht, const string & s)
-{
-    return s.size() == Hash(ht).hashSize * 2
-        ? parseHash(ht, s)
-        : parseHash32(ht, s);
-}
-
-
 /* Hack to support caching in `nix-prefetch-url'. */
 static void opPrintFixedPath(Strings opFlags, Strings opArgs)
 {
@@ -594,11 +586,7 @@ static void opExport(Strings opFlags, Strings opArgs)
         else throw UsageError(format("unknown flag `%1%'") % *i);
 
     FdSink sink(STDOUT_FILENO);
-    for (Strings::iterator i = opArgs.begin(); i != opArgs.end(); ++i) {
-        writeInt(1, sink);
-        store->exportPath(*i, sign, sink);
-    }
-    writeInt(0, sink);
+    exportPaths(*store, opArgs, sign, sink);
 }
 
 
@@ -612,12 +600,10 @@ static void opImport(Strings opFlags, Strings opArgs)
     if (!opArgs.empty()) throw UsageError("no arguments expected");
     
     FdSource source(STDIN_FILENO);
-    while (true) {
-        unsigned long long n = readLongLong(source);
-        if (n == 0) break;
-        if (n != 1) throw Error("input doesn't look like something created by `nix-store --export'");
-        cout << format("%1%\n") % store->importPath(requireSignature, source) << std::flush;
-    }
+    Paths paths = store->importPaths(requireSignature, source);
+
+    foreach (Paths::iterator, i, paths)
+        cout << format("%1%\n") % *i << std::flush;
 }
 
 
diff --git a/src/nix-worker/nix-worker.cc b/src/nix-worker/nix-worker.cc
index 3587bd7fde2e..68567f341e05 100644
--- a/src/nix-worker/nix-worker.cc
+++ b/src/nix-worker/nix-worker.cc
@@ -56,7 +56,8 @@ static void tunnelStderr(const unsigned char * buf, size_t count)
     if (canSendStderr && myPid == getpid()) {
         try {
             writeInt(STDERR_NEXT, to);
-            writeString(string((char *) buf, count), to);
+            writeString(buf, count, to);
+            to.flush();
         } catch (...) {
             /* Write failed; that means that the other side is
                gone. */
@@ -200,26 +201,20 @@ static void stopWork(bool success = true, const string & msg = "", unsigned int
 struct TunnelSink : Sink
 {
     Sink & to;
-    TunnelSink(Sink & to) : to(to)
-    {
-    }
-    virtual void operator ()
-        (const unsigned char * data, unsigned int len)
+    TunnelSink(Sink & to) : to(to) { }
+    virtual void operator () (const unsigned char * data, size_t len)
     {
         writeInt(STDERR_WRITE, to);
-        writeString(string((const char *) data, len), to);
+        writeString(data, len, to);
     }
 };
 
 
-struct TunnelSource : Source
+struct TunnelSource : BufferedSource
 {
     Source & from;
-    TunnelSource(Source & from) : from(from)
-    {
-    }
-    virtual void operator ()
-        (unsigned char * data, unsigned int len)
+    TunnelSource(Source & from) : from(from) { }
+    size_t readUnbuffered(unsigned char * data, size_t len)
     {
         /* Careful: we're going to receive data from the client now,
            so we have to disable the SIGPOLL handler. */
@@ -228,11 +223,12 @@ struct TunnelSource : Source
         
         writeInt(STDERR_READ, to);
         writeInt(len, to);
-        string s = readString(from);
-        if (s.size() != len) throw Error("not enough data");
-        memcpy(data, (const unsigned char *) s.c_str(), len);
+        to.flush();
+        size_t n = readString(data, len, from);
 
         startWork();
+        if (n == 0) throw EndOfFile("unexpected end-of-file");
+        return n;
     }
 };
 
@@ -241,11 +237,14 @@ struct TunnelSource : Source
    the contents of the file to `s'.  Otherwise barf. */
 struct RetrieveRegularNARSink : ParseSink
 {
+    bool regular;
     string s;
 
+    RetrieveRegularNARSink() : regular(true) { }
+
     void createDirectory(const Path & path)
     {
-        throw Error("regular file expected");
+        regular = false;
     }
 
     void receiveContents(unsigned char * data, unsigned int len)
@@ -255,7 +254,7 @@ struct RetrieveRegularNARSink : ParseSink
 
     void createSymlink(const Path & path, const string & target)
     {
-        throw Error("regular file expected");
+        regular = false;
     }
 };
 
@@ -266,10 +265,11 @@ struct SavingSourceAdapter : Source
     Source & orig;
     string s;
     SavingSourceAdapter(Source & orig) : orig(orig) { }
-    void operator () (unsigned char * data, unsigned int len)
+    size_t read(unsigned char * data, size_t len)
     {
-        orig(data, len);
-        s.append((const char *) data, len);
+        size_t n = orig.read(data, len);
+        s.append((const char *) data, n);
+        return n;
     }
 };
 
@@ -327,7 +327,7 @@ static void performOp(unsigned int clientVersion,
             store->queryReferrers(path, paths);
         else paths = store->queryDerivationOutputs(path);
         stopWork();
-        writeStringSet(paths, to);
+        writeStrings(paths, to);
         break;
     }
 
@@ -371,11 +371,11 @@ static void performOp(unsigned int clientVersion,
                addToStoreFromDump(). */
             ParseSink sink; /* null sink; just parse the NAR */
             parseDump(sink, savedNAR);
-        } else {
+        } else
             parseDump(savedRegular, from);
-        }
             
         startWork();
+        if (!savedRegular.regular) throw Error("regular file expected");
         Path path = dynamic_cast<LocalStore *>(store.get())
             ->addToStoreFromDump(recursive ? savedNAR.s : savedRegular.s, baseName, recursive, hashAlgo);
         stopWork();
@@ -387,7 +387,7 @@ static void performOp(unsigned int clientVersion,
     case wopAddTextToStore: {
         string suffix = readString(from);
         string s = readString(from);
-        PathSet refs = readStorePaths(from);
+        PathSet refs = readStorePaths<PathSet>(from);
         startWork();
         Path path = store->addTextToStore(suffix, s, refs);
         stopWork();
@@ -406,17 +406,17 @@ static void performOp(unsigned int clientVersion,
         break;
     }
 
-    case wopImportPath: {
+    case wopImportPaths: {
         startWork();
         TunnelSource source(from);
-        Path path = store->importPath(true, source);
+        Paths paths = store->importPaths(true, source);
         stopWork();
-        writeString(path, to);
+        writeStrings(paths, to);
         break;
     }
 
     case wopBuildDerivations: {
-        PathSet drvs = readStorePaths(from);
+        PathSet drvs = readStorePaths<PathSet>(from);
         startWork();
         store->buildDerivations(drvs);
         stopWork();
@@ -474,7 +474,7 @@ static void performOp(unsigned int clientVersion,
     case wopCollectGarbage: {
         GCOptions options;
         options.action = (GCOptions::GCAction) readInt(from);
-        options.pathsToDelete = readStorePaths(from);
+        options.pathsToDelete = readStorePaths<PathSet>(from);
         options.ignoreLiveness = readInt(from);
         options.maxFreed = readLongLong(from);
         options.maxLinks = readInt(from);
@@ -492,7 +492,7 @@ static void performOp(unsigned int clientVersion,
         store->collectGarbage(options, results);
         stopWork();
         
-        writeStringSet(results.paths, to);
+        writeStrings(results.paths, to);
         writeLongLong(results.bytesFreed, to);
         writeLongLong(results.blocksFreed, to);
         
@@ -530,7 +530,7 @@ static void performOp(unsigned int clientVersion,
         writeInt(res ? 1 : 0, to);
         if (res) {
             writeString(info.deriver, to);
-            writeStringSet(info.references, to);
+            writeStrings(info.references, to);
             writeLongLong(info.downloadSize, to);
             if (GET_PROTOCOL_MINOR(clientVersion) >= 7)
                 writeLongLong(info.narSize, to);
@@ -542,7 +542,7 @@ static void performOp(unsigned int clientVersion,
         startWork();
         PathSet paths = store->queryValidPaths();
         stopWork();
-        writeStringSet(paths, to);
+        writeStrings(paths, to);
         break;
     }
 
@@ -550,12 +550,12 @@ static void performOp(unsigned int clientVersion,
         startWork();
         PathSet paths = store->queryFailedPaths();
         stopWork();
-        writeStringSet(paths, to);
+        writeStrings(paths, to);
         break;
     }
 
     case wopClearFailedPaths: {
-        PathSet paths = readStringSet(from);
+        PathSet paths = readStrings<PathSet>(from);
         startWork();
         store->clearFailedPaths(paths);
         stopWork();
@@ -570,7 +570,7 @@ static void performOp(unsigned int clientVersion,
         stopWork();
         writeString(info.deriver, to);
         writeString(printHash(info.hash), to);
-        writeStringSet(info.references, to);
+        writeStrings(info.references, to);
         writeInt(info.registrationTime, to);
         writeLongLong(info.narSize, to);
         break;
@@ -603,8 +603,8 @@ static void processConnection()
     unsigned int magic = readInt(from);
     if (magic != WORKER_MAGIC_1) throw Error("protocol mismatch");
     writeInt(WORKER_MAGIC_2, to);
-
     writeInt(PROTOCOL_VERSION, to);
+    to.flush();
     unsigned int clientVersion = readInt(from);
 
     /* Send startup error messages to the client. */
@@ -626,9 +626,11 @@ static void processConnection()
         store = boost::shared_ptr<StoreAPI>(new LocalStore());
 
         stopWork();
+        to.flush();
         
     } catch (Error & e) {
         stopWork(false, e.msg());
+        to.flush();
         return;
     }
 
@@ -648,9 +650,19 @@ static void processConnection()
         try {
             performOp(clientVersion, from, to, op);
         } catch (Error & e) {
+            /* If we're not in a state were we can send replies, then
+               something went wrong processing the input of the
+               client.  This can happen especially if I/O errors occur
+               during addTextToStore() / importPath().  If that
+               happens, just send the error message and exit. */
+            bool errorAllowed = canSendStderr;
+            if (!errorAllowed) printMsg(lvlError, format("error processing client input: %1%") % e.msg());
             stopWork(false, e.msg(), GET_PROTOCOL_MINOR(clientVersion) >= 8 ? e.status : 0);
+            if (!errorAllowed) break;
         }
 
+        to.flush();
+
         assert(!canSendStderr);
     };
 
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 0418f73e6cf5..8b5aa4bd99d0 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -1,4 +1,4 @@
-TESTS_ENVIRONMENT = $(bash) -e
+TESTS_ENVIRONMENT = NIX_REMOTE= $(bash) -e
 
 extra1 = $(shell pwd)/test-tmp/shared
 
diff --git a/tests/common.sh.in b/tests/common.sh.in
index 62ac669df665..4ab490a62645 100644
--- a/tests/common.sh.in
+++ b/tests/common.sh.in
@@ -23,8 +23,6 @@ export SHARED=$TEST_ROOT/shared
 
 export PATH=$NIX_BIN_DIR:$TOP/scripts:$PATH
 
-export NIX_REMOTE=
-
 export REAL_BIN_DIR=@bindir@
 export REAL_LIBEXEC_DIR=@libexecdir@
 export REAL_LOCALSTATE_DIR=@localstatedir@
diff --git a/tests/remote-builds.nix b/tests/remote-builds.nix
index 201ca9dba19b..de127b8aee16 100644
--- a/tests/remote-builds.nix
+++ b/tests/remote-builds.nix
@@ -72,6 +72,7 @@ in
       $client->succeed("chmod 600 /root/.ssh/id_dsa");
 
       # Install the SSH key on the slaves.
+      $client->waitForJob("network-interfaces");
       foreach my $slave ($slave1, $slave2) {
           $slave->succeed("mkdir -m 700 /root/.ssh");
           $slave->copyFileFromHost("key.pub", "/root/.ssh/authorized_keys");
diff --git a/tests/user-envs.sh b/tests/user-envs.sh
index 025a5ff81716..5037e28b916b 100644
--- a/tests/user-envs.sh
+++ b/tests/user-envs.sh
@@ -36,7 +36,7 @@ nix-env -p $profiles/test -q '*' | grep -q foo-2.0pre1
 test "$($profiles/test/bin/foo)" = "foo-2.0pre1"
 
 # Upgrade "foo": should install foo-2.0.
-nix-env -p $profiles/test -f ./user-envs.nix -u foo
+NIX_PATH=nixpkgs=./user-envs.nix nix-env -p $profiles/test -f '<nixpkgs>' -u foo
 
 # Query installed: should contain foo-2.0 now.
 test "$(nix-env -p $profiles/test -q '*' | wc -l)" -eq 1