From 705868a8a96a10f70e629433cfffc2d5cd2703eb Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <e.dolstra@tudelft.nl>
Date: Mon, 4 Oct 2010 17:55:38 +0000
Subject: * Make sure that config.h is included before the system headers,  
 because it defines _FILE_OFFSET_BITS.  Without this, on   OpenSolaris the
 system headers define it to be 32, and then   the 32-bit stat() ends up being
 called with a 64-bit "struct   stat", or vice versa.

  This also ensures that we get 64-bit file sizes everywhere.

* Remove the redundant call to stat() in parseExprFromFile().
  The file cannot be a symlink because that's the exit condition
  of the loop before.
---
 src/nix-instantiate/nix-instantiate.cc | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

(limited to 'src/nix-instantiate')

diff --git a/src/nix-instantiate/nix-instantiate.cc b/src/nix-instantiate/nix-instantiate.cc
index 4d629ea1b333..2925f9c5efb7 100644
--- a/src/nix-instantiate/nix-instantiate.cc
+++ b/src/nix-instantiate/nix-instantiate.cc
@@ -1,6 +1,3 @@
-#include <map>
-#include <iostream>
-
 #include "globals.hh"
 #include "shared.hh"
 #include "eval.hh"
@@ -13,6 +10,9 @@
 #include "common-opts.hh"
 #include "help.txt.hh"
 
+#include <map>
+#include <iostream>
+
 
 using namespace nix;
 
-- 
cgit 1.4.1


From e879a0371ba7ef99da2d82547823c3f96b445fdb Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <e.dolstra@tudelft.nl>
Date: Wed, 20 Oct 2010 11:38:30 +0000
Subject: * Use the Boehm garbage collector to reclaim unused memory in the Nix
   expression evaluator.

---
 src/libexpr/Makefile.am         |  3 ++-
 src/libexpr/eval.cc             | 23 ++++++++++++++---------
 src/libexpr/eval.hh             |  5 ++++-
 src/nix-env/Makefile.am         |  6 ++++--
 src/nix-instantiate/Makefile.am |  7 +++++--
 5 files changed, 29 insertions(+), 15 deletions(-)

(limited to 'src/nix-instantiate')

diff --git a/src/libexpr/Makefile.am b/src/libexpr/Makefile.am
index e7228e183581..24aa2968b195 100644
--- a/src/libexpr/Makefile.am
+++ b/src/libexpr/Makefile.am
@@ -20,7 +20,8 @@ EXTRA_DIST = lexer.l parser.y
 
 AM_CXXFLAGS = \
  -I$(srcdir)/.. \
- -I$(srcdir)/../libutil -I$(srcdir)/../libstore
+ -I$(srcdir)/../libutil -I$(srcdir)/../libstore \
+ -I/home/eelco/Dev/nix/boehmgc/include
 
 
 # Parser generation.
diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index e55f28822b6a..ba331749fe9c 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -8,6 +8,9 @@
 
 #include <cstring>
 
+#include <gc/gc.h>
+#include <gc/gc_cpp.h>
+
 
 #define LocalNoInline(f) static f __attribute__((noinline)); f
 #define LocalNoInlineNoReturn(f) static f __attribute__((noinline, noreturn)); f
@@ -147,7 +150,7 @@ void EvalState::addPrimOp(const string & name,
     v.type = tPrimOp;
     v.primOp.arity = arity;
     v.primOp.fun = primOp;
-    v.primOp.name = strdup(name2.c_str());
+    v.primOp.name = GC_strdup(name2.c_str());
     staticBaseEnv.vars[symbols.create(name)] = baseEnvDispl;
     baseEnv.values[baseEnvDispl++] = v;
     (*baseEnv.values[0].attrs)[symbols.create(name2)].value = v;
@@ -218,7 +221,7 @@ LocalNoInline(void addErrorPrefix(Error & e, const char * s, const string & s2,
 void mkString(Value & v, const char * s)
 {
     v.type = tString;
-    v.string.s = strdup(s);
+    v.string.s = GC_strdup(s);
     v.string.context = 0;
 }
 
@@ -228,9 +231,10 @@ void mkString(Value & v, const string & s, const PathSet & context)
     mkString(v, s.c_str());
     if (!context.empty()) {
         unsigned int n = 0;
-        v.string.context = new const char *[context.size() + 1];
+        v.string.context = (const char * *)
+            GC_malloc((context.size() + 1) * sizeof(char *));
         foreach (PathSet::const_iterator, i, context) 
-            v.string.context[n++] = strdup(i->c_str());
+            v.string.context[n++] = GC_strdup(i->c_str());
         v.string.context[n] = 0;
     }
 }
@@ -239,7 +243,7 @@ void mkString(Value & v, const string & s, const PathSet & context)
 void mkPath(Value & v, const char * s)
 {
     v.type = tPath;
-    v.path = strdup(s);
+    v.path = GC_strdup(s);
 }
 
 
@@ -264,7 +268,7 @@ Value * EvalState::lookupVar(Env * env, const VarRef & var)
 Value * EvalState::allocValues(unsigned int count)
 {
     nrValues += count;
-    return new Value[count]; // !!! check destructor
+    return (Value *) GC_MALLOC(count * sizeof(Value));
 }
 
 
@@ -272,7 +276,7 @@ Env & EvalState::allocEnv(unsigned int size)
 {
     nrEnvs++;
     nrValuesInEnvs += size;
-    Env * env = (Env *) malloc(sizeof(Env) + size * sizeof(Value));
+    Env * env = (Env *) GC_MALLOC(sizeof(Env) + size * sizeof(Value));
     return *env;
 }
 
@@ -281,7 +285,7 @@ void EvalState::mkList(Value & v, unsigned int length)
 {
     v.type = tList;
     v.list.length = length;
-    v.list.elems = new Value *[length];
+    v.list.elems = (Value * *) GC_MALLOC(length * sizeof(Value *));
     nrListElems += length;
 }
 
@@ -289,7 +293,7 @@ void EvalState::mkList(Value & v, unsigned int length)
 void EvalState::mkAttrs(Value & v)
 {
     v.type = tAttrs;
-    v.attrs = new Bindings;
+    v.attrs = new (UseGC) Bindings;
 }
 
 
@@ -1089,6 +1093,7 @@ void EvalState::printStats()
     bool showStats = getEnv("NIX_SHOW_STATS", "0") != "0";
     Verbosity v = showStats ? lvlInfo : lvlDebug;
     printMsg(v, "evaluation statistics:");
+    printMsg(v, format("  size of a value: %1%") % sizeof(Value));
     printMsg(v, format("  expressions evaluated: %1%") % nrEvaluated);
     printMsg(v, format("  stack space used: %1% bytes") % (&x - deepestStack));
     printMsg(v, format("  max eval() nesting depth: %1%") % maxRecursionDepth);
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index 501ac93d016e..d74a0350624d 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -7,6 +7,8 @@
 
 #include <map>
 
+#include <gc/gc_allocator.h>
+
 
 namespace nix {
 
@@ -16,7 +18,7 @@ struct Env;
 struct Value;
 struct Attr;
 
-typedef std::map<Symbol, Attr> Bindings;
+typedef std::map<Symbol, Attr, std::less<Symbol>, gc_allocator<std::pair<const Symbol, Attr> > > Bindings;
 
 
 typedef enum {
@@ -313,6 +315,7 @@ private:
     char * deepestStack; /* for measuring stack usage */
     
     friend class RecursionCounter;
+    friend class ExprOpUpdate;
 };
 
 
diff --git a/src/nix-env/Makefile.am b/src/nix-env/Makefile.am
index 7dfa7425a062..169c85fcb679 100644
--- a/src/nix-env/Makefile.am
+++ b/src/nix-env/Makefile.am
@@ -4,7 +4,8 @@ nix_env_SOURCES = nix-env.cc profiles.cc profiles.hh user-env.cc user-env.hh hel
 
 nix_env_LDADD = ../libmain/libmain.la ../libexpr/libexpr.la \
  ../libstore/libstore.la ../libutil/libutil.la \
- ../boost/format/libformat.la @ADDITIONAL_NETWORK_LIBS@
+ ../boost/format/libformat.la @ADDITIONAL_NETWORK_LIBS@ \
+ -L/home/eelco/Dev/nix/boehmgc/lib -lgc
 
 nix-env.o: help.txt.hh
 
@@ -14,4 +15,5 @@ nix-env.o: help.txt.hh
 AM_CXXFLAGS = \
  -I$(srcdir)/.. \
  -I$(srcdir)/../libutil -I$(srcdir)/../libstore \
- -I$(srcdir)/../libexpr -I$(srcdir)/../libmain -I../libexpr
+ -I$(srcdir)/../libexpr -I$(srcdir)/../libmain -I../libexpr \
+ -I/home/eelco/Dev/nix/boehmgc/include
diff --git a/src/nix-instantiate/Makefile.am b/src/nix-instantiate/Makefile.am
index a65907a8d40a..c6455b116d43 100644
--- a/src/nix-instantiate/Makefile.am
+++ b/src/nix-instantiate/Makefile.am
@@ -3,7 +3,8 @@ bin_PROGRAMS = nix-instantiate
 nix_instantiate_SOURCES = nix-instantiate.cc help.txt
 nix_instantiate_LDADD = ../libmain/libmain.la ../libexpr/libexpr.la \
  ../libstore/libstore.la ../libutil/libutil.la \
- ../boost/format/libformat.la @ADDITIONAL_NETWORK_LIBS@
+ ../boost/format/libformat.la @ADDITIONAL_NETWORK_LIBS@ \
+ -L/home/eelco/Dev/nix/boehmgc/lib -lgc
 
 nix-instantiate.o: help.txt.hh
 
@@ -12,4 +13,6 @@ nix-instantiate.o: help.txt.hh
 
 AM_CXXFLAGS = \
  -I$(srcdir)/.. -I$(srcdir)/../libutil -I$(srcdir)/../libstore \
- -I$(srcdir)/../libexpr -I$(srcdir)/../libmain -I../libexpr
+ -I$(srcdir)/../libexpr -I$(srcdir)/../libmain -I../libexpr \
+ -I/home/eelco/Dev/nix/boehmgc/include
+
-- 
cgit 1.4.1


From 64c3325b0bef8c0234bf797033e129323b36ad1e Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <e.dolstra@tudelft.nl>
Date: Fri, 22 Oct 2010 13:39:15 +0000
Subject: * Make building against the Boehm GC a configure option.

---
 configure.ac                    | 13 +++++++++++++
 src/libexpr/Makefile.am         |  3 +--
 src/libexpr/eval.cc             | 23 ++++++++++++++++++-----
 src/libexpr/eval.hh             |  6 ++++++
 src/nix-env/Makefile.am         |  5 ++---
 src/nix-instantiate/Makefile.am |  6 ++----
 6 files changed, 42 insertions(+), 14 deletions(-)

(limited to 'src/nix-instantiate')

diff --git a/configure.ac b/configure.ac
index 1caa9be5c4a6..02eebf6924b7 100644
--- a/configure.ac
+++ b/configure.ac
@@ -250,6 +250,19 @@ AC_SUBST(bzip2_bin)
 AC_SUBST(bzip2_bin_test)
 
 
+# Whether to use the Boehm garbage collector.
+AC_ARG_WITH(boehm-gc, AC_HELP_STRING([--with-boehm-gc=PATH],
+  [prefix of the Boehm GC package to enable garbage collection in the Nix expression evaluator]),
+  boehmgc=$withval, boehmgc=)
+if test -n "$boehmgc"; then
+  boehmgc_lib="-L$boehmgc/lib -lgc"
+  CXXFLAGS="-I$boehmgc/include $CXXFLAGS"
+  AC_DEFINE(HAVE_BOEHMGC, 1, [Whether to use the Boehm garbage collector.])
+fi
+AC_SUBST(boehmgc_lib)
+AC_SUBST(boehmgc_include)
+  
+
 AC_ARG_ENABLE(init-state, AC_HELP_STRING([--disable-init-state],
   [do not initialise DB etc. in `make install']),
   init_state=$enableval, init_state=yes)
diff --git a/src/libexpr/Makefile.am b/src/libexpr/Makefile.am
index 24aa2968b195..e7228e183581 100644
--- a/src/libexpr/Makefile.am
+++ b/src/libexpr/Makefile.am
@@ -20,8 +20,7 @@ EXTRA_DIST = lexer.l parser.y
 
 AM_CXXFLAGS = \
  -I$(srcdir)/.. \
- -I$(srcdir)/../libutil -I$(srcdir)/../libstore \
- -I/home/eelco/Dev/nix/boehmgc/include
+ -I$(srcdir)/../libutil -I$(srcdir)/../libstore
 
 
 # Parser generation.
diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 46978f6d0b81..c8a031ac6d0a 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -8,9 +8,18 @@
 
 #include <cstring>
 
+#if HAVE_BOEHMGC
+
 #include <gc/gc.h>
 #include <gc/gc_cpp.h>
 
+#else
+
+#define GC_STRDUP strdup
+#define GC_MALLOC malloc
+
+#endif
+
 
 #define LocalNoInline(f) static f __attribute__((noinline)); f
 #define LocalNoInlineNoReturn(f) static f __attribute__((noinline, noreturn)); f
@@ -151,7 +160,7 @@ void EvalState::addPrimOp(const string & name,
     v.type = tPrimOp;
     v.primOp.arity = arity;
     v.primOp.fun = primOp;
-    v.primOp.name = GC_strdup(name2.c_str());
+    v.primOp.name = GC_STRDUP(name2.c_str());
     staticBaseEnv.vars[symbols.create(name)] = baseEnvDispl;
     baseEnv.values[baseEnvDispl++] = v;
     (*baseEnv.values[0].attrs)[symbols.create(name2)].value = v;
@@ -222,7 +231,7 @@ LocalNoInline(void addErrorPrefix(Error & e, const char * s, const string & s2,
 void mkString(Value & v, const char * s)
 {
     v.type = tString;
-    v.string.s = GC_strdup(s);
+    v.string.s = GC_STRDUP(s);
     v.string.context = 0;
 }
 
@@ -233,9 +242,9 @@ void mkString(Value & v, const string & s, const PathSet & context)
     if (!context.empty()) {
         unsigned int n = 0;
         v.string.context = (const char * *)
-            GC_malloc((context.size() + 1) * sizeof(char *));
+            GC_MALLOC((context.size() + 1) * sizeof(char *));
         foreach (PathSet::const_iterator, i, context) 
-            v.string.context[n++] = GC_strdup(i->c_str());
+            v.string.context[n++] = GC_STRDUP(i->c_str());
         v.string.context[n] = 0;
     }
 }
@@ -244,7 +253,7 @@ void mkString(Value & v, const string & s, const PathSet & context)
 void mkPath(Value & v, const char * s)
 {
     v.type = tPath;
-    v.path = GC_strdup(s);
+    v.path = GC_STRDUP(s);
 }
 
 
@@ -294,7 +303,11 @@ void EvalState::mkList(Value & v, unsigned int length)
 void EvalState::mkAttrs(Value & v)
 {
     v.type = tAttrs;
+#if HAVE_BOEHMGC
     v.attrs = new (UseGC) Bindings;
+#else
+    v.attrs = new Bindings;
+#endif
     nrAttrsets++;
 }
 
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index 9144d99a4b38..738ca9439f6d 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -7,7 +7,9 @@
 
 #include <map>
 
+#if HAVE_BOEHMGC
 #include <gc/gc_allocator.h>
+#endif
 
 
 namespace nix {
@@ -18,7 +20,11 @@ struct Env;
 struct Value;
 struct Attr;
 
+#if HAVE_BOEHMGC
 typedef std::map<Symbol, Attr, std::less<Symbol>, gc_allocator<std::pair<const Symbol, Attr> > > Bindings;
+#else
+typedef std::map<Symbol, Attr> Bindings;
+#endif
 
 
 typedef enum {
diff --git a/src/nix-env/Makefile.am b/src/nix-env/Makefile.am
index 169c85fcb679..a876b3eb386d 100644
--- a/src/nix-env/Makefile.am
+++ b/src/nix-env/Makefile.am
@@ -5,7 +5,7 @@ nix_env_SOURCES = nix-env.cc profiles.cc profiles.hh user-env.cc user-env.hh hel
 nix_env_LDADD = ../libmain/libmain.la ../libexpr/libexpr.la \
  ../libstore/libstore.la ../libutil/libutil.la \
  ../boost/format/libformat.la @ADDITIONAL_NETWORK_LIBS@ \
- -L/home/eelco/Dev/nix/boehmgc/lib -lgc
+ @boehmgc_lib@
 
 nix-env.o: help.txt.hh
 
@@ -15,5 +15,4 @@ nix-env.o: help.txt.hh
 AM_CXXFLAGS = \
  -I$(srcdir)/.. \
  -I$(srcdir)/../libutil -I$(srcdir)/../libstore \
- -I$(srcdir)/../libexpr -I$(srcdir)/../libmain -I../libexpr \
- -I/home/eelco/Dev/nix/boehmgc/include
+ -I$(srcdir)/../libexpr -I$(srcdir)/../libmain -I../libexpr
diff --git a/src/nix-instantiate/Makefile.am b/src/nix-instantiate/Makefile.am
index c6455b116d43..bc9792818c3c 100644
--- a/src/nix-instantiate/Makefile.am
+++ b/src/nix-instantiate/Makefile.am
@@ -4,7 +4,7 @@ nix_instantiate_SOURCES = nix-instantiate.cc help.txt
 nix_instantiate_LDADD = ../libmain/libmain.la ../libexpr/libexpr.la \
  ../libstore/libstore.la ../libutil/libutil.la \
  ../boost/format/libformat.la @ADDITIONAL_NETWORK_LIBS@ \
- -L/home/eelco/Dev/nix/boehmgc/lib -lgc
+ @boehmgc_lib@
 
 nix-instantiate.o: help.txt.hh
 
@@ -13,6 +13,4 @@ nix-instantiate.o: help.txt.hh
 
 AM_CXXFLAGS = \
  -I$(srcdir)/.. -I$(srcdir)/../libutil -I$(srcdir)/../libstore \
- -I$(srcdir)/../libexpr -I$(srcdir)/../libmain -I../libexpr \
- -I/home/eelco/Dev/nix/boehmgc/include
-
+ -I$(srcdir)/../libexpr -I$(srcdir)/../libmain -I../libexpr
-- 
cgit 1.4.1


From 41c45a9b319a5578e2731505ca3de2b9c50b4988 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <e.dolstra@tudelft.nl>
Date: Fri, 22 Oct 2010 14:47:42 +0000
Subject: * Store Value nodes outside of attribute sets.  I.e., Attr now stores
   a pointer to a Value, rather than the Value directly.  This improves   the
 effectiveness of garbage collection a lot: if the Value is   stored inside
 the set directly, then any live pointer to the Value   causes all other
 attributes in the set to be live as well.

---
 src/libexpr/Makefile.am                |  2 +-
 src/libexpr/attr-path.cc               |  5 +-
 src/libexpr/attr-path.hh               |  2 +-
 src/libexpr/common-opts.cc             |  7 +--
 src/libexpr/eval.cc                    | 97 ++++++++++++++++++++--------------
 src/libexpr/eval.hh                    |  7 ++-
 src/libexpr/get-drvs.cc                | 40 +++++++-------
 src/libexpr/get-drvs.hh                |  2 +-
 src/libexpr/nixexpr.cc                 |  4 +-
 src/libexpr/nixexpr.hh                 |  1 +
 src/libexpr/primops.cc                 | 70 ++++++++++++------------
 src/libexpr/value-to-xml.cc            | 14 ++---
 src/nix-env/nix-env.cc                 |  4 +-
 src/nix-env/user-env.cc                | 23 ++++----
 src/nix-instantiate/nix-instantiate.cc |  2 +-
 15 files changed, 150 insertions(+), 130 deletions(-)

(limited to 'src/nix-instantiate')

diff --git a/src/libexpr/Makefile.am b/src/libexpr/Makefile.am
index e7228e183581..6c38ecdd565f 100644
--- a/src/libexpr/Makefile.am
+++ b/src/libexpr/Makefile.am
@@ -11,7 +11,7 @@ pkginclude_HEADERS = \
  names.hh symbol-table.hh
 
 libexpr_la_LIBADD = ../libutil/libutil.la ../libstore/libstore.la \
- ../boost/format/libformat.la
+ ../boost/format/libformat.la @boehmgc_lib@
 
 BUILT_SOURCES = \
  parser-tab.hh lexer-tab.hh parser-tab.cc lexer-tab.cc
diff --git a/src/libexpr/attr-path.cc b/src/libexpr/attr-path.cc
index 0660ba1c1efc..365b03c0bf60 100644
--- a/src/libexpr/attr-path.cc
+++ b/src/libexpr/attr-path.cc
@@ -5,8 +5,9 @@
 namespace nix {
 
 
+// !!! Shouldn't we return a pointer to a Value?
 void findAlongAttrPath(EvalState & state, const string & attrPath,
-    const Bindings & autoArgs, Expr * e, Value & v)
+    Bindings & autoArgs, Expr * e, Value & v)
 {
     Strings tokens = tokenizeString(attrPath, ".");
 
@@ -48,7 +49,7 @@ void findAlongAttrPath(EvalState & state, const string & attrPath,
             Bindings::iterator a = v.attrs->find(state.symbols.create(attr));
             if (a == v.attrs->end())
                 throw Error(format("attribute `%1%' in selection path `%2%' not found") % attr % curPath);
-            v = a->second.value;
+            v = *a->second.value;
         }
 
         else if (apType == apIndex) {
diff --git a/src/libexpr/attr-path.hh b/src/libexpr/attr-path.hh
index b4f5c29d2ed8..b106da5ef817 100644
--- a/src/libexpr/attr-path.hh
+++ b/src/libexpr/attr-path.hh
@@ -11,7 +11,7 @@ namespace nix {
 
     
 void findAlongAttrPath(EvalState & state, const string & attrPath,
-    const Bindings & autoArgs, Expr * e, Value & v);
+    Bindings & autoArgs, Expr * e, Value & v);
 
     
 }
diff --git a/src/libexpr/common-opts.cc b/src/libexpr/common-opts.cc
index 9131951e315d..6b393c07df50 100644
--- a/src/libexpr/common-opts.cc
+++ b/src/libexpr/common-opts.cc
@@ -20,12 +20,13 @@ bool parseOptionArg(const string & arg, Strings::iterator & i,
     if (i == argsEnd) throw error;
     string value = *i++;
 
-    Value & v(autoArgs[state.symbols.create(name)].value);
+    Value * v = state.allocValue();
+    autoArgs[state.symbols.create(name)].value = v;
 
     if (arg == "--arg")
-        state.mkThunk_(v, parseExprFromString(state, value, absPath(".")));
+        state.mkThunk_(*v, parseExprFromString(state, value, absPath(".")));
     else
-        mkString(v, value);
+        mkString(*v, value);
     
     return true;
 }
diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index c8a031ac6d0a..ea48947258ec 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -58,7 +58,7 @@ std::ostream & operator << (std::ostream & str, const Value & v)
         typedef std::map<string, Value *> Sorted;
         Sorted sorted;
         foreach (Bindings::iterator, i, *v.attrs)
-            sorted[i->first] = &i->second.value;
+            sorted[i->first] = i->second.value;
         foreach (Sorted::iterator, i, sorted)
             str << i->first << " = " << *i->second << "; ";
         str << "}";
@@ -145,24 +145,26 @@ EvalState::~EvalState()
 
 void EvalState::addConstant(const string & name, Value & v)
 {
+    Value * v2 = allocValue();
+    *v2 = v;
     staticBaseEnv.vars[symbols.create(name)] = baseEnvDispl;
     baseEnv.values[baseEnvDispl++] = v;
     string name2 = string(name, 0, 2) == "__" ? string(name, 2) : name;
-    (*baseEnv.values[0].attrs)[symbols.create(name2)].value = v;
+    (*baseEnv.values[0].attrs)[symbols.create(name2)].value = v2;
 }
 
 
 void EvalState::addPrimOp(const string & name,
     unsigned int arity, PrimOp primOp)
 {
-    Value v;
+    Value * v = allocValue();
     string name2 = string(name, 0, 2) == "__" ? string(name, 2) : name;
-    v.type = tPrimOp;
-    v.primOp.arity = arity;
-    v.primOp.fun = primOp;
-    v.primOp.name = GC_STRDUP(name2.c_str());
+    v->type = tPrimOp;
+    v->primOp.arity = arity;
+    v->primOp.fun = primOp;
+    v->primOp.name = GC_STRDUP(name2.c_str());
     staticBaseEnv.vars[symbols.create(name)] = baseEnvDispl;
-    baseEnv.values[baseEnvDispl++] = v;
+    baseEnv.values[baseEnvDispl++] = *v;
     (*baseEnv.values[0].attrs)[symbols.create(name2)].value = v;
 }
 
@@ -265,7 +267,7 @@ Value * EvalState::lookupVar(Env * env, const VarRef & var)
         while (1) {
             Bindings::iterator j = env->values[0].attrs->find(var.name);
             if (j != env->values[0].attrs->end())
-                return &j->second.value;
+                return j->second.value;
             if (env->prevWith == 0)
                 throwEvalError("undefined variable `%1%'", var.name);
             for (unsigned int l = env->prevWith; l; --l, env = env->up) ;
@@ -275,6 +277,13 @@ Value * EvalState::lookupVar(Env * env, const VarRef & var)
 }
 
 
+Value * EvalState::allocValue()
+{
+    nrValues++;
+    return (Value *) GC_MALLOC(sizeof(Value));
+}
+
+
 Value * EvalState::allocValues(unsigned int count)
 {
     nrValues += count;
@@ -291,6 +300,14 @@ Env & EvalState::allocEnv(unsigned int size)
 }
 
 
+Value * EvalState::allocAttr(Value & vAttrs, const Symbol & name)
+{
+    Attr & a = (*vAttrs.attrs)[name];
+    a.value = allocValue();
+    return a.value;
+}
+
+    
 void EvalState::mkList(Value & v, unsigned int length)
 {
     v.type = tList;
@@ -321,11 +338,8 @@ void EvalState::mkThunk_(Value & v, Expr * expr)
 void EvalState::cloneAttrs(Value & src, Value & dst)
 {
     mkAttrs(dst);
-    foreach (Bindings::iterator, i, *src.attrs) {
-        Attr & a = (*dst.attrs)[i->first];
-        mkCopy(a.value, i->second.value);
-        a.pos = i->second.pos;
-    }
+    foreach (Bindings::iterator, i, *src.attrs)
+        (*dst.attrs)[i->first] = i->second;
 }
 
 
@@ -449,8 +463,9 @@ void ExprAttrs::eval(EvalState & state, Env & env, Value & v)
            environment. */
         foreach (Attrs::iterator, i, attrs) {
             nix::Attr & a = (*v.attrs)[i->first];
-            mkThunk(a.value, env2, i->second.first);
-            mkCopy(env2.values[displ++], a.value);
+            a.value = state.allocValue();
+            mkThunk(*a.value, env2, i->second.first);
+            mkCopy(env2.values[displ++], *a.value);
             a.pos = &i->second.second;
         }
 
@@ -459,7 +474,7 @@ void ExprAttrs::eval(EvalState & state, Env & env, Value & v)
         foreach (list<Inherited>::iterator, i, inherited) {
             nix::Attr & a = (*v.attrs)[i->first.name];
             Value * v2 = state.lookupVar(&env, i->first);
-            mkCopy(a.value, *v2);
+            a.value = v2;
             mkCopy(env2.values[displ++], *v2);
             a.pos = &i->second;
         }
@@ -474,10 +489,12 @@ void ExprAttrs::eval(EvalState & state, Env & env, Value & v)
            Hence we need __overrides.) */
         Bindings::iterator overrides = v.attrs->find(state.sOverrides);
         if (overrides != v.attrs->end()) {
-            state.forceAttrs(overrides->second.value);
-            foreach (Bindings::iterator, i, *overrides->second.value.attrs) {
+            state.forceAttrs(*overrides->second.value);
+            foreach (Bindings::iterator, i, *overrides->second.value->attrs) {
                 nix::Attr & a = (*v.attrs)[i->first];
-                mkCopy(a.value, i->second.value);
+                if (a.value)
+                    mkCopy(env2.values[displs[i->first]], *i->second.value);
+                a = i->second;
             }
         }
     }
@@ -485,13 +502,14 @@ void ExprAttrs::eval(EvalState & state, Env & env, Value & v)
     else {
         foreach (Attrs::iterator, i, attrs) {
             nix::Attr & a = (*v.attrs)[i->first];
-            mkThunk(a.value, env, i->second.first);
+            a.value = state.allocValue();
+            mkThunk(*a.value, env, i->second.first);
             a.pos = &i->second.second;
         }
 
         foreach (list<Inherited>::iterator, i, inherited) {
             nix::Attr & a = (*v.attrs)[i->first.name];
-            mkCopy(a.value, *state.lookupVar(&env, i->first));
+            a.value = state.lookupVar(&env, i->first);
             a.pos = &i->second;
         }
     }
@@ -548,13 +566,13 @@ void ExprSelect::eval(EvalState & state, Env & env, Value & v)
     if (i == v2.attrs->end())
         throwEvalError("attribute `%1%' missing", name);
     try {            
-        state.forceValue(i->second.value);
+        state.forceValue(*i->second.value);
     } catch (Error & e) {
         addErrorPrefix(e, "while evaluating the attribute `%1%' at %2%:\n",
             name, *i->second.pos);
         throw;
     }
-    v = i->second.value;
+    v = *i->second.value;
 }
 
 
@@ -578,9 +596,9 @@ void ExprApp::eval(EvalState & state, Env & env, Value & v)
 {
     Value vFun;
     state.eval(env, e1, vFun);
-    Value vArg;
-    mkThunk(vArg, env, e2); // !!! should this be on the heap?
-    state.callFunction(vFun, vArg, v);
+    Value * vArg = state.allocValue();
+    mkThunk(*vArg, env, e2);
+    state.callFunction(vFun, *vArg, v);
 }
 
 
@@ -656,7 +674,7 @@ void EvalState::callFunction(Value & fun, Value & arg, Value & v)
                 mkThunk(env2.values[displ++], env2, i->def);
             } else {
                 attrsUsed++;
-                mkCopy(env2.values[displ++], j->second.value);
+                mkCopy(env2.values[displ++], *j->second.value);
             }
         }
 
@@ -677,7 +695,7 @@ void EvalState::callFunction(Value & fun, Value & arg, Value & v)
 }
 
 
-void EvalState::autoCallFunction(const Bindings & args, Value & fun, Value & res)
+void EvalState::autoCallFunction(Bindings & args, Value & fun, Value & res)
 {
     forceValue(fun);
 
@@ -690,7 +708,7 @@ void EvalState::autoCallFunction(const Bindings & args, Value & fun, Value & res
     mkAttrs(actualArgs);
 
     foreach (Formals::Formals_::iterator, i, fun.lambda.fun->formals->formals) {
-        Bindings::const_iterator j = args.find(i->name);
+        Bindings::iterator j = args.find(i->name);
         if (j != args.end())
             (*actualArgs.attrs)[i->name] = j->second;
         else if (!i->def)
@@ -780,11 +798,8 @@ void ExprOpUpdate::eval(EvalState & state, Env & env, Value & v)
 
     state.cloneAttrs(v1, v);
 
-    foreach (Bindings::iterator, i, *v2.attrs) {
-        Attr & a = (*v.attrs)[i->first];
-        mkCopy(a.value, i->second.value);
-        a.pos = i->second.pos;
-    }
+    foreach (Bindings::iterator, i, *v2.attrs)
+        (*v.attrs)[i->first] = i->second;
 
     state.nrOpUpdateValuesCopied += v.attrs->size();
 }
@@ -866,7 +881,7 @@ void EvalState::strictForceValue(Value & v)
     
     if (v.type == tAttrs) {
         foreach (Bindings::iterator, i, *v.attrs)
-            strictForceValue(i->second.value);
+            strictForceValue(*i->second.value);
     }
     
     else if (v.type == tList) {
@@ -957,7 +972,7 @@ bool EvalState::isDerivation(Value & v)
 {
     if (v.type != tAttrs) return false;
     Bindings::iterator i = v.attrs->find(sType);
-    return i != v.attrs->end() && forceStringNoCtx(i->second.value) == "derivation";
+    return i != v.attrs->end() && forceStringNoCtx(*i->second.value) == "derivation";
 }
 
 
@@ -1001,7 +1016,7 @@ string EvalState::coerceToString(Value & v, PathSet & context,
         Bindings::iterator i = v.attrs->find(sOutPath);
         if (i == v.attrs->end())
             throwTypeError("cannot coerce an attribute set (except a derivation) to a string");
-        return coerceToString(i->second.value, context, coerceMore, copyToStore);
+        return coerceToString(*i->second.value, context, coerceMore, copyToStore);
     }
 
     if (coerceMore) {
@@ -1087,9 +1102,9 @@ bool EvalState::eqValues(Value & v1, Value & v2)
 
         case tAttrs: {
             if (v1.attrs->size() != v2.attrs->size()) return false;
-            Bindings::iterator i, j;
-            for (i = v1.attrs->begin(), j = v2.attrs->begin(); i != v1.attrs->end(); ++i, ++j)
-                if (i->first != j->first || !eqValues(i->second.value, j->second.value))
+            Bindings::iterator i = v1.attrs->begin(), j = v2.attrs->begin();
+            for ( ; i != v1.attrs->end(); ++i, ++j)
+                if (i->first != j->first || !eqValues(*i->second.value, *j->second.value))
                     return false;
             return true;
         }
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index 738ca9439f6d..ee7db91a08b2 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -122,7 +122,7 @@ struct Env
 
 struct Attr
 {
-    Value value;
+    Value * value;
     Pos * pos;
     Attr() : pos(&noPos) { };
 };
@@ -294,12 +294,15 @@ public:
 
     /* Automatically call a function for which each argument has a
        default value or has a binding in the `args' map. */
-    void autoCallFunction(const Bindings & args, Value & fun, Value & res);
+    void autoCallFunction(Bindings & args, Value & fun, Value & res);
     
     /* Allocation primitives. */
+    Value * allocValue();
     Value * allocValues(unsigned int count);
     Env & allocEnv(unsigned int size);
 
+    Value * allocAttr(Value & vAttrs, const Symbol & name);
+
     void mkList(Value & v, unsigned int length);
     void mkAttrs(Value & v);
     void mkThunk_(Value & v, Expr * expr);
diff --git a/src/libexpr/get-drvs.cc b/src/libexpr/get-drvs.cc
index 82a92416bed6..63106b87b5af 100644
--- a/src/libexpr/get-drvs.cc
+++ b/src/libexpr/get-drvs.cc
@@ -10,7 +10,7 @@ string DrvInfo::queryDrvPath(EvalState & state) const
     if (drvPath == "" && attrs) {
         Bindings::iterator i = attrs->find(state.sDrvPath);
         PathSet context;
-        (string &) drvPath = i != attrs->end() ? state.coerceToPath(i->second.value, context) : "";
+        (string &) drvPath = i != attrs->end() ? state.coerceToPath(*i->second.value, context) : "";
     }
     return drvPath;
 }
@@ -21,7 +21,7 @@ string DrvInfo::queryOutPath(EvalState & state) const
     if (outPath == "" && attrs) {
         Bindings::iterator i = attrs->find(state.sOutPath);
         PathSet context;
-        (string &) outPath = i != attrs->end() ? state.coerceToPath(i->second.value, context) : "";
+        (string &) outPath = i != attrs->end() ? state.coerceToPath(*i->second.value, context) : "";
     }
     return outPath;
 }
@@ -36,21 +36,21 @@ MetaInfo DrvInfo::queryMetaInfo(EvalState & state) const
     Bindings::iterator a = attrs->find(state.sMeta);
     if (a == attrs->end()) return meta; /* fine, empty meta information */
 
-    state.forceAttrs(a->second.value);
+    state.forceAttrs(*a->second.value);
 
-    foreach (Bindings::iterator, i, *a->second.value.attrs) {
+    foreach (Bindings::iterator, i, *a->second.value->attrs) {
         MetaValue value;
-        state.forceValue(i->second.value);
-        if (i->second.value.type == tString) {
+        state.forceValue(*i->second.value);
+        if (i->second.value->type == tString) {
             value.type = MetaValue::tpString;
-            value.stringValue = i->second.value.string.s;
-        } else if (i->second.value.type == tInt) {
+            value.stringValue = i->second.value->string.s;
+        } else if (i->second.value->type == tInt) {
             value.type = MetaValue::tpInt;
-            value.intValue = i->second.value.integer;
-        } else if (i->second.value.type == tList) {
+            value.intValue = i->second.value->integer;
+        } else if (i->second.value->type == tList) {
             value.type = MetaValue::tpStrings;
-            for (unsigned int j = 0; j < i->second.value.list.length; ++j)
-                value.stringValues.push_back(state.forceStringNoCtx(*i->second.value.list.elems[j]));
+            for (unsigned int j = 0; j < i->second.value->list.length; ++j)
+                value.stringValues.push_back(state.forceStringNoCtx(*i->second.value->list.elems[j]));
         } else continue;
         ((MetaInfo &) meta)[i->first] = value;
     }
@@ -99,13 +99,13 @@ static bool getDerivation(EvalState & state, Value & v,
         Bindings::iterator i = v.attrs->find(state.sName);
         /* !!! We really would like to have a decent back trace here. */
         if (i == v.attrs->end()) throw TypeError("derivation name missing");
-        drv.name = state.forceStringNoCtx(i->second.value);
+        drv.name = state.forceStringNoCtx(*i->second.value);
 
-        i = v.attrs->find(state.sSystem);
-        if (i == v.attrs->end())
+        Bindings::iterator i2 = v.attrs->find(state.sSystem);
+        if (i2 == v.attrs->end())
             drv.system = "unknown";
         else
-            drv.system = state.forceStringNoCtx(i->second.value);
+            drv.system = state.forceStringNoCtx(*i2->second.value);
 
         drv.attrs = v.attrs;
 
@@ -138,7 +138,7 @@ static string addToPath(const string & s1, const string & s2)
 
 
 static void getDerivations(EvalState & state, Value & vIn,
-    const string & pathPrefix, const Bindings & autoArgs,
+    const string & pathPrefix, Bindings & autoArgs,
     DrvInfos & drvs, Done & done)
 {
     Value v;
@@ -168,7 +168,7 @@ static void getDerivations(EvalState & state, Value & vIn,
         foreach (SortedSymbols::iterator, i, attrs) {
             startNest(nest, lvlDebug, format("evaluating attribute `%1%'") % i->first);
             string pathPrefix2 = addToPath(pathPrefix, i->first);
-            Value & v2((*v.attrs)[i->second].value);
+            Value & v2(*(*v.attrs)[i->second].value);
             if (combineChannels)
                 getDerivations(state, v2, pathPrefix2, autoArgs, drvs, done);
             else if (getDerivation(state, v2, pathPrefix2, drvs, done)) {
@@ -178,7 +178,7 @@ static void getDerivations(EvalState & state, Value & vIn,
                    attribute. */
                 if (v2.type == tAttrs) {
                     Bindings::iterator j = v2.attrs->find(state.symbols.create("recurseForDerivations"));
-                    if (j != v2.attrs->end() && state.forceBool(j->second.value))
+                    if (j != v2.attrs->end() && state.forceBool(*j->second.value))
                         getDerivations(state, v2, pathPrefix2, autoArgs, drvs, done);
                 }
             }
@@ -200,7 +200,7 @@ static void getDerivations(EvalState & state, Value & vIn,
 
 
 void getDerivations(EvalState & state, Value & v, const string & pathPrefix,
-    const Bindings & autoArgs, DrvInfos & drvs)
+    Bindings & autoArgs, DrvInfos & drvs)
 {
     Done done;
     getDerivations(state, v, pathPrefix, autoArgs, drvs, done);
diff --git a/src/libexpr/get-drvs.hh b/src/libexpr/get-drvs.hh
index 7b96decf4a08..7c014b7e41f2 100644
--- a/src/libexpr/get-drvs.hh
+++ b/src/libexpr/get-drvs.hh
@@ -70,7 +70,7 @@ typedef list<DrvInfo> DrvInfos;
 bool getDerivation(EvalState & state, Value & v, DrvInfo & drv);
 
 void getDerivations(EvalState & state, Value & v, const string & pathPrefix,
-    const Bindings & autoArgs, DrvInfos & drvs);
+    Bindings & autoArgs, DrvInfos & drvs);
 
  
 }
diff --git a/src/libexpr/nixexpr.cc b/src/libexpr/nixexpr.cc
index 898fdb609417..9f2ea78831f2 100644
--- a/src/libexpr/nixexpr.cc
+++ b/src/libexpr/nixexpr.cc
@@ -213,10 +213,10 @@ void ExprAttrs::bindVars(const StaticEnv & env)
         unsigned int displ = 0;
 
         foreach (ExprAttrs::Attrs::iterator, i, attrs)
-            newEnv.vars[i->first] = displ++;
+            displs[i->first] = newEnv.vars[i->first] = displ++;
 
         foreach (list<Inherited>::iterator, i, inherited) {
-            newEnv.vars[i->first.name] = displ++;
+            displs[i->first.name] = newEnv.vars[i->first.name] = displ++;
             i->first.bind(env);
         }
 
diff --git a/src/libexpr/nixexpr.hh b/src/libexpr/nixexpr.hh
index 1d03220f644a..5c0071dca2ce 100644
--- a/src/libexpr/nixexpr.hh
+++ b/src/libexpr/nixexpr.hh
@@ -137,6 +137,7 @@ struct ExprAttrs : Expr
     Attrs attrs;
     list<Inherited> inherited;
     std::map<Symbol, Pos> attrNames; // used during parsing
+    std::map<Symbol, unsigned int> displs;
     ExprAttrs() : recursive(false) { };
     COMMON_METHODS
 };
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 973670e68384..c7709ca9eb36 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -119,24 +119,24 @@ static void prim_genericClosure(EvalState & state, Value * * args, Value & v)
         args[0]->attrs->find(state.symbols.create("startSet"));
     if (startSet == args[0]->attrs->end())
         throw EvalError("attribute `startSet' required");
-    state.forceList(startSet->second.value);
+    state.forceList(*startSet->second.value);
 
     list<Value *> workSet;
-    for (unsigned int n = 0; n < startSet->second.value.list.length; ++n)
-        workSet.push_back(startSet->second.value.list.elems[n]);
+    for (unsigned int n = 0; n < startSet->second.value->list.length; ++n)
+        workSet.push_back(startSet->second.value->list.elems[n]);
 
     /* Get the operator. */
     Bindings::iterator op =
         args[0]->attrs->find(state.symbols.create("operator"));
     if (op == args[0]->attrs->end())
         throw EvalError("attribute `operator' required");
-    state.forceValue(op->second.value);
+    state.forceValue(*op->second.value);
 
     /* Construct the closure by applying the operator to element of
        `workSet', adding the result to `workSet', continuing until
        no new elements are found. */
     list<Value> res;
-    set<Value, CompareValues> doneKeys;
+    set<Value, CompareValues> doneKeys; // !!! use Value *?
     while (!workSet.empty()) {
 	Value * e = *(workSet.begin());
 	workSet.pop_front();
@@ -147,15 +147,15 @@ static void prim_genericClosure(EvalState & state, Value * * args, Value & v)
             e->attrs->find(state.symbols.create("key"));
         if (key == e->attrs->end())
             throw EvalError("attribute `key' required");
-        state.forceValue(key->second.value);
+        state.forceValue(*key->second.value);
 
-        if (doneKeys.find(key->second.value) != doneKeys.end()) continue;
-        doneKeys.insert(key->second.value);
+        if (doneKeys.find(*key->second.value) != doneKeys.end()) continue;
+        doneKeys.insert(*key->second.value);
         res.push_back(*e);
         
         /* Call the `operator' function with `e' as argument. */
         Value call;
-        mkApp(call, op->second.value, *e);
+        mkApp(call, *op->second.value, *e);
         state.forceList(call);
 
         /* Add the values returned by the operator to the work set. */
@@ -213,11 +213,13 @@ static void prim_tryEval(EvalState & state, Value * * args, Value & v)
     state.mkAttrs(v);
     try {
         state.forceValue(*args[0]);
-        (*v.attrs)[state.symbols.create("value")].value = *args[0];
-        mkBool((*v.attrs)[state.symbols.create("success")].value, true);
+        printMsg(lvlError, format("%1%") % *args[0]);
+        (*v.attrs)[state.symbols.create("value")].value = args[0];
+        mkBool(*state.allocAttr(v, state.symbols.create("success")), true);
+        printMsg(lvlError, format("%1%") % v);
     } catch (AssertionError & e) {
-        mkBool((*v.attrs)[state.symbols.create("value")].value, false);
-        mkBool((*v.attrs)[state.symbols.create("success")].value, false);
+        mkBool(*state.allocAttr(v, state.symbols.create("value")), false);
+        mkBool(*state.allocAttr(v, state.symbols.create("success")), false);
     }
 }
 
@@ -326,7 +328,7 @@ static void prim_derivationStrict(EvalState & state, Value * * args, Value & v)
     string drvName;
     Pos & posDrvName(*attr->second.pos);
     try {        
-        drvName = state.forceStringNoCtx(attr->second.value);
+        drvName = state.forceStringNoCtx(*attr->second.value);
     } catch (Error & e) {
         e.addPrefix(format("while evaluating the derivation attribute `name' at %1%:\n") % posDrvName);
         throw;
@@ -349,9 +351,9 @@ static void prim_derivationStrict(EvalState & state, Value * * args, Value & v)
             /* The `args' attribute is special: it supplies the
                command-line arguments to the builder. */
             if (key == "args") {
-                state.forceList(i->second.value);
-                for (unsigned int n = 0; n < i->second.value.list.length; ++n) {
-                    string s = state.coerceToString(*i->second.value.list.elems[n], context, true);
+                state.forceList(*i->second.value);
+                for (unsigned int n = 0; n < i->second.value->list.length; ++n) {
+                    string s = state.coerceToString(*i->second.value->list.elems[n], context, true);
                     drv.args.push_back(s);
                 }
             }
@@ -359,7 +361,7 @@ static void prim_derivationStrict(EvalState & state, Value * * args, Value & v)
             /* All other attributes are passed to the builder through
                the environment. */
             else {
-                string s = state.coerceToString(i->second.value, context, true);
+                string s = state.coerceToString(*i->second.value, context, true);
                 drv.env[key] = s;
                 if (key == "builder") drv.builder = s;
                 else if (i->first == state.sSystem) drv.platform = s;
@@ -488,8 +490,8 @@ static void prim_derivationStrict(EvalState & state, Value * * args, Value & v)
 
     /* !!! assumes a single output */
     state.mkAttrs(v);
-    mkString((*v.attrs)[state.sOutPath].value, outPath, singleton<PathSet>(drvPath));
-    mkString((*v.attrs)[state.sDrvPath].value, drvPath, singleton<PathSet>("=" + drvPath));
+    mkString(*state.allocAttr(v, state.sOutPath), outPath, singleton<PathSet>(drvPath));
+    mkString(*state.allocAttr(v, state.sDrvPath), drvPath, singleton<PathSet>("=" + drvPath));
 }
 
 
@@ -713,8 +715,8 @@ static void prim_getAttr(EvalState & state, Value * * args, Value & v)
     if (i == args[1]->attrs->end())
         throw EvalError(format("attribute `%1%' missing") % attr);
     // !!! add to stack trace?
-    state.forceValue(i->second.value);
-    v = i->second.value;
+    state.forceValue(*i->second.value);
+    v = *i->second.value;
 }
 
 
@@ -766,15 +768,13 @@ static void prim_listToAttrs(EvalState & state, Value * * args, Value & v)
         Bindings::iterator j = v2.attrs->find(state.sName);
         if (j == v2.attrs->end())
             throw TypeError("`name' attribute missing in a call to `listToAttrs'");
-        string name = state.forceStringNoCtx(j->second.value);
+        string name = state.forceStringNoCtx(*j->second.value);
         
-        j = v2.attrs->find(state.symbols.create("value"));
-        if (j == v2.attrs->end())
+        Bindings::iterator j2 = v2.attrs->find(state.symbols.create("value"));
+        if (j2 == v2.attrs->end())
             throw TypeError("`value' attribute missing in a call to `listToAttrs'");
 
-        Attr & a = (*v.attrs)[state.symbols.create(name)];
-        mkCopy(a.value, j->second.value);
-        a.pos = j->second.pos;
+        (*v.attrs)[state.symbols.create(name)] = j2->second;
     }
 }
 
@@ -791,11 +791,8 @@ static void prim_intersectAttrs(EvalState & state, Value * * args, Value & v)
 
     foreach (Bindings::iterator, i, *args[0]->attrs) {
         Bindings::iterator j = args[1]->attrs->find(i->first);
-        if (j != args[1]->attrs->end()) {
-            Attr & a = (*v.attrs)[j->first];
-            mkCopy(a.value, j->second.value);
-            a.pos = j->second.pos;
-        }
+        if (j != args[1]->attrs->end())
+            (*v.attrs)[j->first] = j->second;
     }
 }
 
@@ -824,7 +821,8 @@ static void prim_functionArgs(EvalState & state, Value * * args, Value & v)
     if (!args[0]->lambda.fun->matchAttrs) return;
 
     foreach (Formals::Formals_::iterator, i, args[0]->lambda.fun->formals->formals)
-        mkBool((*v.attrs)[i->name].value, i->def);
+        // !!! should optimise booleans (allocate only once)
+        mkBool(*state.allocAttr(v, i->name), i->def);
 }
 
 
@@ -1007,8 +1005,8 @@ static void prim_parseDrvName(EvalState & state, Value * * args, Value & v)
     string name = state.forceStringNoCtx(*args[0]);
     DrvName parsed(name);
     state.mkAttrs(v);
-    mkString((*v.attrs)[state.sName].value, parsed.name);
-    mkString((*v.attrs)[state.symbols.create("version")].value, parsed.version);
+    mkString(*state.allocAttr(v, state.sName), parsed.name);
+    mkString(*state.allocAttr(v, state.symbols.create("version")), parsed.version);
 }
 
 
diff --git a/src/libexpr/value-to-xml.cc b/src/libexpr/value-to-xml.cc
index 8955a8a33931..1bb200fb858b 100644
--- a/src/libexpr/value-to-xml.cc
+++ b/src/libexpr/value-to-xml.cc
@@ -45,7 +45,7 @@ static void showAttrs(EvalState & state, bool strict, bool location,
         
         XMLOpenElement _(doc, "attr", xmlAttrs);
         printValueAsXML(state, strict, location,
-            a.value, doc, context, drvsSeen);
+            *a.value, doc, context, drvsSeen);
     }
 }
 
@@ -90,16 +90,16 @@ static void printValueAsXML(EvalState & state, bool strict, bool location,
                 Path drvPath;
                 a = v.attrs->find(state.sDrvPath);
                 if (a != v.attrs->end()) {
-                    if (strict) state.forceValue(a->second.value);
-                    if (a->second.value.type == tString)
-                        xmlAttrs["drvPath"] = drvPath = a->second.value.string.s;
+                    if (strict) state.forceValue(*a->second.value);
+                    if (a->second.value->type == tString)
+                        xmlAttrs["drvPath"] = drvPath = a->second.value->string.s;
                 }
         
                 a = v.attrs->find(state.sOutPath);
                 if (a != v.attrs->end()) {
-                    if (strict) state.forceValue(a->second.value);
-                    if (a->second.value.type == tString)
-                        xmlAttrs["outPath"] = a->second.value.string.s;
+                    if (strict) state.forceValue(*a->second.value);
+                    if (a->second.value->type == tString)
+                        xmlAttrs["outPath"] = a->second.value->string.s;
                 }
 
                 XMLOpenElement _(doc, "derivation", xmlAttrs);
diff --git a/src/nix-env/nix-env.cc b/src/nix-env/nix-env.cc
index df32b9f603ab..4895c68e94a8 100644
--- a/src/nix-env/nix-env.cc
+++ b/src/nix-env/nix-env.cc
@@ -161,7 +161,7 @@ static Expr * loadSourceExpr(EvalState & state, const Path & path)
 
 
 static void loadDerivations(EvalState & state, Path nixExprPath,
-    string systemFilter, const Bindings & autoArgs,
+    string systemFilter, Bindings & autoArgs,
     const string & pathPrefix, DrvInfos & elems)
 {
     Value v;
@@ -321,7 +321,7 @@ static bool isPath(const string & s)
 
 
 static void queryInstSources(EvalState & state,
-    const InstallSourceInfo & instSource, const Strings & args,
+    InstallSourceInfo & instSource, const Strings & args,
     DrvInfos & elems, bool newestOnly)
 {
     InstallSourceType type = instSource.type;
diff --git a/src/nix-env/user-env.cc b/src/nix-env/user-env.cc
index 0a619f698f98..07c94fe4d49a 100644
--- a/src/nix-env/user-env.cc
+++ b/src/nix-env/user-env.cc
@@ -25,7 +25,8 @@ DrvInfos queryInstalled(EvalState & state, const Path & userEnv)
     if (pathExists(manifestFile)) {
         Value v;
         state.eval(parseExprFromFile(state, manifestFile), v);
-        getDerivations(state, v, "", Bindings(), elems);
+        Bindings bindings;
+        getDerivations(state, v, "", bindings, elems);
     } else if (pathExists(oldManifestFile))
         readLegacyManifest(oldManifestFile, elems);
 
@@ -62,19 +63,19 @@ bool createUserEnv(EvalState & state, DrvInfos & elems,
         manifest.list.elems[n++] = &v;
         state.mkAttrs(v);
 
-        mkString((*v.attrs)[state.sType].value, "derivation");
-        mkString((*v.attrs)[state.sName].value, i->name);
-        mkString((*v.attrs)[state.sSystem].value, i->system);
-        mkString((*v.attrs)[state.sOutPath].value, i->queryOutPath(state));
+        mkString(*state.allocAttr(v, state.sType), "derivation");
+        mkString(*state.allocAttr(v, state.sName), i->name);
+        mkString(*state.allocAttr(v, state.sSystem), i->system);
+        mkString(*state.allocAttr(v, state.sOutPath), i->queryOutPath(state));
         if (drvPath != "")
-            mkString((*v.attrs)[state.sDrvPath].value, i->queryDrvPath(state));
+            mkString(*state.allocAttr(v, state.sDrvPath), i->queryDrvPath(state));
         
-        state.mkAttrs((*v.attrs)[state.sMeta].value);
+        state.mkAttrs(*state.allocAttr(v, state.sMeta));
         
         MetaInfo meta = i->queryMetaInfo(state);
 
         foreach (MetaInfo::const_iterator, j, meta) {
-            Value & v2((*(*v.attrs)[state.sMeta].value.attrs)[state.symbols.create(j->first)].value);
+            Value & v2(*state.allocAttr(*(*v.attrs)[state.sMeta].value, state.symbols.create(j->first)));
             switch (j->second.type) {
                 case MetaValue::tpInt: mkInt(v2, j->second.intValue); break;
                 case MetaValue::tpString: mkString(v2, j->second.stringValue); break;
@@ -114,10 +115,10 @@ bool createUserEnv(EvalState & state, DrvInfos & elems,
        builder with the manifest as argument. */
     Value args, topLevel;
     state.mkAttrs(args);
-    mkString((*args.attrs)[state.sSystem].value, thisSystem);
-    mkString((*args.attrs)[state.symbols.create("manifest")].value,
+    mkString(*state.allocAttr(args, state.sSystem), thisSystem);
+    mkString(*state.allocAttr(args, state.symbols.create("manifest")),
         manifestFile, singleton<PathSet>(manifestFile));
-    (*args.attrs)[state.symbols.create("derivations")].value = manifest;
+    (*args.attrs)[state.symbols.create("derivations")].value = &manifest;
     mkApp(topLevel, envBuilder, args);
         
     /* Evaluate it. */
diff --git a/src/nix-instantiate/nix-instantiate.cc b/src/nix-instantiate/nix-instantiate.cc
index 2925f9c5efb7..b330f0cf11f8 100644
--- a/src/nix-instantiate/nix-instantiate.cc
+++ b/src/nix-instantiate/nix-instantiate.cc
@@ -38,7 +38,7 @@ static bool indirectRoot = false;
 
 
 void processExpr(EvalState & state, const Strings & attrPaths,
-    bool parseOnly, bool strict, const Bindings & autoArgs,
+    bool parseOnly, bool strict, Bindings & autoArgs,
     bool evalOnly, bool xmlOutput, bool location, Expr * e)
 {
     if (parseOnly)
-- 
cgit 1.4.1


From e11e6fb1c6709ca3f0e596a7b1fb988df2fbd9b1 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <e.dolstra@tudelft.nl>
Date: Thu, 28 Oct 2010 12:29:40 +0000
Subject: * Handle out of memory condition.

---
 src/libexpr/eval.cc             | 10 +++++-----
 src/libmain/Makefile.am         |  2 +-
 src/libmain/shared.cc           | 20 ++++++++++++++++++++
 src/nix-env/Makefile.am         |  3 +--
 src/nix-instantiate/Makefile.am |  3 +--
 5 files changed, 28 insertions(+), 10 deletions(-)

(limited to 'src/nix-instantiate')

diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 919ebd4ba9b6..c36a679d350d 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -259,9 +259,8 @@ void mkString(Value & v, const string & s, const PathSet & context)
     mkString(v, s.c_str());
     if (!context.empty()) {
         unsigned int n = 0;
-        v.string.context = (const char * *)
-            GC_MALLOC((context.size() + 1) * sizeof(char *));
-        foreach (PathSet::const_iterator, i, context) 
+        v.string.context = NEW const char *[context.size() + 1];
+        foreach (PathSet::const_iterator, i, context)  
             v.string.context[n++] = GC_STRDUP(i->c_str());
         v.string.context[n] = 0;
     }
@@ -305,7 +304,7 @@ Value * EvalState::lookupVar(Env * env, const VarRef & var)
 Value * EvalState::allocValue()
 {
     nrValues++;
-    return (Value *) GC_MALLOC(sizeof(Value));
+    return NEW Value;
 }
 
 
@@ -314,6 +313,7 @@ Env & EvalState::allocEnv(unsigned int size)
     nrEnvs++;
     nrValuesInEnvs += size;
     Env * env = (Env *) GC_MALLOC(sizeof(Env) + size * sizeof(Value *));
+    if (!env) throw std::bad_alloc();
 
     /* Clear the values because maybeThunk() expects this. */
     for (unsigned i = 0; i < size; ++i)
@@ -335,7 +335,7 @@ void EvalState::mkList(Value & v, unsigned int length)
 {
     v.type = tList;
     v.list.length = length;
-    v.list.elems = (Value * *) GC_MALLOC(length * sizeof(Value *));
+    v.list.elems = NEW Value *[length];
     nrListElems += length;
 }
 
diff --git a/src/libmain/Makefile.am b/src/libmain/Makefile.am
index a9ee6604255e..1a2146e0448f 100644
--- a/src/libmain/Makefile.am
+++ b/src/libmain/Makefile.am
@@ -2,7 +2,7 @@ pkglib_LTLIBRARIES = libmain.la
 
 libmain_la_SOURCES = shared.cc
 
-libmain_la_LIBADD = ../libstore/libstore.la
+libmain_la_LIBADD = ../libstore/libstore.la @boehmgc_lib@
 
 pkginclude_HEADERS = shared.hh
 
diff --git a/src/libmain/shared.cc b/src/libmain/shared.cc
index eddc4e64b3d7..440949bd2a0a 100644
--- a/src/libmain/shared.cc
+++ b/src/libmain/shared.cc
@@ -13,6 +13,10 @@
 #include <sys/stat.h>
 #include <unistd.h>
 
+#if HAVE_BOEHMGC
+#include <gc/gc.h>
+#endif
+
 
 namespace nix {
 
@@ -314,6 +318,14 @@ static void setuidInit()
 }
 
 
+/* Called when the Boehm GC runs out of memory. */
+static void * oomHandler(size_t requested)
+{
+    /* Convert this to a proper C++ exception. */
+    throw std::bad_alloc();
+}
+
+
 }
 
 
@@ -335,6 +347,14 @@ int main(int argc, char * * argv)
 
     std::ios::sync_with_stdio(false);
 
+#if HAVE_BOEHMGC
+    /* Initialise the Boehm garbage collector.  This isn't necessary
+       on most platforms, but for portability we do it anyway. */
+    GC_INIT();
+
+    GC_oom_fn = oomHandler;
+#endif
+
     try {
         try {
             initAndRun(argc, argv);
diff --git a/src/nix-env/Makefile.am b/src/nix-env/Makefile.am
index a876b3eb386d..7dfa7425a062 100644
--- a/src/nix-env/Makefile.am
+++ b/src/nix-env/Makefile.am
@@ -4,8 +4,7 @@ nix_env_SOURCES = nix-env.cc profiles.cc profiles.hh user-env.cc user-env.hh hel
 
 nix_env_LDADD = ../libmain/libmain.la ../libexpr/libexpr.la \
  ../libstore/libstore.la ../libutil/libutil.la \
- ../boost/format/libformat.la @ADDITIONAL_NETWORK_LIBS@ \
- @boehmgc_lib@
+ ../boost/format/libformat.la @ADDITIONAL_NETWORK_LIBS@
 
 nix-env.o: help.txt.hh
 
diff --git a/src/nix-instantiate/Makefile.am b/src/nix-instantiate/Makefile.am
index bc9792818c3c..a65907a8d40a 100644
--- a/src/nix-instantiate/Makefile.am
+++ b/src/nix-instantiate/Makefile.am
@@ -3,8 +3,7 @@ bin_PROGRAMS = nix-instantiate
 nix_instantiate_SOURCES = nix-instantiate.cc help.txt
 nix_instantiate_LDADD = ../libmain/libmain.la ../libexpr/libexpr.la \
  ../libstore/libstore.la ../libutil/libutil.la \
- ../boost/format/libformat.la @ADDITIONAL_NETWORK_LIBS@ \
- @boehmgc_lib@
+ ../boost/format/libformat.la @ADDITIONAL_NETWORK_LIBS@
 
 nix-instantiate.o: help.txt.hh
 
-- 
cgit 1.4.1