* Removed the `id' attribute hack.

* Formalise the notion of fixed-output derivations, i.e., derivations
  for which a cryptographic hash of the output is known in advance.
  Changes to such derivations should not propagate upwards through the
  dependency graph.  Previously this was done by specifying the hash
  component of the output path through the `id' attribute, but this is
  insecure since you can lie about it (i.e., you can specify any hash
  and then produce a completely different output).  Now the
  responsibility for checking the output is moved from the builder to
  Nix itself.

  A fixed-output derivation can be created by specifying the
  `outputHash' and `outputHashAlgo' attributes, the latter taking
  values `md5', `sha1', and `sha256', and the former specifying the
  actual hash in hexadecimal or in base-32 (auto-detected by looking
  at the length of the attribute value).  MD5 is included for
  compatibility but should be considered deprecated.

* Removed the `drvPath' pseudo-attribute in derivation results.  It's
  no longer necessary.

* Cleaned up the support for multiple output paths in derivation store
  expressions.  Each output now has a unique identifier (e.g., `out',
  `devel', `docs').  Previously there was no way to tell output paths
  apart at the store expression level.

* `nix-hash' now has a flag `--base32' to specify that the hash should
  be printed in base-32 notation.

* `fetchurl' accepts parameters `sha256' and `sha1' in addition to
  `md5'.

* `nix-prefetch-url' now prints out a SHA-1 hash in base-32.  (TODO: a
  flag to specify the hash.)

1 files changed, 32 insertions, 5 deletions

diff --git a/src/libstore/storeexpr.cc b/src/libstore/storeexpr.cc
index de29959edf60..d8300a066a0e 100644
--- a/src/libstore/storeexpr.cc
+++ b/src/libstore/storeexpr.cc
@@ -8,7 +8,7 @@
 
 Hash hashTerm(ATerm t)
 {
-    return hashString(atPrint(t), htMD5);
+    return hashString(htSHA256, atPrint(t));
 }
 
 
@@ -20,14 +20,20 @@ Path writeTerm(ATerm t, const string & suffix)
 }
 
 
+void checkPath(const string & s)
+{
+    if (s.size() == 0 || s[0] != '/')
+        throw Error(format("bad path `%1%' in store expression") % s);
+}
+    
+
 static void parsePaths(ATermList paths, PathSet & out)
 {
     for (ATermIterator i(paths); i; ++i) {
         if (ATgetType(*i) != AT_APPL)
             throw badTerm("not a path", *i);
         string s = aterm2String(*i);
-        if (s.size() == 0 || s[0] != '/')
-            throw badTerm("not a path", *i);
+        checkPath(s);
         out.insert(s);
     }
 }
@@ -92,7 +98,18 @@ static bool parseDerivation(ATerm t, Derivation & derivation)
     if (!matchDerive(t, outs, ins, platform, builder, args, bnds))
         return false;
 
-    parsePaths(outs, derivation.outputs);
+    for (ATermIterator i(outs); i; ++i) {
+        ATerm id, path, hashAlgo, hash;
+        if (!matchDerivationOutput(*i, id, path, hashAlgo, hash))
+            return false;
+        DerivationOutput out;
+        out.path = aterm2String(path);
+        checkPath(out.path);
+        out.hashAlgo = aterm2String(hashAlgo);
+        out.hash = aterm2String(hash);
+        derivation.outputs[aterm2String(id)] = out;
+    }
+
     parsePaths(ins, derivation.inputs);
 
     derivation.builder = aterm2String(builder);
@@ -155,6 +172,16 @@ static ATerm unparseClosure(const Closure & closure)
 
 static ATerm unparseDerivation(const Derivation & derivation)
 {
+    ATermList outputs = ATempty;
+    for (DerivationOutputs::const_iterator i = derivation.outputs.begin();
+         i != derivation.outputs.end(); i++)
+        outputs = ATinsert(outputs,
+            makeDerivationOutput(
+                toATerm(i->first),
+                toATerm(i->second.path),
+                toATerm(i->second.hashAlgo),
+                toATerm(i->second.hash)));
+
     ATermList args = ATempty;
     for (Strings::const_iterator i = derivation.args.begin();
          i != derivation.args.end(); i++)
@@ -169,7 +196,7 @@ static ATerm unparseDerivation(const Derivation & derivation)
                 toATerm(i->second)));
 
     return makeDerive(
-        unparsePaths(derivation.outputs),
+        ATreverse(outputs),
         unparsePaths(derivation.inputs),
         toATerm(derivation.platform),
         toATerm(derivation.builder),