* 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.)

2 files changed, 12 insertions, 7 deletions

diff --git a/src/nix-hash/help.txt b/src/nix-hash/help.txt
index a38c2ab9ed06..31fff1ffabd6 100644
--- a/src/nix-hash/help.txt
+++ b/src/nix-hash/help.txt
@@ -4,3 +4,5 @@ nix-hash [OPTIONS...] [FILES...]
 files.
 
   --flat: compute hash of regular file contents, not metadata
+  --base32: print hash in base-32 instead of hexadecimal
+  --type HASH: use hash algorithm HASH ("md5" (default), "sha1", "sha256")
diff --git a/src/nix-hash/nix-hash.cc b/src/nix-hash/nix-hash.cc
index 2cef7818e857..78c6f44012b4 100644
--- a/src/nix-hash/nix-hash.cc
+++ b/src/nix-hash/nix-hash.cc
@@ -15,22 +15,25 @@ void run(Strings args)
 {
     HashType ht = htMD5;
     bool flat = false;
+    bool base32 = false;
     
     for (Strings::iterator i = args.begin();
          i != args.end(); i++)
     {
         if (*i == "--flat") flat = true;
+        else if (*i == "--base32") base32 = true;
         else if (*i == "--type") {
             ++i;
             if (i == args.end()) throw UsageError("`--type' requires an argument");
-            if (*i == "md5") ht = htMD5;
-            else if (*i == "sha1") ht = htSHA1;
-            else if (*i == "sha256") ht = htSHA256;
-            else throw UsageError(format("unknown hash type `%1%'") % *i);
+            ht = parseHashType(*i);
+            if (ht == htUnknown)
+                throw UsageError(format("unknown hash type `%1%'") % *i);
+        }
+        else {
+            Hash h = flat ? hashFile(ht, *i) : hashPath(ht, *i);
+            cout << format("%1%\n") %
+                (base32 ? printHash32(h) : printHash(h));
         }
-        else
-            cout << format("%1%\n") % printHash(
-                (flat ? hashFile(*i, ht) : hashPath(*i, ht)));
     }
 }