Merge branch 'nix'.

This is a squashed commit of the following:

commit 0dccab9f417b406f5d4aedc81900fc7b2f16c9f6
Author: Eelco Dolstra <eelco.dolstra@logicblox.com>
Date:   Thu Jul 2 00:30:16 2015 +0200

    Typo

commit 2cd28517b13524c242c7758783b0b2d8250fdded
Author: Ludovic Courtès <ludo@gnu.org>
Date:   Wed Jul 1 14:56:34 2015 +0200

    Preserve supplementary groups of build users

    The following patch is an attempt to address this bug (see
    <http://bugs.gnu.org/18994>) by preserving the supplementary groups of
    build users in the build environment.

    In practice, I would expect that supplementary groups would contain only
    one or two groups: the build users group, and possibly the “kvm” group.

    [Changed &at(0) to data() and removed tabs - Eelco]

commit 6e38685ef65284093df79ebe7378bac33b0e7e5d
Author: Eelco Dolstra <eelco.dolstra@logicblox.com>
Date:   Tue Jun 30 21:41:26 2015 +0200

    GC: Handle ENOSPC creating/moving to the trash directory

    Issue #564.

commit 5e0a9ae2e25a1016389f4893a6ed6682aadcf51d
Author: Eelco Dolstra <eelco.dolstra@logicblox.com>
Date:   Mon Jun 22 15:54:55 2015 +0200

    Use posix_fallocate to create /nix/var/nix/db/reserved

commit 4e5ab98d6d14f8b0e3bd1d77b2f4f2354e7a49a8
Author: Eelco Dolstra <eelco.dolstra@logicblox.com>
Date:   Mon Jun 22 15:47:40 2015 +0200

    Make /nix/var/nix/db/reserved bigger

    Issue #564.

commit 60bda60fc06135aa97a93301b1a9e2270768f5b3
Author: Eelco Dolstra <eelco.dolstra@logicblox.com>
Date:   Wed Jun 10 16:17:06 2015 +0200

    Export outputPaths function

    This is useful for the new hydra-queue-runner.

commit 5dfea34048aa8541f20aeb2fbcd163561b609a49
Author: Eelco Dolstra <eelco.dolstra@logicblox.com>
Date:   Thu Jul 2 22:51:33 2015 +0200

    Use std::vector::data()

commit 2459458bc8257734ca78cb7a2db3df20bd730ec0
Author: Eelco Dolstra <eelco.dolstra@logicblox.com>
Date:   Thu Jun 4 16:04:41 2015 +0200

    Allow substitutes for builds that have preferLocalBuild set

    Not substituting builds with "preferLocalBuild = true" was a bad idea,
    because it didn't take the cost of dependencies into account. For
    instance, if we can't substitute a fetchgit call, then we have to
    download/build git and all its dependencies.

    Partially reverts 5558652709f27e8a887580b77b93c705659d7a4b and adds a
    new derivation attribute "allowSubstitutes" to specify whether a
    derivation may be substituted.

1 files changed, 13 insertions, 5 deletions

diff --git a/nix/libstore/local-store.cc b/nix/libstore/local-store.cc
index 630cb80c41..b2c78477b6 100644
--- a/nix/libstore/local-store.cc
+++ b/nix/libstore/local-store.cc
@@ -288,7 +288,17 @@ LocalStore::LocalStore(bool reserveSpace)
             struct stat st;
             if (stat(reservedPath.c_str(), &st) == -1 ||
                 st.st_size != settings.reservedSize)
-                writeFile(reservedPath, string(settings.reservedSize, 'X'));
+            {
+                AutoCloseFD fd = open(reservedPath.c_str(), O_WRONLY | O_CREAT, 0600);
+                int res = -1;
+#if HAVE_POSIX_FALLOCATE
+                res = posix_fallocate(fd, 0, settings.reservedSize);
+#endif
+                if (res == -1) {
+                    writeFull(fd, string(settings.reservedSize, 'X'));
+                    ftruncate(fd, settings.reservedSize);
+                }
+            }
         }
         else
             deletePath(reservedPath);
@@ -1166,10 +1176,8 @@ string LocalStore::getLineFromSubstituter(RunningSubstituter & run)
             if (n == 0) throw EndOfFile(format("substituter `%1%' died unexpectedly") % run.program);
             err.append(buf, n);
             string::size_type p;
-            while (((p = err.find('\n')) != string::npos)
-		   || ((p = err.find('\r')) != string::npos)) {
-	        string thing(err, 0, p + 1);
-		writeToStderr(run.program + ": " + thing);
+            while ((p = err.find('\n')) != string::npos) {
+                printMsg(lvlError, run.program + ": " + string(err, 0, p));
                 err = string(err, p + 1);
             }
         }