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authorEelco Dolstra <eelco.dolstra@logicblox.com>2015-12-02 14:59:07 +0100
committerLudovic Courtès <ludo@gnu.org>2015-12-09 14:29:41 +0100
commitcb9601029ea164b86bdf997f7160d494c15d344b (patch)
treed3ee490acee71bf9199f7f2cd0426faeb2b6c419 /nix
parenta8d65643fb21fdf6c46b3d248bda411d970e53ab (diff)
daemon: Use deterministic $TMPDIR in chroot.
Rather than using $<host-TMPDIR>/nix-build-<drvname>-<number>, the temporary directory is now always /tmp/nix-build-<drvname>-0. This improves bitwise-exact reproducibility for builds that store $TMPDIR in their build output. (Of course, those should still be fixed...) * nix/libstore/build.cc (DerivationGoal)[tmpDirInSandbox]: New field. (DerivationGoal::startBuilder): Initialize 'useChroot' earlier. Compute 'tmpDirInSandbox', and use it when populating 'dirsInChroot'. * doc/guix.texi (Build Environment Setup): Document it. Co-authored-by: Ludovic Courtès <ludo@gnu.org>
Diffstat (limited to 'nix')
-rw-r--r--nix/libstore/build.cc24
1 files changed, 16 insertions, 8 deletions
diff --git a/nix/libstore/build.cc b/nix/libstore/build.cc
index e19c32b1c9..47c7f9728e 100644
--- a/nix/libstore/build.cc
+++ b/nix/libstore/build.cc
@@ -736,6 +736,9 @@ private:
/* The temporary directory. */
Path tmpDir;
+ /* The path of the temporary directory in the sandbox. */
+ Path tmpDirInSandbox;
+
/* File descriptor for the log file. */
FILE * fLogFile;
BZFILE * bzLogFile;
@@ -1662,6 +1665,8 @@ void DerivationGoal::startBuilder()
% drv.platform % settings.thisSystem % drvPath);
}
+ useChroot = settings.useChroot;
+
/* Construct the environment passed to the builder. */
env.clear();
@@ -1694,20 +1699,25 @@ void DerivationGoal::startBuilder()
/* Create a temporary directory where the build will take
place. */
- tmpDir = createTempDir("", "nix-build-" + storePathToName(drvPath), false, false, 0700);
+ auto drvName = storePathToName(drvPath);
+ tmpDir = createTempDir("", "nix-build-" + drvName, false, false, 0700);
+
+ /* In a sandbox, for determinism, always use the same temporary
+ directory. */
+ tmpDirInSandbox = useChroot ? "/tmp/nix-build-" + drvName + "-0" : tmpDir;
/* For convenience, set an environment pointing to the top build
directory. */
- env["NIX_BUILD_TOP"] = tmpDir;
+ env["NIX_BUILD_TOP"] = tmpDirInSandbox;
/* Also set TMPDIR and variants to point to this directory. */
- env["TMPDIR"] = env["TEMPDIR"] = env["TMP"] = env["TEMP"] = tmpDir;
+ env["TMPDIR"] = env["TEMPDIR"] = env["TMP"] = env["TEMP"] = tmpDirInSandbox;
/* Explicitly set PWD to prevent problems with chroot builds. In
particular, dietlibc cannot figure out the cwd because the
inode of the current directory doesn't appear in .. (because
getdents returns the inode of the mount point). */
- env["PWD"] = tmpDir;
+ env["PWD"] = tmpDirInSandbox;
/* Compatibility hack with Nix <= 0.7: if this is a fixed-output
derivation, tell the builder, so that for instance `fetchurl'
@@ -1792,8 +1802,6 @@ void DerivationGoal::startBuilder()
throw SysError(format("cannot change ownership of '%1%'") % tmpDir);
}
- useChroot = settings.useChroot;
-
if (useChroot) {
#if CHROOT_ENABLED
/* Create a temporary directory in which we set up the chroot
@@ -1855,7 +1863,7 @@ void DerivationGoal::startBuilder()
else
dirsInChroot[string(i, 0, p)] = string(i, p + 1);
}
- dirsInChroot[tmpDir] = tmpDir;
+ dirsInChroot[tmpDirInSandbox] = tmpDir;
/* Make the closure of the inputs available in the chroot,
rather than the whole Nix store. This prevents any access
@@ -2173,7 +2181,7 @@ void DerivationGoal::runChild()
}
#endif
- if (chdir(tmpDir.c_str()) == -1)
+ if (chdir(tmpDirInSandbox.c_str()) == -1)
throw SysError(format("changing into `%1%'") % tmpDir);
/* Close all other file descriptors. */