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authorEelco Dolstra <eelco.dolstra@logicblox.com>2014-02-18T00·01+0100
committerEelco Dolstra <eelco.dolstra@logicblox.com>2014-02-18T00·01+0100
commit1aa19b24b27c6bbf4d46cdd7f6d06b534dd67c19 (patch)
treec406737fe705ef010f7efb555c6b319b1c984754 /src/nix-store/dotgraph.hh
parent4ec626a286afd4a9596357fc6d36aaf8bc07442a (diff)
Add a flag ‘--check’ to verify build determinism
The flag ‘--check’ to ‘nix-store -r’ or ‘nix-build’ will cause Nix to
redo the build of a derivation whose output paths are already valid.
If the new output differs from the original output, an error is
printed.  This makes it easier to test if a build is deterministic.
(Obviously this cannot catch all sources of non-determinism, but it
catches the most common one, namely the current time.)

For example:

  $ nix-build '<nixpkgs>' -A patchelf
  ...
  $ nix-build '<nixpkgs>' -A patchelf --check
  error: derivation `/nix/store/1ipvxsdnbhl1rw6siz6x92s7sc8nwkkb-patchelf-0.6' may not be deterministic: hash mismatch in output `/nix/store/4pc1dmw5xkwmc6q3gdc9i5nbjl4dkjpp-patchelf-0.6.drv'

The --check build fails if not all outputs are valid.  Thus the first
call to nix-build is necessary to ensure that all outputs are valid.

The current outputs are left untouched: the new outputs are either put
in a chroot or diverted to a different location in the store using
hash rewriting.
Diffstat (limited to 'src/nix-store/dotgraph.hh')
0 files changed, 0 insertions, 0 deletions