64 lines
1.8 KiB
Perl
64 lines
1.8 KiB
Perl
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Test deduplication of build artifacts when using Dune cache with hard links.
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$ export DUNE_CACHE=enabled
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$ export DUNE_CACHE_ROOT=$PWD/.cache
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$ cat > dune-project <<EOF
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> (lang dune 2.1)
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> EOF
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$ cat > dune <<EOF
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> (rule
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> (deps source)
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> (targets target)
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> (action (copy source target)))
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> EOF
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$ cat > source <<EOF
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> \_o< COIN
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> EOF
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Here we build [target], which is a copy of [source]. After the build, the same
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file will appear in the build directory twice: (i) as [_build/default/source],
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because all sources are first copied to the build directory, and (ii) as
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[_build/default/target], as the build result. Furthermore, the same file will
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also be stored to the build cache, somewhere in the [files/v4] directory. Dune
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cache will recognise that all three files are identical and will use hard links
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to share them on disk, hence the hard link counts of 3.
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$ dune build target
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$ cat _build/default/target
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\_o< COIN
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$ dune_cmd stat hardlinks _build/default/source
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3
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$ dune_cmd stat hardlinks _build/default/target
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3
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Demonstrate that sharing of build artifacts can be abused to corrupt the cache.
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$ chmod 777 _build/default/target
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$ echo "\_o< MEOW" > _build/default/target
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$ rm -rf _build
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$ dune build target
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$ cat _build/default/target
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\_o< MEOW
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Test that by using the [copy] mode we can disable the sharing.
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$ rm -rf $DUNE_CACHE_ROOT
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$ rm -rf _build
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$ dune build target --cache-storage-mode=copy
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$ cat _build/default/target
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\_o< COIN
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$ dune_cmd stat hardlinks _build/default/source
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1
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$ dune_cmd stat hardlinks _build/default/target
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1
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In the [copy] mode, we can't corrupt the cache so easily.
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$ chmod 777 _build/default/target
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$ echo "\_o< MEOW" > _build/default/target
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$ rm -rf _build
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$ dune build target
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$ cat _build/default/target
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\_o< COIN
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