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![Filip Hejsek](/assets/img/avatar_default.png)
While it is expected to have several git dirs within the `.git/modules/`
tree, it is important that they do not interfere with each other. For
example, if one submodule was called "captain" and another submodule
"captain/hooks", their respective git dirs would clash, as they would be
located in `.git/modules/captain/` and `.git/modules/captain/hooks/`,
respectively, i.e. the latter's files could clash with the actual Git
hooks of the former.
To prevent these clashes, and in particular to prevent hooks from being
written and then executed as part of a recursive clone, we introduced
checks as part of the fix for CVE-2019-1387 in a8dee3ca61
(Disallow
dubiously-nested submodule git directories, 2019-10-01).
It is currently possible to bypass the check for clashing submodule
git dirs in two ways:
1. parallel cloning
2. checkout --recurse-submodules
Let's check not only before, but also after parallel cloning (and before
checking out the submodule), that the git dir is not clashing with
another one, otherwise fail. This addresses the parallel cloning issue.
As to the parallel checkout issue: It requires quite a few manual steps
to create clashing git dirs because Git itself would refuse to
initialize the inner one, as demonstrated by the test case.
Nevertheless, let's teach the recursive checkout (namely, the
`submodule_move_head()` function that is used by the recursive checkout)
to be careful to verify that it does not use a clashing git dir, and if
it does, disable it (by deleting the `HEAD` file so that subsequent Git
calls won't recognize it as a git dir anymore).
Note: The parallel cloning test case contains a `cat err` that proved to
be highly useful when analyzing the racy nature of the operation (the
operation can fail with three different error messages, depending on
timing), and was left on purpose to ease future debugging should the
need arise.
Signed-off-by: Filip Hejsek <filip.hejsek@gmail.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
349 lines
9.5 KiB
Bash
Executable file
349 lines
9.5 KiB
Bash
Executable file
#!/bin/sh
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test_description='check broken or malicious patterns in .git* files
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Such as:
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- presence of .. in submodule names;
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Exercise the name-checking function on a variety of names, and then give a
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real-world setup that confirms we catch this in practice.
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- nested submodule names
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- symlinked .gitmodules, etc
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'
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. ./test-lib.sh
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. "$TEST_DIRECTORY"/lib-pack.sh
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test_expect_success 'setup' '
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git config --global protocol.file.allow always
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'
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test_expect_success 'check names' '
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cat >expect <<-\EOF &&
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valid
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valid/with/paths
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EOF
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test-tool submodule check-name >actual <<-\EOF &&
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valid
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valid/with/paths
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../foo
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/../foo
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..\foo
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\..\foo
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foo/..
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foo/../
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foo\..
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foo\..\
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foo/../bar
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EOF
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test_cmp expect actual
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'
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test_expect_success 'create innocent subrepo' '
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git init innocent &&
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git -C innocent commit --allow-empty -m foo
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'
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test_expect_success 'submodule add refuses invalid names' '
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test_must_fail \
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git submodule add --name ../../modules/evil "$PWD/innocent" evil
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'
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test_expect_success 'add evil submodule' '
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git submodule add "$PWD/innocent" evil &&
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mkdir modules &&
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cp -r .git/modules/evil modules &&
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write_script modules/evil/hooks/post-checkout <<-\EOF &&
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echo >&2 "RUNNING POST CHECKOUT"
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EOF
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git config -f .gitmodules submodule.evil.update checkout &&
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git config -f .gitmodules --rename-section \
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submodule.evil submodule.../../modules/evil &&
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git add modules &&
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git commit -am evil
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'
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# This step seems like it shouldn't be necessary, since the payload is
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# contained entirely in the evil submodule. But due to the vagaries of the
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# submodule code, checking out the evil module will fail unless ".git/modules"
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# exists. Adding another submodule (with a name that sorts before "evil") is an
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# easy way to make sure this is the case in the victim clone.
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test_expect_success 'add other submodule' '
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git submodule add "$PWD/innocent" another-module &&
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git add another-module &&
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git commit -am another
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'
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test_expect_success 'clone evil superproject' '
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git clone --recurse-submodules . victim >output 2>&1 &&
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! grep "RUNNING POST CHECKOUT" output
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'
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test_expect_success 'fsck detects evil superproject' '
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test_must_fail git fsck
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'
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test_expect_success 'transfer.fsckObjects detects evil superproject (unpack)' '
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rm -rf dst.git &&
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git init --bare dst.git &&
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git -C dst.git config transfer.fsckObjects true &&
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test_must_fail git push dst.git HEAD
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'
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test_expect_success 'transfer.fsckObjects detects evil superproject (index)' '
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rm -rf dst.git &&
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git init --bare dst.git &&
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git -C dst.git config transfer.fsckObjects true &&
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git -C dst.git config transfer.unpackLimit 1 &&
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test_must_fail git push dst.git HEAD
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'
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# Normally our packs contain commits followed by trees followed by blobs. This
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# reverses the order, which requires backtracking to find the context of a
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# blob. We'll start with a fresh gitmodules-only tree to make it simpler.
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test_expect_success 'create oddly ordered pack' '
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git checkout --orphan odd &&
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git rm -rf --cached . &&
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git add .gitmodules &&
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git commit -m odd &&
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{
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pack_header 3 &&
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pack_obj $(git rev-parse HEAD:.gitmodules) &&
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pack_obj $(git rev-parse HEAD^{tree}) &&
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pack_obj $(git rev-parse HEAD)
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} >odd.pack &&
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pack_trailer odd.pack
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'
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test_expect_success 'transfer.fsckObjects handles odd pack (unpack)' '
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rm -rf dst.git &&
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git init --bare dst.git &&
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test_must_fail git -C dst.git unpack-objects --strict <odd.pack
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'
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test_expect_success 'transfer.fsckObjects handles odd pack (index)' '
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rm -rf dst.git &&
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git init --bare dst.git &&
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test_must_fail git -C dst.git index-pack --strict --stdin <odd.pack
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'
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test_expect_success 'index-pack --strict works for non-repo pack' '
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rm -rf dst.git &&
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git init --bare dst.git &&
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cp odd.pack dst.git &&
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test_must_fail git -C dst.git index-pack --strict odd.pack 2>output &&
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# Make sure we fail due to bad gitmodules content, not because we
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# could not read the blob in the first place.
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grep gitmodulesName output
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'
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check_dotx_symlink () {
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fsck_must_fail=test_must_fail
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fsck_prefix=error
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refuse_index=t
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case "$1" in
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--warning)
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fsck_must_fail=
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fsck_prefix=warning
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refuse_index=
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shift
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;;
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esac
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name=$1
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type=$2
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path=$3
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dir=symlink-$name-$type
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test_expect_success "set up repo with symlinked $name ($type)" '
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git init $dir &&
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(
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cd $dir &&
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# Make the tree directly to avoid index restrictions.
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#
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# Because symlinks store the target as a blob, choose
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# a pathname that could be parsed as a .gitmodules file
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# to trick naive non-symlink-aware checking.
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tricky="[foo]bar=true" &&
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content=$(git hash-object -w ../.gitmodules) &&
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target=$(printf "$tricky" | git hash-object -w --stdin) &&
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{
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printf "100644 blob $content\t$tricky\n" &&
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printf "120000 blob $target\t$path\n"
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} >bad-tree
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) &&
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tree=$(git -C $dir mktree <$dir/bad-tree)
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'
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test_expect_success "fsck detects symlinked $name ($type)" '
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(
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cd $dir &&
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# Check not only that we fail, but that it is due to the
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# symlink detector
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$fsck_must_fail git fsck 2>output &&
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grep "$fsck_prefix.*tree $tree: ${name}Symlink" output
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)
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'
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test -n "$refuse_index" &&
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test_expect_success "refuse to load symlinked $name into index ($type)" '
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test_must_fail \
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git -C $dir \
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-c core.protectntfs \
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-c core.protecthfs \
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read-tree $tree 2>err &&
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grep "invalid path.*$name" err &&
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git -C $dir ls-files -s >out &&
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test_must_be_empty out
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'
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}
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check_dotx_symlink gitmodules vanilla .gitmodules
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check_dotx_symlink gitmodules ntfs ".gitmodules ."
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check_dotx_symlink gitmodules hfs ".${u200c}gitmodules"
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check_dotx_symlink --warning gitattributes vanilla .gitattributes
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check_dotx_symlink --warning gitattributes ntfs ".gitattributes ."
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check_dotx_symlink --warning gitattributes hfs ".${u200c}gitattributes"
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check_dotx_symlink --warning gitignore vanilla .gitignore
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check_dotx_symlink --warning gitignore ntfs ".gitignore ."
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check_dotx_symlink --warning gitignore hfs ".${u200c}gitignore"
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check_dotx_symlink --warning mailmap vanilla .mailmap
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check_dotx_symlink --warning mailmap ntfs ".mailmap ."
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check_dotx_symlink --warning mailmap hfs ".${u200c}mailmap"
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test_expect_success 'fsck detects non-blob .gitmodules' '
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git init non-blob &&
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(
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cd non-blob &&
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# As above, make the funny tree directly to avoid index
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# restrictions.
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mkdir subdir &&
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cp ../.gitmodules subdir/file &&
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git add subdir/file &&
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git commit -m ok &&
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git ls-tree HEAD | sed s/subdir/.gitmodules/ | git mktree &&
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test_must_fail git fsck 2>output &&
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test_i18ngrep gitmodulesBlob output
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)
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'
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test_expect_success 'fsck detects corrupt .gitmodules' '
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git init corrupt &&
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(
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cd corrupt &&
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echo "[broken" >.gitmodules &&
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git add .gitmodules &&
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git commit -m "broken gitmodules" &&
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git fsck 2>output &&
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test_i18ngrep gitmodulesParse output &&
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test_i18ngrep ! "bad config" output
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)
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'
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test_expect_success WINDOWS 'prevent git~1 squatting on Windows' '
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git init squatting &&
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(
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cd squatting &&
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mkdir a &&
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touch a/..git &&
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git add a/..git &&
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test_tick &&
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git commit -m initial &&
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modules="$(test_write_lines \
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"[submodule \"b.\"]" "url = ." "path = c" \
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"[submodule \"b\"]" "url = ." "path = d\\\\a" |
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git hash-object -w --stdin)" &&
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rev="$(git rev-parse --verify HEAD)" &&
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hash="$(echo x | git hash-object -w --stdin)" &&
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test_must_fail git update-index --add \
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--cacheinfo 160000,$rev,d\\a 2>err &&
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test_i18ngrep "Invalid path" err &&
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git -c core.protectNTFS=false update-index --add \
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--cacheinfo 100644,$modules,.gitmodules \
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--cacheinfo 160000,$rev,c \
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--cacheinfo 160000,$rev,d\\a \
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--cacheinfo 100644,$hash,d./a/x \
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--cacheinfo 100644,$hash,d./a/..git &&
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test_tick &&
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git -c core.protectNTFS=false commit -m "module"
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) &&
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if test_have_prereq MINGW
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then
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test_must_fail git -c core.protectNTFS=false \
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clone --recurse-submodules squatting squatting-clone 2>err &&
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test_i18ngrep -e "directory not empty" -e "not an empty directory" err &&
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! grep gitdir squatting-clone/d/a/git~2
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fi
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'
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test_expect_success 'setup submodules with nested git dirs' '
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git init nested &&
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test_commit -C nested nested &&
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(
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cd nested &&
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cat >.gitmodules <<-EOF &&
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[submodule "hippo"]
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url = .
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path = thing1
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[submodule "hippo/hooks"]
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url = .
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path = thing2
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EOF
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git clone . thing1 &&
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git clone . thing2 &&
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git add .gitmodules thing1 thing2 &&
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test_tick &&
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git commit -m nested
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)
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'
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test_expect_success 'git dirs of sibling submodules must not be nested' '
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test_must_fail git clone --recurse-submodules nested clone 2>err &&
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test_i18ngrep "is inside git dir" err
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'
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test_expect_success 'submodule git dir nesting detection must work with parallel cloning' '
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test_must_fail git clone --recurse-submodules --jobs=2 nested clone_parallel 2>err &&
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cat err &&
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grep -E "(already exists|is inside git dir|not a git repository)" err &&
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{
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test_path_is_missing .git/modules/hippo/HEAD ||
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test_path_is_missing .git/modules/hippo/hooks/HEAD
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}
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'
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test_expect_success 'checkout -f --recurse-submodules must not use a nested gitdir' '
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git clone nested nested_checkout &&
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(
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cd nested_checkout &&
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git submodule init &&
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git submodule update thing1 &&
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mkdir -p .git/modules/hippo/hooks/refs &&
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mkdir -p .git/modules/hippo/hooks/objects/info &&
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echo "../../../../objects" >.git/modules/hippo/hooks/objects/info/alternates &&
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echo "ref: refs/heads/master" >.git/modules/hippo/hooks/HEAD
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) &&
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test_must_fail git -C nested_checkout checkout -f --recurse-submodules HEAD 2>err &&
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cat err &&
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grep "is inside git dir" err &&
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test_path_is_missing nested_checkout/thing2/.git
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'
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test_done
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