git-commit-vandalism/t/t6102-rev-list-unexpected-objects.sh
Jeff King c78fe00459 parse_commit_buffer(): treat lookup_commit() failure as parse error
While parsing the parents of a commit, if we are able to parse an actual
oid but lookup_commit() fails on it (because we previously saw it in
this process as a different object type), we silently omit the parent
and do not report any error to the caller.

The caller has no way of knowing this happened, because even an empty
parent list is a valid parse result. As a result, it's possible to fool
our "rev-list" connectivity check into accepting a corrupted set of
objects.

There's a test for this case already in t6102, but unfortunately it has
a slight error. It creates a broken commit with a parent line pointing
to a blob, and then checks that rev-list notices the problem in two
cases:

  1. the "lone" case: we traverse the broken commit by itself (here we
     try to actually load the blob from disk and find out that it's not
     a commit)

  2. the "seen" case: we parse the blob earlier in the process, and then
     when calling lookup_commit() we realize immediately that it's not a
     commit

The "seen" variant for this test mistakenly parsed another commit
instead of the blob, meaning that we were actually just testing the
"lone" case again. Changing that reveals the breakage (and shows that
this fixes it).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-10-21 11:15:23 +09:00

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#!/bin/sh
test_description='git rev-list should handle unexpected object types'
. ./test-lib.sh
test_expect_success 'setup well-formed objects' '
blob="$(printf "foo" | git hash-object -w --stdin)" &&
tree="$(printf "100644 blob $blob\tfoo" | git mktree)" &&
commit="$(git commit-tree $tree -m "first commit")" &&
git cat-file commit $commit >good-commit
'
test_expect_success 'setup unexpected non-blob entry' '
printf "100644 foo\0$(echo $tree | hex2oct)" >broken-tree &&
broken_tree="$(git hash-object -w --literally -t tree broken-tree)"
'
test_expect_failure 'traverse unexpected non-blob entry (lone)' '
test_must_fail git rev-list --objects $broken_tree
'
test_expect_success 'traverse unexpected non-blob entry (seen)' '
test_must_fail git rev-list --objects $tree $broken_tree >output 2>&1 &&
test_i18ngrep "is not a blob" output
'
test_expect_success 'setup unexpected non-tree entry' '
printf "40000 foo\0$(echo $blob | hex2oct)" >broken-tree &&
broken_tree="$(git hash-object -w --literally -t tree broken-tree)"
'
test_expect_success 'traverse unexpected non-tree entry (lone)' '
test_must_fail git rev-list --objects $broken_tree
'
test_expect_success 'traverse unexpected non-tree entry (seen)' '
test_must_fail git rev-list --objects $blob $broken_tree >output 2>&1 &&
test_i18ngrep "is not a tree" output
'
test_expect_success 'setup unexpected non-commit parent' '
sed "/^author/ { h; s/.*/parent $blob/; G; }" <good-commit \
>broken-commit &&
broken_commit="$(git hash-object -w --literally -t commit \
broken-commit)"
'
test_expect_success 'traverse unexpected non-commit parent (lone)' '
test_must_fail git rev-list --objects $broken_commit >output 2>&1 &&
test_i18ngrep "not a commit" output
'
test_expect_success 'traverse unexpected non-commit parent (seen)' '
test_must_fail git rev-list --objects $blob $broken_commit \
>output 2>&1 &&
test_i18ngrep "not a commit" output
'
test_expect_success 'setup unexpected non-tree root' '
sed -e "s/$tree/$blob/" <good-commit >broken-commit &&
broken_commit="$(git hash-object -w --literally -t commit \
broken-commit)"
'
test_expect_success 'traverse unexpected non-tree root (lone)' '
test_must_fail git rev-list --objects $broken_commit
'
test_expect_success 'traverse unexpected non-tree root (seen)' '
test_must_fail git rev-list --objects $blob $broken_commit \
>output 2>&1 &&
test_i18ngrep "not a tree" output
'
test_expect_success 'setup unexpected non-commit tag' '
git tag -a -m "tagged commit" tag $commit &&
git cat-file tag tag >good-tag &&
test_when_finished "git tag -d tag" &&
sed -e "s/$commit/$blob/" <good-tag >broken-tag &&
tag=$(git hash-object -w --literally -t tag broken-tag)
'
test_expect_success 'traverse unexpected non-commit tag (lone)' '
test_must_fail git rev-list --objects $tag
'
test_expect_success 'traverse unexpected non-commit tag (seen)' '
test_must_fail git rev-list --objects $blob $tag >output 2>&1 &&
test_i18ngrep "not a commit" output
'
test_expect_success 'setup unexpected non-tree tag' '
git tag -a -m "tagged tree" tag $tree &&
git cat-file tag tag >good-tag &&
test_when_finished "git tag -d tag" &&
sed -e "s/$tree/$blob/" <good-tag >broken-tag &&
tag=$(git hash-object -w --literally -t tag broken-tag)
'
test_expect_success 'traverse unexpected non-tree tag (lone)' '
test_must_fail git rev-list --objects $tag
'
test_expect_success 'traverse unexpected non-tree tag (seen)' '
test_must_fail git rev-list --objects $blob $tag >output 2>&1 &&
test_i18ngrep "not a tree" output
'
test_expect_success 'setup unexpected non-blob tag' '
git tag -a -m "tagged blob" tag $blob &&
git cat-file tag tag >good-tag &&
test_when_finished "git tag -d tag" &&
sed -e "s/$blob/$commit/" <good-tag >broken-tag &&
tag=$(git hash-object -w --literally -t tag broken-tag)
'
test_expect_failure 'traverse unexpected non-blob tag (lone)' '
test_must_fail git rev-list --objects $tag
'
test_expect_success 'traverse unexpected non-blob tag (seen)' '
test_must_fail git rev-list --objects $commit $tag >output 2>&1 &&
test_i18ngrep "not a blob" output
'
test_done