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![Jeff King](/assets/img/avatar_default.png)
In parse_object(), we try to handle blobs by streaming rather than
loading them entirely into memory. The most common case here will be
that we haven't seen the object yet and check oid_object_info(), which
tells us we have a blob.
But we trigger this code on one other case: when we have an in-memory
object struct with type OBJ_BLOB (and without its "parsed" flag set,
since otherwise we'd return early from the function). This indicates
that some other part of the code suspected we have a blob (e.g., it was
mentioned by a tree or tag) but we haven't yet looked at the on-disk
copy.
In this case before hitting the streaming path, we check if we have the
object on-disk at all. This is mostly pointless extra work, as the
streaming path would complain if it couldn't open the object (albeit
with the message "hash mismatch", which is a little misleading).
But it's also insufficient to catch all problems. The streaming code
will only tell us "yes, the on-disk object matches the oid". But it
doesn't actually confirm that what we found was indeed a blob, and
neither does repo_has_object_file().
One way to improve this would be to teach stream_object_signature() to
check the type (either by returning it to us to check, or taking an
"expected" type). But there's an even simpler fix here: if we suspect
the object is a blob, just call oid_object_info() to confirm that we
have it on-disk, and that it really is a blob.
This is slightly less efficient than teaching stream_object_signature()
to do it (since it has to open the object already). But this case very
rarely comes up. In practice, we usually don't have any clue what the
type is, in which case we already call oid_object_info(). This
"suspected" case happens only when some other code created an object
struct but didn't actually parse the blob, which is actually tricky to
trigger at all (see the discussion of the test below).
I reworked the conditional a bit so that instead of:
if ((suspected_blob && oid_object_info() == OBJ_BLOB)
(no_clue && oid_object_info() == OBJ_BLOB)
we have the simpler:
if ((suspected_blob || no_clue) && oid_object_info() == OBJ_BLOB)
This is shorter, but also reflects what we really want say, which is
"have we ruled out this being a blob; if not, check it on-disk".
In either case, if oid_object_info() fails to tell us it's a blob, we'll
skip the streaming code path and call repo_read_object_file(), just as
before. And if we really do have a mismatch with the existing object
struct, we'll eventually call lookup_commit(), etc, via
parse_object_buffer(), which will complain that it doesn't match our
existing obj->type.
So this fixes one of the lingering expect_failure cases from 0616617c7e
(t: introduce tests for unexpected object types, 2019-04-09). That test
works by peeling a tag that claims to point to a blob (triggering us to
create the struct), but really points to something else, which we later
discover when we call parse_object() as part of the actual traversal).
Prior to this commit, we'd quietly check the sha1 and mark the blob as
"parsed". Now we correctly complain about the mismatch.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
134 lines
4.2 KiB
Bash
Executable file
134 lines
4.2 KiB
Bash
Executable file
#!/bin/sh
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test_description='git rev-list should handle unexpected object types'
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TEST_PASSES_SANITIZE_LEAK=true
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. ./test-lib.sh
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test_expect_success 'setup well-formed objects' '
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blob="$(printf "foo" | git hash-object -w --stdin)" &&
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tree="$(printf "100644 blob $blob\tfoo" | git mktree)" &&
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commit="$(git commit-tree $tree -m "first commit")" &&
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git cat-file commit $commit >good-commit
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'
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test_expect_success 'setup unexpected non-blob entry' '
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printf "100644 foo\0$(echo $tree | hex2oct)" >broken-tree &&
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broken_tree="$(git hash-object -w --literally -t tree broken-tree)"
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'
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test_expect_success 'TODO (should fail!): traverse unexpected non-blob entry (lone)' '
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sed "s/Z$//" >expect <<-EOF &&
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$broken_tree Z
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$tree foo
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EOF
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git rev-list --objects $broken_tree >actual &&
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test_cmp expect actual
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'
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test_expect_success 'traverse unexpected non-blob entry (seen)' '
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test_must_fail git rev-list --objects $tree $broken_tree >output 2>&1 &&
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test_i18ngrep "is not a blob" output
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'
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test_expect_success 'setup unexpected non-tree entry' '
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printf "40000 foo\0$(echo $blob | hex2oct)" >broken-tree &&
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broken_tree="$(git hash-object -w --literally -t tree broken-tree)"
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'
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test_expect_success 'traverse unexpected non-tree entry (lone)' '
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test_must_fail git rev-list --objects $broken_tree
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'
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test_expect_success 'traverse unexpected non-tree entry (seen)' '
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test_must_fail git rev-list --objects $blob $broken_tree >output 2>&1 &&
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test_i18ngrep "is not a tree" output
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'
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test_expect_success 'setup unexpected non-commit parent' '
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sed "/^author/ { h; s/.*/parent $blob/; G; }" <good-commit \
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>broken-commit &&
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broken_commit="$(git hash-object -w --literally -t commit \
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broken-commit)"
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'
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test_expect_success 'traverse unexpected non-commit parent (lone)' '
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test_must_fail git rev-list --objects $broken_commit >output 2>&1 &&
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test_i18ngrep "not a commit" output
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'
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test_expect_success 'traverse unexpected non-commit parent (seen)' '
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test_must_fail git rev-list --objects $blob $broken_commit \
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>output 2>&1 &&
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test_i18ngrep "not a commit" output
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'
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test_expect_success 'setup unexpected non-tree root' '
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sed -e "s/$tree/$blob/" <good-commit >broken-commit &&
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broken_commit="$(git hash-object -w --literally -t commit \
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broken-commit)"
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'
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test_expect_success 'traverse unexpected non-tree root (lone)' '
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test_must_fail git rev-list --objects $broken_commit
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'
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test_expect_success 'traverse unexpected non-tree root (seen)' '
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test_must_fail git rev-list --objects $blob $broken_commit \
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>output 2>&1 &&
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test_i18ngrep "not a tree" output
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'
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test_expect_success 'setup unexpected non-commit tag' '
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git tag -a -m "tagged commit" tag $commit &&
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git cat-file tag tag >good-tag &&
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test_when_finished "git tag -d tag" &&
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sed -e "s/$commit/$blob/" <good-tag >broken-tag &&
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tag=$(git hash-object -w --literally -t tag broken-tag)
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'
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test_expect_success 'traverse unexpected non-commit tag (lone)' '
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test_must_fail git rev-list --objects $tag
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'
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test_expect_success 'traverse unexpected non-commit tag (seen)' '
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test_must_fail git rev-list --objects $blob $tag >output 2>&1 &&
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test_i18ngrep "not a commit" output
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'
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test_expect_success 'setup unexpected non-tree tag' '
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git tag -a -m "tagged tree" tag $tree &&
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git cat-file tag tag >good-tag &&
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test_when_finished "git tag -d tag" &&
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sed -e "s/$tree/$blob/" <good-tag >broken-tag &&
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tag=$(git hash-object -w --literally -t tag broken-tag)
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'
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test_expect_success 'traverse unexpected non-tree tag (lone)' '
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test_must_fail git rev-list --objects $tag
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'
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test_expect_success 'traverse unexpected non-tree tag (seen)' '
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test_must_fail git rev-list --objects $blob $tag >output 2>&1 &&
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test_i18ngrep "not a tree" output
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'
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test_expect_success 'setup unexpected non-blob tag' '
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git tag -a -m "tagged blob" tag $blob &&
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git cat-file tag tag >good-tag &&
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test_when_finished "git tag -d tag" &&
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sed -e "s/$blob/$commit/" <good-tag >broken-tag &&
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tag=$(git hash-object -w --literally -t tag broken-tag)
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'
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test_expect_success 'traverse unexpected non-blob tag (lone)' '
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test_must_fail git rev-list --objects $tag
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'
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test_expect_success 'traverse unexpected non-blob tag (seen)' '
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test_must_fail git rev-list --objects $commit $tag >output 2>&1 &&
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test_i18ngrep "not a blob" output
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'
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test_done
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