[PATCH 3/3] fsck: detect null sha1 in tree entries
- From
Jeff King <peff@peff.net>
- Date
- Jul 28, 2012, 15:06 UTC
- Message-ID
- <20120728150629.GC25269@sigill.intra.peff.net>
- In-Reply-To
- <20120728150132.GA25042@sigill.intra.peff.net>
Short of somebody happening to beat the 1 in 2^160 odds of actually generating content that hashes to the null sha1, we should never see this value in a tree entry. So let's have fsck warn if it it seen.
As in the previous commit, we test both blob and submodule entries to future-proof the test suite against the implementation depending on connectivity to notice the error.
Signed-off-by: Jeff King <peff@peff.net> --- I left this as a warning, because git can still mostly handle such trees, which may aid in debugging or salvaging data.
fsck.c | 8 +++++++- t/t1450-fsck.sh | 26 ++++++++++++++++++++++++++ 2 files changed, 33 insertions(+), 1 deletion(-)
diff --git a/fsck.c b/fsck.c index 4c63b2c..7395ef6 100644 --- a/fsck.c +++ b/fsck.c @@ -139,6 +139,7 @@ static int verify_ordered(unsigned mode1, const char *name1, unsigned mode2, con static int fsck_tree(struct tree *item, int strict, fsck_error error_func) { int retval; + int has_null_sha1 = 0; int has_full_path = 0; int has_empty_name = 0; int has_zero_pad = 0; @@ -157,9 +158,12 @@ static int fsck_tree(struct tree *item, int strict, fsck_error error_func) while (desc.size) { unsigned mode; const char *name; + const unsigned char *sha1; - tree_entry_extract(&desc, &name, &mode); + sha1 = tree_entry_extract(&desc, &name, &mode); + if (is_null_sha1(sha1)) + has_null_sha1 = 1; if (strchr(name, '/')) has_full_path = 1; if (!*name) @@ -207,6 +211,8 @@ static int fsck_tree(struct tree *item, int strict, fsck_error error_func) } retval = 0; + if (has_null_sha1) + retval += error_func(&item->object, FSCK_WARN, "contains entries pointing to null sha1"); if (has_full_path) retval += error_func(&item->object, FSCK_WARN, "contains full pathnames"); if (has_empty_name) diff --git a/t/t1450-fsck.sh b/t/t1450-fsck.sh index 5b79c51..bf7a2cd 100755 --- a/t/t1450-fsck.sh +++ b/t/t1450-fsck.sh @@ -213,4 +213,30 @@ test_expect_success 'rev-list --verify-objects with bad sha1' ' grep -q "error: sha1 mismatch 63ffffffffffffffffffffffffffffffffffffff" out ' +_bz='\0' +_bz5="$_bz$_bz$_bz$_bz$_bz" +_bz20="$_bz5$_bz5$_bz5$_bz5" + +test_expect_success 'fsck notices blob entry pointing to null sha1' ' + (git init null-blob && + cd null-blob && + sha=$(printf "100644 file$_bz$_bz20" | + git hash-object -w --stdin -t tree) && + git fsck 2>out && + cat out && + grep "warning.*null sha1" out + ) +' + +test_expect_success 'fsck notices submodule entry pointing to null sha1' ' + (git init null-commit && + cd null-commit && + sha=$(printf "160000 submodule$_bz$_bz20" | + git hash-object -w --stdin -t tree) && + git fsck 2>out && + cat out && + grep "warning.*null sha1" out + ) +' + test_done
-- 1.7.11.3.42.g90758bf