fsck: detect null sha1 in tree entries
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>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/fsck.c b/fsck.c
index 6c855f8..da53cf4 100644
--- a/fsck.c
+++ b/fsck.c
@@ -139,6 +139,7 @@
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 @@
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 @@
}
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 5b8ebd8..5e36cc7 100755
--- a/t/t1450-fsck.sh
+++ b/t/t1450-fsck.sh
@@ -217,4 +217,30 @@
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
