In 6411a0a896 (builtin/blame: fix type of `length` variable when
emitting object ID, 2024-12-06) we have fixed the type of the `length`
variable. In order to avoid a cast from `size_t` to `int` in the call to
printf(3p) with the "%.*s" formatter we have converted the code to
instead use fwrite(3p), which accepts the length as a `size_t`.
It was reported though that this makes us read over the end of the OID
array when the provided `--abbrev=` length exceeds the length of the
object ID. This is because fwrite(3p) of course doesn't stop when it
sees a NUL byte, whereas printf(3p) does.
Fix the bug by reverting back to printf(3p) and culling the provided
length to `GIT_MAX_HEXSZ` to keep it from overflowing when cast to an
`int`.
Reported-by: Johannes Schindelin <Johannes.Schindelin@xxxxxx>
Signed-off-by: Patrick Steinhardt <ps@xxxxxx>
---
This fixes the issue reported in [1]. Thanks!
Changes in v2:
- Take into account that we may strip ^, * and ? indicators by moving
around the check.
- Fix the testcase so that it actually fails without the fix.
- Link to v1: https://lore.kernel.org/r/20250109-b4-pks-blame-truncate-hash-length-v1-1-9ad4bb09e059@xxxxxx
Patrick
[1]: <4d812802-afbc-4635-7a19-73896fcda625@xxxxxx>
---
builtin/blame.c | 5 ++++-
t/t8002-blame.sh | 4 ++++
2 files changed, 8 insertions(+), 1 deletion(-)
diff --git a/builtin/blame.c b/builtin/blame.c
index 867032e4c16878ffd56df8a73162b89ca4bd2694..f92e487bed22eec576a4716f2e654cb61efb9903 100644
--- a/builtin/blame.c
+++ b/builtin/blame.c
@@ -505,7 +505,10 @@ static void emit_other(struct blame_scoreboard *sb, struct blame_entry *ent, int
length--;
putchar('?');
}
- fwrite(hex, 1, length, stdout);
+
+ if (length > GIT_MAX_HEXSZ)
+ length = GIT_MAX_HEXSZ;
+ printf("%.*s", (int)length, hex);
if (opt & OUTPUT_ANNOTATE_COMPAT) {
const char *name;
if (opt & OUTPUT_SHOW_EMAIL)
diff --git a/t/t8002-blame.sh b/t/t8002-blame.sh
index 0147de304b4d104cc7f05ea1f8d68f1a07ceb80d..7cf6e0253a5bbd4d6e438e627dc18b47eac4df66 100755
--- a/t/t8002-blame.sh
+++ b/t/t8002-blame.sh
@@ -126,6 +126,10 @@ test_expect_success '--no-abbrev works like --abbrev with full length' '
check_abbrev $hexsz --no-abbrev
'
+test_expect_success 'blame --abbrev gets truncated' '
+ check_abbrev $hexsz --abbrev=9000 HEAD
+'
+
test_expect_success '--exclude-promisor-objects does not BUG-crash' '
test_must_fail git blame --exclude-promisor-objects one
'
---
base-commit: 14650065b76b28d3cfa9453356ac5669b19e706e
change-id: 20250109-b4-pks-blame-truncate-hash-length-c875cac66d71
