Some refs in Git are more special than others due to reasons explained
in the next commit. These refs are read via `refs_read_special_head()`,
but this function doesn't behave the same as when we try to read a
normal ref. Most importantly, we do not propagate `failure_errno` in the
case where the reference does not exist, which is behaviour that we rely
on in many parts of Git.
Fix this bug by propagating errno when `strbuf_read_file()` fails.
Signed-off-by: Patrick Steinhardt <ps@xxxxxx>
---
refs.c | 6 +++++-
t/t1403-show-ref.sh | 9 +++++++++
2 files changed, 14 insertions(+), 1 deletion(-)
diff --git a/refs.c b/refs.c
index fcae5dddc6..7d4a057f36 100644
--- a/refs.c
+++ b/refs.c
@@ -1806,8 +1806,12 @@ static int refs_read_special_head(struct ref_store *ref_store,
int result = -1;
strbuf_addf(&full_path, "%s/%s", ref_store->gitdir, refname);
- if (strbuf_read_file(&content, full_path.buf, 0) < 0)
+ errno = 0;
+
+ if (strbuf_read_file(&content, full_path.buf, 0) < 0) {
+ *failure_errno = errno;
goto done;
+ }
result = parse_loose_ref_contents(content.buf, oid, referent, type,
failure_errno);
diff --git a/t/t1403-show-ref.sh b/t/t1403-show-ref.sh
index b50ae6fcf1..37af154d27 100755
--- a/t/t1403-show-ref.sh
+++ b/t/t1403-show-ref.sh
@@ -266,4 +266,13 @@ test_expect_success '--exists with directory fails with generic error' '
test_cmp expect err
'
+test_expect_success '--exists with non-existent special ref' '
+ test_expect_code 2 git show-ref --exists FETCH_HEAD
+'
+
+test_expect_success '--exists with existing special ref' '
+ git rev-parse HEAD >.git/FETCH_HEAD &&
+ git show-ref --exists FETCH_HEAD
+'
+
test_done
--
2.43.0
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