refs: make errno output explicit for read_raw_ref_fn
This makes it explicit how alternative ref backends should report errors in
read_raw_ref_fn.
read_raw_ref_fn needs to supply a credible errno for a number of cases. These
are primarily:
1) The files backend calls read_raw_ref from lock_raw_ref, and uses the
resulting error codes to create/remove directories as needed.
2) ENOENT should be translated in a zero OID, optionally with REF_ISBROKEN set,
returning the last successfully resolved symref. This is necessary so
read_raw_ref("HEAD") on an empty repo returns refs/heads/main (or the default branch
du-jour), and we know on which branch to create the first commit.
Make this information flow explicit by adding a failure_errno to the signature
of read_raw_ref. All errnos from the files backend are still propagated
unchanged, even though inspection suggests only ENOTDIR, EISDIR and ENOENT are
relevant.
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/refs/files-backend.c b/refs/files-backend.c
index c1794dc..b3de363 100644
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -341,9 +341,9 @@ static struct ref_cache *get_loose_ref_cache(struct files_ref_store *refs)
return refs->loose;
}
-static int files_read_raw_ref(struct ref_store *ref_store,
- const char *refname, struct object_id *oid,
- struct strbuf *referent, unsigned int *type)
+static int files_read_raw_ref(struct ref_store *ref_store, const char *refname,
+ struct object_id *oid, struct strbuf *referent,
+ unsigned int *type, int *failure_errno)
{
struct files_ref_store *refs =
files_downcast(ref_store, REF_STORE_READ, "read_raw_ref");
@@ -354,7 +354,6 @@ static int files_read_raw_ref(struct ref_store *ref_store,
struct stat st;
int fd;
int ret = -1;
- int save_errno;
int remaining_retries = 3;
*type = 0;
@@ -459,10 +458,9 @@ static int files_read_raw_ref(struct ref_store *ref_store,
ret = parse_loose_ref_contents(buf, oid, referent, type);
out:
- save_errno = errno;
+ *failure_errno = errno;
strbuf_release(&sb_path);
strbuf_release(&sb_contents);
- errno = save_errno;
return ret;
}
@@ -540,6 +538,7 @@ static int lock_raw_ref(struct files_ref_store *refs,
struct strbuf ref_file = STRBUF_INIT;
int attempts_remaining = 3;
int ret = TRANSACTION_GENERIC_ERROR;
+ int failure_errno;
assert(err);
files_assert_main_repository(refs, "lock_raw_ref");
@@ -610,7 +609,9 @@ static int lock_raw_ref(struct files_ref_store *refs,
if (hold_lock_file_for_update_timeout(
&lock->lk, ref_file.buf, LOCK_NO_DEREF,
get_files_ref_lock_timeout_ms()) < 0) {
- if (errno == ENOENT && --attempts_remaining > 0) {
+ int myerr = errno;
+ errno = 0;
+ if (myerr == ENOENT && --attempts_remaining > 0) {
/*
* Maybe somebody just deleted one of the
* directories leading to ref_file. Try
@@ -618,7 +619,7 @@ static int lock_raw_ref(struct files_ref_store *refs,
*/
goto retry;
} else {
- unable_to_lock_message(ref_file.buf, errno, err);
+ unable_to_lock_message(ref_file.buf, myerr, err);
goto error_return;
}
}
@@ -628,9 +629,9 @@ static int lock_raw_ref(struct files_ref_store *refs,
* fear that its value will change.
*/
- if (files_read_raw_ref(&refs->base, refname,
- &lock->old_oid, referent, type)) {
- if (errno == ENOENT) {
+ if (files_read_raw_ref(&refs->base, refname, &lock->old_oid, referent,
+ type, &failure_errno)) {
+ if (failure_errno == ENOENT) {
if (mustexist) {
/* Garden variety missing reference. */
strbuf_addf(err, "unable to resolve reference '%s'",
@@ -654,7 +655,7 @@ static int lock_raw_ref(struct files_ref_store *refs,
* reference named "refs/foo/bar/baz".
*/
}
- } else if (errno == EISDIR) {
+ } else if (failure_errno == EISDIR) {
/*
* There is a directory in the way. It might have
* contained references that have been deleted. If
@@ -692,13 +693,13 @@ static int lock_raw_ref(struct files_ref_store *refs,
goto error_return;
}
}
- } else if (errno == EINVAL && (*type & REF_ISBROKEN)) {
+ } else if (failure_errno == EINVAL && (*type & REF_ISBROKEN)) {
strbuf_addf(err, "unable to resolve reference '%s': "
"reference broken", refname);
goto error_return;
} else {
strbuf_addf(err, "unable to resolve reference '%s': %s",
- refname, strerror(errno));
+ refname, strerror(failure_errno));
goto error_return;
}
