From: Han-Wen Nienhuys <hanwen@xxxxxxxxxx>
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@xxxxxxxxxx>
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@xxxxxxxxx>
---
refs.c | 2 +-
refs/debug.c | 7 +++----
refs/files-backend.c | 29 +++++++++++++++--------------
refs/packed-backend.c | 8 ++++----
refs/refs-internal.h | 20 ++++++++++++--------
5 files changed, 35 insertions(+), 31 deletions(-)
diff --git a/refs.c b/refs.c
index 05944d8e725..da0cc82ca66 100644
--- a/refs.c
+++ b/refs.c
@@ -1682,7 +1682,7 @@ int refs_read_raw_ref(struct ref_store *ref_store,
}
return ref_store->be->read_raw_ref(ref_store, refname, oid, referent,
- type);
+ type, &errno);
}
/* This function needs to return a meaningful errno on failure */
diff --git a/refs/debug.c b/refs/debug.c
index bf4a82bccb6..8667c640237 100644
--- a/refs/debug.c
+++ b/refs/debug.c
@@ -239,15 +239,14 @@ debug_ref_iterator_begin(struct ref_store *ref_store, const char *prefix,
static int debug_read_raw_ref(struct ref_store *ref_store, const char *refname,
struct object_id *oid, struct strbuf *referent,
- unsigned int *type)
+ unsigned int *type, int *failure_errno)
{
struct debug_ref_store *drefs = (struct debug_ref_store *)ref_store;
int res = 0;
oidcpy(oid, null_oid());
- errno = 0;
res = drefs->refs->be->read_raw_ref(drefs->refs, refname, oid, referent,
- type);
+ type, failure_errno);
if (res == 0) {
trace_printf_key(&trace_refs, "read_raw_ref: %s: %s (=> %s) type %x: %d\n",
@@ -255,7 +254,7 @@ static int debug_read_raw_ref(struct ref_store *ref_store, const char *refname,
} else {
trace_printf_key(&trace_refs,
"read_raw_ref: %s: %d (errno %d)\n", refname,
- res, errno);
+ res, *failure_errno);
}
return res;
}
diff --git a/refs/files-backend.c b/refs/files-backend.c
index c1794dcd295..b3de3633969 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;
}
diff --git a/refs/packed-backend.c b/refs/packed-backend.c
index 65ba4214b8d..47247a14917 100644
--- a/refs/packed-backend.c
+++ b/refs/packed-backend.c
@@ -724,9 +724,9 @@ static struct snapshot *get_snapshot(struct packed_ref_store *refs)
return refs->snapshot;
}
-static int packed_read_raw_ref(struct ref_store *ref_store,
- const char *refname, struct object_id *oid,
- struct strbuf *referent, unsigned int *type)
+static int packed_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 packed_ref_store *refs =
packed_downcast(ref_store, REF_STORE_READ, "read_raw_ref");
@@ -739,7 +739,7 @@ static int packed_read_raw_ref(struct ref_store *ref_store,
if (!rec) {
/* refname is not a packed reference. */
- errno = ENOENT;
+ *failure_errno = ENOENT;
return -1;
}
diff --git a/refs/refs-internal.h b/refs/refs-internal.h
index 1c6e5ab51d7..ddd6d7f8ebd 100644
--- a/refs/refs-internal.h
+++ b/refs/refs-internal.h
@@ -620,11 +620,15 @@ typedef int reflog_expire_fn(struct ref_store *ref_store,
* properly-formatted or even safe reference name. NEITHER INPUT NOR
* OUTPUT REFERENCE NAMES ARE VALIDATED WITHIN THIS FUNCTION.
*
- * Return 0 on success. If the ref doesn't exist, set errno to ENOENT
- * and return -1. If the ref exists but is neither a symbolic ref nor
- * an object ID, it is broken; set REF_ISBROKEN in type, and return -1
- * (errno should not be ENOENT) If there is another error reading the
- * ref, set errno appropriately and return -1.
+ * Return 0 on success, or -1 on failure. If the ref exists but is neither a
+ * symbolic ref nor an object ID, it is broken. In this case set REF_ISBROKEN in
+ * type, and return -1 (failure_errno should not be ENOENT)
+ *
+ * failure_errno provides errno codes that are interpreted beyond error
+ * reporting. The following error codes have special meaning:
+ * * ENOENT: the ref doesn't exist
+ * * EISDIR: ref name is a directory
+ * * ENOTDIR: ref prefix is not a directory
*
* Backend-specific flags might be set in type as well, regardless of
* outcome.
@@ -638,9 +642,9 @@ typedef int reflog_expire_fn(struct ref_store *ref_store,
* - in all other cases, referent will be untouched, and therefore
* refname will still be valid and unchanged.
*/
-typedef int read_raw_ref_fn(struct ref_store *ref_store,
- const char *refname, struct object_id *oid,
- struct strbuf *referent, unsigned int *type);
+typedef int read_raw_ref_fn(struct ref_store *ref_store, const char *refname,
+ struct object_id *oid, struct strbuf *referent,
+ unsigned int *type, int *failure_errno);
struct ref_storage_be {
struct ref_storage_be *next;
--
2.33.0.662.g438caf9576d
