When performing a fetch with the default `--write-fetch-head` option, we
write all updated references to FETCH_HEAD while the updates are
performed. Given that updates are not performed atomically, it means
that we we write to FETCH_HEAD even if some or all of the reference
updates fail.
Given that we simply update FETCH_HEAD ad-hoc with each reference, the
logic is completely contained in `store_update_refs` and thus quite hard
to extend. This can already be seen by the way we skip writing to the
FETCH_HEAD: instead of having a conditional which simply skips writing,
we instead open "/dev/null" and needlessly write all updates there.
We are about to extend git-fetch(1) to accept an `--atomic` flag which
will make the fetch an all-or-nothing operation with regards to the
reference updates. This will also require us to make the updates to
FETCH_HEAD an all-or-nothing operation, but as explained doing so is not
easy with the current layout. This commit thus refactors the wa we write
to FETCH_HEAD and pulls out the logic to open, append to, commit and
close the file. While this may seem rather over-the top at first,
pulling out this logic will make it a lot easier to update the code in a
subsequent commit. It also allows us to easily skip writing completely
in case `--no-write-fetch-head` was passed.
Signed-off-by: Patrick Steinhardt <ps@xxxxxx>
---
builtin/fetch.c | 108 +++++++++++++++++++++++++++++++++++-------------
remote.h | 2 +-
2 files changed, 80 insertions(+), 30 deletions(-)
diff --git a/builtin/fetch.c b/builtin/fetch.c
index ecf8537605..50f0306a92 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -897,6 +897,73 @@ static int iterate_ref_map(void *cb_data, struct object_id *oid)
return 0;
}
+struct fetch_head {
+ FILE *fp;
+};
+
+static int open_fetch_head(struct fetch_head *fetch_head)
+{
+ const char *filename = git_path_fetch_head(the_repository);
+
+ if (write_fetch_head) {
+ fetch_head->fp = fopen(filename, "a");
+ if (!fetch_head->fp)
+ return error_errno(_("cannot open %s"), filename);
+ } else {
+ fetch_head->fp = NULL;
+ }
+
+ return 0;
+}
+
+static void append_fetch_head(struct fetch_head *fetch_head,
+ const struct object_id *old_oid,
+ enum fetch_head_status fetch_head_status,
+ const char *note,
+ const char *url, size_t url_len)
+{
+ char old_oid_hex[GIT_MAX_HEXSZ + 1];
+ const char *merge_status_marker;
+ size_t i;
+
+ if (!fetch_head->fp)
+ return;
+
+ switch (fetch_head_status) {
+ case FETCH_HEAD_NOT_FOR_MERGE:
+ merge_status_marker = "not-for-merge";
+ break;
+ case FETCH_HEAD_MERGE:
+ merge_status_marker = "";
+ break;
+ default:
+ /* do not write anything to FETCH_HEAD */
+ return;
+ }
+
+ fprintf(fetch_head->fp, "%s\t%s\t%s",
+ oid_to_hex_r(old_oid_hex, old_oid), merge_status_marker, note);
+ for (i = 0; i < url_len; ++i)
+ if ('\n' == url[i])
+ fputs("\\n", fetch_head->fp);
+ else
+ fputc(url[i], fetch_head->fp);
+ fputc('\n', fetch_head->fp);
+}
+
+static void commit_fetch_head(struct fetch_head *fetch_head)
+{
+ /* Nothing to commit yet. */
+}
+
+static void close_fetch_head(struct fetch_head *fetch_head)
+{
+ if (!fetch_head->fp)
+ return;
+
+ fclose(fetch_head->fp);
+}
+
static const char warn_show_forced_updates[] =
N_("Fetch normally indicates which branches had a forced update,\n"
"but that check has been disabled. To re-enable, use '--show-forced-updates'\n"
@@ -909,22 +976,19 @@ N_("It took %.2f seconds to check forced updates. You can use\n"
static int store_updated_refs(const char *raw_url, const char *remote_name,
int connectivity_checked, struct ref *ref_map)
{
- FILE *fp;
+ struct fetch_head fetch_head;
struct commit *commit;
int url_len, i, rc = 0;
struct strbuf note = STRBUF_INIT;
const char *what, *kind;
struct ref *rm;
char *url;
- const char *filename = (!write_fetch_head
- ? "/dev/null"
- : git_path_fetch_head(the_repository));
int want_status;
int summary_width = transport_summary_width(ref_map);
- fp = fopen(filename, "a");
- if (!fp)
- return error_errno(_("cannot open %s"), filename);
+ rc = open_fetch_head(&fetch_head);
+ if (rc)
+ return -1;
if (raw_url)
url = transport_anonymize_url(raw_url);
@@ -953,7 +1017,6 @@ static int store_updated_refs(const char *raw_url, const char *remote_name,
want_status++) {
for (rm = ref_map; rm; rm = rm->next) {
struct ref *ref = NULL;
- const char *merge_status_marker = "";
if (rm->status == REF_STATUS_REJECT_SHALLOW) {
if (want_status == FETCH_HEAD_MERGE)
@@ -1011,26 +1074,10 @@ static int store_updated_refs(const char *raw_url, const char *remote_name,
strbuf_addf(¬e, "%s ", kind);
strbuf_addf(¬e, "'%s' of ", what);
}
- switch (rm->fetch_head_status) {
- case FETCH_HEAD_NOT_FOR_MERGE:
- merge_status_marker = "not-for-merge";
- /* fall-through */
- case FETCH_HEAD_MERGE:
- fprintf(fp, "%s\t%s\t%s",
- oid_to_hex(&rm->old_oid),
- merge_status_marker,
- note.buf);
- for (i = 0; i < url_len; ++i)
- if ('\n' == url[i])
- fputs("\\n", fp);
- else
- fputc(url[i], fp);
- fputc('\n', fp);
- break;
- default:
- /* do not write anything to FETCH_HEAD */
- break;
- }
+
+ append_fetch_head(&fetch_head, &rm->old_oid,
+ rm->fetch_head_status,
+ note.buf, url, url_len);
strbuf_reset(¬e);
if (ref) {
@@ -1060,6 +1107,9 @@ static int store_updated_refs(const char *raw_url, const char *remote_name,
}
}
+ if (!rc)
+ commit_fetch_head(&fetch_head);
+
if (rc & STORE_REF_ERROR_DF_CONFLICT)
error(_("some local refs could not be updated; try running\n"
" 'git remote prune %s' to remove any old, conflicting "
@@ -1077,7 +1127,7 @@ static int store_updated_refs(const char *raw_url, const char *remote_name,
abort:
strbuf_release(¬e);
free(url);
- fclose(fp);
+ close_fetch_head(&fetch_head);
return rc;
}
diff --git a/remote.h b/remote.h
index 3211abdf05..aad1a0f080 100644
--- a/remote.h
+++ b/remote.h
@@ -134,7 +134,7 @@ struct ref {
* should be 0, so that xcalloc'd structures get it
* by default.
*/
- enum {
+ enum fetch_head_status {
FETCH_HEAD_MERGE = -1,
FETCH_HEAD_NOT_FOR_MERGE = 0,
FETCH_HEAD_IGNORE = 1
--
2.30.0
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