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authorPatrick Steinhardt <ps@pks.im>2021-01-12 12:27:35 (GMT)
committerJunio C Hamano <gitster@pobox.com>2021-01-12 20:06:14 (GMT)
commit58a646a3688ea3c15adaf481e440e9ca2d3bce06 (patch)
tree80a8b3dc704040eadae7bdbcad8f60f98139b08a
parent72c4083ddf91b489b7b7b812df67ee8842177d98 (diff)
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fetch: extract writing to FETCH_HEAD
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@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
-rw-r--r--builtin/fetch.c108
-rw-r--r--remote.h2
2 files changed, 80 insertions, 30 deletions
diff --git a/builtin/fetch.c b/builtin/fetch.c
index ecf8537..2dd5fcb 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(&note, "%s ", kind);
strbuf_addf(&note, "'%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(&note);
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(&note);
free(url);
- fclose(fp);
+ close_fetch_head(&fetch_head);
return rc;
}
diff --git a/remote.h b/remote.h
index 3211abd..aad1a0f 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