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 | 80 ++++++++++++++++++++++++++++++++++++++-----------
1 file changed, 62 insertions(+), 18 deletions(-)
diff --git a/builtin/fetch.c b/builtin/fetch.c
index ecf8537605..557ec130db 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -897,6 +897,56 @@ 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)
+ return 0;
+
+ fetch_head->fp = fopen(filename, "a");
+ if (!fetch_head->fp)
+ return error_errno(_("cannot open %s"), filename);
+
+ return 0;
+}
+
+static void append_fetch_head(struct fetch_head *fetch_head, const char *old_oid,
+ const char *merge_status_marker, const char *note,
+ const char *url, size_t url_len)
+{
+ size_t i;
+
+ if (!write_fetch_head)
+ return;
+
+ fprintf(fetch_head->fp, "%s\t%s\t%s",
+ 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 (!write_fetch_head)
+ 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 +959,19 @@ 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);
@@ -1016,16 +1063,10 @@ static int store_updated_refs(const char *raw_url, const char *remote_name,
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);
+ append_fetch_head(&fetch_head,
+ oid_to_hex(&rm->old_oid),
+ merge_status_marker,
+ note.buf, url, url_len);
break;
default:
/* do not write anything to FETCH_HEAD */
@@ -1060,6 +1101,9 @@ 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 +1121,7 @@ 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;
}
--
2.30.0
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