fetch: use strbuf to format FETCH_HEAD updates

This commit refactors `append_fetch_head()` to use a `struct strbuf` for
formatting the update which we're about to append to the FETCH_HEAD
file. While the refactoring doesn't have much of a benefit right now, it
serves as a preparatory step to implement atomic fetches where we need
to buffer all updates to FETCH_HEAD and only flush them out if all
reference updates succeeded.

No change in behaviour is expected from this commit.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/fetch.c b/builtin/fetch.c
index 2dd5fcb652760215bb9af0bd3a833c3395c79a3d..e317e828cda31f6a18c8b5ac2ffd4f78c4c47c0e 100644 (file)
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -899,6 +899,7 @@ static int iterate_ref_map(void *cb_data, struct object_id *oid)
 
 struct fetch_head {
        FILE *fp;
+       struct strbuf buf;
 };
 
 static int open_fetch_head(struct fetch_head *fetch_head)
@@ -909,6 +910,7 @@ static int open_fetch_head(struct fetch_head *fetch_head)
                fetch_head->fp = fopen(filename, "a");
                if (!fetch_head->fp)
                        return error_errno(_("cannot open %s"), filename);
+               strbuf_init(&fetch_head->buf, 0);
        } else {
                fetch_head->fp = NULL;
        }
@@ -941,14 +943,17 @@ static void append_fetch_head(struct fetch_head *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);
+       strbuf_addf(&fetch_head->buf, "%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);
+                       strbuf_addstr(&fetch_head->buf, "\\n");
                else
-                       fputc(url[i], fetch_head->fp);
-       fputc('\n', fetch_head->fp);
+                       strbuf_addch(&fetch_head->buf, url[i]);
+       strbuf_addch(&fetch_head->buf, '\n');
+
+       strbuf_write(&fetch_head->buf, fetch_head->fp);
+       strbuf_reset(&fetch_head->buf);
 }
 
 static void commit_fetch_head(struct fetch_head *fetch_head)
@@ -962,6 +967,7 @@ static void close_fetch_head(struct fetch_head *fetch_head)
                return;
 
        fclose(fetch_head->fp);
+       strbuf_release(&fetch_head->buf);
 }
 
 static const char warn_show_forced_updates[] =