convert log_ref_write_fd() to use strbuf

Since we don't care about how many bytes were written, simplify the return
value logic.

log_ref_write_fd() was written long before strbuf was fleshed out. Remove
the old manual buffer management code and replace it with strbuf(). Also
update copy_reflog_msg() which is called only by log_ref_write_fd() to use
strbuf as it keeps things consistent.

Signed-off-by: Ben Peart <Ben.Peart@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

3 files changed, 17 insertions, 31 deletions

diff --git a/refs.c b/refs.c
index 0eb379f931..50fe5c5d2c 100644
--- a/refs.c
+++ b/refs.c
@@ -786,25 +786,21 @@ int delete_ref(const char *msg, const char *refname,
 			       old_oid, flags);
 }
 
-int copy_reflog_msg(char *buf, const char *msg)
+void copy_reflog_msg(struct strbuf *sb, const char *msg)
 {
-	char *cp = buf;
 	char c;
 	int wasspace = 1;
 
-	*cp++ = '\t';
+	strbuf_addch(sb, '\t');
 	while ((c = *msg++)) {
 		if (wasspace && isspace(c))
 			continue;
 		wasspace = isspace(c);
 		if (wasspace)
 			c = ' ';
-		*cp++ = c;
+		strbuf_addch(sb, c);
 	}
-	while (buf < cp && isspace(cp[-1]))
-		cp--;
-	*cp++ = '\n';
-	return cp - buf;
+	strbuf_rtrim(sb);
 }
 
 int should_autocreate_reflog(const char *refname)
diff --git a/refs/files-backend.c b/refs/files-backend.c
index a9a066dcfb..054306d779 100644
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -1582,26 +1582,17 @@ static int log_ref_write_fd(int fd, const struct object_id *old_oid,
 			    const struct object_id *new_oid,
 			    const char *committer, const char *msg)
 {
-	int msglen, written;
-	unsigned maxlen, len;
-	char *logrec;
-
-	msglen = msg ? strlen(msg) : 0;
-	maxlen = strlen(committer) + msglen + 100;
-	logrec = xmalloc(maxlen);
-	len = xsnprintf(logrec, maxlen, "%s %s %s\n",
-			oid_to_hex(old_oid),
-			oid_to_hex(new_oid),
-			committer);
-	if (msglen)
-		len += copy_reflog_msg(logrec + len - 1, msg) - 1;
-
-	written = len <= maxlen ? write_in_full(fd, logrec, len) : -1;
-	free(logrec);
-	if (written < 0)
-		return -1;
+	struct strbuf sb = STRBUF_INIT;
+	int ret = 0;
 
-	return 0;
+	strbuf_addf(&sb, "%s %s %s", oid_to_hex(old_oid), oid_to_hex(new_oid), committer);
+	if (msg && *msg)
+		copy_reflog_msg(&sb, msg);
+	strbuf_addch(&sb, '\n');
+	if (write_in_full(fd, sb.buf, sb.len) < 0)
+		ret = -1;
+	strbuf_release(&sb);
+	return ret;
 }
 
 static int files_log_ref_write(struct files_ref_store *refs,
diff --git a/refs/refs-internal.h b/refs/refs-internal.h
index dd834314bd..17a526078f 100644
--- a/refs/refs-internal.h
+++ b/refs/refs-internal.h
@@ -91,11 +91,10 @@ enum peel_status {
 enum peel_status peel_object(const struct object_id *name, struct object_id *oid);
 
 /*
- * Copy the reflog message msg to buf, which has been allocated sufficiently
- * large, while cleaning up the whitespaces.  Especially, convert LF to space,
- * because reflog file is one line per entry.
+ * Copy the reflog message msg to sb while cleaning up the whitespaces.
+ * Especially, convert LF to space, because reflog file is one line per entry.
  */
-int copy_reflog_msg(char *buf, const char *msg);
+void copy_reflog_msg(struct strbuf *sb, const char *msg);
 
 /**
  * Information needed for a single ref update. Set new_oid to the new