refs: simplify parsing of reflog entries

The current code for reflog entries uses a lot of hard-coded constants,
making it hard to read and modify.  Use parse_oid_hex and two temporary
variables to simplify the code and reduce the use of magic constants.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: bk2204

refs/files-backend.c

@@ -3117,12 +3117,13 @@ static int show_one_reflog_ent(struct strbuf *sb, each_reflog_ent_fn fn, void *c
 	char *email_end, *message;
 	unsigned long timestamp;
 	int tz;
+	const char *p = sb->buf;
 
 	/* old SP new SP name <email> SP time TAB msg LF */
-	if (sb->len < 83 || sb->buf[sb->len - 1] != '\n' ||
-	    get_oid_hex(sb->buf, &ooid) || sb->buf[40] != ' ' ||
-	    get_oid_hex(sb->buf + 41, &noid) || sb->buf[81] != ' ' ||
-	    !(email_end = strchr(sb->buf + 82, '>')) ||
+	if (!sb->len || sb->buf[sb->len - 1] != '\n' ||
+	    parse_oid_hex(p, &ooid, &p) || *p++ != ' ' ||
+	    parse_oid_hex(p, &noid, &p) || *p++ != ' ' ||
+	    !(email_end = strchr(p, '>')) ||
 	    email_end[1] != ' ' ||
 	    !(timestamp = strtoul(email_end + 2, &message, 10)) ||
 	    !message || message[0] != ' ' ||
@@ -3136,7 +3137,7 @@ static int show_one_reflog_ent(struct strbuf *sb, each_reflog_ent_fn fn, void *c
 		message += 6;
 	else
 		message += 7;
-	return fn(&ooid, &noid, sb->buf + 82, timestamp, tz, message, cb_data);
+	return fn(&ooid, &noid, p, timestamp, tz, message, cb_data);
 }
 
 static char *find_beginning_of_line(char *bob, char *scan)