[PATCH/RFC v3 2/6] reflog: refactor log open+mmap

@@ -1389,12 +1389,31 @@ static void parse_reflog_line(const char *buf, int len,
 		*message = tzstr+6;
 }
 
+static char *open_reflog(const char *ref, size_t *mapsz, const char **logfile)
+{
+	struct stat st;
+	int logfd;
+	char *map;
+
+	*logfile = git_path("logs/%s", ref);
+	logfd = open(*logfile, O_RDONLY, 0);
+	if (logfd < 0)
+		return NULL;
+	if (fstat(logfd, &st))
+		return NULL;
+
+	*mapsz = xsize_t(st.st_size);
+	map = xmmap(NULL, *mapsz, PROT_READ, MAP_PRIVATE, logfd, 0);
+	close(logfd);
+	return map;
+}
+
+
 int read_ref_at(const char *ref, unsigned long at_time, int cnt, unsigned char *sha1, char **msg, unsigned long *cutoff_time, int *cutoff_tz, int *cutoff_cnt)
 {
-	const char *logfile, *logdata, *logend, *rec, *start;
+	const char *logfile, *logdata, *logend, *rec, *end;
 	char *email, *message;
-	int logfd, tz, reccnt = 0;
-	struct stat st;
+	int tz, reccnt = 0;
 	unsigned long date;
 	unsigned char new_sha1[20];
 	unsigned char old_sha1[20];

@@ -1402,28 +1421,20 @@ int read_ref_at(const char *ref, unsigned long at_time, int cnt, unsigned char *
 	void *log_mapped;
 	size_t mapsz;
 
-	logfile = git_path("logs/%s", ref);
-	logfd = open(logfile, O_RDONLY, 0);
-	if (logfd < 0)
+	logdata = log_mapped = open_reflog(ref, &mapsz, &logfile);
+	if (!logdata)
 		die("Unable to read log %s: %s", logfile, strerror(errno));
-	fstat(logfd, &st);
-	if (!st.st_size)
+	if (!mapsz)
 		die("Log %s is empty.", logfile);
-	mapsz = xsize_t(st.st_size);
-	log_mapped = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, logfd, 0);
-	logdata = log_mapped;
-	close(logfd);
 
-	rec = logend = logdata + st.st_size;
-	if (logdata < rec && *(rec-1) == '\n')
-		rec--;
+	rec = logend = logdata + mapsz;
 	while (logdata < rec) {
-		start = memrchr(logdata, '\n', rec-logdata);
-		if (start)
-			start++;
-		else
-			start = logdata;
-		parse_reflog_line(start, rec-start+1,
+		if (logdata < rec && rec[-1] == '\n')
+			rec--;
+		end = rec;
+		while (logdata < rec && rec[-1] != '\n')
+			rec--;
+		parse_reflog_line(rec, end-rec+1,
 				  old_sha1, new_sha1,
 				  &email, &date, &tz, &message,
 				  logfile);

@@ -1454,7 +1465,6 @@ int read_ref_at(const char *ref, unsigned long at_time, int cnt, unsigned char *
 		}
 
 		hashcpy(next_sha1, old_sha1);
-		rec = start-1;
 		if (cnt > 0)
 			cnt--;
 		reccnt++;