blame.c: prepare_lines should not call xrealloc for every line

Making a single preparation run for counting the lines will avoid memory
fragmentation.  Also, fix the allocated memory size which was wrong
when sizeof(int *) != sizeof(int), and would have been too small
for sizeof(int *) < sizeof(int), admittedly unlikely.

Signed-off-by: David Kastrup <dak@gnu.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/blame.c b/builtin/blame.c
index 9566a5ea4eabcdf83af46032283fa6ede426bca0..ec1955d1b060c03bc17d2a9096d40e5a1e1aa27c 100644 (file)
--- a/builtin/blame.c
+++ b/builtin/blame.c
@@ -1756,25 +1756,41 @@ static int prepare_lines(struct scoreboard *sb)
 {
        const char *buf = sb->final_buf;
        unsigned long len = sb->final_buf_size;
-       int num = 0, incomplete = 0, bol = 1;
+       const char *end = buf + len;
+       const char *p;
+       int *lineno;
+       int num = 0, incomplete = 0;
 
-       if (len && buf[len-1] != '\n')
-               incomplete++; /* incomplete line at the end */
-       while (len--) {
-               if (bol) {
-                       sb->lineno = xrealloc(sb->lineno,
-                                             sizeof(int) * (num + 1));
-                       sb->lineno[num] = buf - sb->final_buf;
-                       bol = 0;
-               }
-               if (*buf++ == '\n') {
+       for (p = buf;;) {
+               p = memchr(p, '\n', end - p);
+               if (p) {
+                       p++;
                        num++;
-                       bol = 1;
+                       continue;
                }
+               break;
        }
-       sb->lineno = xrealloc(sb->lineno,
-                             sizeof(int) * (num + incomplete + 1));
-       sb->lineno[num + incomplete] = buf - sb->final_buf;
+
+       if (len && end[-1] != '\n')
+               incomplete++; /* incomplete line at the end */
+
+       sb->lineno = xmalloc(sizeof(*sb->lineno) * (num + incomplete + 1));
+       lineno = sb->lineno;
+
+       *lineno++ = 0;
+       for (p = buf;;) {
+               p = memchr(p, '\n', end - p);
+               if (p) {
+                       p++;
+                       *lineno++ = p - buf;
+                       continue;
+               }
+               break;
+       }
+
+       if (incomplete)
+               *lineno++ = len;
+
        sb->num_lines = num + incomplete;
        return sb->num_lines;
 }