patch-id: use starts_with() and skip_prefix()

Get rid of magic numbers and avoid running over the end of a NUL
terminated string by using starts_with() and skip_prefix() instead
of memcmp().

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/patch-id.c b/builtin/patch-id.c
index 77db8739b5165f15a437651b0803711f6e019839..f21b6e34f6d79942638aeddd1e3cdbeac52a3940 100644 (file)
--- a/builtin/patch-id.c
+++ b/builtin/patch-id.c
@@ -81,16 +81,13 @@ static int get_one_patchid(unsigned char *next_sha1, unsigned char *result,
 
        while (strbuf_getwholeline(line_buf, stdin, '\n') != EOF) {
                char *line = line_buf->buf;
-               char *p = line;
+               const char *p = line;
                int len;
 
-               if (!memcmp(line, "diff-tree ", 10))
-                       p += 10;
-               else if (!memcmp(line, "commit ", 7))
-                       p += 7;
-               else if (!memcmp(line, "From ", 5))
-                       p += 5;
-               else if (!memcmp(line, "\\ ", 2) && 12 < strlen(line))
+               if (!skip_prefix(line, "diff-tree ", &p) &&
+                   !skip_prefix(line, "commit ", &p) &&
+                   !skip_prefix(line, "From ", &p) &&
+                   starts_with(line, "\\ ") && 12 < strlen(line))
                        continue;
 
                if (!get_sha1_hex(p, next_sha1)) {
@@ -99,14 +96,14 @@ static int get_one_patchid(unsigned char *next_sha1, unsigned char *result,
                }
 
                /* Ignore commit comments */
-               if (!patchlen && memcmp(line, "diff ", 5))
+               if (!patchlen && !starts_with(line, "diff "))
                        continue;
 
                /* Parsing diff header?  */
                if (before == -1) {
-                       if (!memcmp(line, "index ", 6))
+                       if (starts_with(line, "index "))
                                continue;
-                       else if (!memcmp(line, "--- ", 4))
+                       else if (starts_with(line, "--- "))
                                before = after = 1;
                        else if (!isalpha(line[0]))
                                break;
@@ -114,14 +111,14 @@ static int get_one_patchid(unsigned char *next_sha1, unsigned char *result,
 
                /* Looking for a valid hunk header?  */
                if (before == 0 && after == 0) {
-                       if (!memcmp(line, "@@ -", 4)) {
+                       if (starts_with(line, "@@ -")) {
                                /* Parse next hunk, but ignore line numbers.  */
                                scan_hunk_header(line, &before, &after);
                                continue;
                        }
 
                        /* Split at the end of the patch.  */
-                       if (memcmp(line, "diff ", 5))
+                       if (!starts_with(line, "diff "))
                                break;
 
                        /* Else we're parsing another header.  */