Parse GIF application extension block correctly (Issue #39)

saitoha · Mar 4, 2015 · 2b66fd7 · 2b66fd7
1 parent 7f73585
commit 2b66fd7
Showing 1 changed file with 15 additions and 21 deletions.
diff --git a/converters/stb_image.h b/converters/stb_image.h
@@ -4060,6 +4060,7 @@ static stbi_uc *stbi__gif_load_next(stbi__context *s, stbi__gif *g, int *comp, i
 {
    int i;
    stbi_uc *old_out = 0;
+   stbi_uc buffer[256];
 
    if (g->out == 0) {
       if (!stbi__gif_header(s, g, comp,0))     return 0; // stbi__g_failure_reason set by stbi__gif_header
@@ -4149,27 +4150,20 @@ static stbi_uc *stbi__gif_load_next(stbi__context *s, stbi__gif *g, int *comp, i
                break;
             case 0xFF: // Application Extension
                len = stbi__get8(s); // block size
-               if (len != 11) break;
-               if (stbi__get8(s) != 'N') break;
-               if (stbi__get8(s) != 'E') break;
-               if (stbi__get8(s) != 'T') break;
-               if (stbi__get8(s) != 'S') break;
-               if (stbi__get8(s) != 'C') break;
-               if (stbi__get8(s) != 'A') break;
-               if (stbi__get8(s) != 'P') break;
-               if (stbi__get8(s) != 'E') break;
-               if (stbi__get8(s) != '2') break;
-               if (stbi__get8(s) != '.') break;
-               if (stbi__get8(s) != '0') break;
-               if (stbi__get8(s) != 0x03) break;
-               // loop count
-               switch (stbi__get8(s)) {
-               case 0x00:
-                  g->loop_count = 1;
-                  break;
-               case 0x01:
-                  g->loop_count = stbi__get16le(s);
-                  break;
+               stbi__getn(s, buffer, len);
+               buffer[len] = 0;
+               if (len == 11 && strcmp((char *)buffer, "NETSCAPE2.0") == 0) {
+                   if (stbi__get8(s) == 0x03) {
+                       // loop count
+                       switch (stbi__get8(s)) {
+                       case 0x00:
+                          g->loop_count = 1;
+                          break;
+                       case 0x01:
+                          g->loop_count = stbi__get16le(s);
+                          break;
+                       }
+                   }
                }
                break;
             default: