[FFmpeg-devel] [PATCH] libavformat/img2dec: fix unable to find svg format when the svg resources start with "<svg"

[1035567130 at qq.com]

From: Wang Yaqiang <wangyaqiang03 at kuaishou.com>

svg is xml, but <?xml is not required,
 it can start with <svg and can have multiple empty lines.

Signed-off-by: Wang Yaqiang <wangyaqiang03 at kuaishou.com>
---
 libavformat/img2dec.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/libavformat/img2dec.c b/libavformat/img2dec.c
index 5a63d7c81d..448a574b59 100644
--- a/libavformat/img2dec.c
+++ b/libavformat/img2dec.c
@@ -25,6 +25,7 @@
 #define _DEFAULT_SOURCE
 #define _BSD_SOURCE
 #include <sys/stat.h>
+#include <ctype.h>
 #include "libavutil/avstring.h"
 #include "libavutil/log.h"
 #include "libavutil/opt.h"
@@ -964,18 +965,19 @@ static int svg_probe(const AVProbeData *p)
 {
     const uint8_t *b = p->buf;
     const uint8_t *end = p->buf + p->buf_size;
-
-    if (memcmp(p->buf, "<?xml", 5))
+    while (b && b < end && isspace(*b)) b++;
+    if (b >= end - 5) return 0;
+    if (memcmp(p->buf, "<?xml", 5) && memcmp(b, "<svg", 4))
         return 0;
     while (b < end) {
         int inc = ff_subtitles_next_line(b);
         if (!inc)
             break;
+        if (!memcmp(b, "<svg", 4))
+            return AVPROBE_SCORE_EXTENSION + 1;
         b += inc;
         if (b >= end - 4)
             return 0;
-        if (!memcmp(b, "<svg", 4))
-            return AVPROBE_SCORE_EXTENSION + 1;
     }
     return 0;
 }
-- 
2.39.2