Move find_info_tag to lavu and add av_ prefix to it

Signed-off-by: Janne Grunau <janne-ffmpeg@jannau.net>
(cherry picked from commit ab0287fcbd)

libavutil/parseutils.c

@@ -608,6 +608,45 @@ int av_parse_time(int64_t *timeval, const char *datestr, int duration)
     return 0;
 }
 
+int av_find_info_tag(char *arg, int arg_size, const char *tag1, const char *info)
+{
+    const char *p;
+    char tag[128], *q;
+
+    p = info;
+    if (*p == '?')
+        p++;
+    for(;;) {
+        q = tag;
+        while (*p != '\0' && *p != '=' && *p != '&') {
+            if ((q - tag) < sizeof(tag) - 1)
+                *q++ = *p;
+            p++;
+        }
+        *q = '\0';
+        q = arg;
+        if (*p == '=') {
+            p++;
+            while (*p != '&' && *p != '\0') {
+                if ((q - arg) < arg_size - 1) {
+                    if (*p == '+')
+                        *q++ = ' ';
+                    else
+                        *q++ = *p;
+                }
+                p++;
+            }
+        }
+        *q = '\0';
+        if (!strcmp(tag, tag1))
+            return 1;
+        if (*p != '&')
+            break;
+        p++;
+    }
+    return 0;
+}
+
 #ifdef TEST
 
 #undef printf

libavutil/parseutils.h

@@ -106,4 +106,12 @@ int av_parse_color(uint8_t *rgba_color, const char *color_string, int slen,
  */
 int av_parse_time(int64_t *timeval, const char *timestr, int duration);
 
+/**
+ * Attempt to find a specific tag in a URL.
+ *
+ * syntax: '?tag1=val1&tag2=val2...'. Little URL decoding is done.
+ * Return 1 if found.
+ */
+int av_find_info_tag(char *arg, int arg_size, const char *tag1, const char *info);
+
 #endif /* AVUTIL_PARSEUTILS_H */