handle jpegtables of zero size correctly

diff --git a/src/swfextract.c b/src/swfextract.c
index b2e049c..f636eea 100644 (file)
--- a/src/swfextract.c
+++ b/src/swfextract.c
@@ -593,14 +593,16 @@ void handlefont(SWF*swf, TAG*tag)
     swf_FontFree(f);
 }
 
-U8*jpegtables = 0;
-int jpegtablessize;
+static char has_jpegtables=0;
+static U8*jpegtables = 0;
+static int jpegtablessize = 0;
 
 void handlejpegtables(TAG*tag)
 {
     if(tag->id == ST_JPEGTABLES) {
        jpegtables = tag->data;
        jpegtablessize = tag->len;
+       has_jpegtables = 1;
     }
 }
 
@@ -645,10 +647,14 @@ void handlejpeg(TAG*tag)
     /* swf jpeg images have two streams, which both start with ff d8 and
        end with ff d9. The following code handles sorting the middle
        <ff d9 ff d8> bytes out, so that one stream remains */
-    if(tag->id == ST_DEFINEBITSJPEG && tag->len>2 && jpegtables) {
+    if(tag->id == ST_DEFINEBITSJPEG && tag->len>2 && has_jpegtables) {
        fi = save_fopen(filename, "wb");
-       fwrite(jpegtables, 1, jpegtablessize-2, fi); //don't write end tag (ff,d8)
-       fwrite(&tag->data[2+2], tag->len-2-2, 1, fi); //don't write start tag (ff,d9)
+       if(jpegtablessize>=2) {
+           fwrite(jpegtables, 1, jpegtablessize-2, fi); //don't write end tag (ff,d8)
+           fwrite(&tag->data[2+2], tag->len-2-2, 1, fi); //don't write start tag (ff,d9)
+       } else {
+           fwrite(tag->data+2, tag->len-2, 1, fi);
+       }
        fclose(fi);
     }
     else if(tag->id == ST_DEFINEBITSJPEG2 && tag->len>2) {
@@ -679,7 +685,7 @@ void handlejpeg(TAG*tag)
     }
     else {
        int id = GET16(tag->data);
-       fprintf(stderr, "Object %d is not a JPEG picture!\n",id);
+       fprintf(stderr, "Object %d is not a JPEG picture!\n",id, jpegtables);
        exit(1);
     }
 }
@@ -1113,8 +1119,9 @@ int main (int argc,char ** argv)
                handlesoundstream(tag);
        }
 
-       if(tag->id == ST_JPEGTABLES)
+       if(tag->id == ST_JPEGTABLES) {
            handlejpegtables(tag);
+       }
 
        if(swf_isDefiningTag(tag)) {
            int id = swf_GetDefineID(tag);