Avoid segfault for long filenames

src/bin/mj2/opj_mj2_extract.c

@@ -82,7 +82,7 @@ int main(int argc, char *argv[])
     mj2_sample_t *sample;
     unsigned char* frame_codestream;
     FILE *file, *outfile;
-    char outfilename[50];
+    char outfilename[FILENAME_MAX];
     mj2_dparameters_t parameters;
 
     if (argc != 3) {
@@ -91,6 +91,11 @@ int main(int argc, char *argv[])
         return 1;
     }
 
+    if(strlen(argv[2]) + 11 > sizeof(outfilename)) {
+        fprintf(stderr,"filename %d too long\n",strlen(argv[2]) + 11);
+        return 1;
+    }
+
     file = fopen(argv[1], "rb");
 
     if (!file) {