Port of r16182 from libvorbis.

Second half of fix to https://bugzilla.mozilla.org/show_bug.cgi?id=500254
Sanity check the floor 1 post list to reject files with repeated values that
 would result in floor line segments with zero length.


git-svn-id: https://svn.xiph.org/trunk/Tremor@17523 0101bb08-14d6-0310-b084-bc0e0c8e3800

floor1.c

@@ -68,6 +68,10 @@ static int ilog(unsigned int v){
   return(ret);
 }
 
+static int icomp(const void *a,const void *b){
+  return(**(int **)a-**(int **)b);
+}
+
 static vorbis_info_floor *floor1_unpack (vorbis_info *vi,oggpack_buffer *opb){
   codec_setup_info     *ci=(codec_setup_info *)vi->codec_setup;
   int j,k,count=0,maxclass=-1,rangebits;
@@ -111,6 +115,17 @@ static vorbis_info_floor *floor1_unpack (vorbis_info *vi,oggpack_buffer *opb){
   info->postlist[0]=0;
   info->postlist[1]=1<<rangebits;
 
+  /* don't allow repeated values in post list as they'd result in
+     zero-length segments */
+  {
+    int *sortpointer[VIF_POSIT+2];
+    for(j=0;j<count+2;j++)sortpointer[j]=info->postlist+j;
+    qsort(sortpointer,count+2,sizeof(*sortpointer),icomp);
+
+    for(j=1;j<count+2;j++)
+      if(*sortpointer[j-1]==*sortpointer[j])goto err_out;
+  }
+
   return(info);
   
  err_out:
@@ -118,10 +133,6 @@ static vorbis_info_floor *floor1_unpack (vorbis_info *vi,oggpack_buffer *opb){
   return(NULL);
 }
 
-static int icomp(const void *a,const void *b){
-  return(**(int **)a-**(int **)b);
-}
-
 static vorbis_look_floor *floor1_look(vorbis_dsp_state *vd,vorbis_info_mode *mi,
                               vorbis_info_floor *in){