The Tor Browser: media/libvorbis/lib/vorbis_codebook.c@97036ab72558 (annotated)

media/libvorbis/lib/vorbis_codebook.c@97036ab72558 (annotated)

media/libvorbis/lib/vorbis_codebook.c

Tue, 06 Jan 2015 21:39:09 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Tue, 06 Jan 2015 21:39:09 +0100
branch: TOR_BUG_9701
changeset 8: 97036ab72558
permissions: -rw-r--r--

Conditionally force memory storage according to privacy.thirdparty.isolate;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.

 /********************************************************************
  *                                                                  *
  * THIS FILE IS PART OF THE OggVorbis SOFTWARE CODEC SOURCE CODE.   *
  * USE, DISTRIBUTION AND REPRODUCTION OF THIS LIBRARY SOURCE IS     *
  * GOVERNED BY A BSD-STYLE SOURCE LICENSE INCLUDED WITH THIS SOURCE *
  * IN 'COPYING'. PLEASE READ THESE TERMS BEFORE DISTRIBUTING.       *
  *                                                                  *
  * THE OggVorbis SOURCE CODE IS (C) COPYRIGHT 1994-2009             *
  * by the Xiph.Org Foundation http://www.xiph.org/                  *
  *                                                                  *
  ********************************************************************
  function: basic codebook pack/unpack/code/decode operations
  last mod: $Id: codebook.c 19057 2014-01-22 12:32:31Z xiphmont $
  ********************************************************************/
 #include <stdlib.h>
 #include <string.h>
 #include <math.h>
 #include <ogg/ogg.h>
 #include "vorbis/codec.h"
 #include "codebook.h"
 #include "scales.h"
 #include "misc.h"
 #include "os.h"
 /* packs the given codebook into the bitstream **************************/
 int vorbis_staticbook_pack(const static_codebook *c,oggpack_buffer *opb){
   long i,j;
   int ordered=0;
   /* first the basic parameters */
   oggpack_write(opb,0x564342,24);
   oggpack_write(opb,c->dim,16);
   oggpack_write(opb,c->entries,24);
   /* pack the codewords.  There are two packings; length ordered and
      length random.  Decide between the two now. */
   for(i=1;i<c->entries;i++)
     if(c->lengthlist[i-1]==0 || c->lengthlist[i]<c->lengthlist[i-1])break;
   if(i==c->entries)ordered=1;
   if(ordered){
     /* length ordered.  We only need to say how many codewords of
        each length.  The actual codewords are generated
        deterministically */
     long count=0;
     oggpack_write(opb,1,1);  /* ordered */
     oggpack_write(opb,c->lengthlist[0]-1,5); /* 1 to 32 */
     for(i=1;i<c->entries;i++){
       char this=c->lengthlist[i];
       char last=c->lengthlist[i-1];
       if(this>last){
         for(j=last;j<this;j++){
           oggpack_write(opb,i-count,_ilog(c->entries-count));
           count=i;
         }
       }
     }
     oggpack_write(opb,i-count,_ilog(c->entries-count));
   }else{
     /* length random.  Again, we don't code the codeword itself, just
        the length.  This time, though, we have to encode each length */
     oggpack_write(opb,0,1);   /* unordered */
     /* algortihmic mapping has use for 'unused entries', which we tag
        here.  The algorithmic mapping happens as usual, but the unused
        entry has no codeword. */
     for(i=0;i<c->entries;i++)
       if(c->lengthlist[i]==0)break;
     if(i==c->entries){
       oggpack_write(opb,0,1); /* no unused entries */
       for(i=0;i<c->entries;i++)
         oggpack_write(opb,c->lengthlist[i]-1,5);
     }else{
       oggpack_write(opb,1,1); /* we have unused entries; thus we tag */
       for(i=0;i<c->entries;i++){
         if(c->lengthlist[i]==0){
           oggpack_write(opb,0,1);
         }else{
           oggpack_write(opb,1,1);
           oggpack_write(opb,c->lengthlist[i]-1,5);
         }
       }
     }
   }
   /* is the entry number the desired return value, or do we have a
      mapping? If we have a mapping, what type? */
   oggpack_write(opb,c->maptype,4);
   switch(c->maptype){
   case 0:
     /* no mapping */
     break;
   case 1:case 2:
     /* implicitly populated value mapping */
     /* explicitly populated value mapping */
     if(!c->quantlist){
       /* no quantlist?  error */
       return(-1);
     }
     /* values that define the dequantization */
     oggpack_write(opb,c->q_min,32);
     oggpack_write(opb,c->q_delta,32);
     oggpack_write(opb,c->q_quant-1,4);
     oggpack_write(opb,c->q_sequencep,1);
     {
       int quantvals;
       switch(c->maptype){
       case 1:
         /* a single column of (c->entries/c->dim) quantized values for
            building a full value list algorithmically (square lattice) */
         quantvals=_book_maptype1_quantvals(c);
         break;
       case 2:
         /* every value (c->entries*c->dim total) specified explicitly */
         quantvals=c->entries*c->dim;
         break;
       default: /* NOT_REACHABLE */
         quantvals=-1;
       }
       /* quantized values */
       for(i=0;i<quantvals;i++)
         oggpack_write(opb,labs(c->quantlist[i]),c->q_quant);
     }
     break;
   default:
     /* error case; we don't have any other map types now */
     return(-1);
   }
   return(0);
 }
 /* unpacks a codebook from the packet buffer into the codebook struct,
    readies the codebook auxiliary structures for decode *************/
 static_codebook *vorbis_staticbook_unpack(oggpack_buffer *opb){
   long i,j;
   static_codebook *s=_ogg_calloc(1,sizeof(*s));
   s->allocedp=1;
   /* make sure alignment is correct */
   if(oggpack_read(opb,24)!=0x564342)goto _eofout;
   /* first the basic parameters */
   s->dim=oggpack_read(opb,16);
   s->entries=oggpack_read(opb,24);
   if(s->entries==-1)goto _eofout;
   if(_ilog(s->dim)+_ilog(s->entries)>24)goto _eofout;
   /* codeword ordering.... length ordered or unordered? */
   switch((int)oggpack_read(opb,1)){
   case 0:{
     long unused;
     /* allocated but unused entries? */
     unused=oggpack_read(opb,1);
     if((s->entries*(unused?1:5)+7)>>3>opb->storage-oggpack_bytes(opb))
       goto _eofout;
     /* unordered */
     s->lengthlist=_ogg_malloc(sizeof(*s->lengthlist)*s->entries);
     /* allocated but unused entries? */
     if(unused){
       /* yes, unused entries */
       for(i=0;i<s->entries;i++){
         if(oggpack_read(opb,1)){
           long num=oggpack_read(opb,5);
           if(num==-1)goto _eofout;
           s->lengthlist[i]=num+1;
         }else
           s->lengthlist[i]=0;
       }
     }else{
       /* all entries used; no tagging */
       for(i=0;i<s->entries;i++){
         long num=oggpack_read(opb,5);
         if(num==-1)goto _eofout;
         s->lengthlist[i]=num+1;
       }
     }
     break;
   }
   case 1:
     /* ordered */
     {
       long length=oggpack_read(opb,5)+1;
       if(length==0)goto _eofout;
       s->lengthlist=_ogg_malloc(sizeof(*s->lengthlist)*s->entries);
       for(i=0;i<s->entries;){
         long num=oggpack_read(opb,_ilog(s->entries-i));
         if(num==-1)goto _eofout;
         if(length>32 || num>s->entries-i ||
            (num>0 && (num-1)>>(length-1)>1)){
           goto _errout;
         }
         if(length>32)goto _errout;
         for(j=0;j<num;j++,i++)
           s->lengthlist[i]=length;
         length++;
       }
     }
     break;
   default:
     /* EOF */
     goto _eofout;
   }
   /* Do we have a mapping to unpack? */
   switch((s->maptype=oggpack_read(opb,4))){
   case 0:
     /* no mapping */
     break;
   case 1: case 2:
     /* implicitly populated value mapping */
     /* explicitly populated value mapping */
     s->q_min=oggpack_read(opb,32);
     s->q_delta=oggpack_read(opb,32);
     s->q_quant=oggpack_read(opb,4)+1;
     s->q_sequencep=oggpack_read(opb,1);
     if(s->q_sequencep==-1)goto _eofout;
     {
       int quantvals=0;
       switch(s->maptype){
       case 1:
         quantvals=(s->dim==0?0:_book_maptype1_quantvals(s));
         break;
       case 2:
         quantvals=s->entries*s->dim;
         break;
       }
       /* quantized values */
       if(((quantvals*s->q_quant+7)>>3)>opb->storage-oggpack_bytes(opb))
         goto _eofout;
       s->quantlist=_ogg_malloc(sizeof(*s->quantlist)*quantvals);
       for(i=0;i<quantvals;i++)
         s->quantlist[i]=oggpack_read(opb,s->q_quant);
       if(quantvals&&s->quantlist[quantvals-1]==-1)goto _eofout;
     }
     break;
   default:
     goto _errout;
   }
   /* all set */
   return(s);
  _errout:
  _eofout:
   vorbis_staticbook_destroy(s);
   return(NULL);
 }
 /* returns the number of bits ************************************************/
 int vorbis_book_encode(codebook *book, int a, oggpack_buffer *b){
   if(a<0 || a>=book->c->entries)return(0);
   oggpack_write(b,book->codelist[a],book->c->lengthlist[a]);
   return(book->c->lengthlist[a]);
 }
 /* the 'eliminate the decode tree' optimization actually requires the
    codewords to be MSb first, not LSb.  This is an annoying inelegancy
    (and one of the first places where carefully thought out design
    turned out to be wrong; Vorbis II and future Ogg codecs should go
    to an MSb bitpacker), but not actually the huge hit it appears to
    be.  The first-stage decode table catches most words so that
    bitreverse is not in the main execution path. */
 static ogg_uint32_t bitreverse(ogg_uint32_t x){
   x=    ((x>>16)&0x0000ffff) | ((x<<16)&0xffff0000);
   x=    ((x>> 8)&0x00ff00ff) | ((x<< 8)&0xff00ff00);
   x=    ((x>> 4)&0x0f0f0f0f) | ((x<< 4)&0xf0f0f0f0);
   x=    ((x>> 2)&0x33333333) | ((x<< 2)&0xcccccccc);
   return((x>> 1)&0x55555555) | ((x<< 1)&0xaaaaaaaa);
 }
 STIN long decode_packed_entry_number(codebook *book, oggpack_buffer *b){
   int  read=book->dec_maxlength;
   long lo,hi;
   long lok = oggpack_look(b,book->dec_firsttablen);
   if (lok >= 0) {
     long entry = book->dec_firsttable[lok];
     if(entry&0x80000000UL){
       lo=(entry>>15)&0x7fff;
       hi=book->used_entries-(entry&0x7fff);
     }else{
       oggpack_adv(b, book->dec_codelengths[entry-1]);
       return(entry-1);
     }
   }else{
     lo=0;
     hi=book->used_entries;
   }
   lok = oggpack_look(b, read);
   while(lok<0 && read>1)
     lok = oggpack_look(b, --read);
   if(lok<0)return -1;
   /* bisect search for the codeword in the ordered list */
   {
     ogg_uint32_t testword=bitreverse((ogg_uint32_t)lok);
     while(hi-lo>1){
       long p=(hi-lo)>>1;
       long test=book->codelist[lo+p]>testword;
       lo+=p&(test-1);
       hi-=p&(-test);
       }
     if(book->dec_codelengths[lo]<=read){
       oggpack_adv(b, book->dec_codelengths[lo]);
       return(lo);
     }
   }
   oggpack_adv(b, read);
   return(-1);
 }
 /* Decode side is specced and easier, because we don't need to find
    matches using different criteria; we simply read and map.  There are
    two things we need to do 'depending':
    We may need to support interleave.  We don't really, but it's
    convenient to do it here rather than rebuild the vector later.
    Cascades may be additive or multiplicitive; this is not inherent in
    the codebook, but set in the code using the codebook.  Like
    interleaving, it's easiest to do it here.
    addmul==0 -> declarative (set the value)
    addmul==1 -> additive
    addmul==2 -> multiplicitive */
 /* returns the [original, not compacted] entry number or -1 on eof *********/
 long vorbis_book_decode(codebook *book, oggpack_buffer *b){
   if(book->used_entries>0){
     long packed_entry=decode_packed_entry_number(book,b);
     if(packed_entry>=0)
       return(book->dec_index[packed_entry]);
   }
   /* if there's no dec_index, the codebook unpacking isn't collapsed */
   return(-1);
 }
 /* returns 0 on OK or -1 on eof *************************************/
 /* decode vector / dim granularity gaurding is done in the upper layer */
 long vorbis_book_decodevs_add(codebook *book,float *a,oggpack_buffer *b,int n){
   if(book->used_entries>0){
     int step=n/book->dim;
     long *entry = alloca(sizeof(*entry)*step);
     float **t = alloca(sizeof(*t)*step);
     int i,j,o;
     for (i = 0; i < step; i++) {
       entry[i]=decode_packed_entry_number(book,b);
       if(entry[i]==-1)return(-1);
       t[i] = book->valuelist+entry[i]*book->dim;
     }
     for(i=0,o=0;i<book->dim;i++,o+=step)
       for (j=0;j<step;j++)
         a[o+j]+=t[j][i];
   }
   return(0);
 }
 /* decode vector / dim granularity gaurding is done in the upper layer */
 long vorbis_book_decodev_add(codebook *book,float *a,oggpack_buffer *b,int n){
   if(book->used_entries>0){
     int i,j,entry;
     float *t;
     if(book->dim>8){
       for(i=0;i<n;){
         entry = decode_packed_entry_number(book,b);
         if(entry==-1)return(-1);
         t     = book->valuelist+entry*book->dim;
         for (j=0;j<book->dim;)
           a[i++]+=t[j++];
       }
     }else{
       for(i=0;i<n;){
         entry = decode_packed_entry_number(book,b);
         if(entry==-1)return(-1);
         t     = book->valuelist+entry*book->dim;
         j=0;
         switch((int)book->dim){
         case 8:
           a[i++]+=t[j++];
         case 7:
           a[i++]+=t[j++];
         case 6:
           a[i++]+=t[j++];
         case 5:
           a[i++]+=t[j++];
         case 4:
           a[i++]+=t[j++];
         case 3:
           a[i++]+=t[j++];
         case 2:
           a[i++]+=t[j++];
         case 1:
           a[i++]+=t[j++];
         case 0:
           break;
         }
       }
     }
   }
   return(0);
 }
 /* unlike the others, we guard against n not being an integer number
    of <dim> internally rather than in the upper layer (called only by
    floor0) */
 long vorbis_book_decodev_set(codebook *book,float *a,oggpack_buffer *b,int n){
   if(book->used_entries>0){
     int i,j,entry;
     float *t;
     for(i=0;i<n;){
       entry = decode_packed_entry_number(book,b);
       if(entry==-1)return(-1);
       t     = book->valuelist+entry*book->dim;
       for (j=0;i<n && j<book->dim;){
         a[i++]=t[j++];
       }
     }
   }else{
     int i;
     for(i=0;i<n;){
       a[i++]=0.f;
     }
   }
   return(0);
 }
 long vorbis_book_decodevv_add(codebook *book,float **a,long offset,int ch,
                               oggpack_buffer *b,int n){
   long i,j,entry;
   int chptr=0;
   if(book->used_entries>0){
     for(i=offset/ch;i<(offset+n)/ch;){
       entry = decode_packed_entry_number(book,b);
       if(entry==-1)return(-1);
       {
         const float *t = book->valuelist+entry*book->dim;
         for (j=0;j<book->dim;j++){
           a[chptr++][i]+=t[j];
           if(chptr==ch){
             chptr=0;
             i++;
           }
         }
       }
     }
   }
   return(0);
 }

The Tor Browser / annotate

media/libvorbis/lib/vorbis_codebook.c@97036ab72558 (annotated)

media/libvorbis/lib/vorbis_codebook.c