[Bug 852345] Re: Libdvdread misses hidden files and causes segfaults to calling programs

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** Tags added: patch

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https://bugs.launchpad.net/bugs/852345

Title:
  Libdvdread misses hidden files and causes segfaults to calling
  programs

Status in “libdvdread” package in Ubuntu:
  Confirmed

Bug description:
  Package: libdvdread4
  Version: 4.1.x and others

  No error message, but symptoms are usually segfault when reading, for example the Movie DVD Thor.
  This results from a new anti-copy scheme where the real video_ts.ifo is hidden. Use of the decoy video_ts.ifo results in a unplayable DVD.

  Discussion is here:
  http://ubuntuforums.org/showthread.php?p=11257764

  Patch is here:

  diff -ru libdvdread-4.1.3/src/dvd_udf.c libdvdread-4.1.3.fixed/src/dvd_udf.c
  --- libdvdread-4.1.3/src/dvd_udf.c    2008-09-06 15:55:51.000000000 -0600
  +++ libdvdread-4.1.3.fixed/src/dvd_udf.c    2011-09-16 14:07:04.000000000 -0600
  @@ -331,21 +331,26 @@
   /* This is wrong with regard to endianess */
   #define GETN(p, n, target) memcpy(target,&data[p], n)

  -static int Unicodedecode( uint8_t *data, int len, char *target )
  +static int Unicodedecode(uint8_t *data, int len, char *target)
   {
  -    int p = 1, i = 0;
  +    len--;
  +    data++;
  +    if (data[-1] == 8 )
  +        memcpy(target, data, len);
  +    else if (data[-1] == 16) {
  +        int i;

  -    if( ( data[ 0 ] == 8 ) || ( data[ 0 ] == 16 ) ) do {
  -        if( data[ 0 ] == 16 ) p++;  /* Ignore MSB of unicode16 */
  -        if( p<  len ) {
  -            target[ i++ ] = data[ p++ ];
  +        for (i = 0; i<  len; i++) {
  +            if (data[i*2] == 0)
  +                target[i] = data[i*2+1];
  +            else
  +                target[i] = 0;
           }
  -    } while( p<  len );
  +    }
  +    target[len] = '\0';

  -    target[ i ] = '\0';
       return 0;
   }
  -
   static int UDFDescriptor( uint8_t *data, uint16_t *TagID )
   {
       *TagID = GETN2(0);

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