bzip2recover.c

/*-----------------------------------------------------------*/
/*--- Block recoverer program for bzip2                   ---*/
/*---                                      bzip2recover.c ---*/
/*-----------------------------------------------------------*/

/* ------------------------------------------------------------------
   This file is part of bzip2/libbzip2, a program and library for
   lossless, block-sorting data compression.

   bzip2/libbzip2 version 1.0.6 of 6 September 2010
   Copyright (C) 1996-2010 Julian Seward <jseward@bzip.org>

   Please read the WARNING, DISCLAIMER and PATENTS sections in the 
   README file.

   This program is released under the terms of the license contained
   in the file LICENSE.
   ------------------------------------------------------------------ */

/* This program is a complete hack and should be rewritten properly.
	 It isn't very complicated. */

#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>


/* This program records bit locations in the file to be recovered.
   That means that if 64-bit ints are not supported, we will not
   be able to recover .bz2 files over 512MB (2^32 bits) long.
   On GNU supported platforms, we take advantage of the 64-bit
   int support to circumvent this problem.  Ditto MSVC.

   This change occurred in version 1.0.2; all prior versions have
   the 512MB limitation.
*/
#ifdef __GNUC__
   typedef  unsigned long long int  MaybeUInt64;
#  define MaybeUInt64_FMT "%Lu"
#else
#ifdef _MSC_VER
   typedef  unsigned __int64  MaybeUInt64;
#  define MaybeUInt64_FMT "%I64u"
#else
   typedef  unsigned int   MaybeUInt64;
#  define MaybeUInt64_FMT "%u"
#endif
#endif

typedef  unsigned int   UInt32;
typedef  int            Int32;
typedef  unsigned char  UChar;
typedef  char           Char;
typedef  unsigned char  Bool;
#define True    ((Bool)1)
#define False   ((Bool)0)


#define BZ_MAX_FILENAME 2000

Char inFileName[BZ_MAX_FILENAME];
Char outFileName[BZ_MAX_FILENAME];
Char progName[BZ_MAX_FILENAME];

MaybeUInt64 bytesOut = 0;
MaybeUInt64 bytesIn  = 0;


/*---------------------------------------------------*/
/*--- Header bytes                                ---*/
/*---------------------------------------------------*/

#define BZ_HDR_B 0x42                         /* 'B' */
#define BZ_HDR_Z 0x5a                         /* 'Z' */
#define BZ_HDR_h 0x68                         /* 'h' */
#define BZ_HDR_0 0x30                         /* '0' */
 

/*---------------------------------------------------*/
/*--- I/O errors                                  ---*/
/*---------------------------------------------------*/

/*---------------------------------------------*/
static void readError ( void )
{
   fprintf ( stderr,
             "%s: I/O error reading `%s', possible reason follows.\n",
            progName, inFileName );
   perror ( progName );
   fprintf ( stderr, "%s: warning: output file(s) may be incomplete.\n",
             progName );
   exit ( 1 );
}


/*---------------------------------------------*/
static void writeError ( void )
{
   fprintf ( stderr,
             "%s: I/O error reading `%s', possible reason follows.\n",
            progName, inFileName );
   perror ( progName );
   fprintf ( stderr, "%s: warning: output file(s) may be incomplete.\n",
             progName );
   exit ( 1 );
}


/*---------------------------------------------*/
static void mallocFail ( Int32 n )
{
   fprintf ( stderr,
             "%s: malloc failed on request for %d bytes.\n",
            progName, n );
   fprintf ( stderr, "%s: warning: output file(s) may be incomplete.\n",
             progName );
   exit ( 1 );
}


/*---------------------------------------------*/
static void tooManyBlocks ( Int32 max_handled_blocks )
{
   fprintf ( stderr,
             "%s: `%s' appears to contain more than %d blocks\n",
            progName, inFileName, max_handled_blocks );
   fprintf ( stderr,
             "%s: and cannot be handled.  To fix, increase\n",
             progName );
   fprintf ( stderr, 
             "%s: BZ_MAX_HANDLED_BLOCKS in bzip2recover.c, and recompile.\n",
             progName );
   exit ( 1 );
}



/*---------------------------------------------------*/
/*--- Bit stream I/O                              ---*/
/*---------------------------------------------------*/

typedef
   struct {
      FILE*  handle;
      Int32  buffer;
      Int32  buffLive;
      Char   mode;
   }
   BitStream;


/*---------------------------------------------*/
static BitStream* bsOpenReadStream ( FILE* stream )
{
   BitStream *bs = malloc ( sizeof(BitStream) );
   if (bs == NULL) mallocFail ( sizeof(BitStream) );
   bs->handle = stream;
   bs->buffer = 0;
   bs->buffLive = 0;
   bs->mode = 'r';
   return bs;
}


/*---------------------------------------------*/
static BitStream* bsOpenWriteStream ( FILE* stream )
{
   BitStream *bs = malloc ( sizeof(BitStream) );
   if (bs == NULL) mallocFail ( sizeof(BitStream) );
   bs->handle = stream;
   bs->buffer = 0;
   bs->buffLive = 0;
   bs->mode = 'w';
   return bs;
}


/*---------------------------------------------*/
static void bsPutBit ( BitStream* bs, Int32 bit )
{
   if (bs->buffLive == 8) {
      Int32 retVal = putc ( (UChar) bs->buffer, bs->handle );
      if (retVal == EOF) writeError();
      bytesOut++;
      bs->buffLive = 1;
      bs->buffer = bit & 0x1;
   } else {
      bs->buffer = ( (bs->buffer << 1) | (bit & 0x1) );
      bs->buffLive++;
   };
}


/*---------------------------------------------*/
/*--
   Returns 0 or 1, or 2 to indicate EOF.
--*/
static Int32 bsGetBit ( BitStream* bs )
{
   if (bs->buffLive > 0) {
      bs->buffLive --;
      return ( ((bs->buffer) >> (bs->buffLive)) & 0x1 );
   } else {
      Int32 retVal = getc ( bs->handle );
      if ( retVal == EOF ) {
         if (errno != 0) readError();
         return 2;
      }
      bs->buffLive = 7;
      bs->buffer = retVal;
      return ( ((bs->buffer) >> 7) & 0x1 );
   }
}


/*---------------------------------------------*/
static void bsClose ( BitStream* bs )
{
   Int32 retVal;

   if ( bs->mode == 'w' ) {
      while ( bs->buffLive < 8 ) {
         bs->buffLive++;
         bs->buffer <<= 1;
      };
      retVal = putc ( (UChar) (bs->buffer), bs->handle );
      if (retVal == EOF) writeError();
      bytesOut++;
      retVal = fflush ( bs->handle );
      if (retVal == EOF) writeError();
   }
   retVal = fclose ( bs->handle );
   if (retVal == EOF) {
      if (bs->mode == 'w') writeError(); else readError();
   }
   free ( bs );
}


/*---------------------------------------------*/
static void bsPutUChar ( BitStream* bs, UChar c )
{
   Int32 i;
   for (i = 7; i >= 0; i--)
      bsPutBit ( bs, (((UInt32) c) >> i) & 0x1 );
}


/*---------------------------------------------*/
static void bsPutUInt32 ( BitStream* bs, UInt32 c )
{
   Int32 i;

   for (i = 31; i >= 0; i--)
      bsPutBit ( bs, (c >> i) & 0x1 );
}


/*---------------------------------------------*/
static Bool endsInBz2 ( Char* name )
{
   Int32 n = strlen ( name );
   if (n <= 4) return False;
   return
      (name[n-4] == '.' &&
       name[n-3] == 'b' &&
       name[n-2] == 'z' &&
       name[n-1] == '2');
}


/*---------------------------------------------------*/
/*---                                             ---*/
/*---------------------------------------------------*/

/* This logic isn't really right when it comes to Cygwin. */
#ifdef _WIN32
#  define  BZ_SPLIT_SYM  '\\'  /* path splitter on Windows platform */
#else
#  define  BZ_SPLIT_SYM  '/'   /* path splitter on Unix platform */
#endif

#define BLOCK_HEADER_HI  0x00003141UL
#define BLOCK_HEADER_LO  0x59265359UL

#define BLOCK_ENDMARK_HI 0x00001772UL
#define BLOCK_ENDMARK_LO 0x45385090UL

/* Increase if necessary.  However, a .bz2 file with > 50000 blocks
   would have an uncompressed size of at least 40GB, so the chances
   are low you'll need to up this.
*/
#define BZ_MAX_HANDLED_BLOCKS 50000

MaybeUInt64 bStart [BZ_MAX_HANDLED_BLOCKS];
MaybeUInt64 bEnd   [BZ_MAX_HANDLED_BLOCKS];
MaybeUInt64 rbStart[BZ_MAX_HANDLED_BLOCKS];
MaybeUInt64 rbEnd  [BZ_MAX_HANDLED_BLOCKS];


/*-----------------------------------------------------------*/
/*--- end                                  bzip2recover.c ---*/
/*-----------------------------------------------------------*/