The Tor Browser / file revision

 /*-

  * Copyright 2003,2004 Colin Percival

  * All rights reserved

  *

  * Redistribution and use in source and binary forms, with or without

  * modification, are permitted providing that the following conditions

  * are met:

  * 1. Redistributions of source code must retain the above copyright

  *    notice, this list of conditions and the following disclaimer.

  * 2. Redistributions in binary form must reproduce the above copyright

  *    notice, this list of conditions and the following disclaimer in the

  *    documentation and/or other materials provided with the distribution.

  *

  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR

  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED

  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY

  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL

  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS

  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,

  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING

  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

  * POSSIBILITY OF SUCH DAMAGE.

  *

  * Changelog:

  * 2005-04-26 - Define the header as a C structure, add a CRC32 checksum to

  *              the header, and make all the types 32-bit.

  *                --Benjamin Smedberg <benjamin@smedbergs.us>

  */

 #include "bspatch.h"

 #include "errors.h"

 #include <sys/stat.h>

 #include <stdlib.h>

 #include <stdio.h>

 #include <fcntl.h>

 #include <string.h>

 #include <limits.h>

 #if defined(XP_WIN)

 # include <io.h>

 #else

 # include <unistd.h>

 #endif

 #ifdef XP_WIN

 # include <winsock2.h>

 #else

 # include <arpa/inet.h>

 #endif

 #ifndef SSIZE_MAX

 # define SSIZE_MAX LONG_MAX

 #endif

 int

 MBS_ReadHeader(FILE* file, MBSPatchHeader *header)

 {

   size_t s = fread(header, 1, sizeof(MBSPatchHeader), file);

   if (s != sizeof(MBSPatchHeader))

     return READ_ERROR;

   header->slen      = ntohl(header->slen);

   header->scrc32    = ntohl(header->scrc32);

   header->dlen      = ntohl(header->dlen);

   header->cblen     = ntohl(header->cblen);

   header->difflen   = ntohl(header->difflen);

   header->extralen  = ntohl(header->extralen);

   struct stat hs;

   s = fstat(fileno(file), &hs);

   if (s)

     return READ_ERROR;

   if (memcmp(header->tag, "MBDIFF10", 8) != 0)

     return UNEXPECTED_BSPATCH_ERROR;

   if (sizeof(MBSPatchHeader) +

       header->cblen +

       header->difflen +

       header->extralen != uint32_t(hs.st_size))

     return UNEXPECTED_BSPATCH_ERROR;

   return OK;

 }

 int

 MBS_ApplyPatch(const MBSPatchHeader *header, FILE* patchFile,

                unsigned char *fbuffer, FILE* file)

 {

   unsigned char *fbufend = fbuffer + header->slen;

   unsigned char *buf = (unsigned char*) malloc(header->cblen +

                                                header->difflen +

                                                header->extralen);

   if (!buf)

     return BSPATCH_MEM_ERROR;

   int rv = OK;

   size_t r = header->cblen + header->difflen + header->extralen;

   unsigned char *wb = buf;

   while (r) {

     const size_t count = (r > SSIZE_MAX) ? SSIZE_MAX : r;

     size_t c = fread(wb, 1, count, patchFile);

     if (c != count) {

       rv = READ_ERROR;

       goto end;

     }

     r -= c;

     wb += c;

   }

   {

     MBSPatchTriple *ctrlsrc = (MBSPatchTriple*) buf;

     unsigned char *diffsrc = buf + header->cblen;

     unsigned char *extrasrc = diffsrc + header->difflen;

     MBSPatchTriple *ctrlend = (MBSPatchTriple*) diffsrc;

     unsigned char *diffend = extrasrc;

     unsigned char *extraend = extrasrc + header->extralen;

     do {

       ctrlsrc->x = ntohl(ctrlsrc->x);

       ctrlsrc->y = ntohl(ctrlsrc->y);

       ctrlsrc->z = ntohl(ctrlsrc->z);

 #ifdef DEBUG_bsmedberg

       printf("Applying block:\n"

              " x: %u\n"

              " y: %u\n"

              " z: %i\n",

              ctrlsrc->x,

              ctrlsrc->y,

              ctrlsrc->z);

 #endif

       /* Add x bytes from oldfile to x bytes from the diff block */

       if (fbuffer + ctrlsrc->x > fbufend ||

           diffsrc + ctrlsrc->x > diffend) {

         rv = UNEXPECTED_BSPATCH_ERROR;

         goto end;

       }

       for (uint32_t i = 0; i < ctrlsrc->x; ++i) {

         diffsrc[i] += fbuffer[i];

       }

       if ((uint32_t) fwrite(diffsrc, 1, ctrlsrc->x, file) != ctrlsrc->x) {

         rv = WRITE_ERROR;

         goto end;

       }

       fbuffer += ctrlsrc->x;

       diffsrc += ctrlsrc->x;

       /* Copy y bytes from the extra block */

       if (extrasrc + ctrlsrc->y > extraend) {

         rv = UNEXPECTED_BSPATCH_ERROR;

         goto end;

       }

       if ((uint32_t) fwrite(extrasrc, 1, ctrlsrc->y, file) != ctrlsrc->y) {

         rv = WRITE_ERROR;

         goto end;

       }

       extrasrc += ctrlsrc->y;

       /* "seek" forwards in oldfile by z bytes */

       if (fbuffer + ctrlsrc->z > fbufend) {

         rv = UNEXPECTED_BSPATCH_ERROR;

         goto end;

       }

       fbuffer += ctrlsrc->z;

       /* and on to the next control block */

       ++ctrlsrc;

     } while (ctrlsrc < ctrlend);

   }

 end:

   free(buf);

   return rv;

 }