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[android-x86/build.git] / tools / applypatch / bsdiff.c
index f502a6b..b6d342b 100644 (file)
 /*
- * Copyright (C) 2008 The Android Open Source Project
+ * Copyright (C) 2009 The Android Open Source Project
  *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
  *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
+ *      http://www.apache.org/licenses/LICENSE-2.0
  *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
- * 02110-1301, USA.
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
  */
 
-// This file is a nearly line-for-line copy of bspatch.c from the
-// bsdiff-4.3 distribution; the primary differences being how the
-// input and output data are read and the error handling.  Running
-// applypatch with the -l option will display the bsdiff license
-// notice.
+/*
+ * Most of this code comes from bsdiff.c from the bsdiff-4.3
+ * distribution, which is:
+ */
+
+/*-
+ * Copyright 2003-2005 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.
+ */
 
+#include <sys/types.h>
+
+#include <bzlib.h>
+#include <err.h>
+#include <fcntl.h>
 #include <stdio.h>
-#include <sys/stat.h>
-#include <errno.h>
-#include <unistd.h>
+#include <stdlib.h>
 #include <string.h>
+#include <unistd.h>
 
-#include <bzlib.h>
+#define MIN(x,y) (((x)<(y)) ? (x) : (y))
+
+static void split(off_t *I,off_t *V,off_t start,off_t len,off_t h)
+{
+       off_t i,j,k,x,tmp,jj,kk;
+
+       if(len<16) {
+               for(k=start;k<start+len;k+=j) {
+                       j=1;x=V[I[k]+h];
+                       for(i=1;k+i<start+len;i++) {
+                               if(V[I[k+i]+h]<x) {
+                                       x=V[I[k+i]+h];
+                                       j=0;
+                               };
+                               if(V[I[k+i]+h]==x) {
+                                       tmp=I[k+j];I[k+j]=I[k+i];I[k+i]=tmp;
+                                       j++;
+                               };
+                       };
+                       for(i=0;i<j;i++) V[I[k+i]]=k+j-1;
+                       if(j==1) I[k]=-1;
+               };
+               return;
+       };
+
+       x=V[I[start+len/2]+h];
+       jj=0;kk=0;
+       for(i=start;i<start+len;i++) {
+               if(V[I[i]+h]<x) jj++;
+               if(V[I[i]+h]==x) kk++;
+       };
+       jj+=start;kk+=jj;
+
+       i=start;j=0;k=0;
+       while(i<jj) {
+               if(V[I[i]+h]<x) {
+                       i++;
+               } else if(V[I[i]+h]==x) {
+                       tmp=I[i];I[i]=I[jj+j];I[jj+j]=tmp;
+                       j++;
+               } else {
+                       tmp=I[i];I[i]=I[kk+k];I[kk+k]=tmp;
+                       k++;
+               };
+       };
+
+       while(jj+j<kk) {
+               if(V[I[jj+j]+h]==x) {
+                       j++;
+               } else {
+                       tmp=I[jj+j];I[jj+j]=I[kk+k];I[kk+k]=tmp;
+                       k++;
+               };
+       };
+
+       if(jj>start) split(I,V,start,jj-start,h);
+
+       for(i=0;i<kk-jj;i++) V[I[jj+i]]=kk-1;
+       if(jj==kk-1) I[jj]=-1;
+
+       if(start+len>kk) split(I,V,kk,start+len-kk,h);
+}
+
+static void qsufsort(off_t *I,off_t *V,u_char *old,off_t oldsize)
+{
+       off_t buckets[256];
+       off_t i,h,len;
+
+       for(i=0;i<256;i++) buckets[i]=0;
+       for(i=0;i<oldsize;i++) buckets[old[i]]++;
+       for(i=1;i<256;i++) buckets[i]+=buckets[i-1];
+       for(i=255;i>0;i--) buckets[i]=buckets[i-1];
+       buckets[0]=0;
+
+       for(i=0;i<oldsize;i++) I[++buckets[old[i]]]=i;
+       I[0]=oldsize;
+       for(i=0;i<oldsize;i++) V[i]=buckets[old[i]];
+       V[oldsize]=0;
+       for(i=1;i<256;i++) if(buckets[i]==buckets[i-1]+1) I[buckets[i]]=-1;
+       I[0]=-1;
+
+       for(h=1;I[0]!=-(oldsize+1);h+=h) {
+               len=0;
+               for(i=0;i<oldsize+1;) {
+                       if(I[i]<0) {
+                               len-=I[i];
+                               i-=I[i];
+                       } else {
+                               if(len) I[i-len]=-len;
+                               len=V[I[i]]+1-i;
+                               split(I,V,i,len,h);
+                               i+=len;
+                               len=0;
+                       };
+               };
+               if(len) I[i-len]=-len;
+       };
+
+       for(i=0;i<oldsize+1;i++) I[V[i]]=i;
+}
+
+static off_t matchlen(u_char *old,off_t oldsize,u_char *new,off_t newsize)
+{
+       off_t i;
+
+       for(i=0;(i<oldsize)&&(i<newsize);i++)
+               if(old[i]!=new[i]) break;
+
+       return i;
+}
 
-#include "mincrypt/sha.h"
-
-void ShowBSDiffLicense() {
-  puts("The bsdiff library used herein is:\n"
-       "\n"
-       "Copyright 2003-2005 Colin Percival\n"
-       "All rights reserved\n"
-       "\n"
-       "Redistribution and use in source and binary forms, with or without\n"
-       "modification, are permitted providing that the following conditions\n"
-       "are met:\n"
-       "1. Redistributions of source code must retain the above copyright\n"
-       "   notice, this list of conditions and the following disclaimer.\n"
-       "2. Redistributions in binary form must reproduce the above copyright\n"
-       "   notice, this list of conditions and the following disclaimer in the\n"
-       "   documentation and/or other materials provided with the distribution.\n"
-       "\n"
-       "THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR\n"
-       "IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED\n"
-       "WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE\n"
-       "ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY\n"
-       "DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL\n"
-       "DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS\n"
-       "OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)\n"
-       "HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,\n"
-       "STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING\n"
-       "IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE\n"
-       "POSSIBILITY OF SUCH DAMAGE.\n"
-       "\n------------------\n\n"
-       "This program uses Julian R Seward's \"libbzip2\" library, available\n"
-       "from http://www.bzip.org/.\n"
-       );
+static off_t search(off_t *I,u_char *old,off_t oldsize,
+               u_char *new,off_t newsize,off_t st,off_t en,off_t *pos)
+{
+       off_t x,y;
+
+       if(en-st<2) {
+               x=matchlen(old+I[st],oldsize-I[st],new,newsize);
+               y=matchlen(old+I[en],oldsize-I[en],new,newsize);
+
+               if(x>y) {
+                       *pos=I[st];
+                       return x;
+               } else {
+                       *pos=I[en];
+                       return y;
+               }
+       };
+
+       x=st+(en-st)/2;
+       if(memcmp(old+I[x],new,MIN(oldsize-I[x],newsize))<0) {
+               return search(I,old,oldsize,new,newsize,x,en,pos);
+       } else {
+               return search(I,old,oldsize,new,newsize,st,x,pos);
+       };
 }
 
-static off_t offtin(u_char *buf)
+static void offtout(off_t x,u_char *buf)
 {
-  off_t y;
+       off_t y;
 
-  y=buf[7]&0x7F;
-  y=y*256;y+=buf[6];
-  y=y*256;y+=buf[5];
-  y=y*256;y+=buf[4];
-  y=y*256;y+=buf[3];
-  y=y*256;y+=buf[2];
-  y=y*256;y+=buf[1];
-  y=y*256;y+=buf[0];
+       if(x<0) y=-x; else y=x;
 
-  if(buf[7]&0x80) y=-y;
+               buf[0]=y%256;y-=buf[0];
+       y=y/256;buf[1]=y%256;y-=buf[1];
+       y=y/256;buf[2]=y%256;y-=buf[2];
+       y=y/256;buf[3]=y%256;y-=buf[3];
+       y=y/256;buf[4]=y%256;y-=buf[4];
+       y=y/256;buf[5]=y%256;y-=buf[5];
+       y=y/256;buf[6]=y%256;y-=buf[6];
+       y=y/256;buf[7]=y%256;
 
-  return y;
+       if(x<0) buf[7]|=0x80;
 }
 
-int ApplyBSDiffPatch(const unsigned char* old_data, ssize_t old_size,
-                     const char* patch_filename,
-                     FILE* output, SHA_CTX* ctx) {
-
-  FILE* f;
-  if ((f = fopen(patch_filename, "rb")) == NULL) {
-    fprintf(stderr, "failed to open patch file\n");
-    return 1;
-  }
-
-  // File format:
-  //   0       8       "BSDIFF40"
-  //   8       8       X
-  //   16      8       Y
-  //   24      8       sizeof(newfile)
-  //   32      X       bzip2(control block)
-  //   32+X    Y       bzip2(diff block)
-  //   32+X+Y  ???     bzip2(extra block)
-  // with control block a set of triples (x,y,z) meaning "add x bytes
-  // from oldfile to x bytes from the diff block; copy y bytes from the
-  // extra block; seek forwards in oldfile by z bytes".
-
-  unsigned char header[32];
-  if (fread(header, 1, 32, f) < 32) {
-    fprintf(stderr, "failed to read patch file header\n");
-    return 1;
-  }
-
-  if (memcmp(header, "BSDIFF40", 8) != 0) {
-    fprintf(stderr, "corrupt patch file header (magic number)\n");
-    return 1;
-  }
-
-  ssize_t ctrl_len, data_len;
-  ssize_t new_size;
-  ctrl_len = offtin(header+8);
-  data_len = offtin(header+16);
-  new_size = offtin(header+24);
-
-  if (ctrl_len < 0 || data_len < 0 || new_size < 0) {
-    fprintf(stderr, "corrupt patch file header (data lengths)\n");
-    return 1;
-  }
-
-  fclose(f);
-
-  int bzerr;
-
-#define OPEN_AT(f, bzf, offset)                                          \
-  FILE* f;                                                               \
-  BZFILE* bzf;                                                           \
-  if ((f = fopen(patch_filename, "rb")) == NULL) {                       \
-    fprintf(stderr, "failed to open patch file\n");                      \
-    return 1;                                                            \
-  }                                                                      \
-  if (fseeko(f, offset, SEEK_SET)) {                                     \
-    fprintf(stderr, "failed to seek in patch file\n");                   \
-    return 1;                                                            \
-  }                                                                      \
-  if ((bzf = BZ2_bzReadOpen(&bzerr, f, 0, 0, NULL, 0)) == NULL) {        \
-    fprintf(stderr, "failed to bzReadOpen in patch file (%d)\n", bzerr); \
-    return 1;                                                            \
-  }
-
-  OPEN_AT(cpf, cpfbz2, 32);
-  OPEN_AT(dpf, dpfbz2, 32+ctrl_len);
-  OPEN_AT(epf, epfbz2, 32+ctrl_len+data_len);
-
-#undef OPEN_AT
-
-  unsigned char* new_data = malloc(new_size);
-  if (new_data == NULL) {
-    fprintf(stderr, "failed to allocate memory for output file\n");
-    return 1;
-  }
-
-  off_t oldpos = 0, newpos = 0;
-  off_t ctrl[3];
-  off_t len_read;
-  int i;
-  unsigned char buf[8];
-  while (newpos < new_size) {
-    // Read control data
-    for (i = 0; i < 3; ++i) {
-      len_read = BZ2_bzRead(&bzerr, cpfbz2, buf, 8);
-      if (len_read < 8 || !(bzerr == BZ_OK || bzerr == BZ_STREAM_END)) {
-        fprintf(stderr, "corrupt patch (read control)\n");
-        return 1;
-      }
-      ctrl[i] = offtin(buf);
-    }
-
-    // Sanity check
-    if (newpos + ctrl[0] > new_size) {
-      fprintf(stderr, "corrupt patch (new file overrun)\n");
-      return 1;
-    }
-
-    // Read diff string
-    len_read = BZ2_bzRead(&bzerr, dpfbz2, new_data + newpos, ctrl[0]);
-    if (len_read < ctrl[0] || !(bzerr == BZ_OK || bzerr == BZ_STREAM_END)) {
-      fprintf(stderr, "corrupt patch (read diff)\n");
-      return 1;
-    }
-
-    // Add old data to diff string
-    for (i = 0; i < ctrl[0]; ++i) {
-      if ((oldpos+i >= 0) && (oldpos+i < old_size)) {
-        new_data[newpos+i] += old_data[oldpos+i];
-      }
-    }
-
-    // Adjust pointers
-    newpos += ctrl[0];
-    oldpos += ctrl[0];
-
-    // Sanity check
-    if (newpos + ctrl[1] > new_size) {
-      fprintf(stderr, "corrupt patch (new file overrun)\n");
-      return 1;
-    }
-
-    // Read extra string
-    len_read = BZ2_bzRead(&bzerr, epfbz2, new_data + newpos, ctrl[1]);
-    if (len_read < ctrl[1] || !(bzerr == BZ_OK || bzerr == BZ_STREAM_END)) {
-      fprintf(stderr, "corrupt patch (read extra)\n");
-      return 1;
-    }
-
-    // Adjust pointers
-    newpos += ctrl[1];
-    oldpos += ctrl[2];
-  }
-
-  BZ2_bzReadClose(&bzerr, cpfbz2);
-  BZ2_bzReadClose(&bzerr, dpfbz2);
-  BZ2_bzReadClose(&bzerr, epfbz2);
-  fclose(cpf);
-  fclose(dpf);
-  fclose(epf);
-
-  if (fwrite(new_data, 1, new_size, output) < new_size) {
-    fprintf(stderr, "short write of output: %d (%s)\n", errno, strerror(errno));
-    return 1;
-  }
-  SHA_update(ctx, new_data, new_size);
-  free(new_data);
-
-  return 0;
+// This is main() from bsdiff.c, with the following changes:
+//
+//    - old, oldsize, new, newsize are arguments; we don't load this
+//      data from files.  old and new are owned by the caller; we
+//      don't free them at the end.
+//
+//    - the "I" block of memory is owned by the caller, who passes a
+//      pointer to *I, which can be NULL.  This way if we call
+//      bsdiff() multiple times with the same 'old' data, we only do
+//      the qsufsort() step the first time.
+//
+int bsdiff(u_char* old, off_t oldsize, off_t** IP, u_char* new, off_t newsize,
+           const char* patch_filename)
+{
+       int fd;
+       off_t *I;
+       off_t scan,pos,len;
+       off_t lastscan,lastpos,lastoffset;
+       off_t oldscore,scsc;
+       off_t s,Sf,lenf,Sb,lenb;
+       off_t overlap,Ss,lens;
+       off_t i;
+       off_t dblen,eblen;
+       u_char *db,*eb;
+       u_char buf[8];
+       u_char header[32];
+       FILE * pf;
+       BZFILE * pfbz2;
+       int bz2err;
+
+        if (*IP == NULL) {
+            off_t* V;
+            *IP = malloc((oldsize+1) * sizeof(off_t));
+            V = malloc((oldsize+1) * sizeof(off_t));
+            qsufsort(*IP, V, old, oldsize);
+            free(V);
+        }
+        I = *IP;
+
+       if(((db=malloc(newsize+1))==NULL) ||
+               ((eb=malloc(newsize+1))==NULL)) err(1,NULL);
+       dblen=0;
+       eblen=0;
+
+       /* Create the patch file */
+       if ((pf = fopen(patch_filename, "w")) == NULL)
+              err(1, "%s", patch_filename);
+
+       /* Header is
+               0       8        "BSDIFF40"
+               8       8       length of bzip2ed ctrl block
+               16      8       length of bzip2ed diff block
+               24      8       length of new file */
+       /* File is
+               0       32      Header
+               32      ??      Bzip2ed ctrl block
+               ??      ??      Bzip2ed diff block
+               ??      ??      Bzip2ed extra block */
+       memcpy(header,"BSDIFF40",8);
+       offtout(0, header + 8);
+       offtout(0, header + 16);
+       offtout(newsize, header + 24);
+       if (fwrite(header, 32, 1, pf) != 1)
+               err(1, "fwrite(%s)", patch_filename);
+
+       /* Compute the differences, writing ctrl as we go */
+       if ((pfbz2 = BZ2_bzWriteOpen(&bz2err, pf, 9, 0, 0)) == NULL)
+               errx(1, "BZ2_bzWriteOpen, bz2err = %d", bz2err);
+       scan=0;len=0;
+       lastscan=0;lastpos=0;lastoffset=0;
+       while(scan<newsize) {
+               oldscore=0;
+
+               for(scsc=scan+=len;scan<newsize;scan++) {
+                       len=search(I,old,oldsize,new+scan,newsize-scan,
+                                       0,oldsize,&pos);
+
+                       for(;scsc<scan+len;scsc++)
+                       if((scsc+lastoffset<oldsize) &&
+                               (old[scsc+lastoffset] == new[scsc]))
+                               oldscore++;
+
+                       if(((len==oldscore) && (len!=0)) ||
+                               (len>oldscore+8)) break;
+
+                       if((scan+lastoffset<oldsize) &&
+                               (old[scan+lastoffset] == new[scan]))
+                               oldscore--;
+               };
+
+               if((len!=oldscore) || (scan==newsize)) {
+                       s=0;Sf=0;lenf=0;
+                       for(i=0;(lastscan+i<scan)&&(lastpos+i<oldsize);) {
+                               if(old[lastpos+i]==new[lastscan+i]) s++;
+                               i++;
+                               if(s*2-i>Sf*2-lenf) { Sf=s; lenf=i; };
+                       };
+
+                       lenb=0;
+                       if(scan<newsize) {
+                               s=0;Sb=0;
+                               for(i=1;(scan>=lastscan+i)&&(pos>=i);i++) {
+                                       if(old[pos-i]==new[scan-i]) s++;
+                                       if(s*2-i>Sb*2-lenb) { Sb=s; lenb=i; };
+                               };
+                       };
+
+                       if(lastscan+lenf>scan-lenb) {
+                               overlap=(lastscan+lenf)-(scan-lenb);
+                               s=0;Ss=0;lens=0;
+                               for(i=0;i<overlap;i++) {
+                                       if(new[lastscan+lenf-overlap+i]==
+                                          old[lastpos+lenf-overlap+i]) s++;
+                                       if(new[scan-lenb+i]==
+                                          old[pos-lenb+i]) s--;
+                                       if(s>Ss) { Ss=s; lens=i+1; };
+                               };
+
+                               lenf+=lens-overlap;
+                               lenb-=lens;
+                       };
+
+                       for(i=0;i<lenf;i++)
+                               db[dblen+i]=new[lastscan+i]-old[lastpos+i];
+                       for(i=0;i<(scan-lenb)-(lastscan+lenf);i++)
+                               eb[eblen+i]=new[lastscan+lenf+i];
+
+                       dblen+=lenf;
+                       eblen+=(scan-lenb)-(lastscan+lenf);
+
+                       offtout(lenf,buf);
+                       BZ2_bzWrite(&bz2err, pfbz2, buf, 8);
+                       if (bz2err != BZ_OK)
+                               errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
+
+                       offtout((scan-lenb)-(lastscan+lenf),buf);
+                       BZ2_bzWrite(&bz2err, pfbz2, buf, 8);
+                       if (bz2err != BZ_OK)
+                               errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
+
+                       offtout((pos-lenb)-(lastpos+lenf),buf);
+                       BZ2_bzWrite(&bz2err, pfbz2, buf, 8);
+                       if (bz2err != BZ_OK)
+                               errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
+
+                       lastscan=scan-lenb;
+                       lastpos=pos-lenb;
+                       lastoffset=pos-scan;
+               };
+       };
+       BZ2_bzWriteClose(&bz2err, pfbz2, 0, NULL, NULL);
+       if (bz2err != BZ_OK)
+               errx(1, "BZ2_bzWriteClose, bz2err = %d", bz2err);
+
+       /* Compute size of compressed ctrl data */
+       if ((len = ftello(pf)) == -1)
+               err(1, "ftello");
+       offtout(len-32, header + 8);
+
+       /* Write compressed diff data */
+       if ((pfbz2 = BZ2_bzWriteOpen(&bz2err, pf, 9, 0, 0)) == NULL)
+               errx(1, "BZ2_bzWriteOpen, bz2err = %d", bz2err);
+       BZ2_bzWrite(&bz2err, pfbz2, db, dblen);
+       if (bz2err != BZ_OK)
+               errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
+       BZ2_bzWriteClose(&bz2err, pfbz2, 0, NULL, NULL);
+       if (bz2err != BZ_OK)
+               errx(1, "BZ2_bzWriteClose, bz2err = %d", bz2err);
+
+       /* Compute size of compressed diff data */
+       if ((newsize = ftello(pf)) == -1)
+               err(1, "ftello");
+       offtout(newsize - len, header + 16);
+
+       /* Write compressed extra data */
+       if ((pfbz2 = BZ2_bzWriteOpen(&bz2err, pf, 9, 0, 0)) == NULL)
+               errx(1, "BZ2_bzWriteOpen, bz2err = %d", bz2err);
+       BZ2_bzWrite(&bz2err, pfbz2, eb, eblen);
+       if (bz2err != BZ_OK)
+               errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
+       BZ2_bzWriteClose(&bz2err, pfbz2, 0, NULL, NULL);
+       if (bz2err != BZ_OK)
+               errx(1, "BZ2_bzWriteClose, bz2err = %d", bz2err);
+
+       /* Seek to the beginning, write the header, and close the file */
+       if (fseeko(pf, 0, SEEK_SET))
+               err(1, "fseeko");
+       if (fwrite(header, 32, 1, pf) != 1)
+               err(1, "fwrite(%s)", patch_filename);
+       if (fclose(pf))
+               err(1, "fclose");
+
+       /* Free the memory we used */
+       free(db);
+       free(eb);
+
+       return 0;
 }