| /*- |
| * 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. |
| */ |
| |
| #if 0 |
| __FBSDID("$FreeBSD: src/usr.bin/bsdiff/bsdiff/bsdiff.c,v 1.1 2005/08/06 01:59:05 cperciva Exp $"); |
| #endif |
| |
| #include "bsdiff/bsdiff.h" |
| |
| #include <sys/types.h> |
| |
| #include <err.h> |
| #include <fcntl.h> |
| #include <stdio.h> |
| #include <stdlib.h> |
| #include <string.h> |
| #include <unistd.h> |
| |
| #include <algorithm> |
| |
| #include "bsdiff/patch_writer.h" |
| |
| namespace bsdiff { |
| |
| static off_t matchlen(const u_char* old, off_t oldsize, const u_char* new_buf, |
| off_t newsize) { |
| off_t i; |
| |
| for(i=0;(i<oldsize)&&(i<newsize);i++) |
| if(old[i]!=new_buf[i]) break; |
| |
| return i; |
| } |
| |
| // This is a binary search of the string |new_buf| of size |newsize| (or a |
| // prefix of it) in the |old| string with size |oldsize| using the suffix array |
| // |I|. |st| and |en| is the start and end of the search range (inclusive). |
| // Returns the length of the longest prefix found and stores the position of the |
| // string found in |*pos|. |
| static off_t search(saidx_t* I, const u_char* old, off_t oldsize, |
| const u_char* new_buf, 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_buf,newsize); |
| y=matchlen(old+I[en],oldsize-I[en],new_buf,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_buf,std::min(oldsize-I[x],newsize))<=0) { |
| return search(I,old,oldsize,new_buf,newsize,x,en,pos); |
| } else { |
| return search(I,old,oldsize,new_buf,newsize,st,x,pos); |
| }; |
| } |
| |
| int bsdiff(const char* old_filename, const char* new_filename, |
| const char* patch_filename) { |
| int fd; |
| u_char *old_buf,*new_buf; |
| off_t oldsize,newsize; |
| |
| /* Allocate oldsize+1 bytes instead of oldsize bytes to ensure |
| that we never try to malloc(0) and get a NULL pointer */ |
| if(((fd=open(old_filename,O_RDONLY,0))<0) || |
| ((oldsize=lseek(fd,0,SEEK_END))==-1) || |
| ((old_buf=static_cast<u_char*>(malloc(oldsize+1)))==NULL) || |
| (lseek(fd,0,SEEK_SET)!=0) || |
| (read(fd,old_buf,oldsize)!=oldsize) || |
| (close(fd)==-1)) err(1,"%s",old_filename); |
| |
| /* Allocate newsize+1 bytes instead of newsize bytes to ensure |
| that we never try to malloc(0) and get a NULL pointer */ |
| if(((fd=open(new_filename,O_RDONLY,0))<0) || |
| ((newsize=lseek(fd,0,SEEK_END))==-1) || |
| ((new_buf = static_cast<u_char*>(malloc(newsize+1)))==NULL) || |
| (lseek(fd,0,SEEK_SET)!=0) || |
| (read(fd,new_buf,newsize)!=newsize) || |
| (close(fd)==-1)) err(1,"%s",new_filename); |
| |
| int ret = bsdiff(old_buf, oldsize, new_buf, newsize, patch_filename, nullptr); |
| |
| free(old_buf); |
| free(new_buf); |
| |
| return ret; |
| } |
| |
| // Generate bsdiff patch from |old_buf| to |new_buf|, save the patch file to |
| // |patch_filename|. Returns 0 on success. |
| // |I_cache| can be used to cache the suffix array if the same |old_buf| is used |
| // repeatedly, pass nullptr if not needed. |
| int bsdiff(const u_char* old_buf, off_t oldsize, const u_char* new_buf, |
| off_t newsize, const char* patch_filename, saidx_t** I_cache) { |
| saidx_t *I; |
| off_t scan,pos=0,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; |
| BsdiffPatchWriter patch(old_buf, oldsize, new_buf, newsize); |
| |
| if (I_cache && *I_cache) { |
| I = *I_cache; |
| } else { |
| if ((I=static_cast<saidx_t*>(malloc((oldsize+1)*sizeof(saidx_t))))==NULL) |
| err(1,NULL); |
| |
| if (divsufsort(old_buf, I, oldsize)) err(1, "divsufsort"); |
| if (I_cache) |
| *I_cache = I; |
| } |
| |
| /* Create the patch file */ |
| if (!patch.Open(patch_filename)) |
| return 1; |
| |
| /* Compute the differences, writing ctrl as we go */ |
| scan=0;len=0; |
| lastscan=0;lastpos=0;lastoffset=0; |
| while(scan<newsize) { |
| oldscore=0; |
| |
| /* If we come across a large block of data that only differs |
| * by less than 8 bytes, this loop will take a long time to |
| * go past that block of data. We need to track the number of |
| * times we're stuck in the block and break out of it. */ |
| int num_less_than_eight = 0; |
| off_t prev_len, prev_oldscore, prev_pos; |
| for(scsc=scan+=len;scan<newsize;scan++) { |
| prev_len=len; |
| prev_oldscore=oldscore; |
| prev_pos=pos; |
| |
| len=search(I,old_buf,oldsize,new_buf+scan,newsize-scan, |
| 0,oldsize-1,&pos); |
| |
| for(;scsc<scan+len;scsc++) |
| if((scsc+lastoffset<oldsize) && |
| (old_buf[scsc+lastoffset] == new_buf[scsc])) |
| oldscore++; |
| |
| if(((len==oldscore) && (len!=0)) || |
| (len>oldscore+8)) break; |
| |
| if((scan+lastoffset<oldsize) && |
| (old_buf[scan+lastoffset] == new_buf[scan])) |
| oldscore--; |
| |
| const off_t fuzz = 8; |
| if (prev_len-fuzz<=len && len<=prev_len && |
| prev_oldscore-fuzz<=oldscore && |
| oldscore<=prev_oldscore && |
| prev_pos<=pos && pos <=prev_pos+fuzz && |
| oldscore<=len && len<=oldscore+fuzz) |
| ++num_less_than_eight; |
| else |
| num_less_than_eight=0; |
| if (num_less_than_eight > 100) break; |
| }; |
| |
| if((len!=oldscore) || (scan==newsize)) { |
| s=0;Sf=0;lenf=0; |
| for(i=0;(lastscan+i<scan)&&(lastpos+i<oldsize);) { |
| if(old_buf[lastpos+i]==new_buf[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_buf[pos-i]==new_buf[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_buf[lastscan+lenf-overlap+i]== |
| old_buf[lastpos+lenf-overlap+i]) s++; |
| if(new_buf[scan-lenb+i]== |
| old_buf[pos-lenb+i]) s--; |
| if(s>Ss) { Ss=s; lens=i+1; }; |
| }; |
| |
| lenf+=lens-overlap; |
| lenb-=lens; |
| }; |
| |
| if (!patch.AddControlEntry(ControlEntry(lenf, |
| (scan - lenb) - (lastscan + lenf), |
| (pos - lenb) - (lastpos + lenf)))) |
| errx(1, "Writing a control entry"); |
| |
| lastscan=scan-lenb; |
| lastpos=pos-lenb; |
| lastoffset=pos-scan; |
| }; |
| }; |
| if (!patch.Close()) |
| errx(1, "Closing the patch file"); |
| |
| if (I_cache == nullptr) |
| free(I); |
| |
| return 0; |
| } |
| |
| } // namespace bsdiff |