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/*-
* 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 <string.h>
#include <algorithm>
#include "bsdiff/diff_encoder.h"
#include "bsdiff/patch_writer.h"
#include "bsdiff/suffix_array_index.h"
namespace bsdiff {
// TODO(deymo): Deprecate this version of the interface and move all callers
// to the underlying version using PatchWriterInterface instead. This allows
// more flexible options including different encodings.
int bsdiff(const uint8_t* old_buf, size_t oldsize, const uint8_t* new_buf,
size_t newsize, const char* patch_filename,
SuffixArrayIndexInterface** sai_cache) {
BsdiffPatchWriter patch(patch_filename);
return bsdiff(old_buf, oldsize, new_buf, newsize, 0, &patch,
sai_cache);
}
int bsdiff(const uint8_t* old_buf, size_t oldsize, const uint8_t* new_buf,
size_t newsize, PatchWriterInterface* patch,
SuffixArrayIndexInterface** sai_cache) {
return bsdiff(old_buf, oldsize, new_buf, newsize, 0, patch,
sai_cache);
}
int bsdiff(const uint8_t* old_buf, size_t oldsize, const uint8_t* new_buf,
size_t newsize, size_t min_length, PatchWriterInterface* patch,
SuffixArrayIndexInterface** sai_cache) {
size_t scsc, scan;
uint64_t pos=0;
size_t len;
size_t lastscan,lastpos,lastoffset;
uint64_t oldscore;
ssize_t s,Sf,lenf,Sb,lenb;
ssize_t overlap,Ss,lens;
ssize_t i;
std::unique_ptr<SuffixArrayIndexInterface> local_sai;
SuffixArrayIndexInterface* sai;
if (sai_cache && *sai_cache) {
sai = *sai_cache;
} else {
local_sai = CreateSuffixArrayIndex(old_buf, oldsize);
if (!local_sai)
return 1;
sai = local_sai.get();
// Transfer ownership to the caller.
if (sai_cache)
*sai_cache = local_sai.release();
}
/* Initialize the patch file encoder */
DiffEncoder diff_encoder(patch, old_buf, oldsize, new_buf, newsize);
if (!diff_encoder.Init())
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;
size_t prev_len;
uint64_t prev_pos, prev_oldscore;
for(scsc=scan+=len;scan<newsize;scan++) {
prev_len=len;
prev_oldscore=oldscore;
prev_pos=pos;
sai->SearchPrefix(new_buf + scan, newsize - scan, &len, &pos);
for(;scsc<scan+len && scsc+lastoffset<oldsize;scsc++)
if(old_buf[scsc+lastoffset] == new_buf[scsc])
oldscore++;
if(((len==oldscore) && (len!=0)) ||
(len>=oldscore+8 && len>=min_length)) break;
if((scan+lastoffset<oldsize) &&
(old_buf[scan+lastoffset] == new_buf[scan]))
oldscore--;
const size_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>=static_cast<uint64_t>(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 (!diff_encoder.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 (!diff_encoder.Close())
errx(1, "Closing the patch file");
return 0;
}
} // namespace bsdiff
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