mirror of
https://github.com/Alcaro/Flips.git
synced 2026-03-22 10:04:23 -05:00
438 lines
11 KiB
C++
438 lines
11 KiB
C++
#include "patch.h"
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namespace patch { namespace bps {
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static uint32_t read32(uint8_t * ptr)
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{
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uint32_t out;
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out =ptr[0];
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out|=ptr[1]<<8;
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out|=ptr[2]<<16;
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out|=ptr[3]<<24;
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return out;
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}
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enum { SourceRead, TargetRead, SourceCopy, TargetCopy };
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static bool try_add(size_t& a, size_t b)
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{
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if (SIZE_MAX-a < b) return false;
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a+=b;
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return true;
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}
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static bool try_shift(size_t& a, size_t b)
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{
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if (SIZE_MAX>>b < a) return false;
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a<<=b;
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return true;
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}
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static bool decodenum(const uint8_t*& ptr, size_t& out)
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{
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out=0;
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unsigned int shift=0;
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while (true)
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{
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uint8_t next=*ptr++;
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size_t addthis=(next&0x7F);
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if (shift) addthis++;
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if (!try_shift(addthis, shift)) return false;
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// unchecked because if it was shifted, the lowest bit is zero, and if not, it's <=0x7F.
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if (!try_add(out, addthis)) return false;
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if (next&0x80) return true;
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shift+=7;
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}
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}
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#define error(which) do { error=which; goto exit; } while(0)
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#define assert_sum(a,b) do { if (SIZE_MAX-(a)<(b)) error(bps_too_big); } while(0)
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#define assert_shift(a,b) do { if (SIZE_MAX>>(b)<(a)) error(bps_too_big); } while(0)
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result apply(const file& patch_, const file& source_, file& target_, bool accept_wrong_input)
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{
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struct mem patch = patch_.mmap();
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struct mem in = source_.mmap();
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struct mem out_;
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struct mem * out = &out_;
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struct mem * metadata = NULL;
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result error = e_ok;
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out->len=0;
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out->ptr=NULL;
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if (metadata)
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{
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metadata->len=0;
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metadata->ptr=NULL;
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}
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if (patch.len<4+3+12) return e_broken;
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if (true)
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{
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#define read8() (*(patchat++))
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#define decodeto(var) \
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do { \
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if (!decodenum(patchat, var)) error(e_too_big); \
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} while(false)
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#define write8(byte) (*(outat++)=byte)
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const uint8_t * patchat=patch.ptr;
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const uint8_t * patchend=patch.ptr+patch.len-12;
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if (read8()!='B') error(e_broken);
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if (read8()!='P') error(e_broken);
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if (read8()!='S') error(e_broken);
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if (read8()!='1') error(e_broken);
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uint32_t crc_in_e = read32(patch.ptr+patch.len-12);
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uint32_t crc_out_e = read32(patch.ptr+patch.len-8);
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uint32_t crc_patch_e = read32(patch.ptr+patch.len-4);
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uint32_t crc_in_a = crc32(in.v());
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uint32_t crc_patch_a = crc32(patch.v().slice(0, patch.len-4));
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if (crc_patch_a != crc_patch_e) error(e_broken);
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size_t inlen;
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decodeto(inlen);
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size_t outlen;
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decodeto(outlen);
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if (inlen!=in.len || crc_in_a!=crc_in_e)
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{
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if (in.len==outlen && crc_in_a==crc_out_e) error=e_to_output;
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else error=e_not_this;
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if (!accept_wrong_input) goto exit;
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}
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out->len=outlen;
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out->ptr=(uint8_t*)malloc(outlen);
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const uint8_t * instart=in.ptr;
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const uint8_t * inreadat=in.ptr;
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const uint8_t * inend=in.ptr+in.len;
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uint8_t * outstart=out->ptr;
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uint8_t * outreadat=out->ptr;
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uint8_t * outat=out->ptr;
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uint8_t * outend=out->ptr+out->len;
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size_t metadatalen;
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decodeto(metadatalen);
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if (metadata && metadatalen)
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{
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metadata->len=metadatalen;
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metadata->ptr=(uint8_t*)malloc(metadatalen+1);
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for (size_t i=0;i<metadatalen;i++) metadata->ptr[i]=read8();
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metadata->ptr[metadatalen]='\0';//just to be on the safe side - that metadata is assumed to be text, might as well terminate it
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}
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else
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{
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for (size_t i=0;i<metadatalen;i++) (void)read8();
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}
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while (patchat<patchend)
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{
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size_t thisinstr;
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decodeto(thisinstr);
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size_t length=(thisinstr>>2)+1;
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int action=(thisinstr&3);
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if (outat+length>outend) error(e_broken);
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switch (action)
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{
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case SourceRead:
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{
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if (outat-outstart+length > in.len) error(e_broken);
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for (size_t i=0;i<length;i++)
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{
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size_t pos = outat-outstart; // don't inline, write8 changes outat
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write8(instart[pos]);
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}
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}
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break;
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case TargetRead:
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{
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if (patchat+length>patchend) error(e_broken);
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for (size_t i=0;i<length;i++) write8(read8());
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}
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break;
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case SourceCopy:
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{
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size_t encodeddistance;
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decodeto(encodeddistance);
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size_t distance=encodeddistance>>1;
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if ((encodeddistance&1)==0) inreadat+=distance;
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else inreadat-=distance;
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if (inreadat<instart || inreadat+length>inend) error(e_broken);
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for (size_t i=0;i<length;i++) write8(*inreadat++);
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}
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break;
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case TargetCopy:
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{
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size_t encodeddistance;
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decodeto(encodeddistance);
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size_t distance=encodeddistance>>1;
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if ((encodeddistance&1)==0) outreadat+=distance;
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else outreadat-=distance;
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if (outreadat<outstart || outreadat>=outat || outreadat+length>outend) error(e_broken);
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for (size_t i=0;i<length;i++) write8(*outreadat++);
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}
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break;
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}
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}
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if (patchat!=patchend) error(e_broken);
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if (outat!=outend) error(e_broken);
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uint32_t crc_out_a = crc32(out->v());
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if (crc_out_a!=crc_out_e)
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{
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error=e_not_this;
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if (!accept_wrong_input) goto exit;
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}
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target_.write(out->v());
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free(out->ptr);
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return error;
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#undef read8
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#undef decodeto
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#undef write8
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}
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exit:
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free(out->ptr);
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out->len=0;
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out->ptr=NULL;
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if (metadata)
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{
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free(metadata->ptr);
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metadata->len=0;
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metadata->ptr=NULL;
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}
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return error;
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}
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#undef error
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result info::parse(const file& patch, bool changefrac)
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{
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size_t len = patch.size();
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if (len<4+3+12) return e_broken;
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uint8_t top[256];
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size_t toplen = len>256 ? 256 : len;
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if (patch.read(arrayvieww<byte>(top, toplen), 0) < toplen) return e_io;
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if (memcmp(top, "BPS1", 4)!=0) return e_broken;
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const uint8_t* patchdat=top+4;
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if (!decodenum(patchdat, this->size_in)) return e_too_big;
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if (!decodenum(patchdat, this->size_out)) return e_too_big;
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uint8_t checksums[12];
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if (patch.read(arrayvieww<byte>(checksums), len-12) < 12) return e_io;
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this->crc_in = read32(checksums+0);
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this->crc_out = read32(checksums+4);
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//this->crc_patch=read32(checksums+8);
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if (changefrac && this->size_in>0)
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{
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//algorithm: each command adds its length to the numerator, unless it's above 32, in which case
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// it adds 32; or if it's SourceRead, in which case it adds 0
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//denominator is just input length
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array<byte> patchbytes = patch.read();
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size_t outpos=0; // position in the output file
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size_t changeamt=0; // change score
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const uint8_t* patchat=patchbytes.ptr()+(patchdat-top);
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size_t metasize;
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if (!decodenum(patchat, metasize)) return e_too_big;
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patchat+=metasize;
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const uint8_t* patchend=patchbytes.ptr()+len-12;
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while (patchat<patchend && outpos<this->size_in)
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{
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size_t thisinstr;
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decodenum(patchat, thisinstr);
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size_t length=(thisinstr>>2)+1;
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int action=(thisinstr&3);
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int min_len_32 = (length<32 ? length : 32);
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switch (action)
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{
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case SourceRead:
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{
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changeamt+=0;
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}
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break;
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case TargetRead:
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{
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changeamt+=min_len_32;
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patchat+=length;
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}
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break;
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case SourceCopy:
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case TargetCopy:
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{
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changeamt+=min_len_32;
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size_t ignore;
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decodenum(patchat, ignore);
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}
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break;
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}
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outpos+=length;
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}
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if (patchat>patchend || outpos>this->size_out) return e_broken;
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this->change_num = (changeamt<this->size_in ? changeamt : this->size_in);
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this->change_denom = this->size_in;
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}
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else
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{
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//this also happens if change fraction is not requested, but if so, reading it is undefined behaviour anyways.
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this->change_num=1;
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this->change_denom=1;
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}
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return e_ok;
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}
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#if 0
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#warning Disable this in release versions.
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#include <stdio.h>
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//Congratulations, you found the undocumented feature! It compares two equivalent BPS patches and
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// tells where each one is more compact. (It crashes or gives bogus answers on invalid or
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// non-equivalent patches.) Have fun.
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void bps_compare(struct mem patch1mem, struct mem patch2mem)
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{
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const uint8_t * patch[2]={patch1mem.ptr, patch2mem.ptr};
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size_t patchpos[2]={0,0};
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size_t patchlen[2]={patch1mem.len-12, patch2mem.len-12};
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size_t patchoutpos[2]={0,0};
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size_t patchcopypos[2][4]={0,0};//[0] and [1] are unused, but this is just debug code, it doesn't need to be neat.
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#define read8(id) (patch[id][patchpos[id]++])
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#define decodeto(id, var) \
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do { \
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var=0; \
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int shift=0; \
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while (true) \
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{ \
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uint8_t next=read8(id); \
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size_t addthis=(next&0x7F)<<shift; \
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var+=addthis; \
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if (next&0x80) break; \
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shift+=7; \
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var+=1<<shift; \
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} \
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} while(false)
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size_t lastmatch=0;
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size_t patchposatmatch[2]={0,0};
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size_t outlen;
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patch[0]+=4; patch[1]+=4;//BPS1
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size_t tempuint;
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decodeto(0, tempuint); decodeto(1, tempuint);//source-size
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decodeto(0, outlen); decodeto(1, outlen);//target-size
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decodeto(0, tempuint); patch[0]+=tempuint;//metadata
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decodeto(1, tempuint); patch[1]+=tempuint;//metadata
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bool show=false;
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while (patchpos[0]<patchlen[0] && patchpos[1]<patchlen[1])
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{
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bool step[2]={(patchoutpos[0]<=patchoutpos[1]), (patchoutpos[0]>=patchoutpos[1])};
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char describe[2][256];
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for (int i=0;i<2;i++)
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{
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if (step[i])
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{
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size_t patchposstart=patchpos[i];
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decodeto(i, tempuint);
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size_t len=(tempuint>>2)+1;
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patchoutpos[i]+=len;
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int action=(tempuint&3);
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//enum { SourceRead, TargetRead, SourceCopy, TargetCopy };
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const char * actionnames[]={"SourceRead", "TargetRead", "SourceCopy", "TargetCopy"};
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if (action==TargetRead) patchpos[i]+=len;
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if (action==SourceCopy || action==TargetCopy)
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{
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decodeto(i, tempuint);
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int delta = tempuint>>1;
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if (tempuint&1) delta=-delta;
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patchcopypos[i][action]+=delta;
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sprintf(describe[i], "%s from %i (%+i) for %i in %i", actionnames[action], patchcopypos[i][action], delta, len, patchpos[i]-patchposstart);
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patchcopypos[i][action]+=len;
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}
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else sprintf(describe[i], "%s from %i for %i in %i", actionnames[action], patchoutpos[i], len, patchpos[i]-patchposstart);
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if (!step[i^1])
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{
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printf("%i: %s\n", i+1, describe[i]);
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show=true;
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}
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}
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}
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if (step[0] && step[1])
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{
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if (!strcmp(describe[0], describe[1])) /*printf("3: %s\n", describe[0])*/;
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else
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{
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printf("1: %s\n2: %s\n", describe[0], describe[1]);
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show=true;
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}
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}
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if (patchoutpos[0]==patchoutpos[1])
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{
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size_t used[2]={patchpos[0]-patchposatmatch[0], patchpos[1]-patchposatmatch[1]};
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char which='=';
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if (used[0]<used[1]) which='+';
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if (used[0]>used[1]) which='-';
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if (show)
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{
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printf("%c: %i,%i bytes since last match (%i)\n", which, used[0], used[1], patchoutpos[0]);
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show=false;
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}
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patchposatmatch[0]=patchpos[0];
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patchposatmatch[1]=patchpos[1];
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lastmatch=patchoutpos[0];
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}
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}
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}
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static struct mem ReadWholeFile(const char * filename)
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{
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struct mem null = {NULL, 0};
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FILE * file=fopen(filename, "rb");
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if (!file) return null;
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fseek(file, 0, SEEK_END);
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size_t len=ftell(file);
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fseek(file, 0, SEEK_SET);
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unsigned char * data=(unsigned char*)malloc(len);
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size_t truelen=fread(data, 1,len, file);
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fclose(file);
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if (len!=truelen)
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{
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free(data);
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return null;
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}
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struct mem ret = { (unsigned char*)data, len };
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return ret;
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}
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int main(int argc,char**argv)
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{
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bps_compare(ReadWholeFile(argv[1]),ReadWholeFile(argv[2]));
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}
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#endif
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}}
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