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Whatever changes I made since 1.31
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Alcaro
158
libbps.cpp
158
libbps.cpp
@@ -1,6 +1,6 @@
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//Module name: libbps
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//Author: Alcaro
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//Date: December 20, 2014
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//Date: November 7, 2015
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//Licence: GPL v3.0 or higher
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#include "libbps.h"
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@@ -22,6 +22,37 @@ static uint32_t read32(uint8_t * ptr)
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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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@@ -42,20 +73,7 @@ enum bpserror bps_apply(struct mem patch, struct mem in, struct mem * out, struc
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#define read8() (*(patchat++))
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#define decodeto(var) \
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do { \
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var=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=read8(); \
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assert_shift(next&0x7F, shift); \
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size_t addthis=(next&0x7F)<<shift; \
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assert_sum(var, addthis); \
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var+=addthis; \
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if (next&0x80) break; \
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shift+=7; \
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assert_sum(var, 1U<<shift); \
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var+=1<<shift; \
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} \
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if (!decodenum(patchat, var)) error(bps_too_big); \
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} while(false)
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#define write8(byte) (*(outat++)=byte)
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@@ -197,6 +215,8 @@ exit:
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return error;
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}
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#define write(val) \
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do { \
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out[outlen++]=(val); \
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@@ -367,26 +387,102 @@ enum bpserror bps_create_linear(struct mem sourcemem, struct mem targetmem, stru
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#undef write
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#undef writenum
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enum bpserror bps_get_checksums(file* patch, uint32_t * inromsum, uint32_t * outromsum, uint32_t * patchsum)
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{
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size_t len = patch->len();
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if (len<4+3+12) return bps_broken;
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uint8_t verify[4];
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if (!patch->read(verify, 0, 4) || memcmp(verify, "BPS1", 4)) return bps_broken;
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uint8_t checksums[12];
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if (!patch->read(checksums, len-12, 12)) return bps_broken;
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if (inromsum) *inromsum =read32(checksums+0);
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if (outromsum) *outromsum=read32(checksums+4);
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if (patchsum) *patchsum =read32(checksums+8);
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return bps_ok;
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}
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void bps_free(struct mem mem)
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{
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free(mem.ptr);
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}
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#undef error
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struct bpsinfo bps_get_info(file* patch, bool changefrac)
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{
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#define error(why) do { ret.error=why; return ret; } while(0)
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struct bpsinfo ret;
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size_t len = patch->len();
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if (len<4+3+12) error(bps_broken);
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uint8_t top[256];
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if (!patch->read(top, 0, len>256 ? 256 : len)) error(bps_io);
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if (memcmp(top, "BPS1", 4)) error(bps_broken);
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const uint8_t* patchdat=top+4;
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if (!decodenum(patchdat, ret.size_in)) error(bps_too_big);
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if (!decodenum(patchdat, ret.size_out)) error(bps_too_big);
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uint8_t checksums[12];
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if (!patch->read(checksums, len-12, 12)) error(bps_io);
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ret.crc_in = read32(checksums+0);
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ret.crc_out = read32(checksums+4);
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ret.crc_patch=read32(checksums+8);
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if (changefrac && ret.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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uint8_t* patchbin=(uint8_t*)malloc(len);
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patch->read(patchbin, 0, len);
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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=patchbin+(patchdat-top);
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size_t metasize;
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if (!decodenum(patchat, metasize)) error(bps_too_big);
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patchat+=metasize;
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const uint8_t* patchend=patchbin+len-12;
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while (patchat<patchend && outpos<ret.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>ret.size_out) error(bps_broken);
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ret.change_num = (changeamt<ret.size_in ? changeamt : ret.size_in);
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ret.change_denom = ret.size_in;
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free(patchbin);
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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 it's undefined behaviour anyways.
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ret.change_num=1;
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ret.change_denom=1;
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}
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ret.error=bps_ok;
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return ret;
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}
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#if 0
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#warning Disable this in release versions.
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