Decompression speed improved in 64-bit mode
Decoding functions are now also immune to out-of-buffer read errors (note : they were already protected against malicious out-of-buffer write attacks) git-svn-id: https://lz4.googlecode.com/svn/trunk@47 650e7d94-2a16-8b24-b05c-7c0b3f6821cd
This commit is contained in:
yann.collet.73@gmail.com
parent
97abf01348
commit
4fa4221c6e
148
lz4.c
148
lz4.c
@ -40,6 +40,12 @@
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#define inline __forceinline
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#endif
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#ifdef __GNUC__
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#define _PACKED __attribute__ ((packed))
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#else
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#define _PACKED
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#endif
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#define ARCH64 (__x86_64__ || __ppc64__ || _WIN64 || __LP64__) // Detect 64 bits mode
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@ -60,7 +66,7 @@
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// Memory usage formula for 32 bits systems : N->2^(N+2) Bytes (examples : 17 -> 512KB ; 12 -> 16KB)
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#define HASH_LOG 12
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//#define _FORCE_SW_LOWBITCOUNT // Uncomment for better performance if target platform has no hardware support for LowBitCount
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//#define _FORCE_SW_BITCOUNT // Uncomment for better performance if target platform has no hardware support for LowBitCount
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//**************************************
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@ -115,12 +121,6 @@ struct refTables
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const BYTE* hashTable[HASHTABLESIZE];
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};
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#ifdef __GNUC__
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# define _PACKED __attribute__ ((packed))
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#else
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# define _PACKED
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#endif
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typedef struct _U64_S
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{
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U64 v;
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@ -150,25 +150,37 @@ typedef struct _U16_S
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#define LZ4_COPYPACKET64(s,d) A64(d) = A64(s); d+=8; s+=8;
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#define LZ4_WILDCOPY32(s,d,e) do { LZ4_COPYPACKET32(s,d) } while (d<e);
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#define LZ4_WILDCOPY64(s,d,e) do { LZ4_COPYPACKET64(s,d) } while (d<e);
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#if ARCH64
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//**************************************
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// Architecture-specific macros
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//**************************************
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#if ARCH64 // 64-bit
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#define LZ4_WILDCOPY LZ4_WILDCOPY64
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#else
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#define LZ4_WILDCOPY LZ4_WILDCOPY32
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#endif
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#define LZ4_BLINDCOPY(s,d,l) { BYTE* e=d+l; LZ4_WILDCOPY(s,d,e); d=e; }
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#else // 32-bit
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#define LZ4_WILDCOPY LZ4_WILDCOPY32
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#define LZ4_BLINDCOPY(s,d,l) { BYTE* e=d+l; LZ4_WILDCOPY(s,d,e); d=e; }
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#endif
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#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
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#define LZ4_READ_LITTLEENDIAN_16(d,s,p) { d = s - A16(p); }
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#define LZ4_WRITE_LITTLEENDIAN_16(p,v) { A16(p) = v; p+=2; }
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#else // Big Endian
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#define LZ4_READ_LITTLEENDIAN_16(d,s,p) { int delta = p[0]; delta += p[1] << 8; d = s - delta; }
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#define LZ4_WRITE_LITTLEENDIAN_16(p,v) { int delta = v; *p++ = delta; *op++ = delta>>8; }
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#endif
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//****************************
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// Compression CODE
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// Private functions
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//****************************
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inline static int LZ4_NbCommonBytes_LittleEndian( register U32 val )
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{
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#if defined(_MSC_VER) && !defined(_FORCE_SW_LOWBITCOUNT)
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#if defined(_MSC_VER) && !defined(_FORCE_SW_BITCOUNT)
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unsigned long b = 0;
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_BitScanForward( &b, val );
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return (int)(b>>3);
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#elif defined(__GNUC__) && !defined(_FORCE_SW_LOWBITCOUNT)
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#elif defined(__GNUC__) && !defined(_FORCE_SW_BITCOUNT)
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return (__builtin_ctz(val) >> 3);
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#else
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static const int DeBruijnBytePos[32] = { 0, 0, 3, 0, 3, 1, 3, 0, 3, 2, 2, 1, 3, 2, 0, 1, 3, 3, 1, 2, 2, 2, 2, 0, 3, 1, 2, 0, 1, 0, 1, 1 };
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@ -177,6 +189,9 @@ inline static int LZ4_NbCommonBytes_LittleEndian( register U32 val )
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}
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//******************************
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// Public Compression functions
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//******************************
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int LZ4_compressCtx(void** ctx,
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char* source,
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char* dest,
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@ -259,11 +274,7 @@ int LZ4_compressCtx(void** ctx,
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_next_match:
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// Encode Offset
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#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
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A16(op) = (ip-ref); op+=2;
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#else
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{ int delta = ip-ref; *op++ = delta; *op++ = delta>>8; }
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#endif
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LZ4_WRITE_LITTLEENDIAN_16(op,ip-ref);
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// Start Counting
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ip+=MINMATCH; ref+=MINMATCH; // MinMatch verified
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@ -409,11 +420,7 @@ int LZ4_compress64kCtx(void** ctx,
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_next_match:
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// Encode Offset
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#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
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A16(op) = (ip-ref); op+=2;
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#else
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{ int delta = ip-ref; *op++ = delta; *op++ = delta>>8; }
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#endif
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LZ4_WRITE_LITTLEENDIAN_16(op,ip-ref);
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// Start Counting
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ip+=MINMATCH; ref+=MINMATCH; // MinMatch verified
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@ -498,10 +505,10 @@ int LZ4_compress(char* source,
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//****************************
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// Note : The decoding functions LZ4_uncompress() and LZ4_uncompress_unknownOutputSize()
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// are safe against "buffer overflow" attack type
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// since they will *never* write outside of the provided output buffer :
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// are safe against "buffer overflow" attack type.
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// They will *never* write nor read outside of the provided input and output buffer :
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// they both check this condition *before* writing anything.
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// A corrupted packet however can make them *read* within the first 64K before the output buffer.
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// A corrupted packet will trigger an error result, a negative int, indicating the position of the error within input stream.
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int LZ4_uncompress(char* source,
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char* dest,
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@ -517,8 +524,11 @@ int LZ4_uncompress(char* source,
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BYTE token;
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U32 dec[4]={0, 3, 2, 3};
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int len, length;
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size_t dec1[] ={0, 3, 2, 3, 0, 0, 0, 0};
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#if ARCH64
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size_t dec2[]={0, 4, 4, 3, 4, 5, 6, 7};
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#endif
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// Main Loop
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@ -539,29 +549,50 @@ int LZ4_uncompress(char* source,
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}
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LZ4_WILDCOPY(ip, op, cpy); ip -= (op-cpy); op = cpy;
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// get offset
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#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
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ref = cpy - A16(ip); ip+=2;
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#else
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{ int delta = *ip++; delta += *ip++ << 8; ref = cpy - delta; }
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#endif
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LZ4_READ_LITTLEENDIAN_16(ref,cpy,ip); ip+=2;
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if (ref < (BYTE* const)dest) goto _output_error;
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// get matchlength
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if ((length=(token&ML_MASK)) == ML_MASK) { for (;*ip==255;length+=255) {ip++;} length += *ip++; }
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// copy repeated sequence
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#if ARCH64
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if (op-ref<8)
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{
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int tmp = dec2[op-ref];
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*op++ = *ref++;
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*op++ = *ref++;
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*op++ = *ref++;
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*op++ = *ref++;
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ref -= dec1[op-ref];
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A32(op)=A32(ref); op += 4; ref += 4;
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ref -= tmp;
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} else { LZ4_COPYPACKET64(ref,op); }
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cpy = op + length - 4;
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if (cpy > oend-COPYLENGTH)
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{
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if (cpy > oend) goto _output_error;
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LZ4_WILDCOPY64(ref, op, (oend-COPYLENGTH));
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while(op<cpy) *op++=*ref++;
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op=cpy;
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if (op == oend) break; // Check EOF (should never happen, since last 5 bytes are supposed to be literals)
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continue;
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}
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LZ4_WILDCOPY64(ref, op, cpy);
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op=cpy; // correction
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#else
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if (op-ref<COPYTOKEN)
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{
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*op++ = *ref++;
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*op++ = *ref++;
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*op++ = *ref++;
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*op++ = *ref++;
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ref -= dec[op-ref];
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ref -= dec1[op-ref];
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A32(op)=A32(ref);
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} else { A32(op)=A32(ref); op+=4; ref+=4; }
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cpy = op + length;
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if (cpy > oend-COPYLENGTH)
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if (cpy>oend-COPYLENGTH)
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{
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if (cpy > oend) goto _output_error;
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LZ4_WILDCOPY32(ref, op, (oend-COPYLENGTH));
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@ -572,6 +603,7 @@ int LZ4_uncompress(char* source,
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}
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LZ4_WILDCOPY32(ref, op, cpy);
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op=cpy; // correction
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#endif
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}
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// end of decoding
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@ -600,8 +632,11 @@ int LZ4_uncompress_unknownOutputSize(
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BYTE token;
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U32 dec[4]={0, 3, 2, 3};
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int len, length;
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size_t dec1[] ={0, 3, 2, 3, 0, 0, 0, 0};
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#if ARCH64
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size_t dec2[]={0, 4, 4, 3, 4, 5, 6, 7};
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#endif
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// Main Loop
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@ -624,23 +659,44 @@ int LZ4_uncompress_unknownOutputSize(
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if (ip>=iend) break; // check EOF
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// get offset
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#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
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ref = cpy - A16(ip); ip+=2;
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#else
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{ int delta = *ip++; delta += *ip++ << 8; ref = cpy - delta; }
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#endif
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LZ4_READ_LITTLEENDIAN_16(ref,cpy,ip); ip+=2;
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if (ref < (BYTE* const)dest) goto _output_error;
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// get matchlength
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if ((length=(token&ML_MASK)) == ML_MASK) { for (;(len=*ip++)==255;length+=255){} length += len; }
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// copy repeated sequence
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#if ARCH64
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if (op-ref<8)
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{
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int tmp = dec2[op-ref];
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*op++ = *ref++;
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*op++ = *ref++;
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*op++ = *ref++;
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*op++ = *ref++;
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ref -= dec1[op-ref];
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A32(op)=A32(ref); op += 4; ref += 4;
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ref -= tmp;
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} else { LZ4_COPYPACKET64(ref,op); }
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cpy = op + length - 4;
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if (cpy > oend-COPYLENGTH)
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{
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if (cpy > oend) goto _output_error;
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LZ4_WILDCOPY64(ref, op, (oend-COPYLENGTH));
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while(op<cpy) *op++=*ref++;
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op=cpy;
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if (op == oend) break; // Check EOF (should never happen, since last 5 bytes are supposed to be literals)
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continue;
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}
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LZ4_WILDCOPY64(ref, op, cpy);
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op=cpy; // correction
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#else
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if (op-ref<COPYTOKEN)
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{
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*op++ = *ref++;
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*op++ = *ref++;
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*op++ = *ref++;
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*op++ = *ref++;
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ref -= dec[op-ref];
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ref -= dec1[op-ref];
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A32(op)=A32(ref);
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} else { A32(op)=A32(ref); op+=4; ref+=4; }
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cpy = op + length;
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@ -655,6 +711,8 @@ int LZ4_uncompress_unknownOutputSize(
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}
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LZ4_WILDCOPY32(ref, op, cpy);
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op=cpy; // correction
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#endif
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}
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// end of decoding
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