static SRes Xz_ReadIndex(CXzStream *p, ILookInStream *stream, UInt64 indexSize, ISzAllocPtr alloc)
{
SRes res;
size_t size;
Byte *buf;
if (indexSize > ((UInt32)1 << 31))
return SZ_ERROR_UNSUPPORTED;
size = (size_t)indexSize;
if (size != indexSize)
return SZ_ERROR_UNSUPPORTED;
buf = (Byte *)ISzAlloc_Alloc(alloc, size);
if (!buf)
return SZ_ERROR_MEM;
res = LookInStream_Read2(stream, buf, size, SZ_ERROR_UNSUPPORTED);
if (res == SZ_OK)
res = Xz_ReadIndex2(p, buf, size, alloc);
ISzAlloc_Free(alloc, buf);
return res;
}
static SRes SzArEx_Open2(
CSzArEx *p,
ILookInStream *inStream,
ISzAlloc *allocMain,
ISzAlloc *allocTemp)
{
uint8_t header[k7zStartHeaderSize];
int64_t startArcPos;
uint64_t nextHeaderOffset, nextHeaderSize;
size_t nextHeaderSizeT;
uint32_t nextHeaderCRC;
CBuf buffer;
SRes res;
startArcPos = 0;
RINOK(inStream->Seek(inStream, &startArcPos, SZ_SEEK_CUR));
RINOK(LookInStream_Read2(inStream, header, k7zStartHeaderSize, SZ_ERROR_NO_ARCHIVE));
if (!TestSignatureCandidate(header))
return SZ_ERROR_NO_ARCHIVE;
if (header[6] != k7zMajorVersion)
return SZ_ERROR_UNSUPPORTED;
nextHeaderOffset = GetUi64(header + 12);
nextHeaderSize = GetUi64(header + 20);
nextHeaderCRC = GetUi32(header + 28);
p->startPosAfterHeader = startArcPos + k7zStartHeaderSize;
if (CrcCalc(header + 12, 20) != GetUi32(header + 8))
return SZ_ERROR_CRC;
nextHeaderSizeT = (size_t)nextHeaderSize;
if (nextHeaderSizeT != nextHeaderSize)
return SZ_ERROR_MEM;
if (nextHeaderSizeT == 0)
return SZ_OK;
if (nextHeaderOffset > nextHeaderOffset + nextHeaderSize ||
nextHeaderOffset > nextHeaderOffset + nextHeaderSize + k7zStartHeaderSize)
return SZ_ERROR_NO_ARCHIVE;
{
int64_t pos = 0;
RINOK(inStream->Seek(inStream, &pos, SZ_SEEK_END));
if ((uint64_t)pos < startArcPos + nextHeaderOffset ||
(uint64_t)pos < startArcPos + k7zStartHeaderSize + nextHeaderOffset ||
(uint64_t)pos < startArcPos + k7zStartHeaderSize + nextHeaderOffset + nextHeaderSize)
return SZ_ERROR_INPUT_EOF;
}
RINOK(LookInStream_SeekTo(inStream, startArcPos + k7zStartHeaderSize + nextHeaderOffset));
if (!Buf_Create(&buffer, nextHeaderSizeT, allocTemp))
return SZ_ERROR_MEM;
res = LookInStream_Read(inStream, buffer.data, nextHeaderSizeT);
if (res == SZ_OK)
{
res = SZ_ERROR_ARCHIVE;
if (CrcCalc(buffer.data, nextHeaderSizeT) == nextHeaderCRC)
{
CSzData sd;
uint64_t type;
sd.Data = buffer.data;
sd.Size = buffer.size;
res = SzReadID(&sd, &type);
if (res == SZ_OK)
{
if (type == k7zIdEncodedHeader)
{
CBuf outBuffer;
Buf_Init(&outBuffer);
res = SzReadAndDecodePackedStreams(inStream, &sd, &outBuffer, p->startPosAfterHeader, allocTemp);
if (res != SZ_OK)
Buf_Free(&outBuffer, allocTemp);
else
{
Buf_Free(&buffer, allocTemp);
buffer.data = outBuffer.data;
buffer.size = outBuffer.size;
sd.Data = buffer.data;
sd.Size = buffer.size;
res = SzReadID(&sd, &type);
}
}
}
if (res == SZ_OK)
{
if (type == k7zIdHeader)
res = SzReadHeader(p, &sd, allocMain, allocTemp);
else
res = SZ_ERROR_UNSUPPORTED;
}
}
}
Buf_Free(&buffer, allocTemp);
return res;
}
SRes LookInStream_Read(ILookInStream *stream, void *buf, size_t size)
{
return LookInStream_Read2(stream, buf, size, SZ_ERROR_INPUT_EOF);
}
static SRes Xz_ReadBackward(CXzStream *p, ILookInStream *stream, Int64 *startOffset, ISzAlloc *alloc)
{
UInt64 indexSize;
Byte buf[XZ_STREAM_FOOTER_SIZE];
if ((*startOffset & 3) != 0 || *startOffset < XZ_STREAM_FOOTER_SIZE)
return SZ_ERROR_NO_ARCHIVE;
*startOffset = -XZ_STREAM_FOOTER_SIZE;
RINOK(SeekFromCur(stream, startOffset));
RINOK(LookInStream_Read2(stream, buf, XZ_STREAM_FOOTER_SIZE, SZ_ERROR_NO_ARCHIVE));
if (memcmp(buf + 10, XZ_FOOTER_SIG, XZ_FOOTER_SIG_SIZE) != 0)
{
UInt32 total = 0;
*startOffset += XZ_STREAM_FOOTER_SIZE;
for (;;)
{
size_t i;
#define TEMP_BUF_SIZE (1 << 10)
Byte tempBuf[TEMP_BUF_SIZE];
if (*startOffset < XZ_STREAM_FOOTER_SIZE || total > (1 << 16))
return SZ_ERROR_NO_ARCHIVE;
i = (*startOffset > TEMP_BUF_SIZE) ? TEMP_BUF_SIZE : (size_t)*startOffset;
total += (UInt32)i;
*startOffset = -(Int64)i;
RINOK(SeekFromCur(stream, startOffset));
RINOK(LookInStream_Read2(stream, tempBuf, i, SZ_ERROR_NO_ARCHIVE));
for (; i != 0; i--)
if (tempBuf[i - 1] != 0)
break;
if (i != 0)
{
if ((i & 3) != 0)
return SZ_ERROR_NO_ARCHIVE;
*startOffset += i;
break;
}
}
if (*startOffset < XZ_STREAM_FOOTER_SIZE)
return SZ_ERROR_NO_ARCHIVE;
*startOffset -= XZ_STREAM_FOOTER_SIZE;
RINOK(stream->Seek(stream, startOffset, SZ_SEEK_SET));
RINOK(LookInStream_Read2(stream, buf, XZ_STREAM_FOOTER_SIZE, SZ_ERROR_NO_ARCHIVE));
if (memcmp(buf + 10, XZ_FOOTER_SIG, XZ_FOOTER_SIG_SIZE) != 0)
return SZ_ERROR_NO_ARCHIVE;
}
p->flags = (CXzStreamFlags)GetBe16(buf + 8);
if (!XzFlags_IsSupported(p->flags))
return SZ_ERROR_UNSUPPORTED;
if (GetUi32(buf) != CrcCalc(buf + 4, 6))
return SZ_ERROR_ARCHIVE;
indexSize = ((UInt64)GetUi32(buf + 4) + 1) << 2;
*startOffset = -(Int64)(indexSize + XZ_STREAM_FOOTER_SIZE);
RINOK(SeekFromCur(stream, startOffset));
RINOK(Xz_ReadIndex(p, stream, indexSize, alloc));
{
UInt64 totalSize = Xz_GetPackSize(p);
UInt64 sum = XZ_STREAM_HEADER_SIZE + totalSize + indexSize;
if (totalSize == XZ_SIZE_OVERFLOW ||
sum >= ((UInt64)1 << 63) ||
totalSize >= ((UInt64)1 << 63))
return SZ_ERROR_ARCHIVE;
*startOffset = -(Int64)sum;
RINOK(SeekFromCur(stream, startOffset));
}
{
CXzStreamFlags headerFlags;
CSecToRead secToRead;
SecToRead_CreateVTable(&secToRead);
secToRead.realStream = stream;
RINOK(Xz_ReadHeader(&headerFlags, &secToRead.s));
return (p->flags == headerFlags) ? SZ_OK : SZ_ERROR_ARCHIVE;
}
}
