/* XzIn.c - Xz input

2018-02-02 : Igor Pavlov : Public domain */

#include "Precomp.h"

#include <string.h>

#include "7zCrc.h"

#include "CpuArch.h"

#include "Xz.h"

/*

#define XZ_FOOTER_SIG_CHECK(p) (memcmp((p), XZ_FOOTER_SIG, XZ_FOOTER_SIG_SIZE) == 0)

*/

#define XZ_FOOTER_SIG_CHECK(p) ((p)[0] == XZ_FOOTER_SIG_0 && (p)[1] == XZ_FOOTER_SIG_1)

SRes Xz_ReadHeader(CXzStreamFlags *p, ISeqInStream *inStream)

{

  Byte sig[XZ_STREAM_HEADER_SIZE];

  RINOK(SeqInStream_Read2(inStream, sig, XZ_STREAM_HEADER_SIZE, SZ_ERROR_NO_ARCHIVE));

  if (memcmp(sig, XZ_SIG, XZ_SIG_SIZE) != 0)

    return SZ_ERROR_NO_ARCHIVE;

  return Xz_ParseHeader(p, sig);

}

#define READ_VARINT_AND_CHECK(buf, pos, size, res) \

  { unsigned s = Xz_ReadVarInt(buf + pos, size - pos, res); \

  if (s == 0) return SZ_ERROR_ARCHIVE; pos += s; }

SRes XzBlock_ReadHeader(CXzBlock *p, ISeqInStream *inStream, Bool *isIndex, UInt32 *headerSizeRes)

{

  Byte header[XZ_BLOCK_HEADER_SIZE_MAX];

  unsigned headerSize;

  *headerSizeRes = 0;

  RINOK(SeqInStream_ReadByte(inStream, &header[0]));

  headerSize = (unsigned)header[0];

  if (headerSize == 0)

  {

    *headerSizeRes = 1;

    *isIndex = True;

    return SZ_OK;

  }

  *isIndex = False;

  headerSize = (headerSize << 2) + 4;

  *headerSizeRes = headerSize;

  RINOK(SeqInStream_Read(inStream, header + 1, headerSize - 1));

  return XzBlock_Parse(p, header);

}

#define ADD_SIZE_CHECK(size, val) \

  { UInt64 newSize = size + (val); if (newSize < size) return XZ_SIZE_OVERFLOW; size = newSize; }

UInt64 Xz_GetUnpackSize(const CXzStream *p)

{

  UInt64 size = 0;

  size_t i;

  for (i = 0; i < p->numBlocks; i++)

    ADD_SIZE_CHECK(size, p->blocks[i].unpackSize);

  return size;

}

UInt64 Xz_GetPackSize(const CXzStream *p)

{

  UInt64 size = 0;

  size_t i;

  for (i = 0; i < p->numBlocks; i++)

    ADD_SIZE_CHECK(size, (p->blocks[i].totalSize + 3) & ~(UInt64)3);

  return size;

}

/*

SRes XzBlock_ReadFooter(CXzBlock *p, CXzStreamFlags f, ISeqInStream *inStream)

{

  return SeqInStream_Read(inStream, p->check, XzFlags_GetCheckSize(f));

}

*/

static SRes Xz_ReadIndex2(CXzStream *p, const Byte *buf, size_t size, ISzAllocPtr alloc)

{

  size_t numBlocks, pos = 1;

  UInt32 crc;

  if (size < 5 || buf[0] != 0)

    return SZ_ERROR_ARCHIVE;

  size -= 4;

  crc = CrcCalc(buf, size);

  if (crc != GetUi32(buf + size))

    return SZ_ERROR_ARCHIVE;

  {

    UInt64 numBlocks64;

    READ_VARINT_AND_CHECK(buf, pos, size, &numBlocks64);

    numBlocks = (size_t)numBlocks64;

    if (numBlocks != numBlocks64 || numBlocks * 2 > size)

      return SZ_ERROR_ARCHIVE;

  }

  Xz_Free(p, alloc);

  if (numBlocks != 0)

  {

    size_t i;

    p->numBlocks = numBlocks;

    p->blocks = (CXzBlockSizes *)ISzAlloc_Alloc(alloc, sizeof(CXzBlockSizes) * numBlocks);

    if (!p->blocks)

      return SZ_ERROR_MEM;

    for (i = 0; i < numBlocks; i++)

    {

      CXzBlockSizes *block = &p->blocks[i];

      READ_VARINT_AND_CHECK(buf, pos, size, &block->totalSize);

      READ_VARINT_AND_CHECK(buf, pos, size, &block->unpackSize);

      if (block->totalSize == 0)

        return SZ_ERROR_ARCHIVE;

    }

  }

  while ((pos & 3) != 0)

    if (buf[pos++] != 0)

      return SZ_ERROR_ARCHIVE;

  return (pos == size) ? SZ_OK : SZ_ERROR_ARCHIVE;

}

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 LookInStream_SeekRead_ForArc(ILookInStream *stream, UInt64 offset, void *buf, size_t size)

{

  RINOK(LookInStream_SeekTo(stream, offset));

  return LookInStream_Read(stream, buf, size);

  /* return LookInStream_Read2(stream, buf, size, SZ_ERROR_NO_ARCHIVE); */

}

static SRes Xz_ReadBackward(CXzStream *p, ILookInStream *stream, Int64 *startOffset, ISzAllocPtr alloc)

{

  UInt64 indexSize;

  Byte buf[XZ_STREAM_FOOTER_SIZE];

  UInt64 pos = *startOffset;

  if ((pos & 3) != 0 || pos < XZ_STREAM_FOOTER_SIZE)

    return SZ_ERROR_NO_ARCHIVE;

  pos -= XZ_STREAM_FOOTER_SIZE;

  RINOK(LookInStream_SeekRead_ForArc(stream, pos, buf, XZ_STREAM_FOOTER_SIZE));

  if (!XZ_FOOTER_SIG_CHECK(buf + 10))

  {

    UInt32 total = 0;

    pos += XZ_STREAM_FOOTER_SIZE;

    for (;;)

    {

      size_t i;

      #define TEMP_BUF_SIZE (1 << 10)

      Byte temp[TEMP_BUF_SIZE];

      i = (pos > TEMP_BUF_SIZE) ? TEMP_BUF_SIZE : (size_t)pos;

      pos -= i;

      RINOK(LookInStream_SeekRead_ForArc(stream, pos, temp, i));

      total += (UInt32)i;

      for (; i != 0; i--)

        if (temp[i - 1] != 0)

          break;

      if (i != 0)

      {

        if ((i & 3) != 0)

          return SZ_ERROR_NO_ARCHIVE;

        pos += i;

        break;

      }

      if (pos < XZ_STREAM_FOOTER_SIZE || total > (1 << 16))

        return SZ_ERROR_NO_ARCHIVE;

    }

    if (pos < XZ_STREAM_FOOTER_SIZE)

      return SZ_ERROR_NO_ARCHIVE;

    pos -= XZ_STREAM_FOOTER_SIZE;

    RINOK(LookInStream_SeekRead_ForArc(stream, pos, buf, XZ_STREAM_FOOTER_SIZE));

    if (!XZ_FOOTER_SIG_CHECK(buf + 10))

      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;

  if (pos < indexSize)

    return SZ_ERROR_ARCHIVE;

  pos -= indexSize;

  RINOK(LookInStream_SeekTo(stream, pos));

  RINOK(Xz_ReadIndex(p, stream, indexSize, alloc));

  {

    UInt64 totalSize = Xz_GetPackSize(p);

    if (totalSize == XZ_SIZE_OVERFLOW

        || totalSize >= ((UInt64)1 << 63)

        || pos < totalSize + XZ_STREAM_HEADER_SIZE)

      return SZ_ERROR_ARCHIVE;

    pos -= (totalSize + XZ_STREAM_HEADER_SIZE);

    RINOK(LookInStream_SeekTo(stream, pos));

    *startOffset = pos;

  }

  {

    CXzStreamFlags headerFlags;

    CSecToRead secToRead;

    SecToRead_CreateVTable(&secToRead);

    secToRead.realStream = stream;

    RINOK(Xz_ReadHeader(&headerFlags, &secToRead.vt));

    return (p->flags == headerFlags) ? SZ_OK : SZ_ERROR_ARCHIVE;

  }

}

/* ---------- Xz Streams ---------- */

void Xzs_Construct(CXzs *p)

{

  p->num = p->numAllocated = 0;

  p->streams = 0;

}

void Xzs_Free(CXzs *p, ISzAllocPtr alloc)

{

  size_t i;

  for (i = 0; i < p->num; i++)

    Xz_Free(&p->streams[i], alloc);

  ISzAlloc_Free(alloc, p->streams);

  p->num = p->numAllocated = 0;

  p->streams = 0;

}

UInt64 Xzs_GetNumBlocks(const CXzs *p)

{

  UInt64 num = 0;

  size_t i;

  for (i = 0; i < p->num; i++)

    num += p->streams[i].numBlocks;

  return num;

}

UInt64 Xzs_GetUnpackSize(const CXzs *p)

{

  UInt64 size = 0;

  size_t i;

  for (i = 0; i < p->num; i++)

    ADD_SIZE_CHECK(size, Xz_GetUnpackSize(&p->streams[i]));

  return size;

}

/*

UInt64 Xzs_GetPackSize(const CXzs *p)

{

  UInt64 size = 0;

  size_t i;

  for (i = 0; i < p->num; i++)

    ADD_SIZE_CHECK(size, Xz_GetTotalSize(&p->streams[i]));

  return size;

}

*/

SRes Xzs_ReadBackward(CXzs *p, ILookInStream *stream, Int64 *startOffset, ICompressProgress *progress, ISzAllocPtr alloc)

{

  Int64 endOffset = 0;

  RINOK(ILookInStream_Seek(stream, &endOffset, SZ_SEEK_END));

  *startOffset = endOffset;

  for (;;)

  {

    CXzStream st;

    SRes res;

    Xz_Construct(&st);

    res = Xz_ReadBackward(&st, stream, startOffset, alloc);

    st.startOffset = *startOffset;

    RINOK(res);

    if (p->num == p->numAllocated)

    {

      size_t newNum = p->num + p->num / 4 + 1;

      Byte *data = (Byte *)ISzAlloc_Alloc(alloc, newNum * sizeof(CXzStream));

      if (!data)

        return SZ_ERROR_MEM;

      p->numAllocated = newNum;

      if (p->num != 0)

        memcpy(data, p->streams, p->num * sizeof(CXzStream));

      ISzAlloc_Free(alloc, p->streams);

      p->streams = (CXzStream *)data;

    }

    p->streams[p->num++] = st;

    if (*startOffset == 0)

      break;

    RINOK(LookInStream_SeekTo(stream, *startOffset));

    if (progress && ICompressProgress_Progress(progress, endOffset - *startOffset, (UInt64)(Int64)-1) != SZ_OK)

      return SZ_ERROR_PROGRESS;

  }

  return SZ_OK;

}