Function SkipBitcodeWrapperHeader

src/include/llvm/Bitcode/BitcodeReader.h:240–257

SkipBitcodeWrapperHeader - Some systems wrap bc files with a special header for padding or other reasons. The format of this header is: struct bc_header { uint32_t Magic; // 0x0B17C0DE uint32_t Version; // Version, currently always 0. uint32_t BitcodeOffset; // Offset to traditional bitcode file. uint32_t BitcodeSize; // Size of traditional bitcode file. ... potentially other gun

  /// If 'VerifyBufferSize' is true, check that the buffer is large enough to
  /// contain the whole bitcode file.
  inline bool SkipBitcodeWrapperHeader(const unsigned char *&BufPtr,
                                       const unsigned char *&BufEnd,
                                       bool VerifyBufferSize) {
    // Must contain the offset and size field!
    if (unsigned(BufEnd - BufPtr) < BWH_SizeField + 4)
      return true;

    unsigned Offset = support::endian::read32le(&BufPtr[BWH_OffsetField]);
    unsigned Size = support::endian::read32le(&BufPtr[BWH_SizeField]);
    uint64_t BitcodeOffsetEnd = (uint64_t)Offset + (uint64_t)Size;

    // Verify that Offset+Size fits in the file.
    if (VerifyBufferSize && BitcodeOffsetEnd > uint64_t(BufEnd-BufPtr))
      return true;
    BufPtr += Offset;
    BufEnd = BufPtr+Size;
    return false;
  }

  const std::error_category &BitcodeErrorCategory();
  enum class BitcodeError { CorruptedBitcode = 1 };