Subversion Repositories QNX 8.QNX8 LLVM/Clang compiler suite

//===- MSFCommon.h - Common types and functions for MSF files ---*- C++ -*-===//

//

// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.

// See https://llvm.org/LICENSE.txt for license information.

// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

//

//===----------------------------------------------------------------------===//

#ifndef LLVM_DEBUGINFO_MSF_MSFCOMMON_H

#define LLVM_DEBUGINFO_MSF_MSFCOMMON_H

#include "llvm/ADT/ArrayRef.h"

#include "llvm/ADT/BitVector.h"

#include "llvm/Support/Endian.h"

#include "llvm/Support/Error.h"

#include "llvm/Support/MathExtras.h"

#include <cstdint>

#include <vector>

namespace llvm {

namespace msf {

static const char Magic[] = {'M',  'i',  'c',    'r', 'o', 's',  'o',  'f',

                             't',  ' ',  'C',    '/', 'C', '+',  '+',  ' ',

                             'M',  'S',  'F',    ' ', '7', '.',  '0',  '0',

                             '\r', '\n', '\x1a', 'D', 'S', '\0', '\0', '\0'};

// The superblock is overlaid at the beginning of the file (offset 0).

// It starts with a magic header and is followed by information which

// describes the layout of the file system.

struct SuperBlock {

  char MagicBytes[sizeof(Magic)];

  // The file system is split into a variable number of fixed size elements.

  // These elements are referred to as blocks.  The size of a block may vary

  // from system to system.

  support::ulittle32_t BlockSize;

  // The index of the free block map.

  support::ulittle32_t FreeBlockMapBlock;

  // This contains the number of blocks resident in the file system.  In

  // practice, NumBlocks * BlockSize is equivalent to the size of the MSF

  // file.

  support::ulittle32_t NumBlocks;

  // This contains the number of bytes which make up the directory.

  support::ulittle32_t NumDirectoryBytes;

  // This field's purpose is not yet known.

  support::ulittle32_t Unknown1;

  // This contains the block # of the block map.

  support::ulittle32_t BlockMapAddr;

};

struct MSFLayout {

  MSFLayout() = default;

  uint32_t mainFpmBlock() const {

    assert(SB->FreeBlockMapBlock == 1 || SB->FreeBlockMapBlock == 2);

    return SB->FreeBlockMapBlock;

  }

  uint32_t alternateFpmBlock() const {

    // If mainFpmBlock is 1, this is 2.  If mainFpmBlock is 2, this is 1.

    return 3U - mainFpmBlock();

  }

  const SuperBlock *SB = nullptr;

  BitVector FreePageMap;

  ArrayRef<support::ulittle32_t> DirectoryBlocks;

  ArrayRef<support::ulittle32_t> StreamSizes;

  std::vector<ArrayRef<support::ulittle32_t>> StreamMap;

};

/// Describes the layout of a stream in an MSF layout.  A "stream" here

/// is defined as any logical unit of data which may be arranged inside the MSF

/// file as a sequence of (possibly discontiguous) blocks.  When we want to read

/// from a particular MSF Stream, we fill out a stream layout structure and the

/// reader uses it to determine which blocks in the underlying MSF file contain

/// the data, so that it can be pieced together in the right order.

class MSFStreamLayout {

public:

  uint32_t Length;

  std::vector<support::ulittle32_t> Blocks;

};

/// Determine the layout of the FPM stream, given the MSF layout.  An FPM

/// stream spans 1 or more blocks, each at equally spaced intervals throughout

/// the file.

MSFStreamLayout getFpmStreamLayout(const MSFLayout &Msf,

                                   bool IncludeUnusedFpmData = false,

                                   bool AltFpm = false);

inline bool isValidBlockSize(uint32_t Size) {

  switch (Size) {

  case 512:

  case 1024:

  case 2048:

  case 4096:

  case 8192:

  case 16384:

  case 32768:

    return true;

  }

  return false;

}

/// Given the specified block size, returns the maximum possible file size.

/// Block Size  |  Max File Size

/// <= 4096     |      4GB

///    8192     |      8GB

///   16384     |      16GB

///   32768     |      32GB

/// \p Size - the block size of the MSF

inline uint64_t getMaxFileSizeFromBlockSize(uint32_t Size) {

  switch (Size) {

  case 8192:

    return (uint64_t)UINT32_MAX * 2ULL;

  case 16384:

    return (uint64_t)UINT32_MAX * 3ULL;

  case 32768:

    return (uint64_t)UINT32_MAX * 4ULL;

  default:

    return (uint64_t)UINT32_MAX;

  }

}

// Super Block, Fpm0, Fpm1, and Block Map

inline uint32_t getMinimumBlockCount() { return 4; }

// Super Block, Fpm0, and Fpm1 are reserved.  The Block Map, although required

// need not be at block 3.

inline uint32_t getFirstUnreservedBlock() { return 3; }

inline uint64_t bytesToBlocks(uint64_t NumBytes, uint64_t BlockSize) {

  return divideCeil(NumBytes, BlockSize);

}

inline uint64_t blockToOffset(uint64_t BlockNumber, uint64_t BlockSize) {

  return BlockNumber * BlockSize;

}

inline uint32_t getFpmIntervalLength(const MSFLayout &L) {

  return L.SB->BlockSize;

}

/// Given an MSF with the specified block size and number of blocks, determine

/// how many pieces the specified Fpm is split into.

/// \p BlockSize - the block size of the MSF

/// \p NumBlocks - the total number of blocks in the MSF

/// \p IncludeUnusedFpmData - When true, this will count every block that is

///    both in the file and matches the form of an FPM block, even if some of

///    those FPM blocks are unused (a single FPM block can describe the

///    allocation status of up to 32,767 blocks, although one appears only

///    every 4,096 blocks).  So there are 8x as many blocks that match the

///    form as there are blocks that are necessary to describe the allocation

///    status of the file.  When this parameter is false, these extraneous

///    trailing blocks are not counted.

inline uint32_t getNumFpmIntervals(uint32_t BlockSize, uint32_t NumBlocks,

                                   bool IncludeUnusedFpmData, int FpmNumber) {

  assert(FpmNumber == 1 || FpmNumber == 2);

  if (IncludeUnusedFpmData) {

    // This calculation determines how many times a number of the form

    // BlockSize * k + N appears in the range [0, NumBlocks).  We only need to

    // do this when unused data is included, since the number of blocks dwarfs

    // the number of fpm blocks.

    return divideCeil(NumBlocks - FpmNumber, BlockSize);

  }

  // We want the minimum number of intervals required, where each interval can

  // represent BlockSize * 8 blocks.

  return divideCeil(NumBlocks, 8 * BlockSize);

}

inline uint32_t getNumFpmIntervals(const MSFLayout &L,

                                   bool IncludeUnusedFpmData = false,

                                   bool AltFpm = false) {

  return getNumFpmIntervals(L.SB->BlockSize, L.SB->NumBlocks,

                            IncludeUnusedFpmData,

                            AltFpm ? L.alternateFpmBlock() : L.mainFpmBlock());

}

Error validateSuperBlock(const SuperBlock &SB);

} // end namespace msf

} // end namespace llvm

#endif // LLVM_DEBUGINFO_MSF_MSFCOMMON_H