| //===- 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: |
| return true; |
| } |
| return false; |
| } |
| |
| // 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 |