1 //===- MSFBuilder.h - MSF Directory & Metadata Builder ----------*- C++ -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #ifndef LLVM_DEBUGINFO_MSF_MSFBUILDER_H 10 #define LLVM_DEBUGINFO_MSF_MSFBUILDER_H 11 12 #include "llvm/ADT/ArrayRef.h" 13 #include "llvm/ADT/BitVector.h" 14 #include "llvm/DebugInfo/MSF/MSFCommon.h" 15 #include "llvm/Support/Allocator.h" 16 #include "llvm/Support/Error.h" 17 #include <cstdint> 18 #include <utility> 19 #include <vector> 20 21 namespace llvm { 22 class FileBufferByteStream; 23 class WritableBinaryStream; 24 namespace msf { 25 26 class MSFBuilder { 27 public: 28 /// Create a new `MSFBuilder`. 29 /// 30 /// \param BlockSize The internal block size used by the PDB file. See 31 /// isValidBlockSize() for a list of valid block sizes. 32 /// 33 /// \param MinBlockCount Causes the builder to reserve up front space for 34 /// at least `MinBlockCount` blocks. This is useful when using `MSFBuilder` 35 /// to read an existing MSF that you want to write back out later. The 36 /// original MSF file's SuperBlock contains the exact number of blocks used 37 /// by the file, so is a good hint as to how many blocks the new MSF file 38 /// will contain. Furthermore, it is actually necessary in this case. To 39 /// preserve stability of the file's layout, it is helpful to try to keep 40 /// all streams mapped to their original block numbers. To ensure that this 41 /// is possible, space for all blocks must be allocated beforehand so that 42 /// streams can be assigned to them. 43 /// 44 /// \param CanGrow If true, any operation which results in an attempt to 45 /// locate a free block when all available blocks have been exhausted will 46 /// allocate a new block, thereby growing the size of the final MSF file. 47 /// When false, any such attempt will result in an error. This is especially 48 /// useful in testing scenarios when you know your test isn't going to do 49 /// anything to increase the size of the file, so having an Error returned if 50 /// it were to happen would catch a programming error 51 /// 52 /// \returns an llvm::Error representing whether the operation succeeded or 53 /// failed. Currently the only way this can fail is if an invalid block size 54 /// is specified, or `MinBlockCount` does not leave enough room for the 55 /// mandatory reserved blocks required by an MSF file. 56 static Expected<MSFBuilder> create(BumpPtrAllocator &Allocator, 57 uint32_t BlockSize, 58 uint32_t MinBlockCount = 0, 59 bool CanGrow = true); 60 61 /// Request the block map to be at a specific block address. This is useful 62 /// when editing a MSF and you want the layout to be as stable as possible. 63 Error setBlockMapAddr(uint32_t Addr); 64 Error setDirectoryBlocksHint(ArrayRef<uint32_t> DirBlocks); 65 void setFreePageMap(uint32_t Fpm); 66 void setUnknown1(uint32_t Unk1); 67 68 /// Add a stream to the MSF file with the given size, occupying the given 69 /// list of blocks. This is useful when reading a MSF file and you want a 70 /// particular stream to occupy the original set of blocks. If the given 71 /// blocks are already allocated, or if the number of blocks specified is 72 /// incorrect for the given stream size, this function will return an Error. 73 Expected<uint32_t> addStream(uint32_t Size, ArrayRef<uint32_t> Blocks); 74 75 /// Add a stream to the MSF file with the given size, occupying any available 76 /// blocks that the builder decides to use. This is useful when building a 77 /// new PDB file from scratch and you don't care what blocks a stream occupies 78 /// but you just want it to work. 79 Expected<uint32_t> addStream(uint32_t Size); 80 81 /// Update the size of an existing stream. This will allocate or deallocate 82 /// blocks as needed to match the requested size. This can fail if `CanGrow` 83 /// was set to false when initializing the `MSFBuilder`. 84 Error setStreamSize(uint32_t Idx, uint32_t Size); 85 86 /// Get the total number of streams in the MSF layout. This should return 1 87 /// for every call to `addStream`. 88 uint32_t getNumStreams() const; 89 90 /// Get the size of a stream by index. 91 uint32_t getStreamSize(uint32_t StreamIdx) const; 92 93 /// Get the list of blocks allocated to a particular stream. 94 ArrayRef<uint32_t> getStreamBlocks(uint32_t StreamIdx) const; 95 96 /// Get the total number of blocks that will be allocated to actual data in 97 /// this MSF file. 98 uint32_t getNumUsedBlocks() const; 99 100 /// Get the total number of blocks that exist in the MSF file but are not 101 /// allocated to any valid data. 102 uint32_t getNumFreeBlocks() const; 103 104 /// Get the total number of blocks in the MSF file. In practice this is equal 105 /// to `getNumUsedBlocks() + getNumFreeBlocks()`. 106 uint32_t getTotalBlockCount() const; 107 108 /// Check whether a particular block is allocated or free. 109 bool isBlockFree(uint32_t Idx) const; 110 111 /// Finalize the layout and build the headers and structures that describe the 112 /// MSF layout and can be written directly to the MSF file. 113 Expected<MSFLayout> generateLayout(); 114 115 /// Write the MSF layout to the underlying file. 116 Expected<FileBufferByteStream> commit(StringRef Path, MSFLayout &Layout); 117 118 BumpPtrAllocator &getAllocator() { return Allocator; } 119 120 private: 121 MSFBuilder(uint32_t BlockSize, uint32_t MinBlockCount, bool CanGrow, 122 BumpPtrAllocator &Allocator); 123 124 Error allocateBlocks(uint32_t NumBlocks, MutableArrayRef<uint32_t> Blocks); 125 uint32_t computeDirectoryByteSize() const; 126 127 using BlockList = std::vector<uint32_t>; 128 129 BumpPtrAllocator &Allocator; 130 131 bool IsGrowable; 132 uint32_t FreePageMap; 133 uint32_t Unknown1 = 0; 134 uint32_t BlockSize; 135 uint32_t BlockMapAddr; 136 BitVector FreeBlocks; 137 std::vector<uint32_t> DirectoryBlocks; 138 std::vector<std::pair<uint32_t, BlockList>> StreamData; 139 }; 140 141 } // end namespace msf 142 } // end namespace llvm 143 144 #endif // LLVM_DEBUGINFO_MSF_MSFBUILDER_H 145