Line data Source code
1 : //===- MSFCommon.h - Common types and functions for MSF files ---*- C++ -*-===//
2 : //
3 : // The LLVM Compiler Infrastructure
4 : //
5 : // This file is distributed under the University of Illinois Open Source
6 : // License. See LICENSE.TXT for details.
7 : //
8 : //===----------------------------------------------------------------------===//
9 :
10 : #ifndef LLVM_DEBUGINFO_MSF_MSFCOMMON_H
11 : #define LLVM_DEBUGINFO_MSF_MSFCOMMON_H
12 :
13 : #include "llvm/ADT/ArrayRef.h"
14 : #include "llvm/ADT/BitVector.h"
15 : #include "llvm/Support/Endian.h"
16 : #include "llvm/Support/Error.h"
17 : #include "llvm/Support/MathExtras.h"
18 : #include <cstdint>
19 : #include <vector>
20 :
21 : namespace llvm {
22 : namespace msf {
23 :
24 : static const char Magic[] = {'M', 'i', 'c', 'r', 'o', 's', 'o', 'f',
25 : 't', ' ', 'C', '/', 'C', '+', '+', ' ',
26 : 'M', 'S', 'F', ' ', '7', '.', '0', '0',
27 : '\r', '\n', '\x1a', 'D', 'S', '\0', '\0', '\0'};
28 :
29 : // The superblock is overlaid at the beginning of the file (offset 0).
30 : // It starts with a magic header and is followed by information which
31 : // describes the layout of the file system.
32 : struct SuperBlock {
33 : char MagicBytes[sizeof(Magic)];
34 : // The file system is split into a variable number of fixed size elements.
35 : // These elements are referred to as blocks. The size of a block may vary
36 : // from system to system.
37 : support::ulittle32_t BlockSize;
38 : // The index of the free block map.
39 : support::ulittle32_t FreeBlockMapBlock;
40 : // This contains the number of blocks resident in the file system. In
41 : // practice, NumBlocks * BlockSize is equivalent to the size of the MSF
42 : // file.
43 : support::ulittle32_t NumBlocks;
44 : // This contains the number of bytes which make up the directory.
45 : support::ulittle32_t NumDirectoryBytes;
46 : // This field's purpose is not yet known.
47 : support::ulittle32_t Unknown1;
48 : // This contains the block # of the block map.
49 : support::ulittle32_t BlockMapAddr;
50 : };
51 :
52 238 : struct MSFLayout {
53 240 : MSFLayout() = default;
54 :
55 0 : uint32_t mainFpmBlock() const {
56 : assert(SB->FreeBlockMapBlock == 1 || SB->FreeBlockMapBlock == 2);
57 0 : return SB->FreeBlockMapBlock;
58 : }
59 :
60 : uint32_t alternateFpmBlock() const {
61 : // If mainFpmBlock is 1, this is 2. If mainFpmBlock is 2, this is 1.
62 678 : return 3U - mainFpmBlock();
63 : }
64 :
65 : const SuperBlock *SB = nullptr;
66 : BitVector FreePageMap;
67 : ArrayRef<support::ulittle32_t> DirectoryBlocks;
68 : ArrayRef<support::ulittle32_t> StreamSizes;
69 : std::vector<ArrayRef<support::ulittle32_t>> StreamMap;
70 : };
71 :
72 : /// Describes the layout of a stream in an MSF layout. A "stream" here
73 : /// is defined as any logical unit of data which may be arranged inside the MSF
74 : /// file as a sequence of (possibly discontiguous) blocks. When we want to read
75 : /// from a particular MSF Stream, we fill out a stream layout structure and the
76 : /// reader uses it to determine which blocks in the underlying MSF file contain
77 : /// the data, so that it can be pieced together in the right order.
78 3424 : class MSFStreamLayout {
79 : public:
80 : uint32_t Length;
81 : std::vector<support::ulittle32_t> Blocks;
82 : };
83 :
84 : /// Determine the layout of the FPM stream, given the MSF layout. An FPM
85 : /// stream spans 1 or more blocks, each at equally spaced intervals throughout
86 : /// the file.
87 : MSFStreamLayout getFpmStreamLayout(const MSFLayout &Msf,
88 : bool IncludeUnusedFpmData = false,
89 : bool AltFpm = false);
90 :
91 : inline bool isValidBlockSize(uint32_t Size) {
92 258 : switch (Size) {
93 : case 512:
94 : case 1024:
95 : case 2048:
96 : case 4096:
97 : return true;
98 : }
99 : return false;
100 : }
101 :
102 : // Super Block, Fpm0, Fpm1, and Block Map
103 : inline uint32_t getMinimumBlockCount() { return 4; }
104 :
105 : // Super Block, Fpm0, and Fpm1 are reserved. The Block Map, although required
106 : // need not be at block 3.
107 : inline uint32_t getFirstUnreservedBlock() { return 3; }
108 :
109 : inline uint64_t bytesToBlocks(uint64_t NumBytes, uint64_t BlockSize) {
110 : return divideCeil(NumBytes, BlockSize);
111 : }
112 :
113 : inline uint64_t blockToOffset(uint64_t BlockNumber, uint64_t BlockSize) {
114 126925 : return BlockNumber * BlockSize;
115 : }
116 :
117 0 : inline uint32_t getFpmIntervalLength(const MSFLayout &L) {
118 0 : return L.SB->BlockSize;
119 : }
120 :
121 : /// Given an MSF with the specified block size and number of blocks, determine
122 : /// how many pieces the specified Fpm is split into.
123 : /// \p BlockSize - the block size of the MSF
124 : /// \p NumBlocks - the total number of blocks in the MSF
125 : /// \p IncludeUnusedFpmData - When true, this will count every block that is
126 : /// both in the file and matches the form of an FPM block, even if some of
127 : /// those FPM blocks are unused (a single FPM block can describe the
128 : /// allocation status of up to 32,767 blocks, although one appears only
129 : /// every 4,096 blocks). So there are 8x as many blocks that match the
130 : /// form as there are blocks that are necessary to describe the allocation
131 : /// status of the file. When this parameter is false, these extraneous
132 : /// trailing blocks are not counted.
133 : inline uint32_t getNumFpmIntervals(uint32_t BlockSize, uint32_t NumBlocks,
134 : bool IncludeUnusedFpmData, int FpmNumber) {
135 : assert(FpmNumber == 1 || FpmNumber == 2);
136 582 : if (IncludeUnusedFpmData) {
137 : // This calculation determines how many times a number of the form
138 : // BlockSize * k + N appears in the range [0, NumBlocks). We only need to
139 : // do this when unused data is included, since the number of blocks dwarfs
140 : // the number of fpm blocks.
141 464 : return divideCeil(NumBlocks - FpmNumber, BlockSize);
142 : }
143 :
144 : // We want the minimum number of intervals required, where each interval can
145 : // represent BlockSize * 8 blocks.
146 728 : return divideCeil(NumBlocks, 8 * BlockSize);
147 : }
148 :
149 582 : inline uint32_t getNumFpmIntervals(const MSFLayout &L,
150 : bool IncludeUnusedFpmData = false,
151 : bool AltFpm = false) {
152 582 : return getNumFpmIntervals(L.SB->BlockSize, L.SB->NumBlocks,
153 : IncludeUnusedFpmData,
154 363 : AltFpm ? L.alternateFpmBlock() : L.mainFpmBlock());
155 : }
156 :
157 : Error validateSuperBlock(const SuperBlock &SB);
158 :
159 : } // end namespace msf
160 : } // end namespace llvm
161 :
162 : #endif // LLVM_DEBUGINFO_MSF_MSFCOMMON_H
|
