LLVM  15.0.0git
MSFCommon.h
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1 //===- MSFCommon.h - Common types and functions for MSF files ---*- 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_MSFCOMMON_H
10 #define LLVM_DEBUGINFO_MSF_MSFCOMMON_H
11 
12 #include "llvm/ADT/ArrayRef.h"
13 #include "llvm/ADT/BitVector.h"
14 #include "llvm/Support/Endian.h"
15 #include "llvm/Support/Error.h"
17 #include <cstdint>
18 #include <vector>
19 
20 namespace llvm {
21 namespace msf {
22 
23 static const char Magic[] = {'M', 'i', 'c', 'r', 'o', 's', 'o', 'f',
24  't', ' ', 'C', '/', 'C', '+', '+', ' ',
25  'M', 'S', 'F', ' ', '7', '.', '0', '0',
26  '\r', '\n', '\x1a', 'D', 'S', '\0', '\0', '\0'};
27 
28 // The superblock is overlaid at the beginning of the file (offset 0).
29 // It starts with a magic header and is followed by information which
30 // describes the layout of the file system.
31 struct SuperBlock {
32  char MagicBytes[sizeof(Magic)];
33  // The file system is split into a variable number of fixed size elements.
34  // These elements are referred to as blocks. The size of a block may vary
35  // from system to system.
37  // The index of the free block map.
39  // This contains the number of blocks resident in the file system. In
40  // practice, NumBlocks * BlockSize is equivalent to the size of the MSF
41  // file.
43  // This contains the number of bytes which make up the directory.
45  // This field's purpose is not yet known.
47  // This contains the block # of the block map.
49 };
50 
51 struct MSFLayout {
52  MSFLayout() = default;
53 
56  return SB->FreeBlockMapBlock;
57  }
58 
60  // If mainFpmBlock is 1, this is 2. If mainFpmBlock is 2, this is 1.
61  return 3U - mainFpmBlock();
62  }
63 
64  const SuperBlock *SB = nullptr;
68  std::vector<ArrayRef<support::ulittle32_t>> StreamMap;
69 };
70 
71 /// Describes the layout of a stream in an MSF layout. A "stream" here
72 /// is defined as any logical unit of data which may be arranged inside the MSF
73 /// file as a sequence of (possibly discontiguous) blocks. When we want to read
74 /// from a particular MSF Stream, we fill out a stream layout structure and the
75 /// reader uses it to determine which blocks in the underlying MSF file contain
76 /// the data, so that it can be pieced together in the right order.
78 public:
80  std::vector<support::ulittle32_t> Blocks;
81 };
82 
83 /// Determine the layout of the FPM stream, given the MSF layout. An FPM
84 /// stream spans 1 or more blocks, each at equally spaced intervals throughout
85 /// the file.
87  bool IncludeUnusedFpmData = false,
88  bool AltFpm = false);
89 
90 inline bool isValidBlockSize(uint32_t Size) {
91  switch (Size) {
92  case 512:
93  case 1024:
94  case 2048:
95  case 4096:
96  case 8192:
97  case 16384:
98  case 32768:
99  return true;
100  }
101  return false;
102 }
103 
104 /// Given the specified block size, returns the maximum possible file size.
105 /// Block Size | Max File Size
106 /// <= 4096 | 4GB
107 /// 8192 | 8GB
108 /// 16384 | 16GB
109 /// 32768 | 32GB
110 /// \p Size - the block size of the MSF
112  switch (Size) {
113  case 8192:
114  return (uint64_t)UINT32_MAX * 2ULL;
115  case 16384:
116  return (uint64_t)UINT32_MAX * 3ULL;
117  case 32768:
118  return (uint64_t)UINT32_MAX * 4ULL;
119  default:
120  return (uint64_t)UINT32_MAX;
121  }
122 }
123 
124 // Super Block, Fpm0, Fpm1, and Block Map
125 inline uint32_t getMinimumBlockCount() { return 4; }
126 
127 // Super Block, Fpm0, and Fpm1 are reserved. The Block Map, although required
128 // need not be at block 3.
129 inline uint32_t getFirstUnreservedBlock() { return 3; }
130 
132  return divideCeil(NumBytes, BlockSize);
133 }
134 
136  return BlockNumber * BlockSize;
137 }
138 
140  return L.SB->BlockSize;
141 }
142 
143 /// Given an MSF with the specified block size and number of blocks, determine
144 /// how many pieces the specified Fpm is split into.
145 /// \p BlockSize - the block size of the MSF
146 /// \p NumBlocks - the total number of blocks in the MSF
147 /// \p IncludeUnusedFpmData - When true, this will count every block that is
148 /// both in the file and matches the form of an FPM block, even if some of
149 /// those FPM blocks are unused (a single FPM block can describe the
150 /// allocation status of up to 32,767 blocks, although one appears only
151 /// every 4,096 blocks). So there are 8x as many blocks that match the
152 /// form as there are blocks that are necessary to describe the allocation
153 /// status of the file. When this parameter is false, these extraneous
154 /// trailing blocks are not counted.
156  bool IncludeUnusedFpmData, int FpmNumber) {
157  assert(FpmNumber == 1 || FpmNumber == 2);
158  if (IncludeUnusedFpmData) {
159  // This calculation determines how many times a number of the form
160  // BlockSize * k + N appears in the range [0, NumBlocks). We only need to
161  // do this when unused data is included, since the number of blocks dwarfs
162  // the number of fpm blocks.
163  return divideCeil(NumBlocks - FpmNumber, BlockSize);
164  }
165 
166  // We want the minimum number of intervals required, where each interval can
167  // represent BlockSize * 8 blocks.
168  return divideCeil(NumBlocks, 8 * BlockSize);
169 }
170 
172  bool IncludeUnusedFpmData = false,
173  bool AltFpm = false) {
175  IncludeUnusedFpmData,
176  AltFpm ? L.alternateFpmBlock() : L.mainFpmBlock());
177 }
178 
179 Error validateSuperBlock(const SuperBlock &SB);
180 
181 } // end namespace msf
182 } // end namespace llvm
183 
184 #endif // LLVM_DEBUGINFO_MSF_MSFCOMMON_H
llvm::msf::MSFLayout::alternateFpmBlock
uint32_t alternateFpmBlock() const
Definition: MSFCommon.h:59
MathExtras.h
llvm::msf::MSFStreamLayout::Blocks
std::vector< support::ulittle32_t > Blocks
Definition: MSFCommon.h:80
llvm
This is an optimization pass for GlobalISel generic memory operations.
Definition: AddressRanges.h:17
BlockSize
static const int BlockSize
Definition: TarWriter.cpp:33
llvm::msf::getNumFpmIntervals
uint32_t getNumFpmIntervals(uint32_t BlockSize, uint32_t NumBlocks, bool IncludeUnusedFpmData, int FpmNumber)
Given an MSF with the specified block size and number of blocks, determine how many pieces the specif...
Definition: MSFCommon.h:155
llvm::msf::MSFLayout::DirectoryBlocks
ArrayRef< support::ulittle32_t > DirectoryBlocks
Definition: MSFCommon.h:66
llvm::msf::bytesToBlocks
uint64_t bytesToBlocks(uint64_t NumBytes, uint64_t BlockSize)
Definition: MSFCommon.h:131
llvm::support::detail::packed_endian_specific_integral
Definition: Endian.h:206
llvm::msf::getMinimumBlockCount
uint32_t getMinimumBlockCount()
Definition: MSFCommon.h:125
llvm::msf::SuperBlock::NumDirectoryBytes
support::ulittle32_t NumDirectoryBytes
Definition: MSFCommon.h:44
llvm::msf::blockToOffset
uint64_t blockToOffset(uint64_t BlockNumber, uint64_t BlockSize)
Definition: MSFCommon.h:135
Error.h
llvm::msf::MSFLayout::FreePageMap
BitVector FreePageMap
Definition: MSFCommon.h:65
llvm::msf::isValidBlockSize
bool isValidBlockSize(uint32_t Size)
Definition: MSFCommon.h:90
llvm::msf::getFpmStreamLayout
MSFStreamLayout getFpmStreamLayout(const MSFLayout &Msf, bool IncludeUnusedFpmData=false, bool AltFpm=false)
Determine the layout of the FPM stream, given the MSF layout.
Definition: MSFCommon.cpp:62
llvm::msf::getMaxFileSizeFromBlockSize
uint64_t getMaxFileSizeFromBlockSize(uint32_t Size)
Given the specified block size, returns the maximum possible file size.
Definition: MSFCommon.h:111
llvm::msf::validateSuperBlock
Error validateSuperBlock(const SuperBlock &SB)
Definition: MSFCommon.cpp:19
llvm::msf::MSFLayout
Definition: MSFCommon.h:51
llvm::msf::MSFLayout::MSFLayout
MSFLayout()=default
BitVector.h
llvm::msf::SuperBlock
Definition: MSFCommon.h:31
llvm::BitVector
Definition: BitVector.h:75
llvm::msf::SuperBlock::NumBlocks
support::ulittle32_t NumBlocks
Definition: MSFCommon.h:42
llvm::msf::MSFLayout::StreamSizes
ArrayRef< support::ulittle32_t > StreamSizes
Definition: MSFCommon.h:67
llvm::divideCeil
uint64_t divideCeil(uint64_t Numerator, uint64_t Denominator)
Returns the integer ceil(Numerator / Denominator).
Definition: MathExtras.h:776
llvm::msf::getFpmIntervalLength
uint32_t getFpmIntervalLength(const MSFLayout &L)
Definition: MSFCommon.h:139
uint64_t
llvm::msf::SuperBlock::FreeBlockMapBlock
support::ulittle32_t FreeBlockMapBlock
Definition: MSFCommon.h:38
ArrayRef.h
assert
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
llvm::ArrayRef
ArrayRef - Represent a constant reference to an array (0 or more elements consecutively in memory),...
Definition: APInt.h:32
llvm::msf::Magic
static const char Magic[]
Definition: MSFCommon.h:23
uint32_t
llvm::msf::MSFLayout::mainFpmBlock
uint32_t mainFpmBlock() const
Definition: MSFCommon.h:54
llvm::msf::SuperBlock::MagicBytes
char MagicBytes[sizeof(Magic)]
Definition: MSFCommon.h:32
llvm::msf::MSFStreamLayout::Length
uint32_t Length
Definition: MSFCommon.h:79
llvm::msf::SuperBlock::BlockSize
support::ulittle32_t BlockSize
Definition: MSFCommon.h:36
llvm::msf::SuperBlock::Unknown1
support::ulittle32_t Unknown1
Definition: MSFCommon.h:46
llvm::Error
Lightweight error class with error context and mandatory checking.
Definition: Error.h:155
llvm::msf::MSFLayout::StreamMap
std::vector< ArrayRef< support::ulittle32_t > > StreamMap
Definition: MSFCommon.h:68
llvm::msf::getFirstUnreservedBlock
uint32_t getFirstUnreservedBlock()
Definition: MSFCommon.h:129
llvm::msf::MSFLayout::SB
const SuperBlock * SB
Definition: MSFCommon.h:64
Endian.h
llvm::msf::SuperBlock::BlockMapAddr
support::ulittle32_t BlockMapAddr
Definition: MSFCommon.h:48
llvm::msf::MSFStreamLayout
Describes the layout of a stream in an MSF layout.
Definition: MSFCommon.h:77