1//===- DbiModuleList.cpp - PDB module information list --------------------===//
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#include "llvm/DebugInfo/PDB/Native/DbiModuleList.h"
10#include "llvm/ADT/StringRef.h"
11#include "llvm/ADT/iterator_range.h"
12#include "llvm/DebugInfo/PDB/Native/RawError.h"
13#include "llvm/Support/BinaryStreamReader.h"
14#include "llvm/Support/Error.h"
15#include <algorithm>
16#include <cassert>
17#include <cstddef>
18#include <cstdint>
19
20using namespace llvm;
21using namespace llvm::pdb;
22
23DbiModuleSourceFilesIterator::DbiModuleSourceFilesIterator(
24    const DbiModuleList &Modules, uint32_t Modi, uint16_t Filei)
25    : Modules(&Modules), Modi(Modi), Filei(Filei) {
26  setValue();
27}
28
29bool DbiModuleSourceFilesIterator::
30operator==(const DbiModuleSourceFilesIterator &R) const {
31  // incompatible iterators are never equal
32  if (!isCompatible(R))
33    return false;
34
35  // If they're compatible, and they're both ends, then they're equal.
36  if (isEnd() && R.isEnd())
37    return true;
38
39  // If one is an end and the other is not, they're not equal.
40  if (isEnd() != R.isEnd())
41    return false;
42
43  // Now we know:
44  // - They're compatible
45  // - They're not *both* end iterators
46  // - Their endness is the same.
47  // Thus, they're compatible iterators pointing to a valid file on the same
48  // module.  All we need to check are the file indices.
49  assert(Modules == R.Modules);
50  assert(Modi == R.Modi);
51  assert(!isEnd());
52  assert(!R.isEnd());
53
54  return (Filei == R.Filei);
55}
56
57bool DbiModuleSourceFilesIterator::
58operator<(const DbiModuleSourceFilesIterator &R) const {
59  assert(isCompatible(R));
60
61  // It's not sufficient to compare the file indices, because default
62  // constructed iterators could be equal to iterators with valid indices.  To
63  // account for this, early-out if they're equal.
64  if (*this == R)
65    return false;
66
67  return Filei < R.Filei;
68}
69
70std::ptrdiff_t DbiModuleSourceFilesIterator::
71operator-(const DbiModuleSourceFilesIterator &R) const {
72  assert(isCompatible(R));
73  assert(!(*this < R));
74
75  // If they're both end iterators, the distance is 0.
76  if (isEnd() && R.isEnd())
77    return 0;
78
79  assert(!R.isEnd());
80
81  // At this point, R cannot be end, but *this can, which means that *this
82  // might be a universal end iterator with none of its fields set.  So in that
83  // case have to rely on R as the authority to figure out how many files there
84  // are to compute the distance.
85  uint32_t Thisi = Filei;
86  if (isEnd()) {
87    uint32_t RealModi = R.Modi;
88    Thisi = R.Modules->getSourceFileCount(RealModi);
89  }
90
91  assert(Thisi >= R.Filei);
92  return Thisi - R.Filei;
93}
94
95DbiModuleSourceFilesIterator &DbiModuleSourceFilesIterator::
96operator+=(std::ptrdiff_t N) {
97  assert(!isEnd());
98
99  Filei += N;
100  assert(Filei <= Modules->getSourceFileCount(Modi));
101  setValue();
102  return *this;
103}
104
105DbiModuleSourceFilesIterator &DbiModuleSourceFilesIterator::
106operator-=(std::ptrdiff_t N) {
107  // Note that we can subtract from an end iterator, but not a universal end
108  // iterator.
109  assert(!isUniversalEnd());
110
111  assert(N <= Filei);
112
113  Filei -= N;
114  return *this;
115}
116
117void DbiModuleSourceFilesIterator::setValue() {
118  if (isEnd()) {
119    ThisValue = "";
120    return;
121  }
122
123  uint32_t Off = Modules->ModuleInitialFileIndex[Modi] + Filei;
124  auto ExpectedValue = Modules->getFileName(Off);
125  if (!ExpectedValue) {
126    consumeError(ExpectedValue.takeError());
127    Filei = Modules->getSourceFileCount(Modi);
128  } else
129    ThisValue = *ExpectedValue;
130}
131
132bool DbiModuleSourceFilesIterator::isEnd() const {
133  if (isUniversalEnd())
134    return true;
135
136  assert(Modules);
137  assert(Modi <= Modules->getModuleCount());
138  assert(Filei <= Modules->getSourceFileCount(Modi));
139
140  if (Modi == Modules->getModuleCount())
141    return true;
142  if (Filei == Modules->getSourceFileCount(Modi))
143    return true;
144  return false;
145}
146
147bool DbiModuleSourceFilesIterator::isUniversalEnd() const { return !Modules; }
148
149bool DbiModuleSourceFilesIterator::isCompatible(
150    const DbiModuleSourceFilesIterator &R) const {
151  // Universal iterators are compatible with any other iterator.
152  if (isUniversalEnd() || R.isUniversalEnd())
153    return true;
154
155  // At this point, neither iterator is a universal end iterator, although one
156  // or both might be non-universal end iterators.  Regardless, the module index
157  // is valid, so they are compatible if and only if they refer to the same
158  // module.
159  return Modi == R.Modi;
160}
161
162Error DbiModuleList::initialize(BinaryStreamRef ModInfo,
163                                BinaryStreamRef FileInfo) {
164  if (auto EC = initializeModInfo(ModInfo))
165    return EC;
166  if (auto EC = initializeFileInfo(FileInfo))
167    return EC;
168
169  return Error::success();
170}
171
172Error DbiModuleList::initializeModInfo(BinaryStreamRef ModInfo) {
173  ModInfoSubstream = ModInfo;
174
175  if (ModInfo.getLength() == 0)
176    return Error::success();
177
178  BinaryStreamReader Reader(ModInfo);
179
180  if (auto EC = Reader.readArray(Descriptors, ModInfo.getLength()))
181    return EC;
182
183  return Error::success();
184}
185
186Error DbiModuleList::initializeFileInfo(BinaryStreamRef FileInfo) {
187  FileInfoSubstream = FileInfo;
188
189  if (FileInfo.getLength() == 0)
190    return Error::success();
191
192  BinaryStreamReader FISR(FileInfo);
193  if (auto EC = FISR.readObject(FileInfoHeader))
194    return EC;
195
196  // First is an array of `NumModules` module indices.  This does not seem to be
197  // used for anything meaningful, so we ignore it.
198  FixedStreamArray<support::ulittle16_t> ModuleIndices;
199  if (auto EC = FISR.readArray(ModuleIndices, FileInfoHeader->NumModules))
200    return EC;
201  if (auto EC = FISR.readArray(ModFileCountArray, FileInfoHeader->NumModules))
202    return EC;
203
204  // Compute the real number of source files.  We can't trust the value in
205  // `FileInfoHeader->NumSourceFiles` because it is a unit16, and the sum of all
206  // source file counts might be larger than a unit16.  So we compute the real
207  // count by summing up the individual counts.
208  uint32_t NumSourceFiles = 0;
209  for (auto Count : ModFileCountArray)
210    NumSourceFiles += Count;
211
212  // In the reference implementation, this array is where the pointer documented
213  // at the definition of ModuleInfoHeader::FileNameOffs points to.  Note that
214  // although the field in ModuleInfoHeader is ignored this array is not, as it
215  // is the authority on where each filename begins in the names buffer.
216  if (auto EC = FISR.readArray(FileNameOffsets, NumSourceFiles))
217    return EC;
218
219  if (auto EC = FISR.readStreamRef(NamesBuffer))
220    return EC;
221
222  auto DescriptorIter = Descriptors.begin();
223  uint32_t NextFileIndex = 0;
224  ModuleInitialFileIndex.resize(FileInfoHeader->NumModules);
225  ModuleDescriptorOffsets.resize(FileInfoHeader->NumModules);
226  for (size_t I = 0; I < FileInfoHeader->NumModules; ++I) {
227    assert(DescriptorIter != Descriptors.end());
228    ModuleInitialFileIndex[I] = NextFileIndex;
229    ModuleDescriptorOffsets[I] = DescriptorIter.offset();
230
231    NextFileIndex += ModFileCountArray[I];
232    ++DescriptorIter;
233  }
234
235  assert(DescriptorIter == Descriptors.end());
236  assert(NextFileIndex == NumSourceFiles);
237
238  return Error::success();
239}
240
241uint32_t DbiModuleList::getModuleCount() const {
242  return FileInfoHeader->NumModules;
243}
244
245uint32_t DbiModuleList::getSourceFileCount() const {
246  return FileNameOffsets.size();
247}
248
249uint16_t DbiModuleList::getSourceFileCount(uint32_t Modi) const {
250  return ModFileCountArray[Modi];
251}
252
253DbiModuleDescriptor DbiModuleList::getModuleDescriptor(uint32_t Modi) const {
254  assert(Modi < getModuleCount());
255  uint32_t Offset = ModuleDescriptorOffsets[Modi];
256  auto Iter = Descriptors.at(Offset);
257  assert(Iter != Descriptors.end());
258  return *Iter;
259}
260
261iterator_range<DbiModuleSourceFilesIterator>
262DbiModuleList::source_files(uint32_t Modi) const {
263  return make_range<DbiModuleSourceFilesIterator>(
264      DbiModuleSourceFilesIterator(*this, Modi, 0),
265      DbiModuleSourceFilesIterator());
266}
267
268Expected<StringRef> DbiModuleList::getFileName(uint32_t Index) const {
269  BinaryStreamReader Names(NamesBuffer);
270  if (Index >= getSourceFileCount())
271    return make_error<RawError>(raw_error_code::index_out_of_bounds);
272
273  uint32_t FileOffset = FileNameOffsets[Index];
274  Names.setOffset(FileOffset);
275  StringRef Name;
276  if (auto EC = Names.readCString(Name))
277    return std::move(EC);
278  return Name;
279}
280