1 //===- MSFBuilder.cpp -----------------------------------------------------===//
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/MSF/MSFBuilder.h"
10 #include "llvm/ADT/ArrayRef.h"
11 #include "llvm/DebugInfo/MSF/MSFError.h"
12 #include "llvm/DebugInfo/MSF/MappedBlockStream.h"
13 #include "llvm/Support/BinaryByteStream.h"
14 #include "llvm/Support/BinaryStreamWriter.h"
15 #include "llvm/Support/Endian.h"
16 #include "llvm/Support/Error.h"
17 #include "llvm/Support/FileOutputBuffer.h"
18 #include <algorithm>
19 #include <cassert>
20 #include <cstdint>
21 #include <cstring>
22 #include <memory>
23 #include <utility>
24 #include <vector>
25 
26 using namespace llvm;
27 using namespace llvm::msf;
28 using namespace llvm::support;
29 
30 static const uint32_t kSuperBlockBlock = 0;
31 static const uint32_t kFreePageMap0Block = 1;
32 static const uint32_t kFreePageMap1Block = 2;
33 static const uint32_t kNumReservedPages = 3;
34 
35 static const uint32_t kDefaultFreePageMap = kFreePageMap1Block;
36 static const uint32_t kDefaultBlockMapAddr = kNumReservedPages;
37 
38 MSFBuilder::MSFBuilder(uint32_t BlockSize, uint32_t MinBlockCount, bool CanGrow,
39                        BumpPtrAllocator &Allocator)
40     : Allocator(Allocator), IsGrowable(CanGrow),
41       FreePageMap(kDefaultFreePageMap), BlockSize(BlockSize),
42       BlockMapAddr(kDefaultBlockMapAddr), FreeBlocks(MinBlockCount, true) {
43   FreeBlocks[kSuperBlockBlock] = false;
44   FreeBlocks[kFreePageMap0Block] = false;
45   FreeBlocks[kFreePageMap1Block] = false;
46   FreeBlocks[BlockMapAddr] = false;
47 }
48 
49 Expected<MSFBuilder> MSFBuilder::create(BumpPtrAllocator &Allocator,
50                                         uint32_t BlockSize,
51                                         uint32_t MinBlockCount, bool CanGrow) {
52   if (!isValidBlockSize(BlockSize))
53     return make_error<MSFError>(msf_error_code::invalid_format,
54                                 "The requested block size is unsupported");
55 
56   return MSFBuilder(BlockSize,
57                     std::max(MinBlockCount, msf::getMinimumBlockCount()),
58                     CanGrow, Allocator);
59 }
60 
61 Error MSFBuilder::setBlockMapAddr(uint32_t Addr) {
62   if (Addr == BlockMapAddr)
63     return Error::success();
64 
65   if (Addr >= FreeBlocks.size()) {
66     if (!IsGrowable)
67       return make_error<MSFError>(msf_error_code::insufficient_buffer,
68                                   "Cannot grow the number of blocks");
69     FreeBlocks.resize(Addr + 1, true);
70   }
71 
72   if (!isBlockFree(Addr))
73     return make_error<MSFError>(
74         msf_error_code::block_in_use,
75         "Requested block map address is already in use");
76   FreeBlocks[BlockMapAddr] = true;
77   FreeBlocks[Addr] = false;
78   BlockMapAddr = Addr;
79   return Error::success();
80 }
81 
82 void MSFBuilder::setFreePageMap(uint32_t Fpm) { FreePageMap = Fpm; }
83 
84 void MSFBuilder::setUnknown1(uint32_t Unk1) { Unknown1 = Unk1; }
85 
86 Error MSFBuilder::setDirectoryBlocksHint(ArrayRef<uint32_t> DirBlocks) {
87   for (auto B : DirectoryBlocks)
88     FreeBlocks[B] = true;
89   for (auto B : DirBlocks) {
90     if (!isBlockFree(B)) {
91       return make_error<MSFError>(msf_error_code::unspecified,
92                                   "Attempt to reuse an allocated block");
93     }
94     FreeBlocks[B] = false;
95   }
96 
97   DirectoryBlocks = DirBlocks;
98   return Error::success();
99 }
100 
101 Error MSFBuilder::allocateBlocks(uint32_t NumBlocks,
102                                  MutableArrayRef<uint32_t> Blocks) {
103   if (NumBlocks == 0)
104     return Error::success();
105 
106   uint32_t NumFreeBlocks = FreeBlocks.count();
107   if (NumFreeBlocks < NumBlocks) {
108     if (!IsGrowable)
109       return make_error<MSFError>(msf_error_code::insufficient_buffer,
110                                   "There are no free Blocks in the file");
111     uint32_t AllocBlocks = NumBlocks - NumFreeBlocks;
112     uint32_t OldBlockCount = FreeBlocks.size();
113     uint32_t NewBlockCount = AllocBlocks + OldBlockCount;
114     uint32_t NextFpmBlock = alignTo(OldBlockCount, BlockSize) + 1;
115     FreeBlocks.resize(NewBlockCount, true);
116     // If we crossed over an fpm page, we actually need to allocate 2 extra
117     // blocks for each FPM group crossed and mark both blocks from the group as
118     // used.  FPM blocks are marked as allocated regardless of whether or not
119     // they ultimately describe the status of blocks in the file.  This means
120     // that not only are extraneous blocks at the end of the main FPM marked as
121     // allocated, but also blocks from the alternate FPM are always marked as
122     // allocated.
123     while (NextFpmBlock < NewBlockCount) {
124       NewBlockCount += 2;
125       FreeBlocks.resize(NewBlockCount, true);
126       FreeBlocks.reset(NextFpmBlock, NextFpmBlock + 2);
127       NextFpmBlock += BlockSize;
128     }
129   }
130 
131   int I = 0;
132   int Block = FreeBlocks.find_first();
133   do {
134     assert(Block != -1 && "We ran out of Blocks!");
135 
136     uint32_t NextBlock = static_cast<uint32_t>(Block);
137     Blocks[I++] = NextBlock;
138     FreeBlocks.reset(NextBlock);
139     Block = FreeBlocks.find_next(Block);
140   } while (--NumBlocks > 0);
141   return Error::success();
142 }
143 
144 uint32_t MSFBuilder::getNumUsedBlocks() const {
145   return getTotalBlockCount() - getNumFreeBlocks();
146 }
147 
148 uint32_t MSFBuilder::getNumFreeBlocks() const { return FreeBlocks.count(); }
149 
150 uint32_t MSFBuilder::getTotalBlockCount() const { return FreeBlocks.size(); }
151 
152 bool MSFBuilder::isBlockFree(uint32_t Idx) const { return FreeBlocks[Idx]; }
153 
154 Expected<uint32_t> MSFBuilder::addStream(uint32_t Size,
155                                          ArrayRef<uint32_t> Blocks) {
156   // Add a new stream mapped to the specified blocks.  Verify that the specified
157   // blocks are both necessary and sufficient for holding the requested number
158   // of bytes, and verify that all requested blocks are free.
159   uint32_t ReqBlocks = bytesToBlocks(Size, BlockSize);
160   if (ReqBlocks != Blocks.size())
161     return make_error<MSFError>(
162         msf_error_code::invalid_format,
163         "Incorrect number of blocks for requested stream size");
164   for (auto Block : Blocks) {
165     if (Block >= FreeBlocks.size())
166       FreeBlocks.resize(Block + 1, true);
167 
168     if (!FreeBlocks.test(Block))
169       return make_error<MSFError>(
170           msf_error_code::unspecified,
171           "Attempt to re-use an already allocated block");
172   }
173   // Mark all the blocks occupied by the new stream as not free.
174   for (auto Block : Blocks) {
175     FreeBlocks.reset(Block);
176   }
177   StreamData.push_back(std::make_pair(Size, Blocks));
178   return StreamData.size() - 1;
179 }
180 
181 Expected<uint32_t> MSFBuilder::addStream(uint32_t Size) {
182   uint32_t ReqBlocks = bytesToBlocks(Size, BlockSize);
183   std::vector<uint32_t> NewBlocks;
184   NewBlocks.resize(ReqBlocks);
185   if (auto EC = allocateBlocks(ReqBlocks, NewBlocks))
186     return std::move(EC);
187   StreamData.push_back(std::make_pair(Size, NewBlocks));
188   return StreamData.size() - 1;
189 }
190 
191 Error MSFBuilder::setStreamSize(uint32_t Idx, uint32_t Size) {
192   uint32_t OldSize = getStreamSize(Idx);
193   if (OldSize == Size)
194     return Error::success();
195 
196   uint32_t NewBlocks = bytesToBlocks(Size, BlockSize);
197   uint32_t OldBlocks = bytesToBlocks(OldSize, BlockSize);
198 
199   if (NewBlocks > OldBlocks) {
200     uint32_t AddedBlocks = NewBlocks - OldBlocks;
201     // If we're growing, we have to allocate new Blocks.
202     std::vector<uint32_t> AddedBlockList;
203     AddedBlockList.resize(AddedBlocks);
204     if (auto EC = allocateBlocks(AddedBlocks, AddedBlockList))
205       return EC;
206     auto &CurrentBlocks = StreamData[Idx].second;
207     CurrentBlocks.insert(CurrentBlocks.end(), AddedBlockList.begin(),
208                          AddedBlockList.end());
209   } else if (OldBlocks > NewBlocks) {
210     // For shrinking, free all the Blocks in the Block map, update the stream
211     // data, then shrink the directory.
212     uint32_t RemovedBlocks = OldBlocks - NewBlocks;
213     auto CurrentBlocks = ArrayRef<uint32_t>(StreamData[Idx].second);
214     auto RemovedBlockList = CurrentBlocks.drop_front(NewBlocks);
215     for (auto P : RemovedBlockList)
216       FreeBlocks[P] = true;
217     StreamData[Idx].second = CurrentBlocks.drop_back(RemovedBlocks);
218   }
219 
220   StreamData[Idx].first = Size;
221   return Error::success();
222 }
223 
224 uint32_t MSFBuilder::getNumStreams() const { return StreamData.size(); }
225 
226 uint32_t MSFBuilder::getStreamSize(uint32_t StreamIdx) const {
227   return StreamData[StreamIdx].first;
228 }
229 
230 ArrayRef<uint32_t> MSFBuilder::getStreamBlocks(uint32_t StreamIdx) const {
231   return StreamData[StreamIdx].second;
232 }
233 
234 uint32_t MSFBuilder::computeDirectoryByteSize() const {
235   // The directory has the following layout, where each item is a ulittle32_t:
236   //    NumStreams
237   //    StreamSizes[NumStreams]
238   //    StreamBlocks[NumStreams][]
239   uint32_t Size = sizeof(ulittle32_t);             // NumStreams
240   Size += StreamData.size() * sizeof(ulittle32_t); // StreamSizes
241   for (const auto &D : StreamData) {
242     uint32_t ExpectedNumBlocks = bytesToBlocks(D.first, BlockSize);
243     assert(ExpectedNumBlocks == D.second.size() &&
244            "Unexpected number of blocks");
245     Size += ExpectedNumBlocks * sizeof(ulittle32_t);
246   }
247   return Size;
248 }
249 
250 Expected<MSFLayout> MSFBuilder::generateLayout() {
251   SuperBlock *SB = Allocator.Allocate<SuperBlock>();
252   MSFLayout L;
253   L.SB = SB;
254 
255   std::memcpy(SB->MagicBytes, Magic, sizeof(Magic));
256   SB->BlockMapAddr = BlockMapAddr;
257   SB->BlockSize = BlockSize;
258   SB->NumDirectoryBytes = computeDirectoryByteSize();
259   SB->FreeBlockMapBlock = FreePageMap;
260   SB->Unknown1 = Unknown1;
261 
262   uint32_t NumDirectoryBlocks = bytesToBlocks(SB->NumDirectoryBytes, BlockSize);
263   if (NumDirectoryBlocks > DirectoryBlocks.size()) {
264     // Our hint wasn't enough to satisfy the entire directory.  Allocate
265     // remaining pages.
266     std::vector<uint32_t> ExtraBlocks;
267     uint32_t NumExtraBlocks = NumDirectoryBlocks - DirectoryBlocks.size();
268     ExtraBlocks.resize(NumExtraBlocks);
269     if (auto EC = allocateBlocks(NumExtraBlocks, ExtraBlocks))
270       return std::move(EC);
271     DirectoryBlocks.insert(DirectoryBlocks.end(), ExtraBlocks.begin(),
272                            ExtraBlocks.end());
273   } else if (NumDirectoryBlocks < DirectoryBlocks.size()) {
274     uint32_t NumUnnecessaryBlocks = DirectoryBlocks.size() - NumDirectoryBlocks;
275     for (auto B :
276          ArrayRef<uint32_t>(DirectoryBlocks).drop_back(NumUnnecessaryBlocks))
277       FreeBlocks[B] = true;
278     DirectoryBlocks.resize(NumDirectoryBlocks);
279   }
280 
281   // Don't set the number of blocks in the file until after allocating Blocks
282   // for the directory, since the allocation might cause the file to need to
283   // grow.
284   SB->NumBlocks = FreeBlocks.size();
285 
286   ulittle32_t *DirBlocks = Allocator.Allocate<ulittle32_t>(NumDirectoryBlocks);
287   std::uninitialized_copy_n(DirectoryBlocks.begin(), NumDirectoryBlocks,
288                             DirBlocks);
289   L.DirectoryBlocks = ArrayRef<ulittle32_t>(DirBlocks, NumDirectoryBlocks);
290 
291   // The stream sizes should be re-allocated as a stable pointer and the stream
292   // map should have each of its entries allocated as a separate stable pointer.
293   if (!StreamData.empty()) {
294     ulittle32_t *Sizes = Allocator.Allocate<ulittle32_t>(StreamData.size());
295     L.StreamSizes = ArrayRef<ulittle32_t>(Sizes, StreamData.size());
296     L.StreamMap.resize(StreamData.size());
297     for (uint32_t I = 0; I < StreamData.size(); ++I) {
298       Sizes[I] = StreamData[I].first;
299       ulittle32_t *BlockList =
300           Allocator.Allocate<ulittle32_t>(StreamData[I].second.size());
301       std::uninitialized_copy_n(StreamData[I].second.begin(),
302                                 StreamData[I].second.size(), BlockList);
303       L.StreamMap[I] =
304           ArrayRef<ulittle32_t>(BlockList, StreamData[I].second.size());
305     }
306   }
307 
308   L.FreePageMap = FreeBlocks;
309 
310   return L;
311 }
312 
313 static void commitFpm(WritableBinaryStream &MsfBuffer, const MSFLayout &Layout,
314                       BumpPtrAllocator &Allocator) {
315   auto FpmStream =
316       WritableMappedBlockStream::createFpmStream(Layout, MsfBuffer, Allocator);
317 
318   // We only need to create the alt fpm stream so that it gets initialized.
319   WritableMappedBlockStream::createFpmStream(Layout, MsfBuffer, Allocator,
320                                              true);
321 
322   uint32_t BI = 0;
323   BinaryStreamWriter FpmWriter(*FpmStream);
324   while (BI < Layout.SB->NumBlocks) {
325     uint8_t ThisByte = 0;
326     for (uint32_t I = 0; I < 8; ++I) {
327       bool IsFree =
328           (BI < Layout.SB->NumBlocks) ? Layout.FreePageMap.test(BI) : true;
329       uint8_t Mask = uint8_t(IsFree) << I;
330       ThisByte |= Mask;
331       ++BI;
332     }
333     cantFail(FpmWriter.writeObject(ThisByte));
334   }
335   assert(FpmWriter.bytesRemaining() == 0);
336 }
337 
338 Expected<FileBufferByteStream> MSFBuilder::commit(StringRef Path,
339                                                   MSFLayout &Layout) {
340   Expected<MSFLayout> L = generateLayout();
341   if (!L)
342     return L.takeError();
343 
344   Layout = std::move(*L);
345 
346   uint64_t FileSize = Layout.SB->BlockSize * Layout.SB->NumBlocks;
347   auto OutFileOrError = FileOutputBuffer::create(Path, FileSize);
348   if (auto EC = OutFileOrError.takeError())
349     return std::move(EC);
350 
351   FileBufferByteStream Buffer(std::move(*OutFileOrError),
352                               llvm::support::little);
353   BinaryStreamWriter Writer(Buffer);
354 
355   if (auto EC = Writer.writeObject(*Layout.SB))
356     return std::move(EC);
357 
358   commitFpm(Buffer, Layout, Allocator);
359 
360   uint32_t BlockMapOffset =
361       msf::blockToOffset(Layout.SB->BlockMapAddr, Layout.SB->BlockSize);
362   Writer.setOffset(BlockMapOffset);
363   if (auto EC = Writer.writeArray(Layout.DirectoryBlocks))
364     return std::move(EC);
365 
366   auto DirStream = WritableMappedBlockStream::createDirectoryStream(
367       Layout, Buffer, Allocator);
368   BinaryStreamWriter DW(*DirStream);
369   if (auto EC = DW.writeInteger<uint32_t>(Layout.StreamSizes.size()))
370     return std::move(EC);
371 
372   if (auto EC = DW.writeArray(Layout.StreamSizes))
373     return std::move(EC);
374 
375   for (const auto &Blocks : Layout.StreamMap) {
376     if (auto EC = DW.writeArray(Blocks))
377       return std::move(EC);
378   }
379 
380   return std::move(Buffer);
381 }
382