Bug Summary

File:tools/lld/COFF/Writer.cpp
Warning:line 479, column 23
Called C++ object pointer is null

Annotated Source Code

1//===- Writer.cpp ---------------------------------------------------------===//
2//
3// The LLVM Linker
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9
10#include "Writer.h"
11#include "Config.h"
12#include "DLL.h"
13#include "Error.h"
14#include "InputFiles.h"
15#include "MapFile.h"
16#include "Memory.h"
17#include "PDB.h"
18#include "SymbolTable.h"
19#include "Symbols.h"
20#include "llvm/ADT/DenseMap.h"
21#include "llvm/ADT/STLExtras.h"
22#include "llvm/ADT/StringSwitch.h"
23#include "llvm/Support/Debug.h"
24#include "llvm/Support/Endian.h"
25#include "llvm/Support/FileOutputBuffer.h"
26#include "llvm/Support/Parallel.h"
27#include "llvm/Support/RandomNumberGenerator.h"
28#include "llvm/Support/raw_ostream.h"
29#include <algorithm>
30#include <cstdio>
31#include <map>
32#include <memory>
33#include <utility>
34
35using namespace llvm;
36using namespace llvm::COFF;
37using namespace llvm::object;
38using namespace llvm::support;
39using namespace llvm::support::endian;
40using namespace lld;
41using namespace lld::coff;
42
43static const int SectorSize = 512;
44static const int DOSStubSize = 64;
45static const int NumberfOfDataDirectory = 16;
46
47namespace {
48
49class DebugDirectoryChunk : public Chunk {
50public:
51 DebugDirectoryChunk(const std::vector<Chunk *> &R) : Records(R) {}
52
53 size_t getSize() const override {
54 return Records.size() * sizeof(debug_directory);
55 }
56
57 void writeTo(uint8_t *B) const override {
58 auto *D = reinterpret_cast<debug_directory *>(B + OutputSectionOff);
59
60 for (const Chunk *Record : Records) {
61 D->Characteristics = 0;
62 D->TimeDateStamp = 0;
63 D->MajorVersion = 0;
64 D->MinorVersion = 0;
65 D->Type = COFF::IMAGE_DEBUG_TYPE_CODEVIEW;
66 D->SizeOfData = Record->getSize();
67 D->AddressOfRawData = Record->getRVA();
68 // TODO(compnerd) get the file offset
69 D->PointerToRawData = 0;
70
71 ++D;
72 }
73 }
74
75private:
76 const std::vector<Chunk *> &Records;
77};
78
79class CVDebugRecordChunk : public Chunk {
80 size_t getSize() const override {
81 return sizeof(codeview::DebugInfo) + Config->PDBPath.size() + 1;
82 }
83
84 void writeTo(uint8_t *B) const override {
85 // Save off the DebugInfo entry to backfill the file signature (build id)
86 // in Writer::writeBuildId
87 DI = reinterpret_cast<codeview::DebugInfo *>(B + OutputSectionOff);
88
89 DI->Signature.CVSignature = OMF::Signature::PDB70;
90
91 // variable sized field (PDB Path)
92 auto *P = reinterpret_cast<char *>(B + OutputSectionOff + sizeof(*DI));
93 if (!Config->PDBPath.empty())
94 memcpy(P, Config->PDBPath.data(), Config->PDBPath.size());
95 P[Config->PDBPath.size()] = '\0';
96 }
97
98public:
99 mutable codeview::DebugInfo *DI = nullptr;
100};
101
102// The writer writes a SymbolTable result to a file.
103class Writer {
104public:
105 Writer(SymbolTable *T) : Symtab(T) {}
106 void run();
107
108private:
109 void createSections();
110 void createMiscChunks();
111 void createImportTables();
112 void createExportTable();
113 void assignAddresses();
114 void removeEmptySections();
115 void createSymbolAndStringTable();
116 void openFile(StringRef OutputPath);
117 template <typename PEHeaderTy> void writeHeader();
118 void fixSafeSEHSymbols();
119 void setSectionPermissions();
120 void writeSections();
121 void sortExceptionTable();
122 void writeBuildId();
123 void applyRelocations();
124
125 llvm::Optional<coff_symbol16> createSymbol(Defined *D);
126 size_t addEntryToStringTable(StringRef Str);
127
128 OutputSection *findSection(StringRef Name);
129 OutputSection *createSection(StringRef Name);
130 void addBaserels(OutputSection *Dest);
131 void addBaserelBlocks(OutputSection *Dest, std::vector<Baserel> &V);
132
133 uint32_t getSizeOfInitializedData();
134 std::map<StringRef, std::vector<DefinedImportData *>> binImports();
135
136 SymbolTable *Symtab;
137 std::unique_ptr<FileOutputBuffer> Buffer;
138 std::vector<OutputSection *> OutputSections;
139 std::vector<char> Strtab;
140 std::vector<llvm::object::coff_symbol16> OutputSymtab;
141 IdataContents Idata;
142 DelayLoadContents DelayIdata;
143 EdataContents Edata;
144 SEHTableChunk *SEHTable = nullptr;
145
146 Chunk *DebugDirectory = nullptr;
147 std::vector<Chunk *> DebugRecords;
148 CVDebugRecordChunk *BuildId = nullptr;
149 ArrayRef<uint8_t> SectionTable;
150
151 uint64_t FileSize;
152 uint32_t PointerToSymbolTable = 0;
153 uint64_t SizeOfImage;
154 uint64_t SizeOfHeaders;
155};
156} // anonymous namespace
157
158namespace lld {
159namespace coff {
160
161void writeResult(SymbolTable *T) { Writer(T).run(); }
162
163void OutputSection::setRVA(uint64_t RVA) {
164 Header.VirtualAddress = RVA;
165 for (Chunk *C : Chunks)
166 C->setRVA(C->getRVA() + RVA);
167}
168
169void OutputSection::setFileOffset(uint64_t Off) {
170 // If a section has no actual data (i.e. BSS section), we want to
171 // set 0 to its PointerToRawData. Otherwise the output is rejected
172 // by the loader.
173 if (Header.SizeOfRawData == 0)
174 return;
175 Header.PointerToRawData = Off;
176}
177
178void OutputSection::addChunk(Chunk *C) {
179 Chunks.push_back(C);
180 C->setOutputSection(this);
181 uint64_t Off = Header.VirtualSize;
182 Off = alignTo(Off, C->getAlign());
183 C->setRVA(Off);
184 C->setOutputSectionOff(Off);
185 Off += C->getSize();
186 Header.VirtualSize = Off;
187 if (C->hasData())
188 Header.SizeOfRawData = alignTo(Off, SectorSize);
189}
190
191void OutputSection::addPermissions(uint32_t C) {
192 Header.Characteristics |= C & PermMask;
193}
194
195void OutputSection::setPermissions(uint32_t C) {
196 Header.Characteristics = C & PermMask;
197}
198
199// Write the section header to a given buffer.
200void OutputSection::writeHeaderTo(uint8_t *Buf) {
201 auto *Hdr = reinterpret_cast<coff_section *>(Buf);
202 *Hdr = Header;
203 if (StringTableOff) {
204 // If name is too long, write offset into the string table as a name.
205 sprintf(Hdr->Name, "/%d", StringTableOff);
206 } else {
207 assert(!Config->Debug || Name.size() <= COFF::NameSize)((!Config->Debug || Name.size() <= COFF::NameSize) ? static_cast
<void> (0) : __assert_fail ("!Config->Debug || Name.size() <= COFF::NameSize"
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn303373/tools/lld/COFF/Writer.cpp"
, 207, __PRETTY_FUNCTION__));
208 strncpy(Hdr->Name, Name.data(),
209 std::min(Name.size(), (size_t)COFF::NameSize));
210 }
211}
212
213uint64_t Defined::getSecrel() {
214 if (auto *D = dyn_cast<DefinedRegular>(this))
215 return getRVA() - D->getChunk()->getOutputSection()->getRVA();
216 fatal("SECREL relocation points to a non-regular symbol");
217}
218
219uint64_t Defined::getSectionIndex() {
220 if (auto *D = dyn_cast<DefinedRegular>(this))
221 return D->getChunk()->getOutputSection()->SectionIndex;
222 fatal("SECTION relocation points to a non-regular symbol");
223}
224
225bool Defined::isExecutable() {
226 const auto X = IMAGE_SCN_MEM_EXECUTE;
227 if (auto *D = dyn_cast<DefinedRegular>(this))
228 return D->getChunk()->getOutputSection()->getPermissions() & X;
229 return isa<DefinedImportThunk>(this);
230}
231
232} // namespace coff
233} // namespace lld
234
235// The main function of the writer.
236void Writer::run() {
237 createSections();
238 createMiscChunks();
239 createImportTables();
240 createExportTable();
241 if (Config->Relocatable)
242 createSection(".reloc");
243 assignAddresses();
244 removeEmptySections();
245 setSectionPermissions();
246 createSymbolAndStringTable();
247 openFile(Config->OutputFile);
248 if (Config->is64()) {
249 writeHeader<pe32plus_header>();
250 } else {
251 writeHeader<pe32_header>();
252 }
253 fixSafeSEHSymbols();
254 writeSections();
255 sortExceptionTable();
256 writeBuildId();
257
258 if (!Config->PDBPath.empty() && Config->Debug) {
259 const llvm::codeview::DebugInfo *DI = nullptr;
260 if (Config->DebugTypes & static_cast<unsigned>(coff::DebugType::CV))
261 DI = BuildId->DI;
262 createPDB(Config->PDBPath, Symtab, SectionTable, DI);
263 }
264
265 writeMapFile(OutputSections);
266
267 if (auto EC = Buffer->commit())
268 fatal(EC, "failed to write the output file");
269}
270
271static StringRef getOutputSection(StringRef Name) {
272 StringRef S = Name.split('$').first;
273 auto It = Config->Merge.find(S);
274 if (It == Config->Merge.end())
275 return S;
276 return It->second;
277}
278
279// Create output section objects and add them to OutputSections.
280void Writer::createSections() {
281 // First, bin chunks by name.
282 std::map<StringRef, std::vector<Chunk *>> Map;
283 for (Chunk *C : Symtab->getChunks()) {
284 auto *SC = dyn_cast<SectionChunk>(C);
285 if (SC && !SC->isLive()) {
286 if (Config->Verbose)
287 SC->printDiscardedMessage();
288 continue;
289 }
290 Map[C->getSectionName()].push_back(C);
291 }
292
293 // Then create an OutputSection for each section.
294 // '$' and all following characters in input section names are
295 // discarded when determining output section. So, .text$foo
296 // contributes to .text, for example. See PE/COFF spec 3.2.
297 SmallDenseMap<StringRef, OutputSection *> Sections;
298 for (auto Pair : Map) {
299 StringRef Name = getOutputSection(Pair.first);
300 OutputSection *&Sec = Sections[Name];
301 if (!Sec) {
302 Sec = make<OutputSection>(Name);
303 OutputSections.push_back(Sec);
304 }
305 std::vector<Chunk *> &Chunks = Pair.second;
306 for (Chunk *C : Chunks) {
307 Sec->addChunk(C);
308 Sec->addPermissions(C->getPermissions());
309 }
310 }
311}
312
313void Writer::createMiscChunks() {
314 OutputSection *RData = createSection(".rdata");
315
316 // Create thunks for locally-dllimported symbols.
317 if (!Symtab->LocalImportChunks.empty()) {
318 for (Chunk *C : Symtab->LocalImportChunks)
319 RData->addChunk(C);
320 }
321
322 // Create Debug Information Chunks
323 if (Config->Debug) {
324 DebugDirectory = make<DebugDirectoryChunk>(DebugRecords);
325
326 // TODO(compnerd) create a coffgrp entry if DebugType::CV is not enabled
327 if (Config->DebugTypes & static_cast<unsigned>(coff::DebugType::CV)) {
328 auto *Chunk = make<CVDebugRecordChunk>();
329
330 BuildId = Chunk;
331 DebugRecords.push_back(Chunk);
332 }
333
334 RData->addChunk(DebugDirectory);
335 for (Chunk *C : DebugRecords)
336 RData->addChunk(C);
337 }
338
339 // Create SEH table. x86-only.
340 if (Config->Machine != I386)
341 return;
342
343 std::set<Defined *> Handlers;
344
345 for (lld::coff::ObjectFile *File : Symtab->ObjectFiles) {
346 if (!File->SEHCompat)
347 return;
348 for (SymbolBody *B : File->SEHandlers)
349 Handlers.insert(cast<Defined>(B));
350 }
351
352 SEHTable = make<SEHTableChunk>(Handlers);
353 RData->addChunk(SEHTable);
354}
355
356// Create .idata section for the DLL-imported symbol table.
357// The format of this section is inherently Windows-specific.
358// IdataContents class abstracted away the details for us,
359// so we just let it create chunks and add them to the section.
360void Writer::createImportTables() {
361 if (Symtab->ImportFiles.empty())
362 return;
363
364 // Initialize DLLOrder so that import entries are ordered in
365 // the same order as in the command line. (That affects DLL
366 // initialization order, and this ordering is MSVC-compatible.)
367 for (ImportFile *File : Symtab->ImportFiles) {
368 std::string DLL = StringRef(File->DLLName).lower();
369 if (Config->DLLOrder.count(DLL) == 0)
370 Config->DLLOrder[DLL] = Config->DLLOrder.size();
371 }
372
373 OutputSection *Text = createSection(".text");
374 for (ImportFile *File : Symtab->ImportFiles) {
375 if (DefinedImportThunk *Thunk = File->ThunkSym)
376 if (Thunk->Live)
377 Text->addChunk(Thunk->getChunk());
378
379 if (Config->DelayLoads.count(StringRef(File->DLLName).lower())) {
380 if (File->ImpSym->Live)
381 DelayIdata.add(File->ImpSym);
382 } else {
383 if (File->ImpSym->Live)
384 Idata.add(File->ImpSym);
385 }
386 }
387
388 if (!Idata.empty()) {
389 OutputSection *Sec = createSection(".idata");
390 for (Chunk *C : Idata.getChunks())
391 Sec->addChunk(C);
392 }
393
394 if (!DelayIdata.empty()) {
395 Defined *Helper = cast<Defined>(Config->DelayLoadHelper);
396 DelayIdata.create(Helper);
397 OutputSection *Sec = createSection(".didat");
398 for (Chunk *C : DelayIdata.getChunks())
399 Sec->addChunk(C);
400 Sec = createSection(".data");
401 for (Chunk *C : DelayIdata.getDataChunks())
402 Sec->addChunk(C);
403 Sec = createSection(".text");
404 for (Chunk *C : DelayIdata.getCodeChunks())
405 Sec->addChunk(C);
406 }
407}
408
409void Writer::createExportTable() {
410 if (Config->Exports.empty())
411 return;
412 OutputSection *Sec = createSection(".edata");
413 for (Chunk *C : Edata.Chunks)
414 Sec->addChunk(C);
415}
416
417// The Windows loader doesn't seem to like empty sections,
418// so we remove them if any.
419void Writer::removeEmptySections() {
420 auto IsEmpty = [](OutputSection *S) { return S->getVirtualSize() == 0; };
421 OutputSections.erase(
422 std::remove_if(OutputSections.begin(), OutputSections.end(), IsEmpty),
423 OutputSections.end());
424 uint32_t Idx = 1;
425 for (OutputSection *Sec : OutputSections)
426 Sec->SectionIndex = Idx++;
427}
428
429size_t Writer::addEntryToStringTable(StringRef Str) {
430 assert(Str.size() > COFF::NameSize)((Str.size() > COFF::NameSize) ? static_cast<void> (
0) : __assert_fail ("Str.size() > COFF::NameSize", "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn303373/tools/lld/COFF/Writer.cpp"
, 430, __PRETTY_FUNCTION__));
431 size_t OffsetOfEntry = Strtab.size() + 4; // +4 for the size field
432 Strtab.insert(Strtab.end(), Str.begin(), Str.end());
433 Strtab.push_back('\0');
434 return OffsetOfEntry;
435}
436
437Optional<coff_symbol16> Writer::createSymbol(Defined *Def) {
438 // Relative symbols are unrepresentable in a COFF symbol table.
439 if (isa<DefinedRelative>(Def))
1
Taking false branch
→
440 return None;
441
442 if (auto *D = dyn_cast<DefinedRegular>(Def))
2
←
Taking false branch
→
443 if (!D->getChunk()->isLive())
444 return None;
445
446 coff_symbol16 Sym;
447 StringRef Name = Def->getName();
448 if (Name.size() > COFF::NameSize) {
3
←
Assuming the condition is false
→
4
←
Taking false branch
→
449 Sym.Name.Offset.Zeroes = 0;
450 Sym.Name.Offset.Offset = addEntryToStringTable(Name);
451 } else {
452 memset(Sym.Name.ShortName, 0, COFF::NameSize);
453 memcpy(Sym.Name.ShortName, Name.data(), Name.size());
454 }
455
456 if (auto *D = dyn_cast<DefinedCOFF>(Def)) {
5
←
Taking false branch
→
457 COFFSymbolRef Ref = D->getCOFFSymbol();
458 Sym.Type = Ref.getType();
459 Sym.StorageClass = Ref.getStorageClass();
460 } else {
461 Sym.Type = IMAGE_SYM_TYPE_NULL;
462 Sym.StorageClass = IMAGE_SYM_CLASS_EXTERNAL;
463 }
464 Sym.NumberOfAuxSymbols = 0;
465
466 switch (Def->kind()) {
6
←
Control jumps to the 'default' case at line 471
→
467 case SymbolBody::DefinedAbsoluteKind:
468 Sym.Value = Def->getRVA();
469 Sym.SectionNumber = IMAGE_SYM_ABSOLUTE;
470 break;
471 default: {
472 uint64_t RVA = Def->getRVA();
473 OutputSection *Sec = nullptr;
7
←
'Sec' initialized to a null pointer value
→
474 for (OutputSection *S : OutputSections) {
475 if (S->getRVA() > RVA)
476 break;
477 Sec = S;
478 }
479 Sym.Value = RVA - Sec->getRVA();
8
←
Called C++ object pointer is null
480 Sym.SectionNumber = Sec->SectionIndex;
481 break;
482 }
483 }
484 return Sym;
485}
486
487void Writer::createSymbolAndStringTable() {
488 if (!Config->Debug || !Config->WriteSymtab)
489 return;
490
491 // Name field in the section table is 8 byte long. Longer names need
492 // to be written to the string table. First, construct string table.
493 for (OutputSection *Sec : OutputSections) {
494 StringRef Name = Sec->getName();
495 if (Name.size() <= COFF::NameSize)
496 continue;
497 Sec->setStringTableOff(addEntryToStringTable(Name));
498 }
499
500 for (lld::coff::ObjectFile *File : Symtab->ObjectFiles) {
501 for (SymbolBody *B : File->getSymbols()) {
502 auto *D = dyn_cast<Defined>(B);
503 if (!D || D->WrittenToSymtab)
504 continue;
505
506 if (auto *S = dyn_cast<DefinedImportData>(D))
507 if (!S->Live)
508 continue;
509 if (auto *S = dyn_cast<DefinedImportThunk>(D))
510 if (!S->Live)
511 continue;
512
513 D->WrittenToSymtab = true;
514 if (Optional<coff_symbol16> Sym = createSymbol(D))
515 OutputSymtab.push_back(*Sym);
516 }
517 }
518
519 OutputSection *LastSection = OutputSections.back();
520 // We position the symbol table to be adjacent to the end of the last section.
521 uint64_t FileOff = LastSection->getFileOff() +
522 alignTo(LastSection->getRawSize(), SectorSize);
523 if (!OutputSymtab.empty()) {
524 PointerToSymbolTable = FileOff;
525 FileOff += OutputSymtab.size() * sizeof(coff_symbol16);
526 }
527 if (!Strtab.empty())
528 FileOff += Strtab.size() + 4;
529 FileSize = alignTo(FileOff, SectorSize);
530}
531
532// Visits all sections to assign incremental, non-overlapping RVAs and
533// file offsets.
534void Writer::assignAddresses() {
535 SizeOfHeaders = DOSStubSize + sizeof(PEMagic) + sizeof(coff_file_header) +
536 sizeof(data_directory) * NumberfOfDataDirectory +
537 sizeof(coff_section) * OutputSections.size();
538 SizeOfHeaders +=
539 Config->is64() ? sizeof(pe32plus_header) : sizeof(pe32_header);
540 SizeOfHeaders = alignTo(SizeOfHeaders, SectorSize);
541 uint64_t RVA = 0x1000; // The first page is kept unmapped.
542 FileSize = SizeOfHeaders;
543 // Move DISCARDABLE (or non-memory-mapped) sections to the end of file because
544 // the loader cannot handle holes.
545 std::stable_partition(
546 OutputSections.begin(), OutputSections.end(), [](OutputSection *S) {
547 return (S->getPermissions() & IMAGE_SCN_MEM_DISCARDABLE) == 0;
548 });
549 for (OutputSection *Sec : OutputSections) {
550 if (Sec->getName() == ".reloc")
551 addBaserels(Sec);
552 Sec->setRVA(RVA);
553 Sec->setFileOffset(FileSize);
554 RVA += alignTo(Sec->getVirtualSize(), PageSize);
555 FileSize += alignTo(Sec->getRawSize(), SectorSize);
556 }
557 SizeOfImage = SizeOfHeaders + alignTo(RVA - 0x1000, PageSize);
558}
559
560template <typename PEHeaderTy> void Writer::writeHeader() {
561 // Write DOS stub
562 uint8_t *Buf = Buffer->getBufferStart();
563 auto *DOS = reinterpret_cast<dos_header *>(Buf);
564 Buf += DOSStubSize;
565 DOS->Magic[0] = 'M';
566 DOS->Magic[1] = 'Z';
567 DOS->AddressOfRelocationTable = sizeof(dos_header);
568 DOS->AddressOfNewExeHeader = DOSStubSize;
569
570 // Write PE magic
571 memcpy(Buf, PEMagic, sizeof(PEMagic));
572 Buf += sizeof(PEMagic);
573
574 // Write COFF header
575 auto *COFF = reinterpret_cast<coff_file_header *>(Buf);
576 Buf += sizeof(*COFF);
577 COFF->Machine = Config->Machine;
578 COFF->NumberOfSections = OutputSections.size();
579 COFF->Characteristics = IMAGE_FILE_EXECUTABLE_IMAGE;
580 if (Config->LargeAddressAware)
581 COFF->Characteristics |= IMAGE_FILE_LARGE_ADDRESS_AWARE;
582 if (!Config->is64())
583 COFF->Characteristics |= IMAGE_FILE_32BIT_MACHINE;
584 if (Config->DLL)
585 COFF->Characteristics |= IMAGE_FILE_DLL;
586 if (!Config->Relocatable)
587 COFF->Characteristics |= IMAGE_FILE_RELOCS_STRIPPED;
588 COFF->SizeOfOptionalHeader =
589 sizeof(PEHeaderTy) + sizeof(data_directory) * NumberfOfDataDirectory;
590
591 // Write PE header
592 auto *PE = reinterpret_cast<PEHeaderTy *>(Buf);
593 Buf += sizeof(*PE);
594 PE->Magic = Config->is64() ? PE32Header::PE32_PLUS : PE32Header::PE32;
595 PE->ImageBase = Config->ImageBase;
596 PE->SectionAlignment = PageSize;
597 PE->FileAlignment = SectorSize;
598 PE->MajorImageVersion = Config->MajorImageVersion;
599 PE->MinorImageVersion = Config->MinorImageVersion;
600 PE->MajorOperatingSystemVersion = Config->MajorOSVersion;
601 PE->MinorOperatingSystemVersion = Config->MinorOSVersion;
602 PE->MajorSubsystemVersion = Config->MajorOSVersion;
603 PE->MinorSubsystemVersion = Config->MinorOSVersion;
604 PE->Subsystem = Config->Subsystem;
605 PE->SizeOfImage = SizeOfImage;
606 PE->SizeOfHeaders = SizeOfHeaders;
607 if (!Config->NoEntry) {
608 Defined *Entry = cast<Defined>(Config->Entry);
609 PE->AddressOfEntryPoint = Entry->getRVA();
610 // Pointer to thumb code must have the LSB set, so adjust it.
611 if (Config->Machine == ARMNT)
612 PE->AddressOfEntryPoint |= 1;
613 }
614 PE->SizeOfStackReserve = Config->StackReserve;
615 PE->SizeOfStackCommit = Config->StackCommit;
616 PE->SizeOfHeapReserve = Config->HeapReserve;
617 PE->SizeOfHeapCommit = Config->HeapCommit;
618 if (Config->AppContainer)
619 PE->DLLCharacteristics |= IMAGE_DLL_CHARACTERISTICS_APPCONTAINER;
620 if (Config->DynamicBase)
621 PE->DLLCharacteristics |= IMAGE_DLL_CHARACTERISTICS_DYNAMIC_BASE;
622 if (Config->HighEntropyVA)
623 PE->DLLCharacteristics |= IMAGE_DLL_CHARACTERISTICS_HIGH_ENTROPY_VA;
624 if (!Config->AllowBind)
625 PE->DLLCharacteristics |= IMAGE_DLL_CHARACTERISTICS_NO_BIND;
626 if (Config->NxCompat)
627 PE->DLLCharacteristics |= IMAGE_DLL_CHARACTERISTICS_NX_COMPAT;
628 if (!Config->AllowIsolation)
629 PE->DLLCharacteristics |= IMAGE_DLL_CHARACTERISTICS_NO_ISOLATION;
630 if (Config->TerminalServerAware)
631 PE->DLLCharacteristics |= IMAGE_DLL_CHARACTERISTICS_TERMINAL_SERVER_AWARE;
632 PE->NumberOfRvaAndSize = NumberfOfDataDirectory;
633 if (OutputSection *Text = findSection(".text")) {
634 PE->BaseOfCode = Text->getRVA();
635 PE->SizeOfCode = Text->getRawSize();
636 }
637 PE->SizeOfInitializedData = getSizeOfInitializedData();
638
639 // Write data directory
640 auto *Dir = reinterpret_cast<data_directory *>(Buf);
641 Buf += sizeof(*Dir) * NumberfOfDataDirectory;
642 if (OutputSection *Sec = findSection(".edata")) {
643 Dir[EXPORT_TABLE].RelativeVirtualAddress = Sec->getRVA();
644 Dir[EXPORT_TABLE].Size = Sec->getVirtualSize();
645 }
646 if (!Idata.empty()) {
647 Dir[IMPORT_TABLE].RelativeVirtualAddress = Idata.getDirRVA();
648 Dir[IMPORT_TABLE].Size = Idata.getDirSize();
649 Dir[IAT].RelativeVirtualAddress = Idata.getIATRVA();
650 Dir[IAT].Size = Idata.getIATSize();
651 }
652 if (OutputSection *Sec = findSection(".rsrc")) {
653 Dir[RESOURCE_TABLE].RelativeVirtualAddress = Sec->getRVA();
654 Dir[RESOURCE_TABLE].Size = Sec->getVirtualSize();
655 }
656 if (OutputSection *Sec = findSection(".pdata")) {
657 Dir[EXCEPTION_TABLE].RelativeVirtualAddress = Sec->getRVA();
658 Dir[EXCEPTION_TABLE].Size = Sec->getVirtualSize();
659 }
660 if (OutputSection *Sec = findSection(".reloc")) {
661 Dir[BASE_RELOCATION_TABLE].RelativeVirtualAddress = Sec->getRVA();
662 Dir[BASE_RELOCATION_TABLE].Size = Sec->getVirtualSize();
663 }
664 if (Symbol *Sym = Symtab->findUnderscore("_tls_used")) {
665 if (Defined *B = dyn_cast<Defined>(Sym->body())) {
666 Dir[TLS_TABLE].RelativeVirtualAddress = B->getRVA();
667 Dir[TLS_TABLE].Size = Config->is64()
668 ? sizeof(object::coff_tls_directory64)
669 : sizeof(object::coff_tls_directory32);
670 }
671 }
672 if (Config->Debug) {
673 Dir[DEBUG_DIRECTORY].RelativeVirtualAddress = DebugDirectory->getRVA();
674 Dir[DEBUG_DIRECTORY].Size = DebugDirectory->getSize();
675 }
676 if (Symbol *Sym = Symtab->findUnderscore("_load_config_used")) {
677 if (auto *B = dyn_cast<DefinedRegular>(Sym->body())) {
678 SectionChunk *SC = B->getChunk();
679 assert(B->getRVA() >= SC->getRVA())((B->getRVA() >= SC->getRVA()) ? static_cast<void
> (0) : __assert_fail ("B->getRVA() >= SC->getRVA()"
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn303373/tools/lld/COFF/Writer.cpp"
, 679, __PRETTY_FUNCTION__));
680 uint64_t OffsetInChunk = B->getRVA() - SC->getRVA();
681 if (!SC->hasData() || OffsetInChunk + 4 > SC->getSize())
682 fatal("_load_config_used is malformed");
683
684 ArrayRef<uint8_t> SecContents = SC->getContents();
685 uint32_t LoadConfigSize =
686 *reinterpret_cast<const ulittle32_t *>(&SecContents[OffsetInChunk]);
687 if (OffsetInChunk + LoadConfigSize > SC->getSize())
688 fatal("_load_config_used is too large");
689 Dir[LOAD_CONFIG_TABLE].RelativeVirtualAddress = B->getRVA();
690 Dir[LOAD_CONFIG_TABLE].Size = LoadConfigSize;
691 }
692 }
693 if (!DelayIdata.empty()) {
694 Dir[DELAY_IMPORT_DESCRIPTOR].RelativeVirtualAddress =
695 DelayIdata.getDirRVA();
696 Dir[DELAY_IMPORT_DESCRIPTOR].Size = DelayIdata.getDirSize();
697 }
698
699 // Write section table
700 for (OutputSection *Sec : OutputSections) {
701 Sec->writeHeaderTo(Buf);
702 Buf += sizeof(coff_section);
703 }
704 SectionTable = ArrayRef<uint8_t>(
705 Buf - OutputSections.size() * sizeof(coff_section), Buf);
706
707 if (OutputSymtab.empty())
708 return;
709
710 COFF->PointerToSymbolTable = PointerToSymbolTable;
711 uint32_t NumberOfSymbols = OutputSymtab.size();
712 COFF->NumberOfSymbols = NumberOfSymbols;
713 auto *SymbolTable = reinterpret_cast<coff_symbol16 *>(
714 Buffer->getBufferStart() + COFF->PointerToSymbolTable);
715 for (size_t I = 0; I != NumberOfSymbols; ++I)
716 SymbolTable[I] = OutputSymtab[I];
717 // Create the string table, it follows immediately after the symbol table.
718 // The first 4 bytes is length including itself.
719 Buf = reinterpret_cast<uint8_t *>(&SymbolTable[NumberOfSymbols]);
720 write32le(Buf, Strtab.size() + 4);
721 if (!Strtab.empty())
722 memcpy(Buf + 4, Strtab.data(), Strtab.size());
723}
724
725void Writer::openFile(StringRef Path) {
726 Buffer = check(
727 FileOutputBuffer::create(Path, FileSize, FileOutputBuffer::F_executable),
728 "failed to open " + Path);
729}
730
731void Writer::fixSafeSEHSymbols() {
732 if (!SEHTable)
733 return;
734 if (auto *T = dyn_cast<DefinedRelative>(Config->SEHTable->body()))
735 T->setRVA(SEHTable->getRVA());
736 if (auto *C = dyn_cast<DefinedAbsolute>(Config->SEHCount->body()))
737 C->setVA(SEHTable->getSize() / 4);
738}
739
740// Handles /section options to allow users to overwrite
741// section attributes.
742void Writer::setSectionPermissions() {
743 for (auto &P : Config->Section) {
744 StringRef Name = P.first;
745 uint32_t Perm = P.second;
746 if (auto *Sec = findSection(Name))
747 Sec->setPermissions(Perm);
748 }
749}
750
751// Write section contents to a mmap'ed file.
752void Writer::writeSections() {
753 uint8_t *Buf = Buffer->getBufferStart();
754 for (OutputSection *Sec : OutputSections) {
755 uint8_t *SecBuf = Buf + Sec->getFileOff();
756 // Fill gaps between functions in .text with INT3 instructions
757 // instead of leaving as NUL bytes (which can be interpreted as
758 // ADD instructions).
759 if (Sec->getPermissions() & IMAGE_SCN_CNT_CODE)
760 memset(SecBuf, 0xCC, Sec->getRawSize());
761 for_each(parallel::par, Sec->getChunks().begin(), Sec->getChunks().end(),
762 [&](Chunk *C) { C->writeTo(SecBuf); });
763 }
764}
765
766// Sort .pdata section contents according to PE/COFF spec 5.5.
767void Writer::sortExceptionTable() {
768 OutputSection *Sec = findSection(".pdata");
769 if (!Sec)
770 return;
771 // We assume .pdata contains function table entries only.
772 uint8_t *Begin = Buffer->getBufferStart() + Sec->getFileOff();
773 uint8_t *End = Begin + Sec->getVirtualSize();
774 if (Config->Machine == AMD64) {
775 struct Entry { ulittle32_t Begin, End, Unwind; };
776 sort(parallel::par, (Entry *)Begin, (Entry *)End,
777 [](const Entry &A, const Entry &B) { return A.Begin < B.Begin; });
778 return;
779 }
780 if (Config->Machine == ARMNT) {
781 struct Entry { ulittle32_t Begin, Unwind; };
782 sort(parallel::par, (Entry *)Begin, (Entry *)End,
783 [](const Entry &A, const Entry &B) { return A.Begin < B.Begin; });
784 return;
785 }
786 errs() << "warning: don't know how to handle .pdata.\n";
787}
788
789// Backfill the CVSignature in a PDB70 Debug Record. This backfilling allows us
790// to get reproducible builds.
791void Writer::writeBuildId() {
792 // There is nothing to backfill if BuildId was not setup.
793 if (BuildId == nullptr)
794 return;
795
796 MD5 Hash;
797 MD5::MD5Result Res;
798
799 Hash.update(ArrayRef<uint8_t>{Buffer->getBufferStart(),
800 Buffer->getBufferEnd()});
801 Hash.final(Res);
802
803 assert(BuildId->DI->Signature.CVSignature == OMF::Signature::PDB70 &&((BuildId->DI->Signature.CVSignature == OMF::Signature::
PDB70 && "only PDB 7.0 is supported") ? static_cast<
void> (0) : __assert_fail ("BuildId->DI->Signature.CVSignature == OMF::Signature::PDB70 && \"only PDB 7.0 is supported\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn303373/tools/lld/COFF/Writer.cpp"
, 804, __PRETTY_FUNCTION__))
804 "only PDB 7.0 is supported")((BuildId->DI->Signature.CVSignature == OMF::Signature::
PDB70 && "only PDB 7.0 is supported") ? static_cast<
void> (0) : __assert_fail ("BuildId->DI->Signature.CVSignature == OMF::Signature::PDB70 && \"only PDB 7.0 is supported\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn303373/tools/lld/COFF/Writer.cpp"
, 804, __PRETTY_FUNCTION__));
805 assert(sizeof(Res) == sizeof(BuildId->DI->PDB70.Signature) &&((sizeof(Res) == sizeof(BuildId->DI->PDB70.Signature) &&
"signature size mismatch") ? static_cast<void> (0) : __assert_fail
("sizeof(Res) == sizeof(BuildId->DI->PDB70.Signature) && \"signature size mismatch\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn303373/tools/lld/COFF/Writer.cpp"
, 806, __PRETTY_FUNCTION__))
806 "signature size mismatch")((sizeof(Res) == sizeof(BuildId->DI->PDB70.Signature) &&
"signature size mismatch") ? static_cast<void> (0) : __assert_fail
("sizeof(Res) == sizeof(BuildId->DI->PDB70.Signature) && \"signature size mismatch\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn303373/tools/lld/COFF/Writer.cpp"
, 806, __PRETTY_FUNCTION__));
807 memcpy(BuildId->DI->PDB70.Signature, Res.Bytes.data(),
808 sizeof(codeview::PDB70DebugInfo::Signature));
809 // TODO(compnerd) track the Age
810 BuildId->DI->PDB70.Age = 1;
811}
812
813OutputSection *Writer::findSection(StringRef Name) {
814 for (OutputSection *Sec : OutputSections)
815 if (Sec->getName() == Name)
816 return Sec;
817 return nullptr;
818}
819
820uint32_t Writer::getSizeOfInitializedData() {
821 uint32_t Res = 0;
822 for (OutputSection *S : OutputSections)
823 if (S->getPermissions() & IMAGE_SCN_CNT_INITIALIZED_DATA)
824 Res += S->getRawSize();
825 return Res;
826}
827
828// Returns an existing section or create a new one if not found.
829OutputSection *Writer::createSection(StringRef Name) {
830 if (auto *Sec = findSection(Name))
831 return Sec;
832 const auto DATA = IMAGE_SCN_CNT_INITIALIZED_DATA;
833 const auto BSS = IMAGE_SCN_CNT_UNINITIALIZED_DATA;
834 const auto CODE = IMAGE_SCN_CNT_CODE;
835 const auto DISCARDABLE = IMAGE_SCN_MEM_DISCARDABLE;
836 const auto R = IMAGE_SCN_MEM_READ;
837 const auto W = IMAGE_SCN_MEM_WRITE;
838 const auto X = IMAGE_SCN_MEM_EXECUTE;
839 uint32_t Perms = StringSwitch<uint32_t>(Name)
840 .Case(".bss", BSS | R | W)
841 .Case(".data", DATA | R | W)
842 .Cases(".didat", ".edata", ".idata", ".rdata", DATA | R)
843 .Case(".reloc", DATA | DISCARDABLE | R)
844 .Case(".text", CODE | R | X)
845 .Default(0);
846 if (!Perms)
847 llvm_unreachable("unknown section name")::llvm::llvm_unreachable_internal("unknown section name", "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn303373/tools/lld/COFF/Writer.cpp"
, 847);
848 auto Sec = make<OutputSection>(Name);
849 Sec->addPermissions(Perms);
850 OutputSections.push_back(Sec);
851 return Sec;
852}
853
854// Dest is .reloc section. Add contents to that section.
855void Writer::addBaserels(OutputSection *Dest) {
856 std::vector<Baserel> V;
857 for (OutputSection *Sec : OutputSections) {
858 if (Sec == Dest)
859 continue;
860 // Collect all locations for base relocations.
861 for (Chunk *C : Sec->getChunks())
862 C->getBaserels(&V);
863 // Add the addresses to .reloc section.
864 if (!V.empty())
865 addBaserelBlocks(Dest, V);
866 V.clear();
867 }
868}
869
870// Add addresses to .reloc section. Note that addresses are grouped by page.
871void Writer::addBaserelBlocks(OutputSection *Dest, std::vector<Baserel> &V) {
872 const uint32_t Mask = ~uint32_t(PageSize - 1);
873 uint32_t Page = V[0].RVA & Mask;
874 size_t I = 0, J = 1;
875 for (size_t E = V.size(); J < E; ++J) {
876 uint32_t P = V[J].RVA & Mask;
877 if (P == Page)
878 continue;
879 Dest->addChunk(make<BaserelChunk>(Page, &V[I], &V[0] + J));
880 I = J;
881 Page = P;
882 }
883 if (I == J)
884 return;
885 Dest->addChunk(make<BaserelChunk>(Page, &V[I], &V[0] + J));
886}