1//===-- MachOUtils.cpp - Mach-o specific helpers for dsymutil ------------===//
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 "MachOUtils.h"
10#include "BinaryHolder.h"
11#include "DebugMap.h"
12#include "LinkUtils.h"
13#include "llvm/ADT/SmallString.h"
14#include "llvm/CodeGen/NonRelocatableStringpool.h"
15#include "llvm/MC/MCAssembler.h"
16#include "llvm/MC/MCMachObjectWriter.h"
17#include "llvm/MC/MCObjectStreamer.h"
18#include "llvm/MC/MCSectionMachO.h"
19#include "llvm/MC/MCStreamer.h"
20#include "llvm/MC/MCSubtargetInfo.h"
21#include "llvm/Object/MachO.h"
22#include "llvm/Support/FileUtilities.h"
23#include "llvm/Support/Program.h"
24#include "llvm/Support/WithColor.h"
25#include "llvm/Support/raw_ostream.h"
26
27namespace llvm {
28namespace dsymutil {
29namespace MachOUtils {
30
31llvm::Error ArchAndFile::createTempFile() {
32 SmallString<256> SS;
33 std::error_code EC = sys::fs::createTemporaryFile(Prefix: "dsym", Suffix: "dwarf", ResultFD&: FD, ResultPath&: SS);
34
35 if (EC)
36 return errorCodeToError(EC);
37
38 Path = SS.str();
39
40 return Error::success();
41}
42
43llvm::StringRef ArchAndFile::getPath() const {
44 assert(!Path.empty() && "path called before createTempFile");
45 return Path;
46}
47
48int ArchAndFile::getFD() const {
49 assert((FD != -1) && "path called before createTempFile");
50 return FD;
51}
52
53ArchAndFile::~ArchAndFile() {
54 if (!Path.empty())
55 sys::fs::remove(path: Path);
56}
57
58std::string getArchName(StringRef Arch) {
59 if (Arch.starts_with(Prefix: "thumb"))
60 return (llvm::Twine("arm") + Arch.drop_front(N: 5)).str();
61 return std::string(Arch);
62}
63
64static bool runLipo(StringRef SDKPath, SmallVectorImpl<StringRef> &Args) {
65 auto Path = sys::findProgramByName(Name: "lipo", Paths: ArrayRef(SDKPath));
66 if (!Path)
67 Path = sys::findProgramByName(Name: "lipo");
68
69 if (!Path) {
70 WithColor::error() << "lipo: " << Path.getError().message() << "\n";
71 return false;
72 }
73
74 std::string ErrMsg;
75 int result =
76 sys::ExecuteAndWait(Program: *Path, Args, Env: std::nullopt, Redirects: {}, SecondsToWait: 0, MemoryLimit: 0, ErrMsg: &ErrMsg);
77 if (result) {
78 WithColor::error() << "lipo: " << ErrMsg << "\n";
79 return false;
80 }
81
82 return true;
83}
84
85bool generateUniversalBinary(SmallVectorImpl<ArchAndFile> &ArchFiles,
86 StringRef OutputFileName,
87 const LinkOptions &Options, StringRef SDKPath,
88 bool Fat64) {
89 // No need to merge one file into a universal fat binary.
90 if (ArchFiles.size() == 1) {
91 llvm::StringRef TmpPath = ArchFiles.front().getPath();
92 if (auto EC = sys::fs::rename(from: TmpPath, to: OutputFileName)) {
93 // If we can't rename, try to copy to work around cross-device link
94 // issues.
95 EC = sys::fs::copy_file(From: TmpPath, To: OutputFileName);
96 if (EC) {
97 WithColor::error() << "while keeping " << TmpPath << " as "
98 << OutputFileName << ": " << EC.message() << "\n";
99 return false;
100 }
101 sys::fs::remove(path: TmpPath);
102 }
103 return true;
104 }
105
106 SmallVector<StringRef, 8> Args;
107 Args.push_back(Elt: "lipo");
108 Args.push_back(Elt: "-create");
109
110 for (auto &Thin : ArchFiles)
111 Args.push_back(Elt: Thin.getPath());
112
113 // Align segments to match dsymutil-classic alignment.
114 for (auto &Thin : ArchFiles) {
115 Thin.Arch = getArchName(Arch: Thin.Arch);
116 Args.push_back(Elt: "-segalign");
117 Args.push_back(Elt: Thin.Arch);
118 Args.push_back(Elt: "20");
119 }
120
121 // Use a 64-bit fat header if requested.
122 if (Fat64)
123 Args.push_back(Elt: "-fat64");
124
125 Args.push_back(Elt: "-output");
126 Args.push_back(Elt: OutputFileName.data());
127
128 if (Options.Verbose) {
129 outs() << "Running lipo\n";
130 for (auto Arg : Args)
131 outs() << ' ' << Arg;
132 outs() << "\n";
133 }
134
135 return Options.NoOutput ? true : runLipo(SDKPath, Args);
136}
137
138// Return a MachO::segment_command_64 that holds the same values as the passed
139// MachO::segment_command. We do that to avoid having to duplicate the logic
140// for 32bits and 64bits segments.
141struct MachO::segment_command_64 adaptFrom32bits(MachO::segment_command Seg) {
142 MachO::segment_command_64 Seg64;
143 Seg64.cmd = Seg.cmd;
144 Seg64.cmdsize = Seg.cmdsize;
145 memcpy(dest: Seg64.segname, src: Seg.segname, n: sizeof(Seg.segname));
146 Seg64.vmaddr = Seg.vmaddr;
147 Seg64.vmsize = Seg.vmsize;
148 Seg64.fileoff = Seg.fileoff;
149 Seg64.filesize = Seg.filesize;
150 Seg64.maxprot = Seg.maxprot;
151 Seg64.initprot = Seg.initprot;
152 Seg64.nsects = Seg.nsects;
153 Seg64.flags = Seg.flags;
154 return Seg64;
155}
156
157// Iterate on all \a Obj segments, and apply \a Handler to them.
158template <typename FunctionTy>
159static void iterateOnSegments(const object::MachOObjectFile &Obj,
160 FunctionTy Handler) {
161 for (const auto &LCI : Obj.load_commands()) {
162 MachO::segment_command_64 Segment;
163 if (LCI.C.cmd == MachO::LC_SEGMENT)
164 Segment = adaptFrom32bits(Seg: Obj.getSegmentLoadCommand(L: LCI));
165 else if (LCI.C.cmd == MachO::LC_SEGMENT_64)
166 Segment = Obj.getSegment64LoadCommand(L: LCI);
167 else
168 continue;
169
170 Handler(Segment);
171 }
172}
173
174// Transfer the symbols described by \a NList to \a NewSymtab which is just the
175// raw contents of the symbol table for the dSYM companion file. \returns
176// whether the symbol was transferred or not.
177template <typename NListTy>
178static bool transferSymbol(NListTy NList, bool IsLittleEndian,
179 StringRef Strings, SmallVectorImpl<char> &NewSymtab,
180 NonRelocatableStringpool &NewStrings,
181 bool &InDebugNote) {
182 // Do not transfer undefined symbols, we want real addresses.
183 if ((NList.n_type & MachO::N_TYPE) == MachO::N_UNDF)
184 return false;
185
186 // Do not transfer N_AST symbols as their content is copied into a section of
187 // the Mach-O companion file.
188 if (NList.n_type == MachO::N_AST)
189 return false;
190
191 StringRef Name = StringRef(Strings.begin() + NList.n_strx);
192
193 // An N_SO with a filename opens a debugging scope and another one without a
194 // name closes it. Don't transfer anything in the debugging scope.
195 if (InDebugNote) {
196 InDebugNote =
197 (NList.n_type != MachO::N_SO) || (!Name.empty() && Name[0] != '\0');
198 return false;
199 } else if (NList.n_type == MachO::N_SO) {
200 InDebugNote = true;
201 return false;
202 }
203
204 // FIXME: The + 1 is here to mimic dsymutil-classic that has 2 empty
205 // strings at the start of the generated string table (There is
206 // corresponding code in the string table emission).
207 NList.n_strx = NewStrings.getStringOffset(S: Name) + 1;
208 if (IsLittleEndian != sys::IsLittleEndianHost)
209 MachO::swapStruct(NList);
210
211 NewSymtab.append(in_start: reinterpret_cast<char *>(&NList),
212 in_end: reinterpret_cast<char *>(&NList + 1));
213 return true;
214}
215
216// Wrapper around transferSymbol to transfer all of \a Obj symbols
217// to \a NewSymtab. This function does not write in the output file.
218// \returns the number of symbols in \a NewSymtab.
219static unsigned transferSymbols(const object::MachOObjectFile &Obj,
220 SmallVectorImpl<char> &NewSymtab,
221 NonRelocatableStringpool &NewStrings) {
222 unsigned Syms = 0;
223 StringRef Strings = Obj.getStringTableData();
224 bool IsLittleEndian = Obj.isLittleEndian();
225 bool InDebugNote = false;
226
227 if (Obj.is64Bit()) {
228 for (const object::SymbolRef &Symbol : Obj.symbols()) {
229 object::DataRefImpl DRI = Symbol.getRawDataRefImpl();
230 if (transferSymbol(NList: Obj.getSymbol64TableEntry(DRI), IsLittleEndian,
231 Strings, NewSymtab, NewStrings, InDebugNote))
232 ++Syms;
233 }
234 } else {
235 for (const object::SymbolRef &Symbol : Obj.symbols()) {
236 object::DataRefImpl DRI = Symbol.getRawDataRefImpl();
237 if (transferSymbol(NList: Obj.getSymbolTableEntry(DRI), IsLittleEndian, Strings,
238 NewSymtab, NewStrings, InDebugNote))
239 ++Syms;
240 }
241 }
242 return Syms;
243}
244
245static MachO::section
246getSection(const object::MachOObjectFile &Obj,
247 const MachO::segment_command &Seg,
248 const object::MachOObjectFile::LoadCommandInfo &LCI, unsigned Idx) {
249 return Obj.getSection(L: LCI, Index: Idx);
250}
251
252static MachO::section_64
253getSection(const object::MachOObjectFile &Obj,
254 const MachO::segment_command_64 &Seg,
255 const object::MachOObjectFile::LoadCommandInfo &LCI, unsigned Idx) {
256 return Obj.getSection64(L: LCI, Index: Idx);
257}
258
259// Transfer \a Segment from \a Obj to the output file. This calls into \a Writer
260// to write these load commands directly in the output file at the current
261// position.
262//
263// The function also tries to find a hole in the address map to fit the __DWARF
264// segment of \a DwarfSegmentSize size. \a EndAddress is updated to point at the
265// highest segment address.
266//
267// When the __LINKEDIT segment is transferred, its offset and size are set resp.
268// to \a LinkeditOffset and \a LinkeditSize.
269//
270// When the eh_frame section is transferred, its offset and size are set resp.
271// to \a EHFrameOffset and \a EHFrameSize.
272template <typename SegmentTy>
273static void transferSegmentAndSections(
274 const object::MachOObjectFile::LoadCommandInfo &LCI, SegmentTy Segment,
275 const object::MachOObjectFile &Obj, MachObjectWriter &Writer,
276 uint64_t LinkeditOffset, uint64_t LinkeditSize, uint64_t EHFrameOffset,
277 uint64_t EHFrameSize, uint64_t DwarfSegmentSize, uint64_t &GapForDwarf,
278 uint64_t &EndAddress) {
279 if (StringRef("__DWARF") == Segment.segname)
280 return;
281
282 if (StringRef("__TEXT") == Segment.segname && EHFrameSize > 0) {
283 Segment.fileoff = EHFrameOffset;
284 Segment.filesize = EHFrameSize;
285 } else if (StringRef("__LINKEDIT") == Segment.segname) {
286 Segment.fileoff = LinkeditOffset;
287 Segment.filesize = LinkeditSize;
288 // Resize vmsize by rounding to the page size.
289 Segment.vmsize = alignTo(Value: LinkeditSize, Align: 0x1000);
290 } else {
291 Segment.fileoff = Segment.filesize = 0;
292 }
293
294 // Check if the end address of the last segment and our current
295 // start address leave a sufficient gap to store the __DWARF
296 // segment.
297 uint64_t PrevEndAddress = EndAddress;
298 EndAddress = alignTo(Value: EndAddress, Align: 0x1000);
299 if (GapForDwarf == UINT64_MAX && Segment.vmaddr > EndAddress &&
300 Segment.vmaddr - EndAddress >= DwarfSegmentSize)
301 GapForDwarf = EndAddress;
302
303 // The segments are not necessarily sorted by their vmaddr.
304 EndAddress =
305 std::max<uint64_t>(PrevEndAddress, Segment.vmaddr + Segment.vmsize);
306 unsigned nsects = Segment.nsects;
307 if (Obj.isLittleEndian() != sys::IsLittleEndianHost)
308 MachO::swapStruct(Segment);
309 Writer.W.OS.write(Ptr: reinterpret_cast<char *>(&Segment), Size: sizeof(Segment));
310 for (unsigned i = 0; i < nsects; ++i) {
311 auto Sect = getSection(Obj, Segment, LCI, i);
312 if (StringRef("__eh_frame") == Sect.sectname) {
313 Sect.offset = EHFrameOffset;
314 Sect.reloff = Sect.nreloc = 0;
315 } else {
316 Sect.offset = Sect.reloff = Sect.nreloc = 0;
317 }
318 if (Obj.isLittleEndian() != sys::IsLittleEndianHost)
319 MachO::swapStruct(Sect);
320 Writer.W.OS.write(Ptr: reinterpret_cast<char *>(&Sect), Size: sizeof(Sect));
321 }
322}
323
324// Write the __DWARF segment load command to the output file.
325static bool createDwarfSegment(const MCAssembler& Asm,uint64_t VMAddr, uint64_t FileOffset,
326 uint64_t FileSize, unsigned NumSections,
327 MachObjectWriter &Writer) {
328 Writer.writeSegmentLoadCommand(Name: "__DWARF", NumSections, VMAddr,
329 VMSize: alignTo(Value: FileSize, Align: 0x1000), SectionDataStartOffset: FileOffset,
330 SectionDataSize: FileSize, /* MaxProt */ 7,
331 /* InitProt =*/3);
332
333 for (unsigned int i = 0, n = Writer.getSectionOrder().size(); i != n; ++i) {
334 MCSection *Sec = Writer.getSectionOrder()[i];
335 if (!Asm.getSectionFileSize(Sec: *Sec))
336 continue;
337
338 Align Alignment = Sec->getAlign();
339 if (Alignment > 1) {
340 VMAddr = alignTo(Size: VMAddr, A: Alignment);
341 FileOffset = alignTo(Size: FileOffset, A: Alignment);
342 if (FileOffset > UINT32_MAX)
343 return error(Error: "section " + Sec->getName() +
344 "'s file offset exceeds 4GB."
345 " Refusing to produce an invalid Mach-O file.");
346 }
347 Writer.writeSection(Asm, Sec: *Sec, VMAddr, FileOffset, Flags: 0, RelocationsStart: 0, NumRelocations: 0);
348
349 FileOffset += Asm.getSectionAddressSize(Sec: *Sec);
350 VMAddr += Asm.getSectionAddressSize(Sec: *Sec);
351 }
352 return true;
353}
354
355static bool isExecutable(const object::MachOObjectFile &Obj) {
356 if (Obj.is64Bit())
357 return Obj.getHeader64().filetype != MachO::MH_OBJECT;
358 else
359 return Obj.getHeader().filetype != MachO::MH_OBJECT;
360}
361
362static unsigned segmentLoadCommandSize(bool Is64Bit, unsigned NumSections) {
363 if (Is64Bit)
364 return sizeof(MachO::segment_command_64) +
365 NumSections * sizeof(MachO::section_64);
366
367 return sizeof(MachO::segment_command) + NumSections * sizeof(MachO::section);
368}
369
370// Stream a dSYM companion binary file corresponding to the binary referenced
371// by \a DM to \a OutFile. The passed \a MS MCStreamer is setup to write to
372// \a OutFile and it must be using a MachObjectWriter object to do so.
373bool generateDsymCompanion(
374 llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS, const DebugMap &DM,
375 MCStreamer &MS, raw_fd_ostream &OutFile,
376 const std::vector<MachOUtils::DwarfRelocationApplicationInfo>
377 &RelocationsToApply) {
378 auto &ObjectStreamer = static_cast<MCObjectStreamer &>(MS);
379 MCAssembler &MCAsm = ObjectStreamer.getAssembler();
380 auto &Writer = static_cast<MachObjectWriter &>(MCAsm.getWriter());
381
382 // Layout but don't emit.
383 MCAsm.layout();
384
385 BinaryHolder InputBinaryHolder(VFS, false);
386
387 auto ObjectEntry = InputBinaryHolder.getObjectEntry(Filename: DM.getBinaryPath());
388 if (!ObjectEntry) {
389 auto Err = ObjectEntry.takeError();
390 return error(Error: Twine("opening ") + DM.getBinaryPath() + ": " +
391 toString(E: std::move(Err)),
392 Context: "output file streaming");
393 }
394
395 auto Object =
396 ObjectEntry->getObjectAs<object::MachOObjectFile>(T: DM.getTriple());
397 if (!Object) {
398 auto Err = Object.takeError();
399 return error(Error: Twine("opening ") + DM.getBinaryPath() + ": " +
400 toString(E: std::move(Err)),
401 Context: "output file streaming");
402 }
403
404 auto &InputBinary = *Object;
405
406 bool Is64Bit = Writer.is64Bit();
407 MachO::symtab_command SymtabCmd = InputBinary.getSymtabLoadCommand();
408
409 // Compute the number of load commands we will need.
410 unsigned LoadCommandSize = 0;
411 unsigned NumLoadCommands = 0;
412
413 bool HasSymtab = false;
414
415 // Check LC_SYMTAB and get LC_UUID and LC_BUILD_VERSION.
416 MachO::uuid_command UUIDCmd;
417 SmallVector<MachO::build_version_command, 2> BuildVersionCmd;
418 memset(s: &UUIDCmd, c: 0, n: sizeof(UUIDCmd));
419 for (auto &LCI : InputBinary.load_commands()) {
420 switch (LCI.C.cmd) {
421 case MachO::LC_UUID:
422 if (UUIDCmd.cmd)
423 return error(Error: "Binary contains more than one UUID");
424 UUIDCmd = InputBinary.getUuidCommand(L: LCI);
425 ++NumLoadCommands;
426 LoadCommandSize += sizeof(UUIDCmd);
427 break;
428 case MachO::LC_BUILD_VERSION: {
429 MachO::build_version_command Cmd;
430 memset(s: &Cmd, c: 0, n: sizeof(Cmd));
431 Cmd = InputBinary.getBuildVersionLoadCommand(L: LCI);
432 ++NumLoadCommands;
433 LoadCommandSize += sizeof(Cmd);
434 // LLDB doesn't care about the build tools for now.
435 Cmd.ntools = 0;
436 BuildVersionCmd.push_back(Elt: Cmd);
437 break;
438 }
439 case MachO::LC_SYMTAB:
440 HasSymtab = true;
441 break;
442 default:
443 break;
444 }
445 }
446
447 // If we have a valid symtab to copy, do it.
448 bool ShouldEmitSymtab = HasSymtab && isExecutable(Obj: InputBinary);
449 if (ShouldEmitSymtab) {
450 LoadCommandSize += sizeof(MachO::symtab_command);
451 ++NumLoadCommands;
452 }
453
454 // If we have a valid eh_frame to copy, do it.
455 uint64_t EHFrameSize = 0;
456 StringRef EHFrameData;
457 for (const object::SectionRef &Section : InputBinary.sections()) {
458 Expected<StringRef> NameOrErr = Section.getName();
459 if (!NameOrErr) {
460 consumeError(Err: NameOrErr.takeError());
461 continue;
462 }
463 StringRef SectionName = *NameOrErr;
464 SectionName = SectionName.substr(Start: SectionName.find_first_not_of(Chars: "._"));
465 if (SectionName == "eh_frame") {
466 if (Expected<StringRef> ContentsOrErr = Section.getContents()) {
467 EHFrameData = *ContentsOrErr;
468 EHFrameSize = Section.getSize();
469 } else {
470 consumeError(Err: ContentsOrErr.takeError());
471 }
472 }
473 }
474
475 unsigned HeaderSize =
476 Is64Bit ? sizeof(MachO::mach_header_64) : sizeof(MachO::mach_header);
477 // We will copy every segment that isn't __DWARF.
478 iterateOnSegments(Obj: InputBinary, Handler: [&](const MachO::segment_command_64 &Segment) {
479 if (StringRef("__DWARF") == Segment.segname)
480 return;
481
482 ++NumLoadCommands;
483 LoadCommandSize += segmentLoadCommandSize(Is64Bit, NumSections: Segment.nsects);
484 });
485
486 // We will add our own brand new __DWARF segment if we have debug
487 // info.
488 unsigned NumDwarfSections = 0;
489 uint64_t DwarfSegmentSize = 0;
490
491 for (unsigned int i = 0, n = Writer.getSectionOrder().size(); i != n; ++i) {
492 MCSection *Sec = Writer.getSectionOrder()[i];
493 if (Sec->begin() == Sec->end())
494 continue;
495
496 if (uint64_t Size = MCAsm.getSectionFileSize(Sec: *Sec)) {
497 DwarfSegmentSize = alignTo(Size: DwarfSegmentSize, A: Sec->getAlign());
498 DwarfSegmentSize += Size;
499 ++NumDwarfSections;
500 }
501 }
502
503 if (NumDwarfSections) {
504 ++NumLoadCommands;
505 LoadCommandSize += segmentLoadCommandSize(Is64Bit, NumSections: NumDwarfSections);
506 }
507
508 SmallString<0> NewSymtab;
509 // Legacy dsymutil puts an empty string at the start of the line table.
510 // thus we set NonRelocatableStringpool(,PutEmptyString=true)
511 NonRelocatableStringpool NewStrings(true);
512 unsigned NListSize = Is64Bit ? sizeof(MachO::nlist_64) : sizeof(MachO::nlist);
513 unsigned NumSyms = 0;
514 uint64_t NewStringsSize = 0;
515 if (ShouldEmitSymtab) {
516 NewSymtab.reserve(N: SymtabCmd.nsyms * NListSize / 2);
517 NumSyms = transferSymbols(Obj: InputBinary, NewSymtab, NewStrings);
518 NewStringsSize = NewStrings.getSize() + 1;
519 }
520
521 uint64_t SymtabStart = LoadCommandSize;
522 SymtabStart += HeaderSize;
523 SymtabStart = alignTo(Value: SymtabStart, Align: 0x1000);
524
525 // We gathered all the information we need, start emitting the output file.
526 Writer.writeHeader(Type: MachO::MH_DSYM, NumLoadCommands, LoadCommandsSize: LoadCommandSize,
527 /*SubsectionsViaSymbols=*/false);
528
529 // Write the load commands.
530 assert(OutFile.tell() == HeaderSize);
531 if (UUIDCmd.cmd != 0) {
532 Writer.W.write<uint32_t>(Val: UUIDCmd.cmd);
533 Writer.W.write<uint32_t>(Val: sizeof(UUIDCmd));
534 OutFile.write(Ptr: reinterpret_cast<const char *>(UUIDCmd.uuid), Size: 16);
535 assert(OutFile.tell() == HeaderSize + sizeof(UUIDCmd));
536 }
537 for (auto Cmd : BuildVersionCmd) {
538 Writer.W.write<uint32_t>(Val: Cmd.cmd);
539 Writer.W.write<uint32_t>(Val: sizeof(Cmd));
540 Writer.W.write<uint32_t>(Val: Cmd.platform);
541 Writer.W.write<uint32_t>(Val: Cmd.minos);
542 Writer.W.write<uint32_t>(Val: Cmd.sdk);
543 Writer.W.write<uint32_t>(Val: Cmd.ntools);
544 }
545
546 assert(SymtabCmd.cmd && "No symbol table.");
547 uint64_t StringStart = SymtabStart + NumSyms * NListSize;
548 if (ShouldEmitSymtab)
549 Writer.writeSymtabLoadCommand(SymbolOffset: SymtabStart, NumSymbols: NumSyms, StringTableOffset: StringStart,
550 StringTableSize: NewStringsSize);
551
552 uint64_t EHFrameStart = StringStart + NewStringsSize;
553 EHFrameStart = alignTo(Value: EHFrameStart, Align: 0x1000);
554
555 uint64_t DwarfSegmentStart = EHFrameStart + EHFrameSize;
556 DwarfSegmentStart = alignTo(Value: DwarfSegmentStart, Align: 0x1000);
557
558 // Write the load commands for the segments and sections we 'import' from
559 // the original binary.
560 uint64_t EndAddress = 0;
561 uint64_t GapForDwarf = UINT64_MAX;
562 for (auto &LCI : InputBinary.load_commands()) {
563 if (LCI.C.cmd == MachO::LC_SEGMENT)
564 transferSegmentAndSections(
565 LCI, Segment: InputBinary.getSegmentLoadCommand(L: LCI), Obj: InputBinary, Writer,
566 LinkeditOffset: SymtabStart, LinkeditSize: StringStart + NewStringsSize - SymtabStart, EHFrameOffset: EHFrameStart,
567 EHFrameSize, DwarfSegmentSize, GapForDwarf, EndAddress);
568 else if (LCI.C.cmd == MachO::LC_SEGMENT_64)
569 transferSegmentAndSections(
570 LCI, Segment: InputBinary.getSegment64LoadCommand(L: LCI), Obj: InputBinary, Writer,
571 LinkeditOffset: SymtabStart, LinkeditSize: StringStart + NewStringsSize - SymtabStart, EHFrameOffset: EHFrameStart,
572 EHFrameSize, DwarfSegmentSize, GapForDwarf, EndAddress);
573 }
574
575 uint64_t DwarfVMAddr = alignTo(Value: EndAddress, Align: 0x1000);
576 uint64_t DwarfVMMax = Is64Bit ? UINT64_MAX : UINT32_MAX;
577 if (DwarfVMAddr + DwarfSegmentSize > DwarfVMMax ||
578 DwarfVMAddr + DwarfSegmentSize < DwarfVMAddr /* Overflow */) {
579 // There is no room for the __DWARF segment at the end of the
580 // address space. Look through segments to find a gap.
581 DwarfVMAddr = GapForDwarf;
582 if (DwarfVMAddr == UINT64_MAX)
583 warn(Warning: "not enough VM space for the __DWARF segment.",
584 Context: "output file streaming");
585 }
586
587 // Write the load command for the __DWARF segment.
588 if (!createDwarfSegment(Asm: MCAsm, VMAddr: DwarfVMAddr, FileOffset: DwarfSegmentStart, FileSize: DwarfSegmentSize,
589 NumSections: NumDwarfSections, Writer))
590 return false;
591
592 assert(OutFile.tell() == LoadCommandSize + HeaderSize);
593 OutFile.write_zeros(NumZeros: SymtabStart - (LoadCommandSize + HeaderSize));
594 assert(OutFile.tell() == SymtabStart);
595
596 // Transfer symbols.
597 if (ShouldEmitSymtab) {
598 OutFile << NewSymtab.str();
599 assert(OutFile.tell() == StringStart);
600
601 // Transfer string table.
602 // FIXME: The NonRelocatableStringpool starts with an empty string, but
603 // dsymutil-classic starts the reconstructed string table with 2 of these.
604 // Reproduce that behavior for now (there is corresponding code in
605 // transferSymbol).
606 OutFile << '\0';
607 std::vector<DwarfStringPoolEntryRef> Strings =
608 NewStrings.getEntriesForEmission();
609 for (auto EntryRef : Strings) {
610 OutFile.write(Ptr: EntryRef.getString().data(),
611 Size: EntryRef.getString().size() + 1);
612 }
613 }
614 assert(OutFile.tell() == StringStart + NewStringsSize);
615
616 // Pad till the EH frame start.
617 OutFile.write_zeros(NumZeros: EHFrameStart - (StringStart + NewStringsSize));
618 assert(OutFile.tell() == EHFrameStart);
619
620 // Transfer eh_frame.
621 if (EHFrameSize > 0)
622 OutFile << EHFrameData;
623 assert(OutFile.tell() == EHFrameStart + EHFrameSize);
624
625 // Pad till the Dwarf segment start.
626 OutFile.write_zeros(NumZeros: DwarfSegmentStart - (EHFrameStart + EHFrameSize));
627 assert(OutFile.tell() == DwarfSegmentStart);
628
629 // Emit the Dwarf sections contents.
630 for (const MCSection &Sec : MCAsm) {
631 uint64_t Pos = OutFile.tell();
632 OutFile.write_zeros(NumZeros: alignTo(Size: Pos, A: Sec.getAlign()) - Pos);
633 MCAsm.writeSectionData(OS&: OutFile, Section: &Sec);
634 }
635
636 // Apply relocations to the contents of the DWARF segment.
637 // We do this here because the final value written depend on the DWARF vm
638 // addr, which is only calculated in this function.
639 if (!RelocationsToApply.empty()) {
640 if (!OutFile.supportsSeeking())
641 report_fatal_error(
642 reason: "Cannot apply relocations to file that doesn't support seeking!");
643
644 uint64_t Pos = OutFile.tell();
645 for (auto &RelocationToApply : RelocationsToApply) {
646 OutFile.seek(off: DwarfSegmentStart + RelocationToApply.AddressFromDwarfStart);
647 int32_t Value = RelocationToApply.Value;
648 if (RelocationToApply.ShouldSubtractDwarfVM)
649 Value -= DwarfVMAddr;
650 OutFile.write(Ptr: (char *)&Value, Size: sizeof(int32_t));
651 }
652 OutFile.seek(off: Pos);
653 }
654
655 return true;
656}
657} // namespace MachOUtils
658} // namespace dsymutil
659} // namespace llvm
660