1 //===- lib/ReaderWriter/MachO/MachONormalizedFileBinaryReader.cpp ---------===//
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
11 /// \file For mach-o object files, this implementation converts from
12 /// mach-o on-disk binary format to in-memory normalized mach-o.
24 #include "MachONormalizedFile.h"
25 #include "ArchHandler.h"
26 #include "MachONormalizedFileBinaryUtils.h"
27 #include "lld/Core/Error.h"
28 #include "lld/Core/LLVM.h"
29 #include "lld/Core/SharedLibraryFile.h"
30 #include "llvm/ADT/SmallString.h"
31 #include "llvm/ADT/StringRef.h"
32 #include "llvm/ADT/StringSwitch.h"
33 #include "llvm/ADT/STLExtras.h"
34 #include "llvm/ADT/Twine.h"
35 #include "llvm/Object/MachO.h"
36 #include "llvm/Support/Casting.h"
37 #include "llvm/Support/Errc.h"
38 #include "llvm/Support/ErrorHandling.h"
39 #include "llvm/Support/FileOutputBuffer.h"
40 #include "llvm/Support/Host.h"
41 #include "llvm/Support/MachO.h"
42 #include "llvm/Support/MemoryBuffer.h"
43 #include "llvm/Support/raw_ostream.h"
45 #include <system_error>
47 using namespace llvm::MachO;
48 using llvm::object::ExportEntry;
49 using llvm::object::MachOObjectFile;
53 namespace normalized {
55 // Utility to call a lambda expression on each load command.
56 static llvm::Error forEachLoadCommand(
57 StringRef lcRange, unsigned lcCount, bool isBig, bool is64,
58 std::function<bool(uint32_t cmd, uint32_t size, const char *lc)> func) {
59 const char* p = lcRange.begin();
60 for (unsigned i=0; i < lcCount; ++i) {
61 const load_command *lc = reinterpret_cast<const load_command*>(p);
63 const load_command *slc = lc;
64 if (isBig != llvm::sys::IsBigEndianHost) {
65 memcpy(&lcCopy, lc, sizeof(load_command));
69 if ( (p + slc->cmdsize) > lcRange.end() )
70 return llvm::make_error<GenericError>("Load command exceeds range");
72 if (func(slc->cmd, slc->cmdsize, p))
81 static std::error_code appendRelocations(Relocations &relocs, StringRef buffer,
83 uint32_t reloff, uint32_t nreloc) {
84 if ((reloff + nreloc*8) > buffer.size())
85 return make_error_code(llvm::errc::executable_format_error);
86 const any_relocation_info* relocsArray =
87 reinterpret_cast<const any_relocation_info*>(buffer.begin()+reloff);
89 for(uint32_t i=0; i < nreloc; ++i) {
90 relocs.push_back(unpackRelocation(relocsArray[i], bigEndian));
92 return std::error_code();
95 static std::error_code
96 appendIndirectSymbols(IndirectSymbols &isyms, StringRef buffer, bool isBig,
97 uint32_t istOffset, uint32_t istCount,
98 uint32_t startIndex, uint32_t count) {
99 if ((istOffset + istCount*4) > buffer.size())
100 return make_error_code(llvm::errc::executable_format_error);
101 if (startIndex+count > istCount)
102 return make_error_code(llvm::errc::executable_format_error);
103 const uint8_t *indirectSymbolArray = (const uint8_t *)buffer.data();
105 for(uint32_t i=0; i < count; ++i) {
106 isyms.push_back(read32(
107 indirectSymbolArray + (startIndex + i) * sizeof(uint32_t), isBig));
109 return std::error_code();
113 template <typename T> static T readBigEndian(T t) {
114 if (llvm::sys::IsLittleEndianHost)
115 llvm::sys::swapByteOrder(t);
120 static bool isMachOHeader(const mach_header *mh, bool &is64, bool &isBig) {
121 switch (read32(&mh->magic, false)) {
122 case llvm::MachO::MH_MAGIC:
126 case llvm::MachO::MH_MAGIC_64:
130 case llvm::MachO::MH_CIGAM:
134 case llvm::MachO::MH_CIGAM_64:
144 bool isThinObjectFile(StringRef path, MachOLinkingContext::Arch &arch) {
145 // Try opening and mapping file at path.
146 ErrorOr<std::unique_ptr<MemoryBuffer>> b = MemoryBuffer::getFileOrSTDIN(path);
150 // If file length < 32 it is too small to be mach-o object file.
151 StringRef fileBuffer = b->get()->getBuffer();
152 if (fileBuffer.size() < 32)
155 // If file buffer does not start with MH_MAGIC (and variants), not obj file.
156 const mach_header *mh = reinterpret_cast<const mach_header *>(
159 if (!isMachOHeader(mh, is64, isBig))
162 // If not MH_OBJECT, not object file.
163 if (read32(&mh->filetype, isBig) != MH_OBJECT)
166 // Lookup up arch from cpu/subtype pair.
167 arch = MachOLinkingContext::archFromCpuType(
168 read32(&mh->cputype, isBig),
169 read32(&mh->cpusubtype, isBig));
173 bool sliceFromFatFile(MemoryBufferRef mb, MachOLinkingContext::Arch arch,
174 uint32_t &offset, uint32_t &size) {
175 const char *start = mb.getBufferStart();
176 const llvm::MachO::fat_header *fh =
177 reinterpret_cast<const llvm::MachO::fat_header *>(start);
178 if (readBigEndian(fh->magic) != llvm::MachO::FAT_MAGIC)
180 uint32_t nfat_arch = readBigEndian(fh->nfat_arch);
181 const fat_arch *fstart =
182 reinterpret_cast<const fat_arch *>(start + sizeof(fat_header));
183 const fat_arch *fend =
184 reinterpret_cast<const fat_arch *>(start + sizeof(fat_header) +
185 sizeof(fat_arch) * nfat_arch);
186 const uint32_t reqCpuType = MachOLinkingContext::cpuTypeFromArch(arch);
187 const uint32_t reqCpuSubtype = MachOLinkingContext::cpuSubtypeFromArch(arch);
188 for (const fat_arch *fa = fstart; fa < fend; ++fa) {
189 if ((readBigEndian(fa->cputype) == reqCpuType) &&
190 (readBigEndian(fa->cpusubtype) == reqCpuSubtype)) {
191 offset = readBigEndian(fa->offset);
192 size = readBigEndian(fa->size);
193 if ((offset + size) > mb.getBufferSize())
201 /// Reads a mach-o file and produces an in-memory normalized view.
202 llvm::Expected<std::unique_ptr<NormalizedFile>>
203 readBinary(std::unique_ptr<MemoryBuffer> &mb,
204 const MachOLinkingContext::Arch arch) {
205 // Make empty NormalizedFile.
206 std::unique_ptr<NormalizedFile> f(new NormalizedFile());
208 const char *start = mb->getBufferStart();
209 size_t objSize = mb->getBufferSize();
210 const mach_header *mh = reinterpret_cast<const mach_header *>(start);
212 uint32_t sliceOffset;
214 if (sliceFromFatFile(mb->getMemBufferRef(), arch, sliceOffset, sliceSize)) {
215 start = &start[sliceOffset];
217 mh = reinterpret_cast<const mach_header *>(start);
220 // Determine endianness and pointer size for mach-o file.
222 if (!isMachOHeader(mh, is64, isBig))
223 return llvm::make_error<GenericError>("File is not a mach-o");
225 // Endian swap header, if needed.
226 mach_header headerCopy;
227 const mach_header *smh = mh;
228 if (isBig != llvm::sys::IsBigEndianHost) {
229 memcpy(&headerCopy, mh, sizeof(mach_header));
230 swapStruct(headerCopy);
234 // Validate head and load commands fit in buffer.
235 const uint32_t lcCount = smh->ncmds;
236 const char *lcStart =
237 start + (is64 ? sizeof(mach_header_64) : sizeof(mach_header));
238 StringRef lcRange(lcStart, smh->sizeofcmds);
239 if (lcRange.end() > (start + objSize))
240 return llvm::make_error<GenericError>("Load commands exceed file size");
242 // Get architecture from mach_header.
243 f->arch = MachOLinkingContext::archFromCpuType(smh->cputype, smh->cpusubtype);
244 if (f->arch != arch) {
245 return llvm::make_error<GenericError>(
246 Twine("file is wrong architecture. Expected "
247 "(" + MachOLinkingContext::nameFromArch(arch)
249 + MachOLinkingContext::nameFromArch(f->arch)
252 // Copy file type and flags
253 f->fileType = HeaderFileType(smh->filetype);
254 f->flags = smh->flags;
257 // Pre-scan load commands looking for indirect symbol table.
258 uint32_t indirectSymbolTableOffset = 0;
259 uint32_t indirectSymbolTableCount = 0;
260 auto ec = forEachLoadCommand(lcRange, lcCount, isBig, is64,
261 [&](uint32_t cmd, uint32_t size,
262 const char *lc) -> bool {
263 if (cmd == LC_DYSYMTAB) {
264 const dysymtab_command *d = reinterpret_cast<const dysymtab_command*>(lc);
265 indirectSymbolTableOffset = read32(&d->indirectsymoff, isBig);
266 indirectSymbolTableCount = read32(&d->nindirectsyms, isBig);
272 return std::move(ec);
274 // Walk load commands looking for segments/sections and the symbol table.
275 const data_in_code_entry *dataInCode = nullptr;
276 const dyld_info_command *dyldInfo = nullptr;
277 uint32_t dataInCodeSize = 0;
278 ec = forEachLoadCommand(lcRange, lcCount, isBig, is64,
279 [&] (uint32_t cmd, uint32_t size, const char* lc) -> bool {
283 const segment_command_64 *seg =
284 reinterpret_cast<const segment_command_64*>(lc);
285 const unsigned sectionCount = read32(&seg->nsects, isBig);
286 const section_64 *sects = reinterpret_cast<const section_64*>
287 (lc + sizeof(segment_command_64));
288 const unsigned lcSize = sizeof(segment_command_64)
289 + sectionCount*sizeof(section_64);
290 // Verify sections don't extend beyond end of segment load command.
293 for (unsigned i=0; i < sectionCount; ++i) {
294 const section_64 *sect = §s[i];
296 section.segmentName = getString16(sect->segname);
297 section.sectionName = getString16(sect->sectname);
298 section.type = (SectionType)(read32(§->flags, isBig) &
300 section.attributes = read32(§->flags, isBig) & SECTION_ATTRIBUTES;
301 section.alignment = 1 << read32(§->align, isBig);
302 section.address = read64(§->addr, isBig);
303 const uint8_t *content =
304 (const uint8_t *)start + read32(§->offset, isBig);
305 size_t contentSize = read64(§->size, isBig);
306 // Note: this assign() is copying the content bytes. Ideally,
307 // we can use a custom allocator for vector to avoid the copy.
308 section.content = llvm::makeArrayRef(content, contentSize);
309 appendRelocations(section.relocations, mb->getBuffer(), isBig,
310 read32(§->reloff, isBig),
311 read32(§->nreloc, isBig));
312 if (section.type == S_NON_LAZY_SYMBOL_POINTERS) {
313 appendIndirectSymbols(section.indirectSymbols, mb->getBuffer(),
315 indirectSymbolTableOffset,
316 indirectSymbolTableCount,
317 read32(§->reserved1, isBig),
320 f->sections.push_back(section);
326 const segment_command *seg =
327 reinterpret_cast<const segment_command*>(lc);
328 const unsigned sectionCount = read32(&seg->nsects, isBig);
329 const section *sects = reinterpret_cast<const section*>
330 (lc + sizeof(segment_command));
331 const unsigned lcSize = sizeof(segment_command)
332 + sectionCount*sizeof(section);
333 // Verify sections don't extend beyond end of segment load command.
336 for (unsigned i=0; i < sectionCount; ++i) {
337 const section *sect = §s[i];
339 section.segmentName = getString16(sect->segname);
340 section.sectionName = getString16(sect->sectname);
341 section.type = (SectionType)(read32(§->flags, isBig) &
344 read32((const uint8_t *)§->flags, isBig) & SECTION_ATTRIBUTES;
345 section.alignment = 1 << read32(§->align, isBig);
346 section.address = read32(§->addr, isBig);
347 const uint8_t *content =
348 (const uint8_t *)start + read32(§->offset, isBig);
349 size_t contentSize = read32(§->size, isBig);
350 // Note: this assign() is copying the content bytes. Ideally,
351 // we can use a custom allocator for vector to avoid the copy.
352 section.content = llvm::makeArrayRef(content, contentSize);
353 appendRelocations(section.relocations, mb->getBuffer(), isBig,
354 read32(§->reloff, isBig),
355 read32(§->nreloc, isBig));
356 if (section.type == S_NON_LAZY_SYMBOL_POINTERS) {
357 appendIndirectSymbols(
358 section.indirectSymbols, mb->getBuffer(), isBig,
359 indirectSymbolTableOffset, indirectSymbolTableCount,
360 read32(§->reserved1, isBig), contentSize / 4);
362 f->sections.push_back(section);
367 const symtab_command *st = reinterpret_cast<const symtab_command*>(lc);
368 const char *strings = start + read32(&st->stroff, isBig);
369 const uint32_t strSize = read32(&st->strsize, isBig);
370 // Validate string pool and symbol table all in buffer.
371 if (read32((const uint8_t *)&st->stroff, isBig) +
372 read32((const uint8_t *)&st->strsize, isBig) >
376 const uint32_t symOffset = read32(&st->symoff, isBig);
377 const uint32_t symCount = read32(&st->nsyms, isBig);
378 if ( symOffset+(symCount*sizeof(nlist_64)) > objSize)
380 const nlist_64 *symbols =
381 reinterpret_cast<const nlist_64 *>(start + symOffset);
382 // Convert each nlist_64 to a lld::mach_o::normalized::Symbol.
383 for(uint32_t i=0; i < symCount; ++i) {
385 memcpy(&tempSym, &symbols[i], sizeof(nlist_64));
386 const nlist_64 *sin = &tempSym;
387 if (isBig != llvm::sys::IsBigEndianHost)
390 if (sin->n_strx > strSize)
392 sout.name = &strings[sin->n_strx];
393 sout.type = (NListType)(sin->n_type & N_TYPE);
394 sout.scope = (sin->n_type & (N_PEXT|N_EXT));
395 sout.sect = sin->n_sect;
396 sout.desc = sin->n_desc;
397 sout.value = sin->n_value;
398 if (sout.type == N_UNDF)
399 f->undefinedSymbols.push_back(sout);
400 else if (sin->n_type & N_EXT)
401 f->globalSymbols.push_back(sout);
403 f->localSymbols.push_back(sout);
406 const uint32_t symOffset = read32(&st->symoff, isBig);
407 const uint32_t symCount = read32(&st->nsyms, isBig);
408 if ( symOffset+(symCount*sizeof(nlist)) > objSize)
410 const nlist *symbols =
411 reinterpret_cast<const nlist *>(start + symOffset);
412 // Convert each nlist to a lld::mach_o::normalized::Symbol.
413 for(uint32_t i=0; i < symCount; ++i) {
414 const nlist *sin = &symbols[i];
416 if (isBig != llvm::sys::IsBigEndianHost) {
417 tempSym = *sin; swapStruct(tempSym); sin = &tempSym;
420 if (sin->n_strx > strSize)
422 sout.name = &strings[sin->n_strx];
423 sout.type = (NListType)(sin->n_type & N_TYPE);
424 sout.scope = (sin->n_type & (N_PEXT|N_EXT));
425 sout.sect = sin->n_sect;
426 sout.desc = sin->n_desc;
427 sout.value = sin->n_value;
428 if (sout.type == N_UNDF)
429 f->undefinedSymbols.push_back(sout);
430 else if (sout.scope == (SymbolScope)N_EXT)
431 f->globalSymbols.push_back(sout);
433 f->localSymbols.push_back(sout);
439 const dylib_command *dl = reinterpret_cast<const dylib_command*>(lc);
440 f->installName = lc + read32(&dl->dylib.name, isBig);
441 f->currentVersion = read32(&dl->dylib.current_version, isBig);
442 f->compatVersion = read32(&dl->dylib.compatibility_version, isBig);
445 case LC_DATA_IN_CODE: {
446 const linkedit_data_command *ldc =
447 reinterpret_cast<const linkedit_data_command*>(lc);
448 dataInCode = reinterpret_cast<const data_in_code_entry *>(
449 start + read32(&ldc->dataoff, isBig));
450 dataInCodeSize = read32(&ldc->datasize, isBig);
454 case LC_LOAD_WEAK_DYLIB:
455 case LC_REEXPORT_DYLIB:
456 case LC_LOAD_UPWARD_DYLIB: {
457 const dylib_command *dl = reinterpret_cast<const dylib_command*>(lc);
458 DependentDylib entry;
459 entry.path = lc + read32(&dl->dylib.name, isBig);
460 entry.kind = LoadCommandType(cmd);
461 entry.compatVersion = read32(&dl->dylib.compatibility_version, isBig);
462 entry.currentVersion = read32(&dl->dylib.current_version, isBig);
463 f->dependentDylibs.push_back(entry);
467 const rpath_command *rpc = reinterpret_cast<const rpath_command *>(lc);
468 f->rpaths.push_back(lc + read32(&rpc->path, isBig));
472 case LC_DYLD_INFO_ONLY:
473 dyldInfo = reinterpret_cast<const dyld_info_command*>(lc);
475 case LC_VERSION_MIN_MACOSX:
476 case LC_VERSION_MIN_IPHONEOS:
477 case LC_VERSION_MIN_WATCHOS:
478 case LC_VERSION_MIN_TVOS:
479 // If we are emitting an object file, then we may take the load command
480 // kind from these commands and pass it on to the output
482 f->minOSVersionKind = (LoadCommandType)cmd;
488 return std::move(ec);
491 // Convert on-disk data_in_code_entry array to DataInCode vector.
492 for (unsigned i=0; i < dataInCodeSize/sizeof(data_in_code_entry); ++i) {
494 entry.offset = read32(&dataInCode[i].offset, isBig);
495 entry.length = read16(&dataInCode[i].length, isBig);
497 (DataRegionType)read16((const uint8_t *)&dataInCode[i].kind, isBig);
498 f->dataInCode.push_back(entry);
503 // If any exports, extract and add to normalized exportInfo vector.
504 if (dyldInfo->export_size) {
505 const uint8_t *trieStart = reinterpret_cast<const uint8_t*>(start +
506 dyldInfo->export_off);
507 ArrayRef<uint8_t> trie(trieStart, dyldInfo->export_size);
508 for (const ExportEntry &trieExport : MachOObjectFile::exports(trie)) {
510 normExport.name = trieExport.name().copy(f->ownedAllocations);
511 normExport.offset = trieExport.address();
512 normExport.kind = ExportSymbolKind(trieExport.flags() & EXPORT_SYMBOL_FLAGS_KIND_MASK);
513 normExport.flags = trieExport.flags() & ~EXPORT_SYMBOL_FLAGS_KIND_MASK;
514 normExport.otherOffset = trieExport.other();
515 if (!trieExport.otherName().empty())
516 normExport.otherName = trieExport.otherName().copy(f->ownedAllocations);
517 f->exportInfo.push_back(normExport);
525 class MachOObjectReader : public Reader {
527 MachOObjectReader(MachOLinkingContext &ctx) : _ctx(ctx) {}
529 bool canParse(file_magic magic, MemoryBufferRef mb) const override {
530 return (magic == llvm::sys::fs::file_magic::macho_object &&
531 mb.getBufferSize() > 32);
534 ErrorOr<std::unique_ptr<File>>
535 loadFile(std::unique_ptr<MemoryBuffer> mb,
536 const Registry ®istry) const override {
537 std::unique_ptr<File> ret =
538 llvm::make_unique<MachOFile>(std::move(mb), &_ctx);
539 return std::move(ret);
543 MachOLinkingContext &_ctx;
546 class MachODylibReader : public Reader {
548 MachODylibReader(MachOLinkingContext &ctx) : _ctx(ctx) {}
550 bool canParse(file_magic magic, MemoryBufferRef mb) const override {
552 case llvm::sys::fs::file_magic::macho_dynamically_linked_shared_lib:
553 case llvm::sys::fs::file_magic::macho_dynamically_linked_shared_lib_stub:
554 return mb.getBufferSize() > 32;
560 ErrorOr<std::unique_ptr<File>>
561 loadFile(std::unique_ptr<MemoryBuffer> mb,
562 const Registry ®istry) const override {
563 std::unique_ptr<File> ret =
564 llvm::make_unique<MachODylibFile>(std::move(mb), &_ctx);
565 return std::move(ret);
569 MachOLinkingContext &_ctx;
572 } // namespace normalized
573 } // namespace mach_o
575 void Registry::addSupportMachOObjects(MachOLinkingContext &ctx) {
576 MachOLinkingContext::Arch arch = ctx.arch();
577 add(std::unique_ptr<Reader>(new mach_o::normalized::MachOObjectReader(ctx)));
578 add(std::unique_ptr<Reader>(new mach_o::normalized::MachODylibReader(ctx)));
579 addKindTable(Reference::KindNamespace::mach_o, ctx.archHandler().kindArch(),
580 ctx.archHandler().kindStrings());
581 add(std::unique_ptr<YamlIOTaggedDocumentHandler>(
582 new mach_o::MachOYamlIOTaggedDocumentHandler(arch)));