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//===- MachOReader.cpp ------------------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "MachOReader.h"
#include "../llvm-objcopy.h"
#include "Object.h"
#include "llvm/BinaryFormat/MachO.h"
#include "llvm/Object/MachO.h"
#include <memory>
namespace llvm {
namespace objcopy {
namespace macho {
void MachOReader::readHeader(Object &O) const {
O.Header.Magic = MachOObj.getHeader().magic;
O.Header.CPUType = MachOObj.getHeader().cputype;
O.Header.CPUSubType = MachOObj.getHeader().cpusubtype;
O.Header.FileType = MachOObj.getHeader().filetype;
O.Header.NCmds = MachOObj.getHeader().ncmds;
O.Header.SizeOfCmds = MachOObj.getHeader().sizeofcmds;
O.Header.Flags = MachOObj.getHeader().flags;
}
template <typename SectionType>
Section constructSectionCommon(SectionType Sec) {
Section S;
S.Sectname =
StringRef(Sec.sectname, strnlen(Sec.sectname, sizeof(Sec.sectname)))
.str();
S.Segname =
StringRef(Sec.segname, strnlen(Sec.segname, sizeof(Sec.sectname))).str();
S.Addr = Sec.addr;
S.Size = Sec.size;
S.Offset = Sec.offset;
S.Align = Sec.align;
S.RelOff = Sec.reloff;
S.NReloc = Sec.nreloc;
S.Flags = Sec.flags;
S.Reserved1 = Sec.reserved1;
S.Reserved2 = Sec.reserved2;
S.Reserved3 = 0;
return S;
}
template <typename SectionType> Section constructSection(SectionType Sec);
template <> Section constructSection(MachO::section Sec) {
return constructSectionCommon(Sec);
}
template <> Section constructSection(MachO::section_64 Sec) {
Section S = constructSectionCommon(Sec);
S.Reserved3 = Sec.reserved3;
return S;
}
// TODO: get rid of reportError and make MachOReader return Expected<> instead.
template <typename SectionType, typename SegmentType>
std::vector<Section>
extractSections(const object::MachOObjectFile::LoadCommandInfo &LoadCmd,
const object::MachOObjectFile &MachOObj,
size_t &NextSectionIndex) {
auto End = LoadCmd.Ptr + LoadCmd.C.cmdsize;
const SectionType *Curr =
reinterpret_cast<const SectionType *>(LoadCmd.Ptr + sizeof(SegmentType));
std::vector<Section> Sections;
for (; reinterpret_cast<const void *>(Curr) < End; Curr++) {
if (MachOObj.isLittleEndian() != sys::IsLittleEndianHost) {
SectionType Sec;
memcpy((void *)&Sec, Curr, sizeof(SectionType));
MachO::swapStruct(Sec);
Sections.push_back(constructSection(Sec));
} else {
Sections.push_back(constructSection(*Curr));
}
Section &S = Sections.back();
Expected<object::SectionRef> SecRef =
MachOObj.getSection(NextSectionIndex++);
if (!SecRef)
reportError(MachOObj.getFileName(), SecRef.takeError());
if (Expected<ArrayRef<uint8_t>> E =
MachOObj.getSectionContents(SecRef->getRawDataRefImpl()))
S.Content =
StringRef(reinterpret_cast<const char *>(E->data()), E->size());
else
reportError(MachOObj.getFileName(), E.takeError());
S.Relocations.reserve(S.NReloc);
for (auto RI = MachOObj.section_rel_begin(SecRef->getRawDataRefImpl()),
RE = MachOObj.section_rel_end(SecRef->getRawDataRefImpl());
RI != RE; ++RI) {
RelocationInfo R;
R.Symbol = nullptr; // We'll fill this field later.
R.Info = MachOObj.getRelocation(RI->getRawDataRefImpl());
R.Scattered = MachOObj.isRelocationScattered(R.Info);
S.Relocations.push_back(R);
}
assert(S.NReloc == S.Relocations.size() &&
"Incorrect number of relocations");
}
return Sections;
}
void MachOReader::readLoadCommands(Object &O) const {
// For MachO sections indices start from 1.
size_t NextSectionIndex = 1;
for (auto LoadCmd : MachOObj.load_commands()) {
LoadCommand LC;
switch (LoadCmd.C.cmd) {
case MachO::LC_SEGMENT:
LC.Sections = extractSections<MachO::section, MachO::segment_command>(
LoadCmd, MachOObj, NextSectionIndex);
break;
case MachO::LC_SEGMENT_64:
LC.Sections =
extractSections<MachO::section_64, MachO::segment_command_64>(
LoadCmd, MachOObj, NextSectionIndex);
break;
case MachO::LC_SYMTAB:
O.SymTabCommandIndex = O.LoadCommands.size();
break;
case MachO::LC_DYLD_INFO:
case MachO::LC_DYLD_INFO_ONLY:
O.DyLdInfoCommandIndex = O.LoadCommands.size();
break;
}
#define HANDLE_LOAD_COMMAND(LCName, LCValue, LCStruct) \
case MachO::LCName: \
memcpy((void *)&(LC.MachOLoadCommand.LCStruct##_data), LoadCmd.Ptr, \
sizeof(MachO::LCStruct)); \
if (MachOObj.isLittleEndian() != sys::IsLittleEndianHost) \
MachO::swapStruct(LC.MachOLoadCommand.LCStruct##_data); \
LC.Payload = ArrayRef<uint8_t>( \
reinterpret_cast<uint8_t *>(const_cast<char *>(LoadCmd.Ptr)) + \
sizeof(MachO::LCStruct), \
LoadCmd.C.cmdsize - sizeof(MachO::LCStruct)); \
break;
switch (LoadCmd.C.cmd) {
default:
memcpy((void *)&(LC.MachOLoadCommand.load_command_data), LoadCmd.Ptr,
sizeof(MachO::load_command));
if (MachOObj.isLittleEndian() != sys::IsLittleEndianHost)
MachO::swapStruct(LC.MachOLoadCommand.load_command_data);
LC.Payload = ArrayRef<uint8_t>(
reinterpret_cast<uint8_t *>(const_cast<char *>(LoadCmd.Ptr)) +
sizeof(MachO::load_command),
LoadCmd.C.cmdsize - sizeof(MachO::load_command));
break;
#include "llvm/BinaryFormat/MachO.def"
}
O.LoadCommands.push_back(std::move(LC));
}
}
template <typename nlist_t>
SymbolEntry constructSymbolEntry(StringRef StrTable, const nlist_t &nlist) {
assert(nlist.n_strx < StrTable.size() &&
"n_strx exceeds the size of the string table");
SymbolEntry SE;
SE.Name = StringRef(StrTable.data() + nlist.n_strx).str();
SE.n_type = nlist.n_type;
SE.n_sect = nlist.n_sect;
SE.n_desc = nlist.n_desc;
SE.n_value = nlist.n_value;
return SE;
}
void MachOReader::readSymbolTable(Object &O) const {
StringRef StrTable = MachOObj.getStringTableData();
for (auto Symbol : MachOObj.symbols()) {
SymbolEntry SE =
(MachOObj.is64Bit()
? constructSymbolEntry(
StrTable,
MachOObj.getSymbol64TableEntry(Symbol.getRawDataRefImpl()))
: constructSymbolEntry(
StrTable,
MachOObj.getSymbolTableEntry(Symbol.getRawDataRefImpl())));
O.SymTable.Symbols.push_back(llvm::make_unique<SymbolEntry>(SE));
}
}
void MachOReader::setSymbolInRelocationInfo(Object &O) const {
for (auto &LC : O.LoadCommands)
for (auto &Sec : LC.Sections)
for (auto &Reloc : Sec.Relocations)
if (!Reloc.Scattered) {
auto *Info = reinterpret_cast<MachO::relocation_info *>(&Reloc.Info);
Reloc.Symbol = O.SymTable.getSymbolByIndex(Info->r_symbolnum);
}
}
void MachOReader::readRebaseInfo(Object &O) const {
O.Rebases.Opcodes = MachOObj.getDyldInfoRebaseOpcodes();
}
void MachOReader::readBindInfo(Object &O) const {
O.Binds.Opcodes = MachOObj.getDyldInfoBindOpcodes();
}
void MachOReader::readWeakBindInfo(Object &O) const {
O.WeakBinds.Opcodes = MachOObj.getDyldInfoWeakBindOpcodes();
}
void MachOReader::readLazyBindInfo(Object &O) const {
O.LazyBinds.Opcodes = MachOObj.getDyldInfoLazyBindOpcodes();
}
void MachOReader::readExportInfo(Object &O) const {
O.Exports.Trie = MachOObj.getDyldInfoExportsTrie();
}
std::unique_ptr<Object> MachOReader::create() const {
auto Obj = llvm::make_unique<Object>();
readHeader(*Obj);
readLoadCommands(*Obj);
readSymbolTable(*Obj);
setSymbolInRelocationInfo(*Obj);
readRebaseInfo(*Obj);
readBindInfo(*Obj);
readWeakBindInfo(*Obj);
readLazyBindInfo(*Obj);
readExportInfo(*Obj);
return Obj;
}
} // end namespace macho
} // end namespace objcopy
} // end namespace llvm
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