//===- yaml2macho - Convert YAML to a Mach object file --------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
///
/// \file
/// The Mach component of yaml2obj.
///
//===----------------------------------------------------------------------===//
#include "llvm/BinaryFormat/MachO.h"
#include "llvm/ObjectYAML/DWARFEmitter.h"
#include "llvm/ObjectYAML/ObjectYAML.h"
#include "llvm/ObjectYAML/yaml2obj.h"
#include "llvm/Support/Errc.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/LEB128.h"
#include "llvm/Support/YAMLTraits.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Support/Format.h"
using namespace llvm;
namespace {
class MachOWriter {
public:
MachOWriter(MachOYAML::Object &Obj) : Obj(Obj), fileStart(0) {
is64Bit = Obj.Header.magic == MachO::MH_MAGIC_64 ||
Obj.Header.magic == MachO::MH_CIGAM_64;
memset(reinterpret_cast<void *>(&Header), 0, sizeof(MachO::mach_header_64));
}
Error writeMachO(raw_ostream &OS);
private:
void writeHeader(raw_ostream &OS);
void writeLoadCommands(raw_ostream &OS);
Error writeSectionData(raw_ostream &OS);
void writeRelocations(raw_ostream &OS);
void writeLinkEditData(raw_ostream &OS);
void writeBindOpcodes(raw_ostream &OS,
std::vector<MachOYAML::BindOpcode> &BindOpcodes);
// LinkEdit writers
void writeRebaseOpcodes(raw_ostream &OS);
void writeBasicBindOpcodes(raw_ostream &OS);
void writeWeakBindOpcodes(raw_ostream &OS);
void writeLazyBindOpcodes(raw_ostream &OS);
void writeNameList(raw_ostream &OS);
void writeStringTable(raw_ostream &OS);
void writeExportTrie(raw_ostream &OS);
void dumpExportEntry(raw_ostream &OS, MachOYAML::ExportEntry &Entry);
void ZeroToOffset(raw_ostream &OS, size_t offset);
MachOYAML::Object &Obj;
bool is64Bit;
uint64_t fileStart;
MachO::mach_header_64 Header;
// Old PPC Object Files didn't have __LINKEDIT segments, the data was just
// stuck at the end of the file.
bool FoundLinkEditSeg = false;
};
Error MachOWriter::writeMachO(raw_ostream &OS) {
fileStart = OS.tell();
writeHeader(OS);
writeLoadCommands(OS);
if (Error Err = writeSectionData(OS))
return Err;
writeRelocations(OS);
if (!FoundLinkEditSeg)
writeLinkEditData(OS);
return Error::success();
}
void MachOWriter::writeHeader(raw_ostream &OS) {
Header.magic = Obj.Header.magic;
Header.cputype = Obj.Header.cputype;
Header.cpusubtype = Obj.Header.cpusubtype;
Header.filetype = Obj.Header.filetype;
Header.ncmds = Obj.Header.ncmds;
Header.sizeofcmds = Obj.Header.sizeofcmds;
Header.flags = Obj.Header.flags;
Header.reserved = Obj.Header.reserved;
if (Obj.IsLittleEndian != sys::IsLittleEndianHost)
MachO::swapStruct(Header);
auto header_size =
is64Bit ? sizeof(MachO::mach_header_64) : sizeof(MachO::mach_header);
OS.write((const char *)&Header, header_size);
}
template <typename SectionType>
SectionType constructSection(MachOYAML::Section Sec) {
SectionType TempSec;
memcpy(reinterpret_cast<void *>(&TempSec.sectname[0]), &Sec.sectname[0], 16);
memcpy(reinterpret_cast<void *>(&TempSec.segname[0]), &Sec.segname[0], 16);
TempSec.addr = Sec.addr;
TempSec.size = Sec.size;
TempSec.offset = Sec.offset;
TempSec.align = Sec.align;
TempSec.reloff = Sec.reloff;
TempSec.nreloc = Sec.nreloc;
TempSec.flags = Sec.flags;
TempSec.reserved1 = Sec.reserved1;
TempSec.reserved2 = Sec.reserved2;
return TempSec;
}
template <typename StructType>
size_t writeLoadCommandData(MachOYAML::LoadCommand &LC, raw_ostream &OS,
bool IsLittleEndian) {
return 0;
}
template <>
size_t writeLoadCommandData<MachO::segment_command>(MachOYAML::LoadCommand &LC,
raw_ostream &OS,
bool IsLittleEndian) {
size_t BytesWritten = 0;
for (const auto &Sec : LC.Sections) {
auto TempSec = constructSection<MachO::section>(Sec);
if (IsLittleEndian != sys::IsLittleEndianHost)
MachO::swapStruct(TempSec);
OS.write(reinterpret_cast<const char *>(&(TempSec)),
sizeof(MachO::section));
BytesWritten += sizeof(MachO::section);
}
return BytesWritten;
}
template <>
size_t writeLoadCommandData<MachO::segment_command_64>(
MachOYAML::LoadCommand &LC, raw_ostream &OS, bool IsLittleEndian) {
size_t BytesWritten = 0;
for (const auto &Sec : LC.Sections) {
auto TempSec = constructSection<MachO::section_64>(Sec);
TempSec.reserved3 = Sec.reserved3;
if (IsLittleEndian != sys::IsLittleEndianHost)
MachO::swapStruct(TempSec);
OS.write(reinterpret_cast<const char *>(&(TempSec)),
sizeof(MachO::section_64));
BytesWritten += sizeof(MachO::section_64);
}
return BytesWritten;
}
size_t writePayloadString(MachOYAML::LoadCommand &LC, raw_ostream &OS) {
size_t BytesWritten = 0;
if (!LC.Content.empty()) {
OS.write(LC.Content.c_str(), LC.Content.length());
BytesWritten = LC.Content.length();
}
return BytesWritten;
}
template <>
size_t writeLoadCommandData<MachO::dylib_command>(MachOYAML::LoadCommand &LC,
raw_ostream &OS,
bool IsLittleEndian) {
return writePayloadString(LC, OS);
}
template <>
size_t writeLoadCommandData<MachO::dylinker_command>(MachOYAML::LoadCommand &LC,
raw_ostream &OS,
bool IsLittleEndian) {
return writePayloadString(LC, OS);
}
template <>
size_t writeLoadCommandData<MachO::rpath_command>(MachOYAML::LoadCommand &LC,
raw_ostream &OS,
bool IsLittleEndian) {
return writePayloadString(LC, OS);
}
template <>
size_t writeLoadCommandData<MachO::build_version_command>(
MachOYAML::LoadCommand &LC, raw_ostream &OS, bool IsLittleEndian) {
size_t BytesWritten = 0;
for (const auto &T : LC.Tools) {
struct MachO::build_tool_version tool = T;
if (IsLittleEndian != sys::IsLittleEndianHost)
MachO::swapStruct(tool);
OS.write(reinterpret_cast<const char *>(&tool),
sizeof(MachO::build_tool_version));
BytesWritten += sizeof(MachO::build_tool_version);
}
return BytesWritten;
}
void ZeroFillBytes(raw_ostream &OS, size_t Size) {
std::vector<uint8_t> FillData(Size, 0);
OS.write(reinterpret_cast<char *>(FillData.data()), Size);
}
void Fill(raw_ostream &OS, size_t Size, uint32_t Data) {
std::vector<uint32_t> FillData((Size / 4) + 1, Data);
OS.write(reinterpret_cast<char *>(FillData.data()), Size);
}
void MachOWriter::ZeroToOffset(raw_ostream &OS, size_t Offset) {
auto currOffset = OS.tell() - fileStart;
if (currOffset < Offset)
ZeroFillBytes(OS, Offset - currOffset);
}
void MachOWriter::writeLoadCommands(raw_ostream &OS) {
for (auto &LC : Obj.LoadCommands) {
size_t BytesWritten = 0;
llvm::MachO::macho_load_command Data = LC.Data;
#define HANDLE_LOAD_COMMAND(LCName, LCValue, LCStruct) \
case MachO::LCName: \
if (Obj.IsLittleEndian != sys::IsLittleEndianHost) \
MachO::swapStruct(Data.LCStruct##_data); \
OS.write(reinterpret_cast<const char *>(&(Data.LCStruct##_data)), \
sizeof(MachO::LCStruct)); \
BytesWritten = sizeof(MachO::LCStruct); \
BytesWritten += \
writeLoadCommandData<MachO::LCStruct>(LC, OS, Obj.IsLittleEndian); \
break;
switch (LC.Data.load_command_data.cmd) {
default:
if (Obj.IsLittleEndian != sys::IsLittleEndianHost)
MachO::swapStruct(Data.load_command_data);
OS.write(reinterpret_cast<const char *>(&(Data.load_command_data)),
sizeof(MachO::load_command));
BytesWritten = sizeof(MachO::load_command);
BytesWritten +=
writeLoadCommandData<MachO::load_command>(LC, OS, Obj.IsLittleEndian);
break;
#include "llvm/BinaryFormat/MachO.def"
}
if (LC.PayloadBytes.size() > 0) {
OS.write(reinterpret_cast<const char *>(LC.PayloadBytes.data()),
LC.PayloadBytes.size());
BytesWritten += LC.PayloadBytes.size();
}
if (LC.ZeroPadBytes > 0) {
ZeroFillBytes(OS, LC.ZeroPadBytes);
BytesWritten += LC.ZeroPadBytes;
}
// Fill remaining bytes with 0. This will only get hit in partially
// specified test cases.
auto BytesRemaining = LC.Data.load_command_data.cmdsize - BytesWritten;
if (BytesRemaining > 0) {
ZeroFillBytes(OS, BytesRemaining);
}
}
}
Error MachOWriter::writeSectionData(raw_ostream &OS) {
for (auto &LC : Obj.LoadCommands) {
switch (LC.Data.load_command_data.cmd) {
case MachO::LC_SEGMENT:
case MachO::LC_SEGMENT_64:
uint64_t segOff = is64Bit ? LC.Data.segment_command_64_data.fileoff
: LC.Data.segment_command_data.fileoff;
if (0 ==
strncmp(&LC.Data.segment_command_data.segname[0], "__LINKEDIT", 16)) {
FoundLinkEditSeg = true;
writeLinkEditData(OS);
}
for (auto &Sec : LC.Sections) {
ZeroToOffset(OS, Sec.offset);
// Zero Fill any data between the end of the last thing we wrote and the
// start of this section.
if (OS.tell() - fileStart > Sec.offset && Sec.offset != (uint32_t)0)
return createStringError(
errc::invalid_argument,
"wrote too much data somewhere, section offsets don't line up");
StringRef SectName(Sec.sectname,
strnlen(Sec.sectname, sizeof(Sec.sectname)));
// If the section's content is specified in the 'DWARF' entry, we will
// emit it regardless of the section's segname.
if (Obj.DWARF.getNonEmptySectionNames().count(SectName.substr(2))) {
if (Sec.content)
return createStringError(errc::invalid_argument,
"cannot specify section '" + SectName +
"' contents in the 'DWARF' entry and "
"the 'content' at the same time");
auto EmitFunc = DWARFYAML::getDWARFEmitterByName(SectName.substr(2));
if (Error Err = EmitFunc(OS, Obj.DWARF))
return Err;
continue;
}
// Skip if it's a virtual section.
if (MachO::isVirtualSection(Sec.flags & MachO::SECTION_TYPE))
continue;
if (Sec.content) {
yaml::BinaryRef Content = *Sec.content;
Content.writeAsBinary(OS);
ZeroFillBytes(OS, Sec.size - Content.binary_size());
} else {
// Fill section data with 0xDEADBEEF.
Fill(OS, Sec.size, 0xDEADBEEFu);
}
}
uint64_t segSize = is64Bit ? LC.Data.segment_command_64_data.filesize
: LC.Data.segment_command_data.filesize;
ZeroToOffset(OS, segOff + segSize);
break;
}
}
return Error::success();
}
// The implementation of makeRelocationInfo and makeScatteredRelocationInfo is
// consistent with how libObject parses MachO binary files. For the reference
// see getStruct, getRelocation, getPlainRelocationPCRel,
// getPlainRelocationLength and related methods in MachOObjectFile.cpp
static MachO::any_relocation_info
makeRelocationInfo(const MachOYAML::Relocation &R, bool IsLE) {
assert(!R.is_scattered && "non-scattered relocation expected");
MachO::any_relocation_info MRE;
MRE.r_word0 = R.address;
if (IsLE)
MRE.r_word1 = ((unsigned)R.symbolnum << 0) | ((unsigned)R.is_pcrel << 24) |
((unsigned)R.length << 25) | ((unsigned)R.is_extern << 27) |
((unsigned)R.type << 28);
else
MRE.r_word1 = ((unsigned)R.symbolnum << 8) | ((unsigned)R.is_pcrel << 7) |
((unsigned)R.length << 5) | ((unsigned)R.is_extern << 4) |
((unsigned)R.type << 0);
return MRE;
}
static MachO::any_relocation_info
makeScatteredRelocationInfo(const MachOYAML::Relocation &R) {
assert(R.is_scattered && "scattered relocation expected");
MachO::any_relocation_info MRE;
MRE.r_word0 = (((unsigned)R.address << 0) | ((unsigned)R.type << 24) |
((unsigned)R.length << 28) | ((unsigned)R.is_pcrel << 30) |
MachO::R_SCATTERED);
MRE.r_word1 = R.value;
return MRE;
}
void MachOWriter::writeRelocations(raw_ostream &OS) {
for (const MachOYAML::LoadCommand &LC : Obj.LoadCommands) {
switch (LC.Data.load_command_data.cmd) {
case MachO::LC_SEGMENT:
case MachO::LC_SEGMENT_64:
for (const MachOYAML::Section &Sec : LC.Sections) {
if (Sec.relocations.empty())
continue;
ZeroToOffset(OS, Sec.reloff);
for (const MachOYAML::Relocation &R : Sec.relocations) {
MachO::any_relocation_info MRE =
R.is_scattered ? makeScatteredRelocationInfo(R)
: makeRelocationInfo(R, Obj.IsLittleEndian);
if (Obj.IsLittleEndian != sys::IsLittleEndianHost)
MachO::swapStruct(MRE);
OS.write(reinterpret_cast<const char *>(&MRE),
sizeof(MachO::any_relocation_info));
}
}
}
}
}
void MachOWriter::writeBindOpcodes(
raw_ostream &OS, std::vector<MachOYAML::BindOpcode> &BindOpcodes) {
for (auto Opcode : BindOpcodes) {
uint8_t OpByte = Opcode.Opcode | Opcode.Imm;
OS.write(reinterpret_cast<char *>(&OpByte), 1);
for (auto Data : Opcode.ULEBExtraData) {
encodeULEB128(Data, OS);
}
for (auto Data : Opcode.SLEBExtraData) {
encodeSLEB128(Data, OS);
}
if (!Opcode.Symbol.empty()) {
OS.write(Opcode.Symbol.data(), Opcode.Symbol.size());
OS.write('\0');
}
}
}
void MachOWriter::dumpExportEntry(raw_ostream &OS,
MachOYAML::ExportEntry &Entry) {
encodeSLEB128(Entry.TerminalSize, OS);
if (Entry.TerminalSize > 0) {
encodeSLEB128(Entry.Flags, OS);
if (Entry.Flags & MachO::EXPORT_SYMBOL_FLAGS_REEXPORT) {
encodeSLEB128(Entry.Other, OS);
OS << Entry.ImportName;
OS.write('\0');
} else {
encodeSLEB128(Entry.Address, OS);
if (Entry.Flags & MachO::EXPORT_SYMBOL_FLAGS_STUB_AND_RESOLVER)
encodeSLEB128(Entry.Other, OS);
}
}
OS.write(static_cast<uint8_t>(Entry.Children.size()));
for (auto EE : Entry.Children) {
OS << EE.Name;
OS.write('\0');
encodeSLEB128(EE.NodeOffset, OS);
}
for (auto EE : Entry.Children)
dumpExportEntry(OS, EE);
}
void MachOWriter::writeExportTrie(raw_ostream &OS) {
dumpExportEntry(OS, Obj.LinkEdit.ExportTrie);
}
template <typename NListType>
void writeNListEntry(MachOYAML::NListEntry &NLE, raw_ostream &OS,
bool IsLittleEndian) {
NListType ListEntry;
ListEntry.n_strx = NLE.n_strx;
ListEntry.n_type = NLE.n_type;
ListEntry.n_sect = NLE.n_sect;
ListEntry.n_desc = NLE.n_desc;
ListEntry.n_value = NLE.n_value;
if (IsLittleEndian != sys::IsLittleEndianHost)
MachO::swapStruct(ListEntry);
OS.write(reinterpret_cast<const char *>(&ListEntry), sizeof(NListType));
}
void MachOWriter::writeLinkEditData(raw_ostream &OS) {
typedef void (MachOWriter::*writeHandler)(raw_ostream &);
typedef std::pair<uint64_t, writeHandler> writeOperation;
std::vector<writeOperation> WriteQueue;
MachO::dyld_info_command *DyldInfoOnlyCmd = 0;
MachO::symtab_command *SymtabCmd = 0;
for (auto &LC : Obj.LoadCommands) {
switch (LC.Data.load_command_data.cmd) {
case MachO::LC_SYMTAB:
SymtabCmd = &LC.Data.symtab_command_data;
WriteQueue.push_back(
std::make_pair(SymtabCmd->symoff, &MachOWriter::writeNameList));
WriteQueue.push_back(
std::make_pair(SymtabCmd->stroff, &MachOWriter::writeStringTable));
break;
case MachO::LC_DYLD_INFO_ONLY:
DyldInfoOnlyCmd = &LC.Data.dyld_info_command_data;
WriteQueue.push_back(std::make_pair(DyldInfoOnlyCmd->rebase_off,
&MachOWriter::writeRebaseOpcodes));
WriteQueue.push_back(std::make_pair(DyldInfoOnlyCmd->bind_off,
&MachOWriter::writeBasicBindOpcodes));
WriteQueue.push_back(std::make_pair(DyldInfoOnlyCmd->weak_bind_off,
&MachOWriter::writeWeakBindOpcodes));
WriteQueue.push_back(std::make_pair(DyldInfoOnlyCmd->lazy_bind_off,
&MachOWriter::writeLazyBindOpcodes));
WriteQueue.push_back(std::make_pair(DyldInfoOnlyCmd->export_off,
&MachOWriter::writeExportTrie));
break;
}
}
llvm::sort(WriteQueue, [](const writeOperation &a, const writeOperation &b) {
return a.first < b.first;
});
for (auto writeOp : WriteQueue) {
ZeroToOffset(OS, writeOp.first);
(this->*writeOp.second)(OS);
}
}
void MachOWriter::writeRebaseOpcodes(raw_ostream &OS) {
MachOYAML::LinkEditData &LinkEdit = Obj.LinkEdit;
for (auto Opcode : LinkEdit.RebaseOpcodes) {
uint8_t OpByte = Opcode.Opcode | Opcode.Imm;
OS.write(reinterpret_cast<char *>(&OpByte), 1);
for (auto Data : Opcode.ExtraData)
encodeULEB128(Data, OS);
}
}
void MachOWriter::writeBasicBindOpcodes(raw_ostream &OS) {
writeBindOpcodes(OS, Obj.LinkEdit.BindOpcodes);
}
void MachOWriter::writeWeakBindOpcodes(raw_ostream &OS) {
writeBindOpcodes(OS, Obj.LinkEdit.WeakBindOpcodes);
}
void MachOWriter::writeLazyBindOpcodes(raw_ostream &OS) {
writeBindOpcodes(OS, Obj.LinkEdit.LazyBindOpcodes);
}
void MachOWriter::writeNameList(raw_ostream &OS) {
for (auto NLE : Obj.LinkEdit.NameList) {
if (is64Bit)
writeNListEntry<MachO::nlist_64>(NLE, OS, Obj.IsLittleEndian);
else
writeNListEntry<MachO::nlist>(NLE, OS, Obj.IsLittleEndian);
}
}
void MachOWriter::writeStringTable(raw_ostream &OS) {
for (auto Str : Obj.LinkEdit.StringTable) {
OS.write(Str.data(), Str.size());
OS.write('\0');
}
}
class UniversalWriter {
public:
UniversalWriter(yaml::YamlObjectFile &ObjectFile)
: ObjectFile(ObjectFile), fileStart(0) {}
Error writeMachO(raw_ostream &OS);
private:
void writeFatHeader(raw_ostream &OS);
void writeFatArchs(raw_ostream &OS);
void ZeroToOffset(raw_ostream &OS, size_t offset);
yaml::YamlObjectFile &ObjectFile;
uint64_t fileStart;
};
Error UniversalWriter::writeMachO(raw_ostream &OS) {
fileStart = OS.tell();
if (ObjectFile.MachO) {
MachOWriter Writer(*ObjectFile.MachO);
return Writer.writeMachO(OS);
}
writeFatHeader(OS);
writeFatArchs(OS);
auto &FatFile = *ObjectFile.FatMachO;
if (FatFile.FatArchs.size() < FatFile.Slices.size())
return createStringError(
errc::invalid_argument,
"cannot write 'Slices' if not described in 'FatArches'");
for (size_t i = 0; i < FatFile.Slices.size(); i++) {
ZeroToOffset(OS, FatFile.FatArchs[i].offset);
MachOWriter Writer(FatFile.Slices[i]);
if (Error Err = Writer.writeMachO(OS))
return Err;
auto SliceEnd = FatFile.FatArchs[i].offset + FatFile.FatArchs[i].size;
ZeroToOffset(OS, SliceEnd);
}
return Error::success();
}
void UniversalWriter::writeFatHeader(raw_ostream &OS) {
auto &FatFile = *ObjectFile.FatMachO;
MachO::fat_header header;
header.magic = FatFile.Header.magic;
header.nfat_arch = FatFile.Header.nfat_arch;
if (sys::IsLittleEndianHost)
swapStruct(header);
OS.write(reinterpret_cast<const char *>(&header), sizeof(MachO::fat_header));
}
template <typename FatArchType>
FatArchType constructFatArch(MachOYAML::FatArch &Arch) {
FatArchType FatArch;
FatArch.cputype = Arch.cputype;
FatArch.cpusubtype = Arch.cpusubtype;
FatArch.offset = Arch.offset;
FatArch.size = Arch.size;
FatArch.align = Arch.align;
return FatArch;
}
template <typename StructType>
void writeFatArch(MachOYAML::FatArch &LC, raw_ostream &OS) {}
template <>
void writeFatArch<MachO::fat_arch>(MachOYAML::FatArch &Arch, raw_ostream &OS) {
auto FatArch = constructFatArch<MachO::fat_arch>(Arch);
if (sys::IsLittleEndianHost)
swapStruct(FatArch);
OS.write(reinterpret_cast<const char *>(&FatArch), sizeof(MachO::fat_arch));
}
template <>
void writeFatArch<MachO::fat_arch_64>(MachOYAML::FatArch &Arch,
raw_ostream &OS) {
auto FatArch = constructFatArch<MachO::fat_arch_64>(Arch);
FatArch.reserved = Arch.reserved;
if (sys::IsLittleEndianHost)
swapStruct(FatArch);
OS.write(reinterpret_cast<const char *>(&FatArch),
sizeof(MachO::fat_arch_64));
}
void UniversalWriter::writeFatArchs(raw_ostream &OS) {
auto &FatFile = *ObjectFile.FatMachO;
bool is64Bit = FatFile.Header.magic == MachO::FAT_MAGIC_64;
for (auto Arch : FatFile.FatArchs) {
if (is64Bit)
writeFatArch<MachO::fat_arch_64>(Arch, OS);
else
writeFatArch<MachO::fat_arch>(Arch, OS);
}
}
void UniversalWriter::ZeroToOffset(raw_ostream &OS, size_t Offset) {
auto currOffset = OS.tell() - fileStart;
if (currOffset < Offset)
ZeroFillBytes(OS, Offset - currOffset);
}
} // end anonymous namespace
namespace llvm {
namespace yaml {
bool yaml2macho(YamlObjectFile &Doc, raw_ostream &Out, ErrorHandler EH) {
UniversalWriter Writer(Doc);
if (Error Err = Writer.writeMachO(Out)) {
handleAllErrors(std::move(Err),
[&](const ErrorInfoBase &Err) { EH(Err.message()); });
return false;
}
return true;
}
} // namespace yaml
} // namespace llvm
