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llvm-project/llvm/tools/yaml2obj/yaml2macho.cpp

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//===- yaml2macho - Convert YAML to a Mach object file --------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
///
/// \file
/// \brief The Mach component of yaml2obj.
///
//===----------------------------------------------------------------------===//
#include "yaml2obj.h"
#include "llvm/ObjectYAML/MachOYAML.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/LEB128.h"
#include "llvm/Support/MachO.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), is64Bit(true), 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));
assert((is64Bit || Obj.Header.reserved == 0xDEADBEEFu) &&
"32-bit MachO has reserved in header");
assert((!is64Bit || Obj.Header.reserved != 0xDEADBEEFu) &&
"64-bit MachO has missing reserved in header");
}
Error writeMachO(raw_ostream &OS);
private:
Error writeHeader(raw_ostream &OS);
Error writeLoadCommands(raw_ostream &OS);
Error writeSectionData(raw_ostream &OS);
Error writeLinkEditData(raw_ostream &OS);
void writeBindOpcodes(raw_ostream &OS,
std::vector<MachOYAML::BindOpcode> &BindOpcodes);
// LinkEdit writers
Error writeRebaseOpcodes(raw_ostream &OS);
Error writeBasicBindOpcodes(raw_ostream &OS);
Error writeWeakBindOpcodes(raw_ostream &OS);
Error writeLazyBindOpcodes(raw_ostream &OS);
Error writeNameList(raw_ostream &OS);
Error writeStringTable(raw_ostream &OS);
Error 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;
};
Error MachOWriter::writeMachO(raw_ostream &OS) {
fileStart = OS.tell();
if (auto Err = writeHeader(OS))
return Err;
if (auto Err = writeLoadCommands(OS))
return Err;
if (auto Err = writeSectionData(OS))
return Err;
return Error::success();
}
Error 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;
auto header_size =
is64Bit ? sizeof(MachO::mach_header_64) : sizeof(MachO::mach_header);
OS.write((const char *)&Header, header_size);
return Error::success();
}
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) {
return 0;
}
template <>
size_t writeLoadCommandData<MachO::segment_command>(MachOYAML::LoadCommand &LC,
raw_ostream &OS) {
size_t BytesWritten = 0;
for (const auto &Sec : LC.Sections) {
auto TempSec = constructSection<MachO::section>(Sec);
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) {
size_t BytesWritten = 0;
for (const auto &Sec : LC.Sections) {
auto TempSec = constructSection<MachO::section_64>(Sec);
TempSec.reserved3 = Sec.reserved3;
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.PayloadString.empty()) {
OS.write(LC.PayloadString.c_str(), LC.PayloadString.length());
BytesWritten = LC.PayloadString.length();
}
return BytesWritten;
}
template <>
size_t writeLoadCommandData<MachO::dylib_command>(MachOYAML::LoadCommand &LC,
raw_ostream &OS) {
return writePayloadString(LC, OS);
}
template <>
size_t writeLoadCommandData<MachO::dylinker_command>(MachOYAML::LoadCommand &LC,
raw_ostream &OS) {
return writePayloadString(LC, OS);
}
template <>
size_t writeLoadCommandData<MachO::rpath_command>(MachOYAML::LoadCommand &LC,
raw_ostream &OS) {
return writePayloadString(LC, OS);
}
void ZeroFillBytes(raw_ostream &OS, size_t Size) {
std::vector<uint8_t> FillData;
FillData.insert(FillData.begin(), 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;
FillData.insert(FillData.begin(), (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);
}
Error MachOWriter::writeLoadCommands(raw_ostream &OS) {
for (auto &LC : Obj.LoadCommands) {
size_t BytesWritten = 0;
#define HANDLE_LOAD_COMMAND(LCName, LCValue, LCStruct) \
case MachO::LCName: \
OS.write(reinterpret_cast<const char *>(&(LC.Data.LCStruct##_data)), \
sizeof(MachO::LCStruct)); \
BytesWritten = sizeof(MachO::LCStruct); \
BytesWritten += writeLoadCommandData<MachO::LCStruct>(LC, OS); \
break;
switch (LC.Data.load_command_data.cmd) {
default:
OS.write(reinterpret_cast<const char *>(&(LC.Data.load_command_data)),
sizeof(MachO::load_command));
BytesWritten = sizeof(MachO::load_command);
BytesWritten += writeLoadCommandData<MachO::load_command>(LC, OS);
break;
#include "llvm/Support/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);
}
}
return Error::success();
}
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:
auto currOffset = OS.tell() - fileStart;
auto segname = LC.Data.segment_command_data.segname;
uint64_t segOff = is64Bit ? LC.Data.segment_command_64_data.fileoff
: LC.Data.segment_command_data.fileoff;
if (0 == strncmp(&segname[0], "__LINKEDIT", 16)) {
if (auto Err = writeLinkEditData(OS))
return Err;
} else {
// Zero Fill any data between the end of the last thing we wrote and the
// start of this section.
if (currOffset < segOff) {
ZeroFillBytes(OS, segOff - currOffset);
}
for (auto &Sec : LC.Sections) {
// Zero Fill any data between the end of the last thing we wrote and
// the
// start of this section.
assert(
OS.tell() - fileStart <= Sec.offset &&
"Wrote too much data somewhere, section offsets don't line up.");
currOffset = OS.tell() - fileStart;
if (currOffset < Sec.offset) {
ZeroFillBytes(OS, Sec.offset - currOffset);
}
// Fills 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();
}
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);
}
Error MachOWriter::writeExportTrie(raw_ostream &OS) {
dumpExportEntry(OS, Obj.LinkEdit.ExportTrie);
return Error::success();
}
template <typename NListType>
void writeNListEntry(MachOYAML::NListEntry &NLE, raw_ostream &OS) {
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;
OS.write(reinterpret_cast<const char *>(&ListEntry), sizeof(NListType));
}
Error MachOWriter::writeLinkEditData(raw_ostream &OS) {
typedef Error (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;
}
}
std::sort(WriteQueue.begin(), WriteQueue.end(),
[](const writeOperation &a, const writeOperation &b) {
return a.first < b.first;
});
for (auto writeOp : WriteQueue) {
ZeroToOffset(OS, writeOp.first);
if (auto Err = (this->*writeOp.second)(OS))
return Err;
}
return Error::success();
}
Error 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);
}
}
return Error::success();
}
Error MachOWriter::writeBasicBindOpcodes(raw_ostream &OS) {
writeBindOpcodes(OS, Obj.LinkEdit.BindOpcodes);
return Error::success();
}
Error MachOWriter::writeWeakBindOpcodes(raw_ostream &OS) {
writeBindOpcodes(OS, Obj.LinkEdit.WeakBindOpcodes);
return Error::success();
}
Error MachOWriter::writeLazyBindOpcodes(raw_ostream &OS) {
writeBindOpcodes(OS, Obj.LinkEdit.LazyBindOpcodes);
return Error::success();
}
Error MachOWriter::writeNameList(raw_ostream &OS) {
for (auto NLE : Obj.LinkEdit.NameList) {
if (is64Bit)
writeNListEntry<MachO::nlist_64>(NLE, OS);
else
writeNListEntry<MachO::nlist>(NLE, OS);
}
return Error::success();
}
Error MachOWriter::writeStringTable(raw_ostream &OS) {
for (auto Str : Obj.LinkEdit.StringTable) {
OS.write(Str.data(), Str.size());
OS.write('\0');
}
return Error::success();
}
} // end anonymous namespace
int yaml2macho(yaml::Input &YIn, raw_ostream &Out) {
MachOYAML::Object Doc;
YIn >> Doc;
if (YIn.error()) {
errs() << "yaml2obj: Failed to parse YAML file!\n";
return 1;
}
MachOWriter Writer(Doc);
if (auto Err = Writer.writeMachO(Out)) {
errs() << toString(std::move(Err));
return 1;
}
return 0;
}
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