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llvm-project/llvm/tools/obj2yaml/macho2yaml.cpp

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//===------ macho2yaml.cpp - obj2yaml conversion tool -----------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "Error.h"
#include "obj2yaml.h"
#include "llvm/DebugInfo/DWARF/DWARFContext.h"
#include "llvm/Object/MachOUniversal.h"
#include "llvm/ObjectYAML/ObjectYAML.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/LEB128.h"
#include <string.h> // for memcpy
using namespace llvm;
class MachODumper {
template <typename StructType>
const char *processLoadCommandData(
MachOYAML::LoadCommand &LC,
const llvm::object::MachOObjectFile::LoadCommandInfo &LoadCmd);
const object::MachOObjectFile &Obj;
void dumpHeader(std::unique_ptr<MachOYAML::Object> &Y);
void dumpLoadCommands(std::unique_ptr<MachOYAML::Object> &Y);
void dumpLinkEdit(std::unique_ptr<MachOYAML::Object> &Y);
void dumpRebaseOpcodes(std::unique_ptr<MachOYAML::Object> &Y);
void dumpBindOpcodes(std::vector<MachOYAML::BindOpcode> &BindOpcodes,
ArrayRef<uint8_t> OpcodeBuffer, bool Lazy = false);
void dumpExportTrie(std::unique_ptr<MachOYAML::Object> &Y);
void dumpSymbols(std::unique_ptr<MachOYAML::Object> &Y);
void dumpDebugAbbrev(DWARFContext &DCtx,
std::unique_ptr<MachOYAML::Object> &Y);
void dumpDebugStrings(DWARFContext &DCtx,
std::unique_ptr<MachOYAML::Object> &Y);
public:
MachODumper(const object::MachOObjectFile &O) : Obj(O) {}
Expected<std::unique_ptr<MachOYAML::Object>> dump();
};
#define HANDLE_LOAD_COMMAND(LCName, LCValue, LCStruct) \
case MachO::LCName: \
memcpy((void *) & (LC.Data.LCStruct##_data), LoadCmd.Ptr, \
sizeof(MachO::LCStruct)); \
if (Obj.isLittleEndian() != sys::IsLittleEndianHost) \
MachO::swapStruct(LC.Data.LCStruct##_data); \
EndPtr = processLoadCommandData<MachO::LCStruct>(LC, LoadCmd); \
break;
template <typename SectionType>
MachOYAML::Section constructSectionCommon(SectionType Sec) {
MachOYAML::Section 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;
TempSec.reserved3 = 0;
return TempSec;
}
template <typename SectionType>
MachOYAML::Section constructSection(SectionType Sec);
template <> MachOYAML::Section constructSection(MachO::section Sec) {
MachOYAML::Section TempSec = constructSectionCommon(Sec);
TempSec.reserved3 = 0;
return TempSec;
}
template <> MachOYAML::Section constructSection(MachO::section_64 Sec) {
MachOYAML::Section TempSec = constructSectionCommon(Sec);
TempSec.reserved3 = Sec.reserved3;
return TempSec;
}
template <typename SectionType, typename SegmentType>
const char *
extractSections(const llvm::object::MachOObjectFile::LoadCommandInfo &LoadCmd,
std::vector<MachOYAML::Section> &Sections,
bool IsLittleEndian) {
auto End = LoadCmd.Ptr + LoadCmd.C.cmdsize;
const SectionType *Curr =
reinterpret_cast<const SectionType *>(LoadCmd.Ptr + sizeof(SegmentType));
for (; reinterpret_cast<const void *>(Curr) < End; Curr++) {
if (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));
}
}
return reinterpret_cast<const char *>(Curr);
}
template <typename StructType>
const char *MachODumper::processLoadCommandData(
MachOYAML::LoadCommand &LC,
const llvm::object::MachOObjectFile::LoadCommandInfo &LoadCmd) {
return LoadCmd.Ptr + sizeof(StructType);
}
template <>
const char *MachODumper::processLoadCommandData<MachO::segment_command>(
MachOYAML::LoadCommand &LC,
const llvm::object::MachOObjectFile::LoadCommandInfo &LoadCmd) {
return extractSections<MachO::section, MachO::segment_command>(
LoadCmd, LC.Sections, Obj.isLittleEndian());
}
template <>
const char *MachODumper::processLoadCommandData<MachO::segment_command_64>(
MachOYAML::LoadCommand &LC,
const llvm::object::MachOObjectFile::LoadCommandInfo &LoadCmd) {
return extractSections<MachO::section_64, MachO::segment_command_64>(
LoadCmd, LC.Sections, Obj.isLittleEndian());
}
template <typename StructType>
const char *
readString(MachOYAML::LoadCommand &LC,
const llvm::object::MachOObjectFile::LoadCommandInfo &LoadCmd) {
auto Start = LoadCmd.Ptr + sizeof(StructType);
auto MaxSize = LoadCmd.C.cmdsize - sizeof(StructType);
auto Size = strnlen(Start, MaxSize);
LC.PayloadString = StringRef(Start, Size).str();
return Start + Size;
}
template <>
const char *MachODumper::processLoadCommandData<MachO::dylib_command>(
MachOYAML::LoadCommand &LC,
const llvm::object::MachOObjectFile::LoadCommandInfo &LoadCmd) {
return readString<MachO::dylib_command>(LC, LoadCmd);
}
template <>
const char *MachODumper::processLoadCommandData<MachO::dylinker_command>(
MachOYAML::LoadCommand &LC,
const llvm::object::MachOObjectFile::LoadCommandInfo &LoadCmd) {
return readString<MachO::dylinker_command>(LC, LoadCmd);
}
template <>
const char *MachODumper::processLoadCommandData<MachO::rpath_command>(
MachOYAML::LoadCommand &LC,
const llvm::object::MachOObjectFile::LoadCommandInfo &LoadCmd) {
return readString<MachO::rpath_command>(LC, LoadCmd);
}
template <>
const char *MachODumper::processLoadCommandData<MachO::build_version_command>(
MachOYAML::LoadCommand &LC,
const llvm::object::MachOObjectFile::LoadCommandInfo &LoadCmd) {
auto Start = LoadCmd.Ptr + sizeof(MachO::build_version_command);
auto NTools = LC.Data.build_version_command_data.ntools;
for (unsigned i = 0; i < NTools; ++i) {
auto Curr = Start + i * sizeof(MachO::build_tool_version);
MachO::build_tool_version BV;
memcpy((void *)&BV, Curr, sizeof(MachO::build_tool_version));
if (Obj.isLittleEndian() != sys::IsLittleEndianHost)
MachO::swapStruct(BV);
LC.Tools.push_back(BV);
}
return Start + NTools * sizeof(MachO::build_tool_version);
}
Expected<std::unique_ptr<MachOYAML::Object>> MachODumper::dump() {
auto Y = make_unique<MachOYAML::Object>();
Y->IsLittleEndian = Obj.isLittleEndian();
dumpHeader(Y);
dumpLoadCommands(Y);
dumpLinkEdit(Y);
std::unique_ptr<DWARFContext> DICtx = DWARFContext::create(Obj);
if (auto Err = dwarf2yaml(*DICtx, Y->DWARF))
return errorCodeToError(Err);
return std::move(Y);
}
void MachODumper::dumpHeader(std::unique_ptr<MachOYAML::Object> &Y) {
Y->Header.magic = Obj.getHeader().magic;
Y->Header.cputype = Obj.getHeader().cputype;
Y->Header.cpusubtype = Obj.getHeader().cpusubtype;
Y->Header.filetype = Obj.getHeader().filetype;
Y->Header.ncmds = Obj.getHeader().ncmds;
Y->Header.sizeofcmds = Obj.getHeader().sizeofcmds;
Y->Header.flags = Obj.getHeader().flags;
Y->Header.reserved = 0;
}
void MachODumper::dumpLoadCommands(std::unique_ptr<MachOYAML::Object> &Y) {
for (auto LoadCmd : Obj.load_commands()) {
MachOYAML::LoadCommand LC;
const char *EndPtr = LoadCmd.Ptr;
switch (LoadCmd.C.cmd) {
default:
memcpy((void *)&(LC.Data.load_command_data), LoadCmd.Ptr,
sizeof(MachO::load_command));
if (Obj.isLittleEndian() != sys::IsLittleEndianHost)
MachO::swapStruct(LC.Data.load_command_data);
EndPtr = processLoadCommandData<MachO::load_command>(LC, LoadCmd);
break;
#include "llvm/BinaryFormat/MachO.def"
}
auto RemainingBytes = LoadCmd.C.cmdsize - (EndPtr - LoadCmd.Ptr);
if (!std::all_of(EndPtr, &EndPtr[RemainingBytes],
[](const char C) { return C == 0; })) {
LC.PayloadBytes.insert(LC.PayloadBytes.end(), EndPtr,
&EndPtr[RemainingBytes]);
RemainingBytes = 0;
}
LC.ZeroPadBytes = RemainingBytes;
Y->LoadCommands.push_back(std::move(LC));
}
}
void MachODumper::dumpLinkEdit(std::unique_ptr<MachOYAML::Object> &Y) {
dumpRebaseOpcodes(Y);
dumpBindOpcodes(Y->LinkEdit.BindOpcodes, Obj.getDyldInfoBindOpcodes());
dumpBindOpcodes(Y->LinkEdit.WeakBindOpcodes,
Obj.getDyldInfoWeakBindOpcodes());
dumpBindOpcodes(Y->LinkEdit.LazyBindOpcodes, Obj.getDyldInfoLazyBindOpcodes(),
true);
dumpExportTrie(Y);
dumpSymbols(Y);
}
void MachODumper::dumpRebaseOpcodes(std::unique_ptr<MachOYAML::Object> &Y) {
MachOYAML::LinkEditData &LEData = Y->LinkEdit;
auto RebaseOpcodes = Obj.getDyldInfoRebaseOpcodes();
for (auto OpCode = RebaseOpcodes.begin(); OpCode != RebaseOpcodes.end();
++OpCode) {
MachOYAML::RebaseOpcode RebaseOp;
RebaseOp.Opcode =
static_cast<MachO::RebaseOpcode>(*OpCode & MachO::REBASE_OPCODE_MASK);
RebaseOp.Imm = *OpCode & MachO::REBASE_IMMEDIATE_MASK;
unsigned Count;
uint64_t ULEB = 0;
switch (RebaseOp.Opcode) {
case MachO::REBASE_OPCODE_DO_REBASE_ULEB_TIMES_SKIPPING_ULEB:
ULEB = decodeULEB128(OpCode + 1, &Count);
RebaseOp.ExtraData.push_back(ULEB);
OpCode += Count;
LLVM_FALLTHROUGH;
// Intentionally no break here -- This opcode has two ULEB values
case MachO::REBASE_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB:
case MachO::REBASE_OPCODE_ADD_ADDR_ULEB:
case MachO::REBASE_OPCODE_DO_REBASE_ULEB_TIMES:
case MachO::REBASE_OPCODE_DO_REBASE_ADD_ADDR_ULEB:
ULEB = decodeULEB128(OpCode + 1, &Count);
RebaseOp.ExtraData.push_back(ULEB);
OpCode += Count;
break;
default:
break;
}
LEData.RebaseOpcodes.push_back(RebaseOp);
if (RebaseOp.Opcode == MachO::REBASE_OPCODE_DONE)
break;
}
}
StringRef ReadStringRef(const uint8_t *Start) {
const uint8_t *Itr = Start;
for (; *Itr; ++Itr)
;
return StringRef(reinterpret_cast<const char *>(Start), Itr - Start);
}
void MachODumper::dumpBindOpcodes(
std::vector<MachOYAML::BindOpcode> &BindOpcodes,
ArrayRef<uint8_t> OpcodeBuffer, bool Lazy) {
for (auto OpCode = OpcodeBuffer.begin(); OpCode != OpcodeBuffer.end();
++OpCode) {
MachOYAML::BindOpcode BindOp;
BindOp.Opcode =
static_cast<MachO::BindOpcode>(*OpCode & MachO::BIND_OPCODE_MASK);
BindOp.Imm = *OpCode & MachO::BIND_IMMEDIATE_MASK;
unsigned Count;
uint64_t ULEB = 0;
int64_t SLEB = 0;
switch (BindOp.Opcode) {
case MachO::BIND_OPCODE_DO_BIND_ULEB_TIMES_SKIPPING_ULEB:
ULEB = decodeULEB128(OpCode + 1, &Count);
BindOp.ULEBExtraData.push_back(ULEB);
OpCode += Count;
LLVM_FALLTHROUGH;
// Intentionally no break here -- this opcode has two ULEB values
case MachO::BIND_OPCODE_SET_DYLIB_ORDINAL_ULEB:
case MachO::BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB:
case MachO::BIND_OPCODE_ADD_ADDR_ULEB:
case MachO::BIND_OPCODE_DO_BIND_ADD_ADDR_ULEB:
ULEB = decodeULEB128(OpCode + 1, &Count);
BindOp.ULEBExtraData.push_back(ULEB);
OpCode += Count;
break;
case MachO::BIND_OPCODE_SET_ADDEND_SLEB:
SLEB = decodeSLEB128(OpCode + 1, &Count);
BindOp.SLEBExtraData.push_back(SLEB);
OpCode += Count;
break;
case MachO::BIND_OPCODE_SET_SYMBOL_TRAILING_FLAGS_IMM:
BindOp.Symbol = ReadStringRef(OpCode + 1);
OpCode += BindOp.Symbol.size() + 1;
break;
default:
break;
}
BindOpcodes.push_back(BindOp);
// Lazy bindings have DONE opcodes between operations, so we need to keep
// processing after a DONE.
if (!Lazy && BindOp.Opcode == MachO::BIND_OPCODE_DONE)
break;
}
}
/*!
* /brief processes a node from the export trie, and its children.
*
* To my knowledge there is no documentation of the encoded format of this data
* other than in the heads of the Apple linker engineers. To that end hopefully
* this comment and the implementation below can serve to light the way for
* anyone crazy enough to come down this path in the future.
*
* This function reads and preserves the trie structure of the export trie. To
* my knowledge there is no code anywhere else that reads the data and preserves
* the Trie. LD64 (sources available at opensource.apple.com) has a similar
* implementation that parses the export trie into a vector. That code as well
* as LLVM's libObject MachO implementation were the basis for this.
*
* The export trie is an encoded trie. The node serialization is a bit awkward.
* The below pseudo-code is the best description I've come up with for it.
*
* struct SerializedNode {
* ULEB128 TerminalSize;
* struct TerminalData { <-- This is only present if TerminalSize > 0
* ULEB128 Flags;
* ULEB128 Address; <-- Present if (! Flags & REEXPORT )
* ULEB128 Other; <-- Present if ( Flags & REEXPORT ||
* Flags & STUB_AND_RESOLVER )
* char[] ImportName; <-- Present if ( Flags & REEXPORT )
* }
* uint8_t ChildrenCount;
* Pair<char[], ULEB128> ChildNameOffsetPair[ChildrenCount];
* SerializedNode Children[ChildrenCount]
* }
*
* Terminal nodes are nodes that represent actual exports. They can appear
* anywhere in the tree other than at the root; they do not need to be leaf
* nodes. When reading the data out of the trie this routine reads it in-order,
* but it puts the child names and offsets directly into the child nodes. This
* results in looping over the children twice during serialization and
* de-serialization, but it makes the YAML representation more human readable.
*
* Below is an example of the graph from a "Hello World" executable:
*
* -------
* | '' |
* -------
* |
* -------
* | '_' |
* -------
* |
* |----------------------------------------|
* | |
* ------------------------ ---------------------
* | '_mh_execute_header' | | 'main' |
* | Flags: 0x00000000 | | Flags: 0x00000000 |
* | Addr: 0x00000000 | | Addr: 0x00001160 |
* ------------------------ ---------------------
*
* This graph represents the trie for the exports "__mh_execute_header" and
* "_main". In the graph only the "_main" and "__mh_execute_header" nodes are
* terminal.
*/
const uint8_t *processExportNode(const uint8_t *CurrPtr,
const uint8_t *const End,
MachOYAML::ExportEntry &Entry) {
if (CurrPtr >= End)
return CurrPtr;
unsigned Count = 0;
Entry.TerminalSize = decodeULEB128(CurrPtr, &Count);
CurrPtr += Count;
if (Entry.TerminalSize != 0) {
Entry.Flags = decodeULEB128(CurrPtr, &Count);
CurrPtr += Count;
if (Entry.Flags & MachO::EXPORT_SYMBOL_FLAGS_REEXPORT) {
Entry.Address = 0;
Entry.Other = decodeULEB128(CurrPtr, &Count);
CurrPtr += Count;
Entry.ImportName = std::string(reinterpret_cast<const char *>(CurrPtr));
} else {
Entry.Address = decodeULEB128(CurrPtr, &Count);
CurrPtr += Count;
if (Entry.Flags & MachO::EXPORT_SYMBOL_FLAGS_STUB_AND_RESOLVER) {
Entry.Other = decodeULEB128(CurrPtr, &Count);
CurrPtr += Count;
} else
Entry.Other = 0;
}
}
uint8_t childrenCount = *CurrPtr++;
if (childrenCount == 0)
return CurrPtr;
Entry.Children.insert(Entry.Children.begin(), (size_t)childrenCount,
MachOYAML::ExportEntry());
for (auto &Child : Entry.Children) {
Child.Name = std::string(reinterpret_cast<const char *>(CurrPtr));
CurrPtr += Child.Name.length() + 1;
Child.NodeOffset = decodeULEB128(CurrPtr, &Count);
CurrPtr += Count;
}
for (auto &Child : Entry.Children) {
CurrPtr = processExportNode(CurrPtr, End, Child);
}
return CurrPtr;
}
void MachODumper::dumpExportTrie(std::unique_ptr<MachOYAML::Object> &Y) {
MachOYAML::LinkEditData &LEData = Y->LinkEdit;
auto ExportsTrie = Obj.getDyldInfoExportsTrie();
processExportNode(ExportsTrie.begin(), ExportsTrie.end(), LEData.ExportTrie);
}
template <typename nlist_t>
MachOYAML::NListEntry constructNameList(const nlist_t &nlist) {
MachOYAML::NListEntry NL;
NL.n_strx = nlist.n_strx;
NL.n_type = nlist.n_type;
NL.n_sect = nlist.n_sect;
NL.n_desc = nlist.n_desc;
NL.n_value = nlist.n_value;
return NL;
}
void MachODumper::dumpSymbols(std::unique_ptr<MachOYAML::Object> &Y) {
MachOYAML::LinkEditData &LEData = Y->LinkEdit;
for (auto Symbol : Obj.symbols()) {
MachOYAML::NListEntry NLE =
Obj.is64Bit()
? constructNameList<MachO::nlist_64>(
Obj.getSymbol64TableEntry(Symbol.getRawDataRefImpl()))
: constructNameList<MachO::nlist>(
Obj.getSymbolTableEntry(Symbol.getRawDataRefImpl()));
LEData.NameList.push_back(NLE);
}
StringRef RemainingTable = Obj.getStringTableData();
while (RemainingTable.size() > 0) {
auto SymbolPair = RemainingTable.split('\0');
RemainingTable = SymbolPair.second;
LEData.StringTable.push_back(SymbolPair.first);
}
}
Error macho2yaml(raw_ostream &Out, const object::MachOObjectFile &Obj) {
MachODumper Dumper(Obj);
Expected<std::unique_ptr<MachOYAML::Object>> YAML = Dumper.dump();
if (!YAML)
return YAML.takeError();
yaml::YamlObjectFile YAMLFile;
YAMLFile.MachO = std::move(YAML.get());
yaml::Output Yout(Out);
Yout << YAMLFile;
return Error::success();
}
Error macho2yaml(raw_ostream &Out, const object::MachOUniversalBinary &Obj) {
yaml::YamlObjectFile YAMLFile;
YAMLFile.FatMachO.reset(new MachOYAML::UniversalBinary());
MachOYAML::UniversalBinary &YAML = *YAMLFile.FatMachO;
YAML.Header.magic = Obj.getMagic();
YAML.Header.nfat_arch = Obj.getNumberOfObjects();
for (auto Slice : Obj.objects()) {
MachOYAML::FatArch arch;
arch.cputype = Slice.getCPUType();
arch.cpusubtype = Slice.getCPUSubType();
arch.offset = Slice.getOffset();
arch.size = Slice.getSize();
arch.align = Slice.getAlign();
arch.reserved = Slice.getReserved();
YAML.FatArchs.push_back(arch);
auto SliceObj = Slice.getAsObjectFile();
if (!SliceObj)
return SliceObj.takeError();
MachODumper Dumper(*SliceObj.get());
Expected<std::unique_ptr<MachOYAML::Object>> YAMLObj = Dumper.dump();
if (!YAMLObj)
return YAMLObj.takeError();
YAML.Slices.push_back(*YAMLObj.get());
}
yaml::Output Yout(Out);
Yout << YAML;
return Error::success();
}
std::error_code macho2yaml(raw_ostream &Out, const object::Binary &Binary) {
if (const auto *MachOObj = dyn_cast<object::MachOUniversalBinary>(&Binary)) {
if (auto Err = macho2yaml(Out, *MachOObj)) {
return errorToErrorCode(std::move(Err));
}
return obj2yaml_error::success;
}
if (const auto *MachOObj = dyn_cast<object::MachOObjectFile>(&Binary)) {
if (auto Err = macho2yaml(Out, *MachOObj)) {
return errorToErrorCode(std::move(Err));
}
return obj2yaml_error::success;
}
return obj2yaml_error::unsupported_obj_file_format;
}
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