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MachONormalizedFileBinaryWriter.cpp
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MachONormalizedFileBinaryWriter.cpp
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//===- lib/ReaderWriter/MachO/MachONormalizedFileBinaryWriter.cpp ---------===//
//
// The LLVM Linker
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
///
/// \file For mach-o object files, this implementation converts normalized
/// mach-o in memory to mach-o binary on disk.
///
/// +---------------+
/// | binary mach-o |
/// +---------------+
/// ^
/// |
/// |
/// +------------+
/// | normalized |
/// +------------+
#include "MachONormalizedFile.h"
#include "MachONormalizedFileBinaryUtils.h"
#include "lld/Common/LLVM.h"
#include "lld/Core/Error.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/ilist.h"
#include "llvm/ADT/ilist_node.h"
#include "llvm/BinaryFormat/MachO.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/Errc.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/FileOutputBuffer.h"
#include "llvm/Support/Format.h"
#include "llvm/Support/Host.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/raw_ostream.h"
#include <functional>
#include <list>
#include <map>
#include <system_error>
using namespace llvm::MachO;
namespace lld {
namespace mach_o {
namespace normalized {
struct TrieNode; // Forward declaration.
struct TrieEdge : public llvm::ilist_node<TrieEdge> {
TrieEdge(StringRef s, TrieNode *node) : _subString(s), _child(node) {}
StringRef _subString;
struct TrieNode *_child;
};
} // namespace normalized
} // namespace mach_o
} // namespace lld
namespace llvm {
using lld::mach_o::normalized::TrieEdge;
template <>
struct ilist_alloc_traits<TrieEdge> : ilist_noalloc_traits<TrieEdge> {};
} // namespace llvm
namespace lld {
namespace mach_o {
namespace normalized {
struct TrieNode {
typedef llvm::ilist<TrieEdge> TrieEdgeList;
TrieNode(StringRef s)
: _cummulativeString(s), _address(0), _flags(0), _other(0),
_trieOffset(0), _hasExportInfo(false) {}
~TrieNode() = default;
void addSymbol(const Export &entry, BumpPtrAllocator &allocator,
std::vector<TrieNode *> &allNodes);
void addOrderedNodes(const Export &entry,
std::vector<TrieNode *> &allNodes);
bool updateOffset(uint32_t &offset);
void appendToByteBuffer(ByteBuffer &out);
private:
StringRef _cummulativeString;
TrieEdgeList _children;
uint64_t _address;
uint64_t _flags;
uint64_t _other;
StringRef _importedName;
uint32_t _trieOffset;
bool _hasExportInfo;
bool _ordered = false;
};
/// Utility class for writing a mach-o binary file given an in-memory
/// normalized file.
class MachOFileLayout {
public:
/// All layout computation is done in the constructor.
MachOFileLayout(const NormalizedFile &file);
/// Returns the final file size as computed in the constructor.
size_t size() const;
// Returns size of the mach_header and load commands.
size_t headerAndLoadCommandsSize() const;
/// Writes the normalized file as a binary mach-o file to the specified
/// path. This does not have a stream interface because the generated
/// file may need the 'x' bit set.
llvm::Error writeBinary(StringRef path);
private:
uint32_t loadCommandsSize(uint32_t &count);
void buildFileOffsets();
void writeMachHeader();
llvm::Error writeLoadCommands();
void writeSectionContent();
void writeRelocations();
void writeSymbolTable();
void writeRebaseInfo();
void writeBindingInfo();
void writeLazyBindingInfo();
void writeExportInfo();
void writeFunctionStartsInfo();
void writeDataInCodeInfo();
void writeLinkEditContent();
void buildLinkEditInfo();
void buildRebaseInfo();
void buildBindInfo();
void buildLazyBindInfo();
void buildExportTrie();
void computeFunctionStartsSize();
void computeDataInCodeSize();
void computeSymbolTableSizes();
void buildSectionRelocations();
void appendSymbols(const std::vector<Symbol> &symbols,
uint32_t &symOffset, uint32_t &strOffset);
uint32_t indirectSymbolIndex(const Section §, uint32_t &index);
uint32_t indirectSymbolElementSize(const Section §);
// For use as template parameter to load command methods.
struct MachO64Trait {
typedef llvm::MachO::segment_command_64 command;
typedef llvm::MachO::section_64 section;
enum { LC = llvm::MachO::LC_SEGMENT_64 };
};
// For use as template parameter to load command methods.
struct MachO32Trait {
typedef llvm::MachO::segment_command command;
typedef llvm::MachO::section section;
enum { LC = llvm::MachO::LC_SEGMENT };
};
template <typename T>
llvm::Error writeSingleSegmentLoadCommand(uint8_t *&lc);
template <typename T> llvm::Error writeSegmentLoadCommands(uint8_t *&lc);
uint32_t pointerAlign(uint32_t value);
static StringRef dyldPath();
struct SegExtraInfo {
uint32_t fileOffset;
uint32_t fileSize;
std::vector<const Section*> sections;
};
typedef std::map<const Segment*, SegExtraInfo> SegMap;
struct SectionExtraInfo {
uint32_t fileOffset;
};
typedef std::map<const Section*, SectionExtraInfo> SectionMap;
const NormalizedFile &_file;
std::error_code _ec;
uint8_t *_buffer;
const bool _is64;
const bool _swap;
const bool _bigEndianArch;
uint64_t _seg1addr;
uint32_t _startOfLoadCommands;
uint32_t _countOfLoadCommands;
uint32_t _endOfLoadCommands;
uint32_t _startOfRelocations;
uint32_t _startOfFunctionStarts;
uint32_t _startOfDataInCode;
uint32_t _startOfSymbols;
uint32_t _startOfIndirectSymbols;
uint32_t _startOfSymbolStrings;
uint32_t _endOfSymbolStrings;
uint32_t _symbolTableLocalsStartIndex;
uint32_t _symbolTableGlobalsStartIndex;
uint32_t _symbolTableUndefinesStartIndex;
uint32_t _symbolStringPoolSize;
uint32_t _symbolTableSize;
uint32_t _functionStartsSize;
uint32_t _dataInCodeSize;
uint32_t _indirectSymbolTableCount;
// Used in object file creation only
uint32_t _startOfSectionsContent;
uint32_t _endOfSectionsContent;
// Used in final linked image only
uint32_t _startOfLinkEdit;
uint32_t _startOfRebaseInfo;
uint32_t _endOfRebaseInfo;
uint32_t _startOfBindingInfo;
uint32_t _endOfBindingInfo;
uint32_t _startOfLazyBindingInfo;
uint32_t _endOfLazyBindingInfo;
uint32_t _startOfExportTrie;
uint32_t _endOfExportTrie;
uint32_t _endOfLinkEdit;
uint64_t _addressOfLinkEdit;
SegMap _segInfo;
SectionMap _sectInfo;
ByteBuffer _rebaseInfo;
ByteBuffer _bindingInfo;
ByteBuffer _lazyBindingInfo;
ByteBuffer _weakBindingInfo;
ByteBuffer _exportTrie;
};
size_t headerAndLoadCommandsSize(const NormalizedFile &file) {
MachOFileLayout layout(file);
return layout.headerAndLoadCommandsSize();
}
StringRef MachOFileLayout::dyldPath() {
return "/usr/lib/dyld";
}
uint32_t MachOFileLayout::pointerAlign(uint32_t value) {
return llvm::alignTo(value, _is64 ? 8 : 4);
}
size_t MachOFileLayout::headerAndLoadCommandsSize() const {
return _endOfLoadCommands;
}
MachOFileLayout::MachOFileLayout(const NormalizedFile &file)
: _file(file),
_is64(MachOLinkingContext::is64Bit(file.arch)),
_swap(!MachOLinkingContext::isHostEndian(file.arch)),
_bigEndianArch(MachOLinkingContext::isBigEndian(file.arch)),
_seg1addr(INT64_MAX) {
_startOfLoadCommands = _is64 ? sizeof(mach_header_64) : sizeof(mach_header);
const size_t segCommandBaseSize =
(_is64 ? sizeof(segment_command_64) : sizeof(segment_command));
const size_t sectsSize = (_is64 ? sizeof(section_64) : sizeof(section));
if (file.fileType == llvm::MachO::MH_OBJECT) {
// object files have just one segment load command containing all sections
_endOfLoadCommands = _startOfLoadCommands
+ segCommandBaseSize
+ file.sections.size() * sectsSize
+ sizeof(symtab_command);
_countOfLoadCommands = 2;
if (file.hasMinVersionLoadCommand) {
_endOfLoadCommands += sizeof(version_min_command);
_countOfLoadCommands++;
}
if (!_file.functionStarts.empty()) {
_endOfLoadCommands += sizeof(linkedit_data_command);
_countOfLoadCommands++;
}
if (_file.generateDataInCodeLoadCommand) {
_endOfLoadCommands += sizeof(linkedit_data_command);
_countOfLoadCommands++;
}
// Assign file offsets to each section.
_startOfSectionsContent = _endOfLoadCommands;
unsigned relocCount = 0;
uint64_t offset = _startOfSectionsContent;
for (const Section § : file.sections) {
if (isZeroFillSection(sect.type))
_sectInfo[§].fileOffset = 0;
else {
offset = llvm::alignTo(offset, sect.alignment);
_sectInfo[§].fileOffset = offset;
offset += sect.content.size();
}
relocCount += sect.relocations.size();
}
_endOfSectionsContent = offset;
computeSymbolTableSizes();
computeFunctionStartsSize();
computeDataInCodeSize();
// Align start of relocations.
_startOfRelocations = pointerAlign(_endOfSectionsContent);
_startOfFunctionStarts = _startOfRelocations + relocCount * 8;
_startOfDataInCode = _startOfFunctionStarts + _functionStartsSize;
_startOfSymbols = _startOfDataInCode + _dataInCodeSize;
// Add Indirect symbol table.
_startOfIndirectSymbols = _startOfSymbols + _symbolTableSize;
// Align start of symbol table and symbol strings.
_startOfSymbolStrings = _startOfIndirectSymbols
+ pointerAlign(_indirectSymbolTableCount * sizeof(uint32_t));
_endOfSymbolStrings = _startOfSymbolStrings
+ pointerAlign(_symbolStringPoolSize);
_endOfLinkEdit = _endOfSymbolStrings;
DEBUG_WITH_TYPE("MachOFileLayout",
llvm::dbgs() << "MachOFileLayout()\n"
<< " startOfLoadCommands=" << _startOfLoadCommands << "\n"
<< " countOfLoadCommands=" << _countOfLoadCommands << "\n"
<< " endOfLoadCommands=" << _endOfLoadCommands << "\n"
<< " startOfRelocations=" << _startOfRelocations << "\n"
<< " startOfSymbols=" << _startOfSymbols << "\n"
<< " startOfSymbolStrings=" << _startOfSymbolStrings << "\n"
<< " endOfSymbolStrings=" << _endOfSymbolStrings << "\n"
<< " startOfSectionsContent=" << _startOfSectionsContent << "\n"
<< " endOfSectionsContent=" << _endOfSectionsContent << "\n");
} else {
// Final linked images have one load command per segment.
_endOfLoadCommands = _startOfLoadCommands
+ loadCommandsSize(_countOfLoadCommands);
// Assign section file offsets.
buildFileOffsets();
buildLinkEditInfo();
// LINKEDIT of final linked images has in order:
// rebase info, binding info, lazy binding info, weak binding info,
// data-in-code, symbol table, indirect symbol table, symbol table strings.
_startOfRebaseInfo = _startOfLinkEdit;
_endOfRebaseInfo = _startOfRebaseInfo + _rebaseInfo.size();
_startOfBindingInfo = _endOfRebaseInfo;
_endOfBindingInfo = _startOfBindingInfo + _bindingInfo.size();
_startOfLazyBindingInfo = _endOfBindingInfo;
_endOfLazyBindingInfo = _startOfLazyBindingInfo + _lazyBindingInfo.size();
_startOfExportTrie = _endOfLazyBindingInfo;
_endOfExportTrie = _startOfExportTrie + _exportTrie.size();
_startOfFunctionStarts = _endOfExportTrie;
_startOfDataInCode = _startOfFunctionStarts + _functionStartsSize;
_startOfSymbols = _startOfDataInCode + _dataInCodeSize;
_startOfIndirectSymbols = _startOfSymbols + _symbolTableSize;
_startOfSymbolStrings = _startOfIndirectSymbols
+ pointerAlign(_indirectSymbolTableCount * sizeof(uint32_t));
_endOfSymbolStrings = _startOfSymbolStrings
+ pointerAlign(_symbolStringPoolSize);
_endOfLinkEdit = _endOfSymbolStrings;
DEBUG_WITH_TYPE("MachOFileLayout",
llvm::dbgs() << "MachOFileLayout()\n"
<< " startOfLoadCommands=" << _startOfLoadCommands << "\n"
<< " countOfLoadCommands=" << _countOfLoadCommands << "\n"
<< " endOfLoadCommands=" << _endOfLoadCommands << "\n"
<< " startOfLinkEdit=" << _startOfLinkEdit << "\n"
<< " startOfRebaseInfo=" << _startOfRebaseInfo << "\n"
<< " endOfRebaseInfo=" << _endOfRebaseInfo << "\n"
<< " startOfBindingInfo=" << _startOfBindingInfo << "\n"
<< " endOfBindingInfo=" << _endOfBindingInfo << "\n"
<< " startOfLazyBindingInfo=" << _startOfLazyBindingInfo << "\n"
<< " endOfLazyBindingInfo=" << _endOfLazyBindingInfo << "\n"
<< " startOfExportTrie=" << _startOfExportTrie << "\n"
<< " endOfExportTrie=" << _endOfExportTrie << "\n"
<< " startOfFunctionStarts=" << _startOfFunctionStarts << "\n"
<< " startOfDataInCode=" << _startOfDataInCode << "\n"
<< " startOfSymbols=" << _startOfSymbols << "\n"
<< " startOfSymbolStrings=" << _startOfSymbolStrings << "\n"
<< " endOfSymbolStrings=" << _endOfSymbolStrings << "\n"
<< " addressOfLinkEdit=" << _addressOfLinkEdit << "\n");
}
}
uint32_t MachOFileLayout::loadCommandsSize(uint32_t &count) {
uint32_t size = 0;
count = 0;
const size_t segCommandSize =
(_is64 ? sizeof(segment_command_64) : sizeof(segment_command));
const size_t sectionSize = (_is64 ? sizeof(section_64) : sizeof(section));
// Add LC_SEGMENT for each segment.
size += _file.segments.size() * segCommandSize;
count += _file.segments.size();
// Add section record for each section.
size += _file.sections.size() * sectionSize;
// If creating a dylib, add LC_ID_DYLIB.
if (_file.fileType == llvm::MachO::MH_DYLIB) {
size += sizeof(dylib_command) + pointerAlign(_file.installName.size() + 1);
++count;
}
// Add LC_DYLD_INFO
size += sizeof(dyld_info_command);
++count;
// Add LC_SYMTAB
size += sizeof(symtab_command);
++count;
// Add LC_DYSYMTAB
if (_file.fileType != llvm::MachO::MH_PRELOAD) {
size += sizeof(dysymtab_command);
++count;
}
// If main executable add LC_LOAD_DYLINKER
if (_file.fileType == llvm::MachO::MH_EXECUTE) {
size += pointerAlign(sizeof(dylinker_command) + dyldPath().size()+1);
++count;
}
// Add LC_VERSION_MIN_MACOSX, LC_VERSION_MIN_IPHONEOS, LC_VERSION_MIN_WATCHOS,
// LC_VERSION_MIN_TVOS
if (_file.hasMinVersionLoadCommand) {
size += sizeof(version_min_command);
++count;
}
// Add LC_SOURCE_VERSION
size += sizeof(source_version_command);
++count;
// If main executable add LC_MAIN
if (_file.fileType == llvm::MachO::MH_EXECUTE) {
size += sizeof(entry_point_command);
++count;
}
// Add LC_LOAD_DYLIB for each dependent dylib.
for (const DependentDylib &dep : _file.dependentDylibs) {
size += sizeof(dylib_command) + pointerAlign(dep.path.size()+1);
++count;
}
// Add LC_RPATH
for (const StringRef &path : _file.rpaths) {
size += pointerAlign(sizeof(rpath_command) + path.size() + 1);
++count;
}
// Add LC_FUNCTION_STARTS if needed
if (!_file.functionStarts.empty()) {
size += sizeof(linkedit_data_command);
++count;
}
// Add LC_DATA_IN_CODE if requested. Note, we do encode zero length entries.
// FIXME: Zero length entries is only to match ld64. Should we change this?
if (_file.generateDataInCodeLoadCommand) {
size += sizeof(linkedit_data_command);
++count;
}
return size;
}
static bool overlaps(const Segment &s1, const Segment &s2) {
if (s2.address >= s1.address+s1.size)
return false;
if (s1.address >= s2.address+s2.size)
return false;
return true;
}
static bool overlaps(const Section &s1, const Section &s2) {
if (s2.address >= s1.address+s1.content.size())
return false;
if (s1.address >= s2.address+s2.content.size())
return false;
return true;
}
void MachOFileLayout::buildFileOffsets() {
// Verify no segments overlap
for (const Segment &sg1 : _file.segments) {
for (const Segment &sg2 : _file.segments) {
if (&sg1 == &sg2)
continue;
if (overlaps(sg1,sg2)) {
_ec = make_error_code(llvm::errc::executable_format_error);
return;
}
}
}
// Verify no sections overlap
for (const Section &s1 : _file.sections) {
for (const Section &s2 : _file.sections) {
if (&s1 == &s2)
continue;
if (overlaps(s1,s2)) {
_ec = make_error_code(llvm::errc::executable_format_error);
return;
}
}
}
// Build side table of extra info about segments and sections.
SegExtraInfo t;
t.fileOffset = 0;
for (const Segment &sg : _file.segments) {
_segInfo[&sg] = t;
}
SectionExtraInfo t2;
t2.fileOffset = 0;
// Assign sections to segments.
for (const Section &s : _file.sections) {
_sectInfo[&s] = t2;
bool foundSegment = false;
for (const Segment &sg : _file.segments) {
if (sg.name.equals(s.segmentName)) {
if ((s.address >= sg.address)
&& (s.address+s.content.size() <= sg.address+sg.size)) {
_segInfo[&sg].sections.push_back(&s);
foundSegment = true;
break;
}
}
}
if (!foundSegment) {
_ec = make_error_code(llvm::errc::executable_format_error);
return;
}
}
// Assign file offsets.
uint32_t fileOffset = 0;
DEBUG_WITH_TYPE("MachOFileLayout",
llvm::dbgs() << "buildFileOffsets()\n");
for (const Segment &sg : _file.segments) {
_segInfo[&sg].fileOffset = fileOffset;
if ((_seg1addr == INT64_MAX) && sg.init_access)
_seg1addr = sg.address;
DEBUG_WITH_TYPE("MachOFileLayout",
llvm::dbgs() << " segment=" << sg.name
<< ", fileOffset=" << _segInfo[&sg].fileOffset << "\n");
uint32_t segFileSize = 0;
// A segment that is not zero-fill must use a least one page of disk space.
if (sg.init_access)
segFileSize = _file.pageSize;
for (const Section *s : _segInfo[&sg].sections) {
uint32_t sectOffset = s->address - sg.address;
uint32_t sectFileSize =
isZeroFillSection(s->type) ? 0 : s->content.size();
segFileSize = std::max(segFileSize, sectOffset + sectFileSize);
_sectInfo[s].fileOffset = _segInfo[&sg].fileOffset + sectOffset;
DEBUG_WITH_TYPE("MachOFileLayout",
llvm::dbgs() << " section=" << s->sectionName
<< ", fileOffset=" << fileOffset << "\n");
}
// round up all segments to page aligned, except __LINKEDIT
if (!sg.name.equals("__LINKEDIT")) {
_segInfo[&sg].fileSize = llvm::alignTo(segFileSize, _file.pageSize);
fileOffset = llvm::alignTo(fileOffset + segFileSize, _file.pageSize);
}
_addressOfLinkEdit = sg.address + sg.size;
}
_startOfLinkEdit = fileOffset;
}
size_t MachOFileLayout::size() const {
return _endOfSymbolStrings;
}
void MachOFileLayout::writeMachHeader() {
auto cpusubtype = MachOLinkingContext::cpuSubtypeFromArch(_file.arch);
// dynamic x86 executables on newer OS version should also set the
// CPU_SUBTYPE_LIB64 mask in the CPU subtype.
// FIXME: Check that this is a dynamic executable, not a static one.
if (_file.fileType == llvm::MachO::MH_EXECUTE &&
cpusubtype == CPU_SUBTYPE_X86_64_ALL &&
_file.os == MachOLinkingContext::OS::macOSX) {
uint32_t version;
bool failed = MachOLinkingContext::parsePackedVersion("10.5", version);
if (!failed && _file.minOSverson >= version)
cpusubtype |= CPU_SUBTYPE_LIB64;
}
mach_header *mh = reinterpret_cast<mach_header*>(_buffer);
mh->magic = _is64 ? llvm::MachO::MH_MAGIC_64 : llvm::MachO::MH_MAGIC;
mh->cputype = MachOLinkingContext::cpuTypeFromArch(_file.arch);
mh->cpusubtype = cpusubtype;
mh->filetype = _file.fileType;
mh->ncmds = _countOfLoadCommands;
mh->sizeofcmds = _endOfLoadCommands - _startOfLoadCommands;
mh->flags = _file.flags;
if (_swap)
swapStruct(*mh);
}
uint32_t MachOFileLayout::indirectSymbolIndex(const Section §,
uint32_t &index) {
if (sect.indirectSymbols.empty())
return 0;
uint32_t result = index;
index += sect.indirectSymbols.size();
return result;
}
uint32_t MachOFileLayout::indirectSymbolElementSize(const Section §) {
if (sect.indirectSymbols.empty())
return 0;
if (sect.type != S_SYMBOL_STUBS)
return 0;
return sect.content.size() / sect.indirectSymbols.size();
}
template <typename T>
llvm::Error MachOFileLayout::writeSingleSegmentLoadCommand(uint8_t *&lc) {
typename T::command* seg = reinterpret_cast<typename T::command*>(lc);
seg->cmd = T::LC;
seg->cmdsize = sizeof(typename T::command)
+ _file.sections.size() * sizeof(typename T::section);
uint8_t *next = lc + seg->cmdsize;
memset(seg->segname, 0, 16);
seg->vmaddr = 0;
seg->vmsize = _file.sections.back().address
+ _file.sections.back().content.size();
seg->fileoff = _endOfLoadCommands;
seg->filesize = _sectInfo[&_file.sections.back()].fileOffset +
_file.sections.back().content.size() -
_sectInfo[&_file.sections.front()].fileOffset;
seg->maxprot = VM_PROT_READ|VM_PROT_WRITE|VM_PROT_EXECUTE;
seg->initprot = VM_PROT_READ|VM_PROT_WRITE|VM_PROT_EXECUTE;
seg->nsects = _file.sections.size();
seg->flags = 0;
if (_swap)
swapStruct(*seg);
typename T::section *sout = reinterpret_cast<typename T::section*>
(lc+sizeof(typename T::command));
uint32_t relOffset = _startOfRelocations;
uint32_t indirectSymRunningIndex = 0;
for (const Section &sin : _file.sections) {
setString16(sin.sectionName, sout->sectname);
setString16(sin.segmentName, sout->segname);
sout->addr = sin.address;
sout->size = sin.content.size();
sout->offset = _sectInfo[&sin].fileOffset;
sout->align = llvm::Log2_32(sin.alignment);
sout->reloff = sin.relocations.empty() ? 0 : relOffset;
sout->nreloc = sin.relocations.size();
sout->flags = sin.type | sin.attributes;
sout->reserved1 = indirectSymbolIndex(sin, indirectSymRunningIndex);
sout->reserved2 = indirectSymbolElementSize(sin);
relOffset += sin.relocations.size() * sizeof(any_relocation_info);
if (_swap)
swapStruct(*sout);
++sout;
}
lc = next;
return llvm::Error::success();
}
template <typename T>
llvm::Error MachOFileLayout::writeSegmentLoadCommands(uint8_t *&lc) {
uint32_t indirectSymRunningIndex = 0;
for (const Segment &seg : _file.segments) {
// Link edit has no sections and a custom range of address, so handle it
// specially.
SegExtraInfo &segInfo = _segInfo[&seg];
if (seg.name.equals("__LINKEDIT")) {
size_t linkeditSize = _endOfLinkEdit - _startOfLinkEdit;
typename T::command* cmd = reinterpret_cast<typename T::command*>(lc);
cmd->cmd = T::LC;
cmd->cmdsize = sizeof(typename T::command);
uint8_t *next = lc + cmd->cmdsize;
setString16("__LINKEDIT", cmd->segname);
cmd->vmaddr = _addressOfLinkEdit;
cmd->vmsize = llvm::alignTo(linkeditSize, _file.pageSize);
cmd->fileoff = _startOfLinkEdit;
cmd->filesize = linkeditSize;
cmd->initprot = seg.init_access;
cmd->maxprot = seg.max_access;
cmd->nsects = 0;
cmd->flags = 0;
if (_swap)
swapStruct(*cmd);
lc = next;
continue;
}
// Write segment command with trailing sections.
typename T::command* cmd = reinterpret_cast<typename T::command*>(lc);
cmd->cmd = T::LC;
cmd->cmdsize = sizeof(typename T::command)
+ segInfo.sections.size() * sizeof(typename T::section);
uint8_t *next = lc + cmd->cmdsize;
setString16(seg.name, cmd->segname);
cmd->vmaddr = seg.address;
cmd->vmsize = seg.size;
cmd->fileoff = segInfo.fileOffset;
cmd->filesize = segInfo.fileSize;
cmd->initprot = seg.init_access;
cmd->maxprot = seg.max_access;
cmd->nsects = segInfo.sections.size();
cmd->flags = 0;
if (_swap)
swapStruct(*cmd);
typename T::section *sect = reinterpret_cast<typename T::section*>
(lc+sizeof(typename T::command));
for (const Section *section : segInfo.sections) {
setString16(section->sectionName, sect->sectname);
setString16(section->segmentName, sect->segname);
sect->addr = section->address;
sect->size = section->content.size();
if (isZeroFillSection(section->type))
sect->offset = 0;
else
sect->offset = section->address - seg.address + segInfo.fileOffset;
sect->align = llvm::Log2_32(section->alignment);
sect->reloff = 0;
sect->nreloc = 0;
sect->flags = section->type | section->attributes;
sect->reserved1 = indirectSymbolIndex(*section, indirectSymRunningIndex);
sect->reserved2 = indirectSymbolElementSize(*section);
if (_swap)
swapStruct(*sect);
++sect;
}
lc = reinterpret_cast<uint8_t*>(next);
}
return llvm::Error::success();
}
static void writeVersionMinLoadCommand(const NormalizedFile &_file,
bool _swap,
uint8_t *&lc) {
if (!_file.hasMinVersionLoadCommand)
return;
version_min_command *vm = reinterpret_cast<version_min_command*>(lc);
switch (_file.os) {
case MachOLinkingContext::OS::unknown:
vm->cmd = _file.minOSVersionKind;
vm->cmdsize = sizeof(version_min_command);
vm->version = _file.minOSverson;
vm->sdk = 0;
break;
case MachOLinkingContext::OS::macOSX:
vm->cmd = LC_VERSION_MIN_MACOSX;
vm->cmdsize = sizeof(version_min_command);
vm->version = _file.minOSverson;
vm->sdk = _file.sdkVersion;
break;
case MachOLinkingContext::OS::iOS:
case MachOLinkingContext::OS::iOS_simulator:
vm->cmd = LC_VERSION_MIN_IPHONEOS;
vm->cmdsize = sizeof(version_min_command);
vm->version = _file.minOSverson;
vm->sdk = _file.sdkVersion;
break;
}
if (_swap)
swapStruct(*vm);
lc += sizeof(version_min_command);
}
llvm::Error MachOFileLayout::writeLoadCommands() {
uint8_t *lc = &_buffer[_startOfLoadCommands];
if (_file.fileType == llvm::MachO::MH_OBJECT) {
// Object files have one unnamed segment which holds all sections.
if (_is64) {
if (auto ec = writeSingleSegmentLoadCommand<MachO64Trait>(lc))
return ec;
} else {
if (auto ec = writeSingleSegmentLoadCommand<MachO32Trait>(lc))
return ec;
}
// Add LC_SYMTAB with symbol table info
symtab_command* st = reinterpret_cast<symtab_command*>(lc);
st->cmd = LC_SYMTAB;
st->cmdsize = sizeof(symtab_command);
st->symoff = _startOfSymbols;
st->nsyms = _file.stabsSymbols.size() + _file.localSymbols.size() +
_file.globalSymbols.size() + _file.undefinedSymbols.size();
st->stroff = _startOfSymbolStrings;
st->strsize = _endOfSymbolStrings - _startOfSymbolStrings;
if (_swap)
swapStruct(*st);
lc += sizeof(symtab_command);
// Add LC_VERSION_MIN_MACOSX, LC_VERSION_MIN_IPHONEOS,
// LC_VERSION_MIN_WATCHOS, LC_VERSION_MIN_TVOS
writeVersionMinLoadCommand(_file, _swap, lc);
// Add LC_FUNCTION_STARTS if needed.
if (_functionStartsSize != 0) {
linkedit_data_command* dl = reinterpret_cast<linkedit_data_command*>(lc);
dl->cmd = LC_FUNCTION_STARTS;
dl->cmdsize = sizeof(linkedit_data_command);
dl->dataoff = _startOfFunctionStarts;
dl->datasize = _functionStartsSize;
if (_swap)
swapStruct(*dl);
lc += sizeof(linkedit_data_command);
}
// Add LC_DATA_IN_CODE if requested.
if (_file.generateDataInCodeLoadCommand) {
linkedit_data_command* dl = reinterpret_cast<linkedit_data_command*>(lc);
dl->cmd = LC_DATA_IN_CODE;
dl->cmdsize = sizeof(linkedit_data_command);
dl->dataoff = _startOfDataInCode;
dl->datasize = _dataInCodeSize;
if (_swap)
swapStruct(*dl);
lc += sizeof(linkedit_data_command);
}
} else {
// Final linked images have sections under segments.
if (_is64) {
if (auto ec = writeSegmentLoadCommands<MachO64Trait>(lc))
return ec;
} else {
if (auto ec = writeSegmentLoadCommands<MachO32Trait>(lc))
return ec;
}
// Add LC_ID_DYLIB command for dynamic libraries.
if (_file.fileType == llvm::MachO::MH_DYLIB) {
dylib_command *dc = reinterpret_cast<dylib_command*>(lc);
StringRef path = _file.installName;
uint32_t size = sizeof(dylib_command) + pointerAlign(path.size() + 1);
dc->cmd = LC_ID_DYLIB;
dc->cmdsize = size;
dc->dylib.name = sizeof(dylib_command); // offset
// needs to be some constant value different than the one in LC_LOAD_DYLIB
dc->dylib.timestamp = 1;
dc->dylib.current_version = _file.currentVersion;
dc->dylib.compatibility_version = _file.compatVersion;
if (_swap)
swapStruct(*dc);
memcpy(lc + sizeof(dylib_command), path.begin(), path.size());
lc[sizeof(dylib_command) + path.size()] = '\0';
lc += size;
}
// Add LC_DYLD_INFO_ONLY.
dyld_info_command* di = reinterpret_cast<dyld_info_command*>(lc);
di->cmd = LC_DYLD_INFO_ONLY;
di->cmdsize = sizeof(dyld_info_command);
di->rebase_off = _rebaseInfo.size() ? _startOfRebaseInfo : 0;
di->rebase_size = _rebaseInfo.size();
di->bind_off = _bindingInfo.size() ? _startOfBindingInfo : 0;
di->bind_size = _bindingInfo.size();
di->weak_bind_off = 0;
di->weak_bind_size = 0;
di->lazy_bind_off = _lazyBindingInfo.size() ? _startOfLazyBindingInfo : 0;
di->lazy_bind_size = _lazyBindingInfo.size();
di->export_off = _exportTrie.size() ? _startOfExportTrie : 0;
di->export_size = _exportTrie.size();
if (_swap)
swapStruct(*di);
lc += sizeof(dyld_info_command);
// Add LC_SYMTAB with symbol table info.
symtab_command* st = reinterpret_cast<symtab_command*>(lc);
st->cmd = LC_SYMTAB;
st->cmdsize = sizeof(symtab_command);
st->symoff = _startOfSymbols;
st->nsyms = _file.stabsSymbols.size() + _file.localSymbols.size() +
_file.globalSymbols.size() + _file.undefinedSymbols.size();
st->stroff = _startOfSymbolStrings;
st->strsize = _endOfSymbolStrings - _startOfSymbolStrings;
if (_swap)
swapStruct(*st);
lc += sizeof(symtab_command);
// Add LC_DYSYMTAB
if (_file.fileType != llvm::MachO::MH_PRELOAD) {
dysymtab_command* dst = reinterpret_cast<dysymtab_command*>(lc);
dst->cmd = LC_DYSYMTAB;
dst->cmdsize = sizeof(dysymtab_command);
dst->ilocalsym = _symbolTableLocalsStartIndex;
dst->nlocalsym = _file.stabsSymbols.size() +
_file.localSymbols.size();
dst->iextdefsym = _symbolTableGlobalsStartIndex;
dst->nextdefsym = _file.globalSymbols.size();
dst->iundefsym = _symbolTableUndefinesStartIndex;
dst->nundefsym = _file.undefinedSymbols.size();
dst->tocoff = 0;
dst->ntoc = 0;
dst->modtaboff = 0;
dst->nmodtab = 0;
dst->extrefsymoff = 0;
dst->nextrefsyms = 0;
dst->indirectsymoff = _startOfIndirectSymbols;
dst->nindirectsyms = _indirectSymbolTableCount;
dst->extreloff = 0;
dst->nextrel = 0;
dst->locreloff = 0;
dst->nlocrel = 0;
if (_swap)
swapStruct(*dst);
lc += sizeof(dysymtab_command);
}
// If main executable, add LC_LOAD_DYLINKER
if (_file.fileType == llvm::MachO::MH_EXECUTE) {
// Build LC_LOAD_DYLINKER load command.
uint32_t size=pointerAlign(sizeof(dylinker_command)+dyldPath().size()+1);
dylinker_command* dl = reinterpret_cast<dylinker_command*>(lc);
dl->cmd = LC_LOAD_DYLINKER;
dl->cmdsize = size;
dl->name = sizeof(dylinker_command); // offset
if (_swap)
swapStruct(*dl);
memcpy(lc+sizeof(dylinker_command), dyldPath().data(), dyldPath().size());
lc[sizeof(dylinker_command)+dyldPath().size()] = '\0';
lc += size;
}
// Add LC_VERSION_MIN_MACOSX, LC_VERSION_MIN_IPHONEOS, LC_VERSION_MIN_WATCHOS,
// LC_VERSION_MIN_TVOS
writeVersionMinLoadCommand(_file, _swap, lc);
// Add LC_SOURCE_VERSION
{
// Note, using a temporary here to appease UB as we may not be aligned
// enough for a struct containing a uint64_t when emitting a 32-bit binary
source_version_command sv;
sv.cmd = LC_SOURCE_VERSION;
sv.cmdsize = sizeof(source_version_command);
sv.version = _file.sourceVersion;
if (_swap)
swapStruct(sv);
memcpy(lc, &sv, sizeof(source_version_command));
lc += sizeof(source_version_command);
}
// If main executable, add LC_MAIN.
if (_file.fileType == llvm::MachO::MH_EXECUTE) {
// Build LC_MAIN load command.
// Note, using a temporary here to appease UB as we may not be aligned
// enough for a struct containing a uint64_t when emitting a 32-bit binary
entry_point_command ep;
ep.cmd = LC_MAIN;
ep.cmdsize = sizeof(entry_point_command);
ep.entryoff = _file.entryAddress - _seg1addr;
ep.stacksize = _file.stackSize;
if (_swap)
swapStruct(ep);
memcpy(lc, &ep, sizeof(entry_point_command));
lc += sizeof(entry_point_command);
}
// Add LC_LOAD_DYLIB commands
for (const DependentDylib &dep : _file.dependentDylibs) {
dylib_command* dc = reinterpret_cast<dylib_command*>(lc);
uint32_t size = sizeof(dylib_command) + pointerAlign(dep.path.size()+1);
dc->cmd = dep.kind;
dc->cmdsize = size;
dc->dylib.name = sizeof(dylib_command); // offset
// needs to be some constant value different than the one in LC_ID_DYLIB
dc->dylib.timestamp = 2;
dc->dylib.current_version = dep.currentVersion;
dc->dylib.compatibility_version = dep.compatVersion;
if (_swap)
swapStruct(*dc);
memcpy(lc+sizeof(dylib_command), dep.path.begin(), dep.path.size());
lc[sizeof(dylib_command)+dep.path.size()] = '\0';
lc += size;
}
// Add LC_RPATH
for (const StringRef &path : _file.rpaths) {
rpath_command *rpc = reinterpret_cast<rpath_command *>(lc);
uint32_t size = pointerAlign(sizeof(rpath_command) + path.size() + 1);
rpc->cmd = LC_RPATH;
rpc->cmdsize = size;
rpc->path = sizeof(rpath_command); // offset
if (_swap)
swapStruct(*rpc);
memcpy(lc+sizeof(rpath_command), path.begin(), path.size());
lc[sizeof(rpath_command)+path.size()] = '\0';
lc += size;
}
// Add LC_FUNCTION_STARTS if needed.
if (_functionStartsSize != 0) {
linkedit_data_command* dl = reinterpret_cast<linkedit_data_command*>(lc);
dl->cmd = LC_FUNCTION_STARTS;
dl->cmdsize = sizeof(linkedit_data_command);
dl->dataoff = _startOfFunctionStarts;
dl->datasize = _functionStartsSize;
if (_swap)
swapStruct(*dl);
lc += sizeof(linkedit_data_command);
}
// Add LC_DATA_IN_CODE if requested.
if (_file.generateDataInCodeLoadCommand) {
linkedit_data_command* dl = reinterpret_cast<linkedit_data_command*>(lc);