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llvm-project/lld/lib/ReaderWriter/MachO/MachONormalizedFileBinaryWriter.cpp
Nick Kledzik 2fcbe822c0 [mach-o] Add support for -sectalign option 
The -sectalign option is used to increase the alignment required for a section.
It required some reworking of how the __TEXT segment is laid out because that
segment also contains the mach_header and load commands. And the size of load
commands depend on the number of segments, sections, and dependent dylibs used.

Using this option will simplify some future test cases because the final
address of code can be pinned down, making tests of its content easier.

llvm-svn: 214268
2014-07-30 00:58:06 +00:00

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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/Core/Error.h"
#include "lld/Core/LLVM.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/Errc.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/FileOutputBuffer.h"
#include "llvm/Support/Host.h"
#include "llvm/Support/LEB128.h"
#include "llvm/Support/MachO.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/raw_ostream.h"
#include <functional>
#include <map>
#include <system_error>
using namespace llvm::MachO;
namespace lld {
namespace mach_o {
namespace normalized {
/// 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.
std::error_code writeBinary(StringRef path);
private:
uint32_t loadCommandsSize(uint32_t &count);
void buildFileOffsets();
void writeMachHeader();
std::error_code writeLoadCommands();
void writeSectionContent();
void writeRelocations();
void writeSymbolTable();
void writeRebaseInfo();
void writeBindingInfo();
void writeLazyBindingInfo();
void writeDataInCodeInfo();
void writeLinkEditContent();
void buildLinkEditInfo();
void buildRebaseInfo();
void buildBindInfo();
void buildLazyBindInfo();
void computeDataInCodeSize();
void computeSymbolTableSizes();
void buildSectionRelocations();
void appendSymbols(const std::vector<Symbol> &symbols,
uint32_t &symOffset, uint32_t &strOffset);
uint32_t indirectSymbolIndex(const Section &sect, uint32_t &index);
uint32_t indirectSymbolElementSize(const Section &sect);
// 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>
std::error_code writeSingleSegmentLoadCommand(uint8_t *&lc);
template <typename T> std::error_code writeSegmentLoadCommands(uint8_t *&lc);
uint32_t pointerAlign(uint32_t value);
static StringRef dyldPath();
class ByteBuffer {
public:
ByteBuffer() : _ostream(_bytes) { }
void append_byte(uint8_t b) {
_ostream << b;
}
void append_uleb128(uint64_t value) {
llvm::encodeULEB128(value, _ostream);
}
void append_sleb128(int64_t value) {
llvm::encodeSLEB128(value, _ostream);
}
void append_string(StringRef str) {
_ostream << str;
append_byte(0);
}
void align(unsigned alignment) {
while ( (_ostream.tell() % alignment) != 0 )
append_byte(0);
}
size_t size() {
return _ostream.tell();
}
const uint8_t *bytes() {
return reinterpret_cast<const uint8_t*>(_ostream.str().data());
}
private:
SmallVector<char, 128> _bytes;
// Stream ivar must be after SmallVector ivar to construct properly.
llvm::raw_svector_ostream _ostream;
};
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 _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 _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 _endOfLinkEdit;
uint64_t _addressOfLinkEdit;
SegMap _segInfo;
SectionMap _sectInfo;
ByteBuffer _rebaseInfo;
ByteBuffer _bindingInfo;
ByteBuffer _lazyBindingInfo;
ByteBuffer _weakBindingInfo;
ByteBuffer _exportInfo;
};
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::RoundUpToAlignment(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.dataInCode.empty()) {
_endOfLoadCommands += sizeof(linkedit_data_command);
_countOfLoadCommands++;
}
// Accumulate size of each section.
_startOfSectionsContent = _endOfLoadCommands;
_endOfSectionsContent = _startOfSectionsContent;
unsigned relocCount = 0;
for (const Section &sect : file.sections) {
_sectInfo[&sect].fileOffset = _endOfSectionsContent;
_endOfSectionsContent += sect.content.size();
relocCount += sect.relocations.size();
}
computeSymbolTableSizes();
computeDataInCodeSize();
// Align start of relocations.
_startOfRelocations = pointerAlign(_endOfSectionsContent);
_startOfDataInCode = _startOfRelocations + relocCount * 8;
_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();
_startOfDataInCode = _endOfLazyBindingInfo;
_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"
<< " 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;
// Add one LC_SEGMENT for implicit __LINKEDIT segment
size += segCommandSize;
++count;
// 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 and LC_MAIN
if (_file.fileType == llvm::MachO::MH_EXECUTE) {
size += pointerAlign(sizeof(dylinker_command) + dyldPath().size()+1);
++count;
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;
}
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;
for (const Segment &sg : _file.segments) {
if ((s.address >= sg.address)
&& (s.address+s.content.size() <= sg.address+sg.size)) {
if (!sg.name.equals(s.segmentName)) {
_ec = make_error_code(llvm::errc::executable_format_error);
return;
}
_segInfo[&sg].sections.push_back(&s);
}
}
}
// 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.access)
_seg1addr = sg.address;
DEBUG_WITH_TYPE("MachOFileLayout",
llvm::dbgs() << " segment=" << sg.name
<< ", fileOffset=" << _segInfo[&sg].fileOffset << "\n");
uint32_t segFileSize = 0;
for (const Section *s : _segInfo[&sg].sections) {
uint32_t sectOffset = s->address - sg.address;
uint32_t sectFileSize =
s->type == llvm::MachO::S_ZEROFILL ? 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");
}
// FIXME: 4096 should be inferred from segments in normalized file.
_segInfo[&sg].fileSize = llvm::RoundUpToAlignment(segFileSize, 4096);
fileOffset = llvm::RoundUpToAlignment(fileOffset + segFileSize, 4096);
_addressOfLinkEdit = sg.address + sg.size;
}
_startOfLinkEdit = fileOffset;
}
size_t MachOFileLayout::size() const {
return _endOfSymbolStrings;
}
void MachOFileLayout::writeMachHeader() {
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 = MachOLinkingContext::cpuSubtypeFromArch(_file.arch);
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 &sect,
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 &sect) {
if (sect.indirectSymbols.empty())
return 0;
if (sect.type != S_SYMBOL_STUBS)
return 0;
return sect.content.size() / sect.indirectSymbols.size();
}
template <typename T>
std::error_code 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 = _endOfSectionsContent - _endOfLoadCommands;
seg->fileoff = _endOfLoadCommands;
seg->filesize = seg->vmsize;
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 contentOffset = _startOfSectionsContent;
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 = contentOffset;
sout->align = 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);
contentOffset += sin.content.size();
if (_swap)
swapStruct(*sout);
++sout;
}
lc = next;
return std::error_code();
}
template <typename T>
std::error_code MachOFileLayout::writeSegmentLoadCommands(uint8_t *&lc) {
uint32_t indirectSymRunningIndex = 0;
for (const Segment &seg : _file.segments) {
// Write segment command with trailing sections.
SegExtraInfo &segInfo = _segInfo[&seg];
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->maxprot = seg.access;
cmd->initprot = seg.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();
sect->offset = section->address - seg.address + segInfo.fileOffset;
sect->align = 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);
}
// Add implicit __LINKEDIT segment
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 = _endOfLinkEdit - _startOfLinkEdit;
cmd->fileoff = _startOfLinkEdit;
cmd->filesize = _endOfLinkEdit - _startOfLinkEdit;
cmd->maxprot = VM_PROT_READ;
cmd->initprot = VM_PROT_READ;
cmd->nsects = 0;
cmd->flags = 0;
if (_swap)
swapStruct(*cmd);
lc = next;
return std::error_code();
}
std::error_code MachOFileLayout::writeLoadCommands() {
std::error_code ec;
uint8_t *lc = &_buffer[_startOfLoadCommands];
if (_file.fileType == llvm::MachO::MH_OBJECT) {
// Object files have one unnamed segment which holds all sections.
if (_is64)
ec = writeSingleSegmentLoadCommand<MachO64Trait>(lc);
else
ec = writeSingleSegmentLoadCommand<MachO32Trait>(lc);
// 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.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_DATA_IN_CODE if needed.
if (_dataInCodeSize != 0) {
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)
ec = writeSegmentLoadCommands<MachO64Trait>(lc);
else
ec = writeSegmentLoadCommands<MachO32Trait>(lc);
// 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
dc->dylib.timestamp = 0; // FIXME
dc->dylib.current_version = 0; // FIXME
dc->dylib.compatibility_version = 0; // FIXME
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 = 0;
di->export_size = 0;
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.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.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 and LC_MAIN.
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;
// Build LC_MAIN load command.
entry_point_command* ep = reinterpret_cast<entry_point_command*>(lc);
ep->cmd = LC_MAIN;
ep->cmdsize = sizeof(entry_point_command);
ep->entryoff = _file.entryAddress - _seg1addr;
ep->stacksize = 0;
if (_swap)
swapStruct(*ep);
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 = LC_LOAD_DYLIB;
dc->cmdsize = size;
dc->dylib.name = sizeof(dylib_command); // offset
dc->dylib.timestamp = 0; // FIXME
dc->dylib.current_version = 0; // FIXME
dc->dylib.compatibility_version = 0; // FIXME
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;
}
}
return ec;
}
void MachOFileLayout::writeSectionContent() {
for (const Section &s : _file.sections) {
// Copy all section content to output buffer.
if (s.type == llvm::MachO::S_ZEROFILL)
continue;
uint32_t offset = _sectInfo[&s].fileOffset;
uint8_t *p = &_buffer[offset];
memcpy(p, &s.content[0], s.content.size());
p += s.content.size();
}
}
void MachOFileLayout::writeRelocations() {
uint32_t relOffset = _startOfRelocations;
for (Section sect : _file.sections) {
for (Relocation r : sect.relocations) {
any_relocation_info* rb = reinterpret_cast<any_relocation_info*>(
&_buffer[relOffset]);
*rb = packRelocation(r, _swap, _bigEndianArch);
relOffset += sizeof(any_relocation_info);
}
}
}
void MachOFileLayout::appendSymbols(const std::vector<Symbol> &symbols,
uint32_t &symOffset, uint32_t &strOffset) {
for (const Symbol &sym : symbols) {
if (_is64) {
nlist_64* nb = reinterpret_cast<nlist_64*>(&_buffer[symOffset]);
nb->n_strx = strOffset - _startOfSymbolStrings;
nb->n_type = sym.type | sym.scope;
nb->n_sect = sym.sect;
nb->n_desc = sym.desc;
nb->n_value = sym.value;
if (_swap)
swapStruct(*nb);
symOffset += sizeof(nlist_64);
} else {
nlist* nb = reinterpret_cast<nlist*>(&_buffer[symOffset]);
nb->n_strx = strOffset - _startOfSymbolStrings;
nb->n_type = sym.type | sym.scope;
nb->n_sect = sym.sect;
nb->n_desc = sym.desc;
nb->n_value = sym.value;
if (_swap)
swapStruct(*nb);
symOffset += sizeof(nlist);
}
memcpy(&_buffer[strOffset], sym.name.begin(), sym.name.size());
strOffset += sym.name.size();
_buffer[strOffset++] ='\0'; // Strings in table have nul terminator.
}
}
void MachOFileLayout::writeDataInCodeInfo() {
uint32_t offset = _startOfDataInCode;
for (const DataInCode &entry : _file.dataInCode) {
data_in_code_entry *dst = reinterpret_cast<data_in_code_entry*>(
&_buffer[offset]);
dst->offset = entry.offset;
dst->length = entry.length;
dst->kind = entry.kind;
if (_swap)
swapStruct(*dst);
offset += sizeof(data_in_code_entry);
}
}
void MachOFileLayout::writeSymbolTable() {
// Write symbol table and symbol strings in parallel.
uint32_t symOffset = _startOfSymbols;
uint32_t strOffset = _startOfSymbolStrings;
_buffer[strOffset++] = '\0'; // Reserve n_strx offset of zero to mean no name.
appendSymbols(_file.localSymbols, symOffset, strOffset);
appendSymbols(_file.globalSymbols, symOffset, strOffset);
appendSymbols(_file.undefinedSymbols, symOffset, strOffset);
// Write indirect symbol table array.
uint32_t *indirects = reinterpret_cast<uint32_t*>
(&_buffer[_startOfIndirectSymbols]);
if (_file.fileType == llvm::MachO::MH_OBJECT) {
// Object files have sections in same order as input normalized file.
for (const Section &section : _file.sections) {
for (uint32_t index : section.indirectSymbols) {
if (_swap)
*indirects++ = llvm::sys::getSwappedBytes(index);
else
*indirects++ = index;
}
}
} else {
// Final linked images must sort sections from normalized file.
for (const Segment &seg : _file.segments) {
SegExtraInfo &segInfo = _segInfo[&seg];
for (const Section *section : segInfo.sections) {
for (uint32_t index : section->indirectSymbols) {
if (_swap)
*indirects++ = llvm::sys::getSwappedBytes(index);
else
*indirects++ = index;
}
}
}
}
}
void MachOFileLayout::writeRebaseInfo() {
memcpy(&_buffer[_startOfRebaseInfo], _rebaseInfo.bytes(), _rebaseInfo.size());
}
void MachOFileLayout::writeBindingInfo() {
memcpy(&_buffer[_startOfBindingInfo],
_bindingInfo.bytes(), _bindingInfo.size());
}
void MachOFileLayout::writeLazyBindingInfo() {
memcpy(&_buffer[_startOfLazyBindingInfo],
_lazyBindingInfo.bytes(), _lazyBindingInfo.size());
}
void MachOFileLayout::buildLinkEditInfo() {
buildRebaseInfo();
buildBindInfo();
buildLazyBindInfo();
computeSymbolTableSizes();
computeDataInCodeSize();
}
void MachOFileLayout::buildSectionRelocations() {
}
void MachOFileLayout::buildRebaseInfo() {
// TODO: compress rebasing info.
for (const RebaseLocation& entry : _file.rebasingInfo) {
_rebaseInfo.append_byte(REBASE_OPCODE_SET_TYPE_IMM | entry.kind);
_rebaseInfo.append_byte(REBASE_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB
| entry.segIndex);
_rebaseInfo.append_uleb128(entry.segOffset);
_rebaseInfo.append_uleb128(REBASE_OPCODE_DO_REBASE_IMM_TIMES | 1);
}
_rebaseInfo.append_byte(REBASE_OPCODE_DONE);
_rebaseInfo.align(_is64 ? 8 : 4);
}
void MachOFileLayout::buildBindInfo() {
// TODO: compress bind info.
for (const BindLocation& entry : _file.bindingInfo) {
_bindingInfo.append_byte(BIND_OPCODE_SET_TYPE_IMM | entry.kind);
_bindingInfo.append_byte(BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB
| entry.segIndex);
_bindingInfo.append_uleb128(entry.segOffset);
_bindingInfo.append_byte(BIND_OPCODE_SET_DYLIB_ORDINAL_IMM | entry.ordinal);
_bindingInfo.append_byte(BIND_OPCODE_SET_SYMBOL_TRAILING_FLAGS_IMM);
_bindingInfo.append_string(entry.symbolName);
if (entry.addend != 0) {
_bindingInfo.append_byte(BIND_OPCODE_SET_ADDEND_SLEB);
_bindingInfo.append_sleb128(entry.addend);
}
_bindingInfo.append_byte(BIND_OPCODE_DO_BIND);
}
_bindingInfo.append_byte(BIND_OPCODE_DONE);
_bindingInfo.align(_is64 ? 8 : 4);
}
void MachOFileLayout::buildLazyBindInfo() {
for (const BindLocation& entry : _file.lazyBindingInfo) {
_lazyBindingInfo.append_byte(BIND_OPCODE_SET_TYPE_IMM | entry.kind);
_lazyBindingInfo.append_byte(BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB
| entry.segIndex);
_lazyBindingInfo.append_uleb128(entry.segOffset);
_lazyBindingInfo.append_byte(BIND_OPCODE_SET_DYLIB_ORDINAL_IMM | entry.ordinal);
_lazyBindingInfo.append_byte(BIND_OPCODE_SET_SYMBOL_TRAILING_FLAGS_IMM);
_lazyBindingInfo.append_string(entry.symbolName);
_lazyBindingInfo.append_byte(BIND_OPCODE_DO_BIND);
}
_lazyBindingInfo.append_byte(BIND_OPCODE_DONE);
_lazyBindingInfo.align(_is64 ? 8 : 4);
}
void MachOFileLayout::computeSymbolTableSizes() {
// MachO symbol tables have three ranges: locals, globals, and undefines
const size_t nlistSize = (_is64 ? sizeof(nlist_64) : sizeof(nlist));
_symbolTableSize = nlistSize * (_file.localSymbols.size()
+ _file.globalSymbols.size()
+ _file.undefinedSymbols.size());
_symbolStringPoolSize = 0;
for (const Symbol &sym : _file.localSymbols) {
_symbolStringPoolSize += (sym.name.size()+1);
}
for (const Symbol &sym : _file.globalSymbols) {
_symbolStringPoolSize += (sym.name.size()+1);
}
for (const Symbol &sym : _file.undefinedSymbols) {
_symbolStringPoolSize += (sym.name.size()+1);
}
_symbolTableLocalsStartIndex = 0;
_symbolTableGlobalsStartIndex = _file.localSymbols.size();
_symbolTableUndefinesStartIndex = _symbolTableGlobalsStartIndex
+ _file.globalSymbols.size();
_indirectSymbolTableCount = 0;
for (const Section &sect : _file.sections) {
_indirectSymbolTableCount += sect.indirectSymbols.size();
}
}
void MachOFileLayout::computeDataInCodeSize() {
_dataInCodeSize = _file.dataInCode.size() * sizeof(data_in_code_entry);
}
void MachOFileLayout::writeLinkEditContent() {
if (_file.fileType == llvm::MachO::MH_OBJECT) {
writeRelocations();
writeDataInCodeInfo();
writeSymbolTable();
} else {
writeRebaseInfo();
writeBindingInfo();
writeLazyBindingInfo();
// TODO: add weak binding info
writeSymbolTable();
}
}
std::error_code MachOFileLayout::writeBinary(StringRef path) {
// Check for pending error from constructor.
if (_ec)
return _ec;
// Create FileOutputBuffer with calculated size.
std::unique_ptr<llvm::FileOutputBuffer> fob;
unsigned flags = 0;
if (_file.fileType != llvm::MachO::MH_OBJECT)
flags = llvm::FileOutputBuffer::F_executable;
std::error_code ec;
ec = llvm::FileOutputBuffer::create(path, size(), fob, flags);
if (ec)
return ec;
// Write content.
_buffer = fob->getBufferStart();
writeMachHeader();
ec = writeLoadCommands();
if (ec)
return ec;
writeSectionContent();
writeLinkEditContent();
fob->commit();
return std::error_code();
}
/// Takes in-memory normalized view and writes a mach-o object file.
std::error_code writeBinary(const NormalizedFile &file, StringRef path) {
MachOFileLayout layout(file);
return layout.writeBinary(path);
}
} // namespace normalized
} // namespace mach_o
} // namespace lld
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