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[mach-o] binary reader and writer This patch adds support for converting normalized mach-o to and from binary mach-o. It also changes WriterMachO (which previously directly wrote a mach-o binary given a set of Atoms) to instead do it in two steps. The first step uses normalizedFromAtoms() to convert Atoms to normalized mach-o, and the second step uses writeBinary() which to generate the mach-o binary file. llvm-svn: 194167
2013-11-07 05:36:55 +08:00
//===- 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/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/FileOutputBuffer.h"
#include "llvm/Support/Host.h"
#include "llvm/Support/MachO.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Support/system_error.h"
#include <functional>
#include <map>
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;
/// 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.
error_code writeBinary(StringRef path);
private:
uint32_t loadCommandsSize(uint32_t &count);
void buildFileOffsets();
void writeMachHeader();
error_code writeLoadCommands();
void writeSectionContent();
void writeRelocations();
void writeSymbolTable();
void writeRebaseInfo();
void writeBindingInfo();
void writeLazyBindingInfo();
void writeLinkEditContent();
void buildLinkEditInfo();
void buildRebaseInfo();
void buildBindInfo();
void buildLazyBindInfo();
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);
error_code writeSingleSegment32LoadCommand(uint8_t *&lc);
error_code writeSingleSegment64LoadCommand(uint8_t *&lc);
error_code writeSegment32LoadCommands(uint8_t *&lc);
error_code writeSegment64LoadCommands(uint8_t *&lc);
uint32_t pointerAlign(uint32_t value);
static StringRef dyldPath();
class ByteBuffer {
public:
ByteBuffer();
void append_byte(uint8_t);
void append_uleb128(uint64_t);
void append_sleb128(int64_t);
void append_string(StringRef);
void align(unsigned);
size_t size();
const uint8_t *bytes();
private:
std::vector<uint8_t> _bytes;
};
struct SegExtraInfo {
uint32_t fileOffset;
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;
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 _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 _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.size();
}
StringRef MachOFileLayout::dyldPath() {
return "/usr/lib/dyld";
}
uint32_t MachOFileLayout::pointerAlign(uint32_t value) {
return llvm::RoundUpToAlignment(value, _is64 ? 8 : 4);
}
MachOFileLayout::ByteBuffer::ByteBuffer() {
_bytes.reserve(256);
}
void MachOFileLayout::ByteBuffer::append_byte(uint8_t b) {
_bytes.push_back(b);
}
void MachOFileLayout::ByteBuffer::append_uleb128(uint64_t value) {
uint8_t byte;
do {
byte = value & 0x7F;
value &= ~0x7F;
if ( value != 0 )
byte |= 0x80;
_bytes.push_back(byte);
value = value >> 7;
} while( byte >= 0x80 );
}
void MachOFileLayout::ByteBuffer::append_sleb128(int64_t value) {
bool isNeg = ( value < 0 );
uint8_t byte;
bool more;
do {
byte = value & 0x7F;
value = value >> 7;
if ( isNeg )
more = ( (value != -1) || ((byte & 0x40) == 0) );
else
more = ( (value != 0) || ((byte & 0x40) != 0) );
if ( more )
byte |= 0x80;
_bytes.push_back(byte);
}
while( more );
}
void MachOFileLayout::ByteBuffer::append_string(StringRef str) {
_bytes.insert(_bytes.end(), str.begin(), str.end());
_bytes.push_back('\0');
}
void MachOFileLayout::ByteBuffer::align(unsigned alignment) {
while ( (_bytes.size() % alignment) != 0 )
_bytes.push_back(0);
}
const uint8_t *MachOFileLayout::ByteBuffer::bytes() {
return &_bytes[0];
}
size_t MachOFileLayout::ByteBuffer::size() {
return _bytes.size();
}
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;
// 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();
// Align start of relocations.
_startOfRelocations = pointerAlign(_endOfSectionsContent);
_startOfSymbols = _startOfRelocations + relocCount * 8;
// 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,
// indirect symbol table, symbol table, symbol table strings.
_startOfRebaseInfo = _startOfLinkEdit;
_endOfRebaseInfo = _startOfRebaseInfo + _rebaseInfo.size();
_startOfBindingInfo = _endOfRebaseInfo;
_endOfBindingInfo = _startOfBindingInfo + _bindingInfo.size();
_startOfLazyBindingInfo = _endOfBindingInfo;
_endOfLazyBindingInfo = _startOfLazyBindingInfo + _lazyBindingInfo.size();
_startOfSymbols = _endOfLazyBindingInfo;
_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"
<< " 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;
// 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 = llvm::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 = llvm::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 = llvm::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) {
// FIXME: 4096 should be infered from segments in normalized file.
_segInfo[&sg].fileOffset = llvm::RoundUpToAlignment(fileOffset, 4096);
if ((_seg1addr == INT64_MAX) && sg.access)
_seg1addr = sg.address;
DEBUG_WITH_TYPE("MachOFileLayout",
llvm::dbgs() << " segment=" << sg.name
<< ", fileOffset=" << _segInfo[&sg].fileOffset << "\n");
for (const Section *s : _segInfo[&sg].sections) {
fileOffset = s->address - sg.address + _segInfo[&sg].fileOffset;
_sectInfo[s].fileOffset = fileOffset;
DEBUG_WITH_TYPE("MachOFileLayout",
llvm::dbgs() << " section=" << s->sectionName
<< ", fileOffset=" << fileOffset << "\n");
}
_addressOfLinkEdit = sg.address + sg.size;
}
_startOfLinkEdit = llvm::RoundUpToAlignment(fileOffset, 4096);
}
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();
}
error_code MachOFileLayout::writeSingleSegment64LoadCommand(uint8_t *&lc) {
segment_command_64* seg = reinterpret_cast<segment_command_64*>(lc);
seg->cmd = LC_SEGMENT_64;
seg->cmdsize = sizeof(segment_command_64)
+ _file.sections.size() * sizeof(section_64);
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);
section_64 *sout = reinterpret_cast<section_64*>
(lc+sizeof(segment_command_64));
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 error_code::success();
}
error_code MachOFileLayout::writeSingleSegment32LoadCommand(uint8_t *&lc) {
segment_command* seg = reinterpret_cast<segment_command*>(lc);
seg->cmd = LC_SEGMENT;
seg->cmdsize = sizeof(segment_command)
+ _file.sections.size() * sizeof(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);
section *sout = reinterpret_cast<section*>(lc+sizeof(segment_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 error_code::success();
}
error_code MachOFileLayout::writeSegment64LoadCommands(uint8_t *&lc) {
uint32_t indirectSymRunningIndex = 0;
for (const Segment &seg : _file.segments) {
// Write segment command with trailing sections.
SegExtraInfo &segInfo = _segInfo[&seg];
segment_command_64* cmd = reinterpret_cast<segment_command_64*>(lc);
cmd->cmd = LC_SEGMENT_64;
cmd->cmdsize = sizeof(segment_command_64)
+ segInfo.sections.size() * sizeof(section_64);
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 = seg.access ? (uint64_t)seg.size : 0;
cmd->maxprot = seg.access;
cmd->initprot = seg.access;
cmd->nsects = segInfo.sections.size();
cmd->flags = 0;
if (_swap)
swapStruct(*cmd);
section_64 *sect = reinterpret_cast<section_64*>
(lc+sizeof(segment_command_64));
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
segment_command_64* cmd = reinterpret_cast<segment_command_64*>(lc);
cmd->cmd = LC_SEGMENT_64;
cmd->cmdsize = sizeof(segment_command_64);
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 error_code::success();
}
// FIXME: See if this can be combined with writeSegment64LoadCommands
// by using templates.
error_code MachOFileLayout::writeSegment32LoadCommands(uint8_t *&lc) {
uint32_t indirectSymRunningIndex = 0;
for (const Segment &seg : _file.segments) {
// Write segment command with trailing sections.
SegExtraInfo &segInfo = _segInfo[&seg];
segment_command* cmd = reinterpret_cast<segment_command*>(lc);
cmd->cmd = LC_SEGMENT;
cmd->cmdsize = sizeof(segment_command)
+ segInfo.sections.size() * sizeof(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 = seg.access ? (uint32_t)seg.size : 0;
cmd->maxprot = seg.access;
cmd->initprot = seg.access;
cmd->nsects = segInfo.sections.size();
cmd->flags = 0;
if (_swap)
swapStruct(*cmd);
section *sect = reinterpret_cast<section*>(lc+sizeof(segment_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);
}
return error_code::success();
}
error_code MachOFileLayout::writeLoadCommands() {
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 = writeSingleSegment64LoadCommand(lc);
else
ec = writeSingleSegment32LoadCommand(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);
} else {
// Final linked images have sections under segments.
if (_is64)
ec = writeSegment64LoadCommands(lc);
else
ec = writeSegment32LoadCommands(lc);
// 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.
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::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++ = SwapByteOrder(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++ = SwapByteOrder(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();
}
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::writeLinkEditContent() {
if (_file.fileType == llvm::MachO::MH_OBJECT) {
writeRelocations();
writeSymbolTable();
} else {
writeRebaseInfo();
writeBindingInfo();
writeLazyBindingInfo();
// TODO: add weak binding info
writeSymbolTable();
}
}
error_code MachOFileLayout::writeBinary(StringRef path) {
// Check for pending error from constructor.
if (_ec)
return _ec;
// Create FileOutputBuffer with calculated size.
OwningPtr<llvm::FileOutputBuffer> fob;
unsigned flags = 0;
if (_file.fileType != llvm::MachO::MH_OBJECT)
flags = llvm::FileOutputBuffer::F_executable;
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 error_code::success();
}
/// Takes in-memory normalized view and writes a mach-o object file.
error_code
writeBinary(const NormalizedFile &file, StringRef path) {
MachOFileLayout layout(file);
return layout.writeBinary(path);
}
} // namespace normalized
} // namespace mach_o
} // namespace lld