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llvm-project/llvm/tools/dsymutil/MachOUtils.cpp

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//===-- MachOUtils.cpp - Mach-o specific helpers for dsymutil ------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "MachOUtils.h"
#include "BinaryHolder.h"
#include "DebugMap.h"
#include "LinkUtils.h"
#include "llvm/CodeGen/NonRelocatableStringpool.h"
#include "llvm/MC/MCAsmLayout.h"
#include "llvm/MC/MCMachObjectWriter.h"
#include "llvm/MC/MCObjectStreamer.h"
#include "llvm/MC/MCSectionMachO.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/Object/MachO.h"
#include "llvm/Support/FileUtilities.h"
#include "llvm/Support/Program.h"
#include "llvm/Support/WithColor.h"
#include "llvm/Support/raw_ostream.h"
namespace llvm {
namespace dsymutil {
namespace MachOUtils {
llvm::Error ArchAndFile::createTempFile() {
llvm::SmallString<128> TmpModel;
llvm::sys::path::system_temp_directory(true, TmpModel);
llvm::sys::path::append(TmpModel, "dsym.tmp%%%%%.dwarf");
Expected<sys::fs::TempFile> T = sys::fs::TempFile::create(TmpModel);
if (!T)
return T.takeError();
File = std::make_unique<sys::fs::TempFile>(std::move(*T));
return Error::success();
}
llvm::StringRef ArchAndFile::path() const { return File->TmpName; }
ArchAndFile::~ArchAndFile() {
if (File)
if (auto E = File->discard())
llvm::consumeError(std::move(E));
}
std::string getArchName(StringRef Arch) {
if (Arch.startswith("thumb"))
return (llvm::Twine("arm") + Arch.drop_front(5)).str();
return std::string(Arch);
}
static bool runLipo(StringRef SDKPath, SmallVectorImpl<StringRef> &Args) {
auto Path = sys::findProgramByName("lipo", makeArrayRef(SDKPath));
if (!Path)
Path = sys::findProgramByName("lipo");
if (!Path) {
WithColor::error() << "lipo: " << Path.getError().message() << "\n";
return false;
}
std::string ErrMsg;
int result = sys::ExecuteAndWait(*Path, Args, None, {}, 0, 0, &ErrMsg);
if (result) {
WithColor::error() << "lipo: " << ErrMsg << "\n";
return false;
}
return true;
}
bool generateUniversalBinary(SmallVectorImpl<ArchAndFile> &ArchFiles,
StringRef OutputFileName,
const LinkOptions &Options, StringRef SDKPath) {
// No need to merge one file into a universal fat binary.
if (ArchFiles.size() == 1) {
if (auto E = ArchFiles.front().File->keep(OutputFileName)) {
WithColor::error() << "while keeping " << ArchFiles.front().path()
<< " as " << OutputFileName << ": "
<< toString(std::move(E)) << "\n";
return false;
}
return true;
}
SmallVector<StringRef, 8> Args;
Args.push_back("lipo");
Args.push_back("-create");
for (auto &Thin : ArchFiles)
Args.push_back(Thin.path());
// Align segments to match dsymutil-classic alignment
for (auto &Thin : ArchFiles) {
Thin.Arch = getArchName(Thin.Arch);
Args.push_back("-segalign");
Args.push_back(Thin.Arch);
Args.push_back("20");
}
Args.push_back("-output");
Args.push_back(OutputFileName.data());
if (Options.Verbose) {
outs() << "Running lipo\n";
for (auto Arg : Args)
outs() << ' ' << Arg;
outs() << "\n";
}
return Options.NoOutput ? true : runLipo(SDKPath, Args);
}
// Return a MachO::segment_command_64 that holds the same values as the passed
// MachO::segment_command. We do that to avoid having to duplicate the logic
// for 32bits and 64bits segments.
struct MachO::segment_command_64 adaptFrom32bits(MachO::segment_command Seg) {
MachO::segment_command_64 Seg64;
Seg64.cmd = Seg.cmd;
Seg64.cmdsize = Seg.cmdsize;
memcpy(Seg64.segname, Seg.segname, sizeof(Seg.segname));
Seg64.vmaddr = Seg.vmaddr;
Seg64.vmsize = Seg.vmsize;
Seg64.fileoff = Seg.fileoff;
Seg64.filesize = Seg.filesize;
Seg64.maxprot = Seg.maxprot;
Seg64.initprot = Seg.initprot;
Seg64.nsects = Seg.nsects;
Seg64.flags = Seg.flags;
return Seg64;
}
// Iterate on all \a Obj segments, and apply \a Handler to them.
template <typename FunctionTy>
static void iterateOnSegments(const object::MachOObjectFile &Obj,
FunctionTy Handler) {
for (const auto &LCI : Obj.load_commands()) {
MachO::segment_command_64 Segment;
if (LCI.C.cmd == MachO::LC_SEGMENT)
Segment = adaptFrom32bits(Obj.getSegmentLoadCommand(LCI));
else if (LCI.C.cmd == MachO::LC_SEGMENT_64)
Segment = Obj.getSegment64LoadCommand(LCI);
else
continue;
Handler(Segment);
}
}
// Transfer the symbols described by \a NList to \a NewSymtab which is just the
// raw contents of the symbol table for the dSYM companion file. \returns
// whether the symbol was transferred or not.
template <typename NListTy>
static bool transferSymbol(NListTy NList, bool IsLittleEndian,
StringRef Strings, SmallVectorImpl<char> &NewSymtab,
NonRelocatableStringpool &NewStrings,
bool &InDebugNote) {
// Do not transfer undefined symbols, we want real addresses.
if ((NList.n_type & MachO::N_TYPE) == MachO::N_UNDF)
return false;
// Do not transfer N_AST symbols as their content is copied into a section of
// the Mach-O companion file.
if (NList.n_type == MachO::N_AST)
return false;
StringRef Name = StringRef(Strings.begin() + NList.n_strx);
// An N_SO with a filename opens a debugging scope and another one without a
// name closes it. Don't transfer anything in the debugging scope.
if (InDebugNote) {
InDebugNote =
(NList.n_type != MachO::N_SO) || (!Name.empty() && Name[0] != '\0');
return false;
} else if (NList.n_type == MachO::N_SO) {
InDebugNote = true;
return false;
}
// FIXME: The + 1 is here to mimic dsymutil-classic that has 2 empty
// strings at the start of the generated string table (There is
// corresponding code in the string table emission).
NList.n_strx = NewStrings.getStringOffset(Name) + 1;
if (IsLittleEndian != sys::IsLittleEndianHost)
MachO::swapStruct(NList);
NewSymtab.append(reinterpret_cast<char *>(&NList),
reinterpret_cast<char *>(&NList + 1));
return true;
}
// Wrapper around transferSymbol to transfer all of \a Obj symbols
// to \a NewSymtab. This function does not write in the output file.
// \returns the number of symbols in \a NewSymtab.
static unsigned transferSymbols(const object::MachOObjectFile &Obj,
SmallVectorImpl<char> &NewSymtab,
NonRelocatableStringpool &NewStrings) {
unsigned Syms = 0;
StringRef Strings = Obj.getStringTableData();
bool IsLittleEndian = Obj.isLittleEndian();
bool InDebugNote = false;
if (Obj.is64Bit()) {
for (const object::SymbolRef &Symbol : Obj.symbols()) {
object::DataRefImpl DRI = Symbol.getRawDataRefImpl();
if (transferSymbol(Obj.getSymbol64TableEntry(DRI), IsLittleEndian,
Strings, NewSymtab, NewStrings, InDebugNote))
++Syms;
}
} else {
for (const object::SymbolRef &Symbol : Obj.symbols()) {
object::DataRefImpl DRI = Symbol.getRawDataRefImpl();
if (transferSymbol(Obj.getSymbolTableEntry(DRI), IsLittleEndian, Strings,
NewSymtab, NewStrings, InDebugNote))
++Syms;
}
}
return Syms;
}
static MachO::section
getSection(const object::MachOObjectFile &Obj,
const MachO::segment_command &Seg,
const object::MachOObjectFile::LoadCommandInfo &LCI, unsigned Idx) {
return Obj.getSection(LCI, Idx);
}
static MachO::section_64
getSection(const object::MachOObjectFile &Obj,
const MachO::segment_command_64 &Seg,
const object::MachOObjectFile::LoadCommandInfo &LCI, unsigned Idx) {
return Obj.getSection64(LCI, Idx);
}
// Transfer \a Segment from \a Obj to the output file. This calls into \a Writer
// to write these load commands directly in the output file at the current
// position.
// The function also tries to find a hole in the address map to fit the __DWARF
// segment of \a DwarfSegmentSize size. \a EndAddress is updated to point at the
// highest segment address.
// When the __LINKEDIT segment is transferred, its offset and size are set resp.
// to \a LinkeditOffset and \a LinkeditSize.
template <typename SegmentTy>
static void transferSegmentAndSections(
const object::MachOObjectFile::LoadCommandInfo &LCI, SegmentTy Segment,
const object::MachOObjectFile &Obj, MachObjectWriter &Writer,
uint64_t LinkeditOffset, uint64_t LinkeditSize, uint64_t DwarfSegmentSize,
uint64_t &GapForDwarf, uint64_t &EndAddress) {
if (StringRef("__DWARF") == Segment.segname)
return;
Segment.fileoff = Segment.filesize = 0;
if (StringRef("__LINKEDIT") == Segment.segname) {
Segment.fileoff = LinkeditOffset;
Segment.filesize = LinkeditSize;
// Resize vmsize by rounding to the page size.
Segment.vmsize = alignTo(LinkeditSize, 0x1000);
}
// Check if the end address of the last segment and our current
// start address leave a sufficient gap to store the __DWARF
// segment.
uint64_t PrevEndAddress = EndAddress;
EndAddress = alignTo(EndAddress, 0x1000);
if (GapForDwarf == UINT64_MAX && Segment.vmaddr > EndAddress &&
Segment.vmaddr - EndAddress >= DwarfSegmentSize)
GapForDwarf = EndAddress;
// The segments are not necessarily sorted by their vmaddr.
EndAddress =
std::max<uint64_t>(PrevEndAddress, Segment.vmaddr + Segment.vmsize);
unsigned nsects = Segment.nsects;
if (Obj.isLittleEndian() != sys::IsLittleEndianHost)
MachO::swapStruct(Segment);
Writer.W.OS.write(reinterpret_cast<char *>(&Segment), sizeof(Segment));
for (unsigned i = 0; i < nsects; ++i) {
auto Sect = getSection(Obj, Segment, LCI, i);
Sect.offset = Sect.reloff = Sect.nreloc = 0;
if (Obj.isLittleEndian() != sys::IsLittleEndianHost)
MachO::swapStruct(Sect);
Writer.W.OS.write(reinterpret_cast<char *>(&Sect), sizeof(Sect));
}
}
// Write the __DWARF segment load command to the output file.
static void createDwarfSegment(uint64_t VMAddr, uint64_t FileOffset,
uint64_t FileSize, unsigned NumSections,
MCAsmLayout &Layout, MachObjectWriter &Writer) {
Writer.writeSegmentLoadCommand("__DWARF", NumSections, VMAddr,
alignTo(FileSize, 0x1000), FileOffset,
FileSize, /* MaxProt */ 7,
/* InitProt =*/3);
for (unsigned int i = 0, n = Layout.getSectionOrder().size(); i != n; ++i) {
MCSection *Sec = Layout.getSectionOrder()[i];
if (Sec->begin() == Sec->end() || !Layout.getSectionFileSize(Sec))
continue;
unsigned Align = Sec->getAlignment();
if (Align > 1) {
VMAddr = alignTo(VMAddr, Align);
FileOffset = alignTo(FileOffset, Align);
}
Writer.writeSection(Layout, *Sec, VMAddr, FileOffset, 0, 0, 0);
FileOffset += Layout.getSectionAddressSize(Sec);
VMAddr += Layout.getSectionAddressSize(Sec);
}
}
static bool isExecutable(const object::MachOObjectFile &Obj) {
if (Obj.is64Bit())
return Obj.getHeader64().filetype != MachO::MH_OBJECT;
else
return Obj.getHeader().filetype != MachO::MH_OBJECT;
}
static bool hasLinkEditSegment(const object::MachOObjectFile &Obj) {
bool HasLinkEditSegment = false;
iterateOnSegments(Obj, [&](const MachO::segment_command_64 &Segment) {
if (StringRef("__LINKEDIT") == Segment.segname)
HasLinkEditSegment = true;
});
return HasLinkEditSegment;
}
static unsigned segmentLoadCommandSize(bool Is64Bit, unsigned NumSections) {
if (Is64Bit)
return sizeof(MachO::segment_command_64) +
NumSections * sizeof(MachO::section_64);
return sizeof(MachO::segment_command) + NumSections * sizeof(MachO::section);
}
// Stream a dSYM companion binary file corresponding to the binary referenced
// by \a DM to \a OutFile. The passed \a MS MCStreamer is setup to write to
// \a OutFile and it must be using a MachObjectWriter object to do so.
bool generateDsymCompanion(llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS,
const DebugMap &DM, SymbolMapTranslator &Translator,
MCStreamer &MS, raw_fd_ostream &OutFile) {
auto &ObjectStreamer = static_cast<MCObjectStreamer &>(MS);
MCAssembler &MCAsm = ObjectStreamer.getAssembler();
auto &Writer = static_cast<MachObjectWriter &>(MCAsm.getWriter());
// Layout but don't emit.
ObjectStreamer.flushPendingLabels();
MCAsmLayout Layout(MCAsm);
MCAsm.layout(Layout);
BinaryHolder InputBinaryHolder(VFS, false);
auto ObjectEntry = InputBinaryHolder.getObjectEntry(DM.getBinaryPath());
if (!ObjectEntry) {
auto Err = ObjectEntry.takeError();
return error(Twine("opening ") + DM.getBinaryPath() + ": " +
toString(std::move(Err)),
"output file streaming");
}
auto Object =
ObjectEntry->getObjectAs<object::MachOObjectFile>(DM.getTriple());
if (!Object) {
auto Err = Object.takeError();
return error(Twine("opening ") + DM.getBinaryPath() + ": " +
toString(std::move(Err)),
"output file streaming");
}
auto &InputBinary = *Object;
bool Is64Bit = Writer.is64Bit();
MachO::symtab_command SymtabCmd = InputBinary.getSymtabLoadCommand();
// Compute the number of load commands we will need.
unsigned LoadCommandSize = 0;
unsigned NumLoadCommands = 0;
// Get LC_UUID and LC_BUILD_VERSION.
MachO::uuid_command UUIDCmd;
SmallVector<MachO::build_version_command, 2> BuildVersionCmd;
memset(&UUIDCmd, 0, sizeof(UUIDCmd));
for (auto &LCI : InputBinary.load_commands()) {
switch (LCI.C.cmd) {
case MachO::LC_UUID:
if (UUIDCmd.cmd)
return error("Binary contains more than one UUID");
UUIDCmd = InputBinary.getUuidCommand(LCI);
++NumLoadCommands;
LoadCommandSize += sizeof(UUIDCmd);
break;
case MachO::LC_BUILD_VERSION: {
MachO::build_version_command Cmd;
memset(&Cmd, 0, sizeof(Cmd));
Cmd = InputBinary.getBuildVersionLoadCommand(LCI);
++NumLoadCommands;
LoadCommandSize += sizeof(Cmd);
// LLDB doesn't care about the build tools for now.
Cmd.ntools = 0;
BuildVersionCmd.push_back(Cmd);
break;
}
default:
break;
}
}
// If we have a valid symtab to copy, do it.
bool ShouldEmitSymtab =
isExecutable(InputBinary) && hasLinkEditSegment(InputBinary);
if (ShouldEmitSymtab) {
LoadCommandSize += sizeof(MachO::symtab_command);
++NumLoadCommands;
}
unsigned HeaderSize =
Is64Bit ? sizeof(MachO::mach_header_64) : sizeof(MachO::mach_header);
// We will copy every segment that isn't __DWARF.
iterateOnSegments(InputBinary, [&](const MachO::segment_command_64 &Segment) {
if (StringRef("__DWARF") == Segment.segname)
return;
++NumLoadCommands;
LoadCommandSize += segmentLoadCommandSize(Is64Bit, Segment.nsects);
});
// We will add our own brand new __DWARF segment if we have debug
// info.
unsigned NumDwarfSections = 0;
uint64_t DwarfSegmentSize = 0;
for (unsigned int i = 0, n = Layout.getSectionOrder().size(); i != n; ++i) {
MCSection *Sec = Layout.getSectionOrder()[i];
if (Sec->begin() == Sec->end())
continue;
if (uint64_t Size = Layout.getSectionFileSize(Sec)) {
DwarfSegmentSize = alignTo(DwarfSegmentSize, Sec->getAlignment());
DwarfSegmentSize += Size;
++NumDwarfSections;
}
}
if (NumDwarfSections) {
++NumLoadCommands;
LoadCommandSize += segmentLoadCommandSize(Is64Bit, NumDwarfSections);
}
SmallString<0> NewSymtab;
std::function<StringRef(StringRef)> TranslationLambda =
Translator ? [&](StringRef Input) { return Translator(Input); }
: static_cast<std::function<StringRef(StringRef)>>(nullptr);
// Legacy dsymutil puts an empty string at the start of the line table.
// thus we set NonRelocatableStringpool(,PutEmptyString=true)
NonRelocatableStringpool NewStrings(TranslationLambda, true);
unsigned NListSize = Is64Bit ? sizeof(MachO::nlist_64) : sizeof(MachO::nlist);
unsigned NumSyms = 0;
uint64_t NewStringsSize = 0;
if (ShouldEmitSymtab) {
NewSymtab.reserve(SymtabCmd.nsyms * NListSize / 2);
NumSyms = transferSymbols(InputBinary, NewSymtab, NewStrings);
NewStringsSize = NewStrings.getSize() + 1;
}
uint64_t SymtabStart = LoadCommandSize;
SymtabStart += HeaderSize;
SymtabStart = alignTo(SymtabStart, 0x1000);
// We gathered all the information we need, start emitting the output file.
Writer.writeHeader(MachO::MH_DSYM, NumLoadCommands, LoadCommandSize, false);
// Write the load commands.
assert(OutFile.tell() == HeaderSize);
if (UUIDCmd.cmd != 0) {
Writer.W.write<uint32_t>(UUIDCmd.cmd);
Writer.W.write<uint32_t>(sizeof(UUIDCmd));
OutFile.write(reinterpret_cast<const char *>(UUIDCmd.uuid), 16);
assert(OutFile.tell() == HeaderSize + sizeof(UUIDCmd));
}
for (auto Cmd : BuildVersionCmd) {
Writer.W.write<uint32_t>(Cmd.cmd);
Writer.W.write<uint32_t>(sizeof(Cmd));
Writer.W.write<uint32_t>(Cmd.platform);
Writer.W.write<uint32_t>(Cmd.minos);
Writer.W.write<uint32_t>(Cmd.sdk);
Writer.W.write<uint32_t>(Cmd.ntools);
}
assert(SymtabCmd.cmd && "No symbol table.");
uint64_t StringStart = SymtabStart + NumSyms * NListSize;
if (ShouldEmitSymtab)
Writer.writeSymtabLoadCommand(SymtabStart, NumSyms, StringStart,
NewStringsSize);
uint64_t DwarfSegmentStart = StringStart + NewStringsSize;
DwarfSegmentStart = alignTo(DwarfSegmentStart, 0x1000);
// Write the load commands for the segments and sections we 'import' from
// the original binary.
uint64_t EndAddress = 0;
uint64_t GapForDwarf = UINT64_MAX;
for (auto &LCI : InputBinary.load_commands()) {
if (LCI.C.cmd == MachO::LC_SEGMENT)
transferSegmentAndSections(LCI, InputBinary.getSegmentLoadCommand(LCI),
InputBinary, Writer, SymtabStart,
StringStart + NewStringsSize - SymtabStart,
DwarfSegmentSize, GapForDwarf, EndAddress);
else if (LCI.C.cmd == MachO::LC_SEGMENT_64)
transferSegmentAndSections(LCI, InputBinary.getSegment64LoadCommand(LCI),
InputBinary, Writer, SymtabStart,
StringStart + NewStringsSize - SymtabStart,
DwarfSegmentSize, GapForDwarf, EndAddress);
}
uint64_t DwarfVMAddr = alignTo(EndAddress, 0x1000);
uint64_t DwarfVMMax = Is64Bit ? UINT64_MAX : UINT32_MAX;
if (DwarfVMAddr + DwarfSegmentSize > DwarfVMMax ||
DwarfVMAddr + DwarfSegmentSize < DwarfVMAddr /* Overflow */) {
// There is no room for the __DWARF segment at the end of the
// address space. Look through segments to find a gap.
DwarfVMAddr = GapForDwarf;
if (DwarfVMAddr == UINT64_MAX)
warn("not enough VM space for the __DWARF segment.",
"output file streaming");
}
// Write the load command for the __DWARF segment.
createDwarfSegment(DwarfVMAddr, DwarfSegmentStart, DwarfSegmentSize,
NumDwarfSections, Layout, Writer);
assert(OutFile.tell() == LoadCommandSize + HeaderSize);
OutFile.write_zeros(SymtabStart - (LoadCommandSize + HeaderSize));
assert(OutFile.tell() == SymtabStart);
// Transfer symbols.
if (ShouldEmitSymtab) {
OutFile << NewSymtab.str();
assert(OutFile.tell() == StringStart);
// Transfer string table.
// FIXME: The NonRelocatableStringpool starts with an empty string, but
// dsymutil-classic starts the reconstructed string table with 2 of these.
// Reproduce that behavior for now (there is corresponding code in
// transferSymbol).
OutFile << '\0';
std::vector<DwarfStringPoolEntryRef> Strings =
NewStrings.getEntriesForEmission();
for (auto EntryRef : Strings) {
OutFile.write(EntryRef.getString().data(),
EntryRef.getString().size() + 1);
}
}
assert(OutFile.tell() == StringStart + NewStringsSize);
// Pad till the Dwarf segment start.
OutFile.write_zeros(DwarfSegmentStart - (StringStart + NewStringsSize));
assert(OutFile.tell() == DwarfSegmentStart);
// Emit the Dwarf sections contents.
for (const MCSection &Sec : MCAsm) {
if (Sec.begin() == Sec.end())
continue;
uint64_t Pos = OutFile.tell();
OutFile.write_zeros(alignTo(Pos, Sec.getAlignment()) - Pos);
MCAsm.writeSectionData(OutFile, &Sec, Layout);
}
return true;
}
} // namespace MachOUtils
} // namespace dsymutil
} // namespace llvm
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