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llvm-for-llvmta/tools/llvm-objcopy/ELF/ELFObjcopy.cpp

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//===- ELFObjcopy.cpp -----------------------------------------------------===//
//
// 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 "ELFObjcopy.h"
#include "Buffer.h"
#include "CopyConfig.h"
#include "Object.h"
#include "llvm/ADT/BitmaskEnum.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/Twine.h"
#include "llvm/BinaryFormat/ELF.h"
#include "llvm/MC/MCTargetOptions.h"
#include "llvm/Object/Binary.h"
#include "llvm/Object/ELFObjectFile.h"
#include "llvm/Object/ELFTypes.h"
#include "llvm/Object/Error.h"
#include "llvm/Option/Option.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/Compression.h"
#include "llvm/Support/Errc.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/ErrorOr.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/Memory.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>
#include <cassert>
#include <cstdlib>
#include <functional>
#include <iterator>
#include <memory>
#include <string>
#include <system_error>
#include <utility>
namespace llvm {
namespace objcopy {
namespace elf {
using namespace object;
using namespace ELF;
using SectionPred = std::function<bool(const SectionBase &Sec)>;
static bool isDebugSection(const SectionBase &Sec) {
return StringRef(Sec.Name).startswith(".debug") ||
StringRef(Sec.Name).startswith(".zdebug") || Sec.Name == ".gdb_index";
}
static bool isDWOSection(const SectionBase &Sec) {
return StringRef(Sec.Name).endswith(".dwo");
}
static bool onlyKeepDWOPred(const Object &Obj, const SectionBase &Sec) {
// We can't remove the section header string table.
if (&Sec == Obj.SectionNames)
return false;
// Short of keeping the string table we want to keep everything that is a DWO
// section and remove everything else.
return !isDWOSection(Sec);
}
uint64_t getNewShfFlags(SectionFlag AllFlags) {
uint64_t NewFlags = 0;
if (AllFlags & SectionFlag::SecAlloc)
NewFlags |= ELF::SHF_ALLOC;
if (!(AllFlags & SectionFlag::SecReadonly))
NewFlags |= ELF::SHF_WRITE;
if (AllFlags & SectionFlag::SecCode)
NewFlags |= ELF::SHF_EXECINSTR;
if (AllFlags & SectionFlag::SecMerge)
NewFlags |= ELF::SHF_MERGE;
if (AllFlags & SectionFlag::SecStrings)
NewFlags |= ELF::SHF_STRINGS;
if (AllFlags & SectionFlag::SecExclude)
NewFlags |= ELF::SHF_EXCLUDE;
return NewFlags;
}
static uint64_t getSectionFlagsPreserveMask(uint64_t OldFlags,
uint64_t NewFlags) {
// Preserve some flags which should not be dropped when setting flags.
// Also, preserve anything OS/processor dependant.
const uint64_t PreserveMask =
(ELF::SHF_COMPRESSED | ELF::SHF_GROUP | ELF::SHF_LINK_ORDER |
ELF::SHF_MASKOS | ELF::SHF_MASKPROC | ELF::SHF_TLS |
ELF::SHF_INFO_LINK) &
~ELF::SHF_EXCLUDE;
return (OldFlags & PreserveMask) | (NewFlags & ~PreserveMask);
}
static void setSectionFlagsAndType(SectionBase &Sec, SectionFlag Flags) {
Sec.Flags = getSectionFlagsPreserveMask(Sec.Flags, getNewShfFlags(Flags));
// In GNU objcopy, certain flags promote SHT_NOBITS to SHT_PROGBITS. This rule
// may promote more non-ALLOC sections than GNU objcopy, but it is fine as
// non-ALLOC SHT_NOBITS sections do not make much sense.
if (Sec.Type == SHT_NOBITS &&
(!(Sec.Flags & ELF::SHF_ALLOC) ||
Flags & (SectionFlag::SecContents | SectionFlag::SecLoad)))
Sec.Type = SHT_PROGBITS;
}
static ElfType getOutputElfType(const Binary &Bin) {
// Infer output ELF type from the input ELF object
if (isa<ELFObjectFile<ELF32LE>>(Bin))
return ELFT_ELF32LE;
if (isa<ELFObjectFile<ELF64LE>>(Bin))
return ELFT_ELF64LE;
if (isa<ELFObjectFile<ELF32BE>>(Bin))
return ELFT_ELF32BE;
if (isa<ELFObjectFile<ELF64BE>>(Bin))
return ELFT_ELF64BE;
llvm_unreachable("Invalid ELFType");
}
static ElfType getOutputElfType(const MachineInfo &MI) {
// Infer output ELF type from the binary arch specified
if (MI.Is64Bit)
return MI.IsLittleEndian ? ELFT_ELF64LE : ELFT_ELF64BE;
else
return MI.IsLittleEndian ? ELFT_ELF32LE : ELFT_ELF32BE;
}
static std::unique_ptr<Writer> createELFWriter(const CopyConfig &Config,
Object &Obj, Buffer &Buf,
ElfType OutputElfType) {
// Depending on the initial ELFT and OutputFormat we need a different Writer.
switch (OutputElfType) {
case ELFT_ELF32LE:
return std::make_unique<ELFWriter<ELF32LE>>(Obj, Buf, !Config.StripSections,
Config.OnlyKeepDebug);
case ELFT_ELF64LE:
return std::make_unique<ELFWriter<ELF64LE>>(Obj, Buf, !Config.StripSections,
Config.OnlyKeepDebug);
case ELFT_ELF32BE:
return std::make_unique<ELFWriter<ELF32BE>>(Obj, Buf, !Config.StripSections,
Config.OnlyKeepDebug);
case ELFT_ELF64BE:
return std::make_unique<ELFWriter<ELF64BE>>(Obj, Buf, !Config.StripSections,
Config.OnlyKeepDebug);
}
llvm_unreachable("Invalid output format");
}
static std::unique_ptr<Writer> createWriter(const CopyConfig &Config,
Object &Obj, Buffer &Buf,
ElfType OutputElfType) {
switch (Config.OutputFormat) {
case FileFormat::Binary:
return std::make_unique<BinaryWriter>(Obj, Buf);
case FileFormat::IHex:
return std::make_unique<IHexWriter>(Obj, Buf);
default:
return createELFWriter(Config, Obj, Buf, OutputElfType);
}
}
template <class ELFT>
static Expected<ArrayRef<uint8_t>>
findBuildID(const CopyConfig &Config, const object::ELFFile<ELFT> &In) {
auto PhdrsOrErr = In.program_headers();
if (auto Err = PhdrsOrErr.takeError())
return createFileError(Config.InputFilename, std::move(Err));
for (const auto &Phdr : *PhdrsOrErr) {
if (Phdr.p_type != PT_NOTE)
continue;
Error Err = Error::success();
for (auto Note : In.notes(Phdr, Err))
if (Note.getType() == NT_GNU_BUILD_ID && Note.getName() == ELF_NOTE_GNU)
return Note.getDesc();
if (Err)
return createFileError(Config.InputFilename, std::move(Err));
}
return createFileError(Config.InputFilename,
createStringError(llvm::errc::invalid_argument,
"could not find build ID"));
}
static Expected<ArrayRef<uint8_t>>
findBuildID(const CopyConfig &Config, const object::ELFObjectFileBase &In) {
if (auto *O = dyn_cast<ELFObjectFile<ELF32LE>>(&In))
return findBuildID(Config, O->getELFFile());
else if (auto *O = dyn_cast<ELFObjectFile<ELF64LE>>(&In))
return findBuildID(Config, O->getELFFile());
else if (auto *O = dyn_cast<ELFObjectFile<ELF32BE>>(&In))
return findBuildID(Config, O->getELFFile());
else if (auto *O = dyn_cast<ELFObjectFile<ELF64BE>>(&In))
return findBuildID(Config, O->getELFFile());
llvm_unreachable("Bad file format");
}
template <class... Ts>
static Error makeStringError(std::error_code EC, const Twine &Msg,
Ts &&... Args) {
std::string FullMsg = (EC.message() + ": " + Msg).str();
return createStringError(EC, FullMsg.c_str(), std::forward<Ts>(Args)...);
}
#define MODEL_8 "%%%%%%%%"
#define MODEL_16 MODEL_8 MODEL_8
#define MODEL_32 (MODEL_16 MODEL_16)
static Error linkToBuildIdDir(const CopyConfig &Config, StringRef ToLink,
StringRef Suffix,
ArrayRef<uint8_t> BuildIdBytes) {
SmallString<128> Path = Config.BuildIdLinkDir;
sys::path::append(Path, llvm::toHex(BuildIdBytes[0], /*LowerCase*/ true));
if (auto EC = sys::fs::create_directories(Path))
return createFileError(
Path.str(),
makeStringError(EC, "cannot create build ID link directory"));
sys::path::append(Path,
llvm::toHex(BuildIdBytes.slice(1), /*LowerCase*/ true));
Path += Suffix;
SmallString<128> TmpPath;
// create_hard_link races so we need to link to a temporary path but
// we want to make sure that we choose a filename that does not exist.
// By using 32 model characters we get 128-bits of entropy. It is
// unlikely that this string has ever existed before much less exists
// on this disk or in the current working directory.
// Additionally we prepend the original Path for debugging but also
// because it ensures that we're linking within a directory on the same
// partition on the same device which is critical. It has the added
// win of yet further decreasing the odds of a conflict.
sys::fs::createUniquePath(Twine(Path) + "-" + MODEL_32 + ".tmp", TmpPath,
/*MakeAbsolute*/ false);
if (auto EC = sys::fs::create_hard_link(ToLink, TmpPath)) {
Path.push_back('\0');
return makeStringError(EC, "cannot link '%s' to '%s'", ToLink.data(),
Path.data());
}
// We then atomically rename the link into place which will just move the
// link. If rename fails something is more seriously wrong so just return
// an error.
if (auto EC = sys::fs::rename(TmpPath, Path)) {
Path.push_back('\0');
return makeStringError(EC, "cannot link '%s' to '%s'", ToLink.data(),
Path.data());
}
// If `Path` was already a hard-link to the same underlying file then the
// temp file will be left so we need to remove it. Remove will not cause
// an error by default if the file is already gone so just blindly remove
// it rather than checking.
if (auto EC = sys::fs::remove(TmpPath)) {
TmpPath.push_back('\0');
return makeStringError(EC, "could not remove '%s'", TmpPath.data());
}
return Error::success();
}
static Error splitDWOToFile(const CopyConfig &Config, const Reader &Reader,
StringRef File, ElfType OutputElfType) {
Expected<std::unique_ptr<Object>> DWOFile = Reader.create(false);
if (!DWOFile)
return DWOFile.takeError();
auto OnlyKeepDWOPred = [&DWOFile](const SectionBase &Sec) {
return onlyKeepDWOPred(**DWOFile, Sec);
};
if (Error E =
(*DWOFile)->removeSections(Config.AllowBrokenLinks, OnlyKeepDWOPred))
return E;
if (Config.OutputArch) {
(*DWOFile)->Machine = Config.OutputArch.getValue().EMachine;
(*DWOFile)->OSABI = Config.OutputArch.getValue().OSABI;
}
FileBuffer FB(File);
std::unique_ptr<Writer> Writer =
createWriter(Config, **DWOFile, FB, OutputElfType);
if (Error E = Writer->finalize())
return E;
return Writer->write();
}
static Error dumpSectionToFile(StringRef SecName, StringRef Filename,
Object &Obj) {
for (auto &Sec : Obj.sections()) {
if (Sec.Name == SecName) {
if (Sec.Type == SHT_NOBITS)
return createStringError(object_error::parse_failed,
"cannot dump section '%s': it has no contents",
SecName.str().c_str());
Expected<std::unique_ptr<FileOutputBuffer>> BufferOrErr =
FileOutputBuffer::create(Filename, Sec.OriginalData.size());
if (!BufferOrErr)
return BufferOrErr.takeError();
std::unique_ptr<FileOutputBuffer> Buf = std::move(*BufferOrErr);
std::copy(Sec.OriginalData.begin(), Sec.OriginalData.end(),
Buf->getBufferStart());
if (Error E = Buf->commit())
return E;
return Error::success();
}
}
return createStringError(object_error::parse_failed, "section '%s' not found",
SecName.str().c_str());
}
static bool isCompressable(const SectionBase &Sec) {
return !(Sec.Flags & ELF::SHF_COMPRESSED) &&
StringRef(Sec.Name).startswith(".debug");
}
static Error replaceDebugSections(
Object &Obj, SectionPred &RemovePred,
function_ref<bool(const SectionBase &)> ShouldReplace,
function_ref<Expected<SectionBase *>(const SectionBase *)> AddSection) {
// Build a list of the debug sections we are going to replace.
// We can't call `AddSection` while iterating over sections,
// because it would mutate the sections array.
SmallVector<SectionBase *, 13> ToReplace;
for (auto &Sec : Obj.sections())
if (ShouldReplace(Sec))
ToReplace.push_back(&Sec);
// Build a mapping from original section to a new one.
DenseMap<SectionBase *, SectionBase *> FromTo;
for (SectionBase *S : ToReplace) {
Expected<SectionBase *> NewSection = AddSection(S);
if (!NewSection)
return NewSection.takeError();
FromTo[S] = *NewSection;
}
// Now we want to update the target sections of relocation
// sections. Also we will update the relocations themselves
// to update the symbol references.
for (auto &Sec : Obj.sections())
Sec.replaceSectionReferences(FromTo);
RemovePred = [ShouldReplace, RemovePred](const SectionBase &Sec) {
return ShouldReplace(Sec) || RemovePred(Sec);
};
return Error::success();
}
static bool isUnneededSymbol(const Symbol &Sym) {
return !Sym.Referenced &&
(Sym.Binding == STB_LOCAL || Sym.getShndx() == SHN_UNDEF) &&
Sym.Type != STT_SECTION;
}
static Error updateAndRemoveSymbols(const CopyConfig &Config, Object &Obj) {
// TODO: update or remove symbols only if there is an option that affects
// them.
if (!Obj.SymbolTable)
return Error::success();
Obj.SymbolTable->updateSymbols([&](Symbol &Sym) {
// Common and undefined symbols don't make sense as local symbols, and can
// even cause crashes if we localize those, so skip them.
if (!Sym.isCommon() && Sym.getShndx() != SHN_UNDEF &&
((Config.LocalizeHidden &&
(Sym.Visibility == STV_HIDDEN || Sym.Visibility == STV_INTERNAL)) ||
Config.SymbolsToLocalize.matches(Sym.Name)))
Sym.Binding = STB_LOCAL;
// Note: these two globalize flags have very similar names but different
// meanings:
//
// --globalize-symbol: promote a symbol to global
// --keep-global-symbol: all symbols except for these should be made local
//
// If --globalize-symbol is specified for a given symbol, it will be
// global in the output file even if it is not included via
// --keep-global-symbol. Because of that, make sure to check
// --globalize-symbol second.
if (!Config.SymbolsToKeepGlobal.empty() &&
!Config.SymbolsToKeepGlobal.matches(Sym.Name) &&
Sym.getShndx() != SHN_UNDEF)
Sym.Binding = STB_LOCAL;
if (Config.SymbolsToGlobalize.matches(Sym.Name) &&
Sym.getShndx() != SHN_UNDEF)
Sym.Binding = STB_GLOBAL;
if (Config.SymbolsToWeaken.matches(Sym.Name) && Sym.Binding == STB_GLOBAL)
Sym.Binding = STB_WEAK;
if (Config.Weaken && Sym.Binding == STB_GLOBAL &&
Sym.getShndx() != SHN_UNDEF)
Sym.Binding = STB_WEAK;
const auto I = Config.SymbolsToRename.find(Sym.Name);
if (I != Config.SymbolsToRename.end())
Sym.Name = std::string(I->getValue());
if (!Config.SymbolsPrefix.empty() && Sym.Type != STT_SECTION)
Sym.Name = (Config.SymbolsPrefix + Sym.Name).str();
});
// The purpose of this loop is to mark symbols referenced by sections
// (like GroupSection or RelocationSection). This way, we know which
// symbols are still 'needed' and which are not.
if (Config.StripUnneeded || !Config.UnneededSymbolsToRemove.empty() ||
!Config.OnlySection.empty()) {
for (SectionBase &Sec : Obj.sections())
Sec.markSymbols();
}
auto RemoveSymbolsPred = [&](const Symbol &Sym) {
if (Config.SymbolsToKeep.matches(Sym.Name) ||
(Config.KeepFileSymbols && Sym.Type == STT_FILE))
return false;
if ((Config.DiscardMode == DiscardType::All ||
(Config.DiscardMode == DiscardType::Locals &&
StringRef(Sym.Name).startswith(".L"))) &&
Sym.Binding == STB_LOCAL && Sym.getShndx() != SHN_UNDEF &&
Sym.Type != STT_FILE && Sym.Type != STT_SECTION)
return true;
if (Config.StripAll || Config.StripAllGNU)
return true;
if (Config.StripDebug && Sym.Type == STT_FILE)
return true;
if (Config.SymbolsToRemove.matches(Sym.Name))
return true;
if ((Config.StripUnneeded ||
Config.UnneededSymbolsToRemove.matches(Sym.Name)) &&
(!Obj.isRelocatable() || isUnneededSymbol(Sym)))
return true;
// We want to remove undefined symbols if all references have been stripped.
if (!Config.OnlySection.empty() && !Sym.Referenced &&
Sym.getShndx() == SHN_UNDEF)
return true;
return false;
};
return Obj.removeSymbols(RemoveSymbolsPred);
}
static Error replaceAndRemoveSections(const CopyConfig &Config, Object &Obj) {
SectionPred RemovePred = [](const SectionBase &) { return false; };
// Removes:
if (!Config.ToRemove.empty()) {
RemovePred = [&Config](const SectionBase &Sec) {
return Config.ToRemove.matches(Sec.Name);
};
}
if (Config.StripDWO || !Config.SplitDWO.empty())
RemovePred = [RemovePred](const SectionBase &Sec) {
return isDWOSection(Sec) || RemovePred(Sec);
};
if (Config.ExtractDWO)
RemovePred = [RemovePred, &Obj](const SectionBase &Sec) {
return onlyKeepDWOPred(Obj, Sec) || RemovePred(Sec);
};
if (Config.StripAllGNU)
RemovePred = [RemovePred, &Obj](const SectionBase &Sec) {
if (RemovePred(Sec))
return true;
if ((Sec.Flags & SHF_ALLOC) != 0)
return false;
if (&Sec == Obj.SectionNames)
return false;
switch (Sec.Type) {
case SHT_SYMTAB:
case SHT_REL:
case SHT_RELA:
case SHT_STRTAB:
return true;
}
return isDebugSection(Sec);
};
if (Config.StripSections) {
RemovePred = [RemovePred](const SectionBase &Sec) {
return RemovePred(Sec) || Sec.ParentSegment == nullptr;
};
}
if (Config.StripDebug || Config.StripUnneeded) {
RemovePred = [RemovePred](const SectionBase &Sec) {
return RemovePred(Sec) || isDebugSection(Sec);
};
}
if (Config.StripNonAlloc)
RemovePred = [RemovePred, &Obj](const SectionBase &Sec) {
if (RemovePred(Sec))
return true;
if (&Sec == Obj.SectionNames)
return false;
return (Sec.Flags & SHF_ALLOC) == 0 && Sec.ParentSegment == nullptr;
};
if (Config.StripAll)
RemovePred = [RemovePred, &Obj](const SectionBase &Sec) {
if (RemovePred(Sec))
return true;
if (&Sec == Obj.SectionNames)
return false;
if (StringRef(Sec.Name).startswith(".gnu.warning"))
return false;
// We keep the .ARM.attribute section to maintain compatibility
// with Debian derived distributions. This is a bug in their
// patchset as documented here:
// https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=943798
if (Sec.Type == SHT_ARM_ATTRIBUTES)
return false;
if (Sec.ParentSegment != nullptr)
return false;
return (Sec.Flags & SHF_ALLOC) == 0;
};
if (Config.ExtractPartition || Config.ExtractMainPartition) {
RemovePred = [RemovePred](const SectionBase &Sec) {
if (RemovePred(Sec))
return true;
if (Sec.Type == SHT_LLVM_PART_EHDR || Sec.Type == SHT_LLVM_PART_PHDR)
return true;
return (Sec.Flags & SHF_ALLOC) != 0 && !Sec.ParentSegment;
};
}
// Explicit copies:
if (!Config.OnlySection.empty()) {
RemovePred = [&Config, RemovePred, &Obj](const SectionBase &Sec) {
// Explicitly keep these sections regardless of previous removes.
if (Config.OnlySection.matches(Sec.Name))
return false;
// Allow all implicit removes.
if (RemovePred(Sec))
return true;
// Keep special sections.
if (Obj.SectionNames == &Sec)
return false;
if (Obj.SymbolTable == &Sec ||
(Obj.SymbolTable && Obj.SymbolTable->getStrTab() == &Sec))
return false;
// Remove everything else.
return true;
};
}
if (!Config.KeepSection.empty()) {
RemovePred = [&Config, RemovePred](const SectionBase &Sec) {
// Explicitly keep these sections regardless of previous removes.
if (Config.KeepSection.matches(Sec.Name))
return false;
// Otherwise defer to RemovePred.
return RemovePred(Sec);
};
}
// This has to be the last predicate assignment.
// If the option --keep-symbol has been specified
// and at least one of those symbols is present
// (equivalently, the updated symbol table is not empty)
// the symbol table and the string table should not be removed.
if ((!Config.SymbolsToKeep.empty() || Config.KeepFileSymbols) &&
Obj.SymbolTable && !Obj.SymbolTable->empty()) {
RemovePred = [&Obj, RemovePred](const SectionBase &Sec) {
if (&Sec == Obj.SymbolTable || &Sec == Obj.SymbolTable->getStrTab())
return false;
return RemovePred(Sec);
};
}
if (Config.CompressionType != DebugCompressionType::None) {
if (Error Err = replaceDebugSections(
Obj, RemovePred, isCompressable,
[&Config, &Obj](const SectionBase *S) -> Expected<SectionBase *> {
Expected<CompressedSection> NewSection =
CompressedSection::create(*S, Config.CompressionType);
if (!NewSection)
return NewSection.takeError();
return &Obj.addSection<CompressedSection>(std::move(*NewSection));
}))
return Err;
} else if (Config.DecompressDebugSections) {
if (Error Err = replaceDebugSections(
Obj, RemovePred,
[](const SectionBase &S) { return isa<CompressedSection>(&S); },
[&Obj](const SectionBase *S) {
const CompressedSection *CS = cast<CompressedSection>(S);
return &Obj.addSection<DecompressedSection>(*CS);
}))
return Err;
}
return Obj.removeSections(Config.AllowBrokenLinks, RemovePred);
}
// This function handles the high level operations of GNU objcopy including
// handling command line options. It's important to outline certain properties
// we expect to hold of the command line operations. Any operation that "keeps"
// should keep regardless of a remove. Additionally any removal should respect
// any previous removals. Lastly whether or not something is removed shouldn't
// depend a) on the order the options occur in or b) on some opaque priority
// system. The only priority is that keeps/copies overrule removes.
static Error handleArgs(const CopyConfig &Config, Object &Obj,
const Reader &Reader, ElfType OutputElfType) {
if (Config.StripSwiftSymbols)
return createStringError(llvm::errc::invalid_argument,
"option not supported by llvm-objcopy for ELF");
if (!Config.SplitDWO.empty())
if (Error E =
splitDWOToFile(Config, Reader, Config.SplitDWO, OutputElfType))
return E;
if (Config.OutputArch) {
Obj.Machine = Config.OutputArch.getValue().EMachine;
Obj.OSABI = Config.OutputArch.getValue().OSABI;
}
// Dump sections before add/remove for compatibility with GNU objcopy.
for (StringRef Flag : Config.DumpSection) {
StringRef SectionName;
StringRef FileName;
std::tie(SectionName, FileName) = Flag.split('=');
if (Error E = dumpSectionToFile(SectionName, FileName, Obj))
return E;
}
// It is important to remove the sections first. For example, we want to
// remove the relocation sections before removing the symbols. That allows
// us to avoid reporting the inappropriate errors about removing symbols
// named in relocations.
if (Error E = replaceAndRemoveSections(Config, Obj))
return E;
if (Error E = updateAndRemoveSymbols(Config, Obj))
return E;
if (!Config.SectionsToRename.empty()) {
for (SectionBase &Sec : Obj.sections()) {
const auto Iter = Config.SectionsToRename.find(Sec.Name);
if (Iter != Config.SectionsToRename.end()) {
const SectionRename &SR = Iter->second;
Sec.Name = std::string(SR.NewName);
if (SR.NewFlags.hasValue())
setSectionFlagsAndType(Sec, SR.NewFlags.getValue());
}
}
}
// Add a prefix to allocated sections and their relocation sections. This
// should be done after renaming the section by Config.SectionToRename to
// imitate the GNU objcopy behavior.
if (!Config.AllocSectionsPrefix.empty()) {
DenseSet<SectionBase *> PrefixedSections;
for (SectionBase &Sec : Obj.sections()) {
if (Sec.Flags & SHF_ALLOC) {
Sec.Name = (Config.AllocSectionsPrefix + Sec.Name).str();
PrefixedSections.insert(&Sec);
} else if (auto *RelocSec = dyn_cast<RelocationSectionBase>(&Sec)) {
// Rename relocation sections associated to the allocated sections.
// For example, if we rename .text to .prefix.text, we also rename
// .rel.text to .rel.prefix.text.
//
// Dynamic relocation sections (SHT_REL[A] with SHF_ALLOC) are handled
// above, e.g., .rela.plt is renamed to .prefix.rela.plt, not
// .rela.prefix.plt since GNU objcopy does so.
const SectionBase *TargetSec = RelocSec->getSection();
if (TargetSec && (TargetSec->Flags & SHF_ALLOC)) {
StringRef prefix;
switch (Sec.Type) {
case SHT_REL:
prefix = ".rel";
break;
case SHT_RELA:
prefix = ".rela";
break;
default:
llvm_unreachable("not a relocation section");
}
// If the relocation section comes *after* the target section, we
// don't add Config.AllocSectionsPrefix because we've already added
// the prefix to TargetSec->Name. Otherwise, if the relocation
// section comes *before* the target section, we add the prefix.
if (PrefixedSections.count(TargetSec))
Sec.Name = (prefix + TargetSec->Name).str();
else
Sec.Name =
(prefix + Config.AllocSectionsPrefix + TargetSec->Name).str();
}
}
}
}
if (!Config.SetSectionAlignment.empty()) {
for (SectionBase &Sec : Obj.sections()) {
auto I = Config.SetSectionAlignment.find(Sec.Name);
if (I != Config.SetSectionAlignment.end())
Sec.Align = I->second;
}
}
if (Config.OnlyKeepDebug)
for (auto &Sec : Obj.sections())
if (Sec.Flags & SHF_ALLOC && Sec.Type != SHT_NOTE)
Sec.Type = SHT_NOBITS;
for (const auto &Flag : Config.AddSection) {
std::pair<StringRef, StringRef> SecPair = Flag.split("=");
StringRef SecName = SecPair.first;
StringRef File = SecPair.second;
ErrorOr<std::unique_ptr<MemoryBuffer>> BufOrErr =
MemoryBuffer::getFile(File);
if (!BufOrErr)
return createFileError(File, errorCodeToError(BufOrErr.getError()));
std::unique_ptr<MemoryBuffer> Buf = std::move(*BufOrErr);
ArrayRef<uint8_t> Data(
reinterpret_cast<const uint8_t *>(Buf->getBufferStart()),
Buf->getBufferSize());
OwnedDataSection &NewSection =
Obj.addSection<OwnedDataSection>(SecName, Data);
if (SecName.startswith(".note") && SecName != ".note.GNU-stack")
NewSection.Type = SHT_NOTE;
}
if (!Config.AddGnuDebugLink.empty())
Obj.addSection<GnuDebugLinkSection>(Config.AddGnuDebugLink,
Config.GnuDebugLinkCRC32);
// If the symbol table was previously removed, we need to create a new one
// before adding new symbols.
if (!Obj.SymbolTable && !Config.ELF->SymbolsToAdd.empty())
if (Error E = Obj.addNewSymbolTable())
return E;
for (const NewSymbolInfo &SI : Config.ELF->SymbolsToAdd) {
SectionBase *Sec = Obj.findSection(SI.SectionName);
uint64_t Value = Sec ? Sec->Addr + SI.Value : SI.Value;
Obj.SymbolTable->addSymbol(
SI.SymbolName, SI.Bind, SI.Type, Sec, Value, SI.Visibility,
Sec ? (uint16_t)SYMBOL_SIMPLE_INDEX : (uint16_t)SHN_ABS, 0);
}
// --set-section-flags works with sections added by --add-section.
if (!Config.SetSectionFlags.empty()) {
for (auto &Sec : Obj.sections()) {
const auto Iter = Config.SetSectionFlags.find(Sec.Name);
if (Iter != Config.SetSectionFlags.end()) {
const SectionFlagsUpdate &SFU = Iter->second;
setSectionFlagsAndType(Sec, SFU.NewFlags);
}
}
}
if (Config.EntryExpr)
Obj.Entry = Config.EntryExpr(Obj.Entry);
return Error::success();
}
static Error writeOutput(const CopyConfig &Config, Object &Obj, Buffer &Out,
ElfType OutputElfType) {
std::unique_ptr<Writer> Writer =
createWriter(Config, Obj, Out, OutputElfType);
if (Error E = Writer->finalize())
return E;
return Writer->write();
}
Error executeObjcopyOnIHex(const CopyConfig &Config, MemoryBuffer &In,
Buffer &Out) {
IHexReader Reader(&In);
Expected<std::unique_ptr<Object>> Obj = Reader.create(true);
if (!Obj)
return Obj.takeError();
const ElfType OutputElfType =
getOutputElfType(Config.OutputArch.getValueOr(MachineInfo()));
if (Error E = handleArgs(Config, **Obj, Reader, OutputElfType))
return E;
return writeOutput(Config, **Obj, Out, OutputElfType);
}
Error executeObjcopyOnRawBinary(const CopyConfig &Config, MemoryBuffer &In,
Buffer &Out) {
uint8_t NewSymbolVisibility =
Config.ELF->NewSymbolVisibility.getValueOr((uint8_t)ELF::STV_DEFAULT);
BinaryReader Reader(&In, NewSymbolVisibility);
Expected<std::unique_ptr<Object>> Obj = Reader.create(true);
if (!Obj)
return Obj.takeError();
// Prefer OutputArch (-O<format>) if set, otherwise fallback to BinaryArch
// (-B<arch>).
const ElfType OutputElfType =
getOutputElfType(Config.OutputArch.getValueOr(MachineInfo()));
if (Error E = handleArgs(Config, **Obj, Reader, OutputElfType))
return E;
return writeOutput(Config, **Obj, Out, OutputElfType);
}
Error executeObjcopyOnBinary(const CopyConfig &Config,
object::ELFObjectFileBase &In, Buffer &Out) {
ELFReader Reader(&In, Config.ExtractPartition);
Expected<std::unique_ptr<Object>> Obj =
Reader.create(!Config.SymbolsToAdd.empty());
if (!Obj)
return Obj.takeError();
// Prefer OutputArch (-O<format>) if set, otherwise infer it from the input.
const ElfType OutputElfType =
Config.OutputArch ? getOutputElfType(Config.OutputArch.getValue())
: getOutputElfType(In);
ArrayRef<uint8_t> BuildIdBytes;
if (!Config.BuildIdLinkDir.empty()) {
auto BuildIdBytesOrErr = findBuildID(Config, In);
if (auto E = BuildIdBytesOrErr.takeError())
return E;
BuildIdBytes = *BuildIdBytesOrErr;
if (BuildIdBytes.size() < 2)
return createFileError(
Config.InputFilename,
createStringError(object_error::parse_failed,
"build ID is smaller than two bytes"));
}
if (!Config.BuildIdLinkDir.empty() && Config.BuildIdLinkInput)
if (Error E =
linkToBuildIdDir(Config, Config.InputFilename,
Config.BuildIdLinkInput.getValue(), BuildIdBytes))
return E;
if (Error E = handleArgs(Config, **Obj, Reader, OutputElfType))
return createFileError(Config.InputFilename, std::move(E));
if (Error E = writeOutput(Config, **Obj, Out, OutputElfType))
return createFileError(Config.InputFilename, std::move(E));
if (!Config.BuildIdLinkDir.empty() && Config.BuildIdLinkOutput)
if (Error E =
linkToBuildIdDir(Config, Config.OutputFilename,
Config.BuildIdLinkOutput.getValue(), BuildIdBytes))
return createFileError(Config.OutputFilename, std::move(E));
return Error::success();
}
} // end namespace elf
} // end namespace objcopy
} // end namespace llvm
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