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llvm-project/llvm/tools/llvm-objcopy/ELF/ELFObjcopy.cpp
Igor Kudrin 68616584c3 [llvm-objcopy][ELF] Avoid reordering section headers 
As for now, llvm-objcopy sorts section headers according to the offsets
of the sections in the input file. That can corrupt section references
in the dynamic symbol table because it is a loadable section and as such
is not updated by the tool. Even though the section references are not
required for loading the binary correctly, they are still handy for a
user who analyzes the file.

While the patch removes global reordering of section headers, it layouts
the sections in the same way as before, i.e. according to their original
offsets. All that helps the output file to resemble the input better.

Note that the patch removes sorting SHT_GROUP sections to the start of
the list, which was introduced in D62620 in order to ensure that they
come before the group members, along with the corresponding test. The
original issue was caused by the sorting of section headers, so dropping
the sorting also resolves the issue.

Differential Revision: https://reviews.llvm.org/D107653
2021-08-12 17:12:09 +07:00

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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 "CommonConfig.h"
#include "ELFConfig.h"
#include "Object.h"
#include "llvm-objcopy.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>
using namespace llvm;
using namespace llvm::ELF;
using namespace llvm::objcopy;
using namespace llvm::objcopy::elf;
using namespace llvm::object;
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);
}
static 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 CommonConfig &Config,
Object &Obj, raw_ostream &Out,
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, Out, !Config.StripSections,
Config.OnlyKeepDebug);
case ELFT_ELF64LE:
return std::make_unique<ELFWriter<ELF64LE>>(Obj, Out, !Config.StripSections,
Config.OnlyKeepDebug);
case ELFT_ELF32BE:
return std::make_unique<ELFWriter<ELF32BE>>(Obj, Out, !Config.StripSections,
Config.OnlyKeepDebug);
case ELFT_ELF64BE:
return std::make_unique<ELFWriter<ELF64BE>>(Obj, Out, !Config.StripSections,
Config.OnlyKeepDebug);
}
llvm_unreachable("Invalid output format");
}
static std::unique_ptr<Writer> createWriter(const CommonConfig &Config,
Object &Obj, raw_ostream &Out,
ElfType OutputElfType) {
switch (Config.OutputFormat) {
case FileFormat::Binary:
return std::make_unique<BinaryWriter>(Obj, Out);
case FileFormat::IHex:
return std::make_unique<IHexWriter>(Obj, Out);
default:
return createELFWriter(Config, Obj, Out, OutputElfType);
}
}
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)...);
}
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, 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;
}
return Obj.replaceSections(FromTo);
}
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 CommonConfig &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 CommonConfig &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)
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 (Error E = Obj.removeSections(Config.AllowBrokenLinks, RemovePred))
return E;
if (Config.CompressionType != DebugCompressionType::None) {
if (Error Err = replaceDebugSections(
Obj, 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,
[](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 Error::success();
}
// Add symbol to the Object symbol table with the specified properties.
static void addSymbol(Object &Obj, const NewSymbolInfo &SymInfo,
uint8_t DefaultVisibility) {
SectionBase *Sec = Obj.findSection(SymInfo.SectionName);
uint64_t Value = Sec ? Sec->Addr + SymInfo.Value : SymInfo.Value;
uint8_t Bind = ELF::STB_GLOBAL;
uint8_t Type = ELF::STT_NOTYPE;
uint8_t Visibility = DefaultVisibility;
for (SymbolFlag FlagValue : SymInfo.Flags)
switch (FlagValue) {
case SymbolFlag::Global:
Bind = ELF::STB_GLOBAL;
break;
case SymbolFlag::Local:
Bind = ELF::STB_LOCAL;
break;
case SymbolFlag::Weak:
Bind = ELF::STB_WEAK;
break;
case SymbolFlag::Default:
Visibility = ELF::STV_DEFAULT;
break;
case SymbolFlag::Hidden:
Visibility = ELF::STV_HIDDEN;
break;
case SymbolFlag::Protected:
Visibility = ELF::STV_PROTECTED;
break;
case SymbolFlag::File:
Type = ELF::STT_FILE;
break;
case SymbolFlag::Section:
Type = ELF::STT_SECTION;
break;
case SymbolFlag::Object:
Type = ELF::STT_OBJECT;
break;
case SymbolFlag::Function:
Type = ELF::STT_FUNC;
break;
case SymbolFlag::IndirectFunction:
Type = ELF::STT_GNU_IFUNC;
break;
default: /* Other flag values are ignored for ELF. */
break;
};
Obj.SymbolTable->addSymbol(
SymInfo.SymbolName, Bind, Type, Sec, Value, Visibility,
Sec ? (uint16_t)SYMBOL_SIMPLE_INDEX : (uint16_t)SHN_ABS, 0);
}
// 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 CommonConfig &Config, const ELFConfig &ELFConfig,
Object &Obj) {
if (Config.OutputArch) {
Obj.Machine = Config.OutputArch.getValue().EMachine;
Obj.OSABI = Config.OutputArch.getValue().OSABI;
}
if (!Config.SplitDWO.empty() && Config.ExtractDWO) {
return Obj.removeSections(
Config.AllowBrokenLinks,
[&Obj](const SectionBase &Sec) { return onlyKeepDWOPred(Obj, Sec); });
}
// 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.SymbolsToAdd.empty())
if (Error E = Obj.addNewSymbolTable())
return E;
for (const NewSymbolInfo &SI : Config.SymbolsToAdd)
addSymbol(Obj, SI, ELFConfig.NewSymbolVisibility);
// --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 CommonConfig &Config, Object &Obj,
raw_ostream &Out, ElfType OutputElfType) {
std::unique_ptr<Writer> Writer =
createWriter(Config, Obj, Out, OutputElfType);
if (Error E = Writer->finalize())
return E;
return Writer->write();
}
Error objcopy::elf::executeObjcopyOnIHex(const CommonConfig &Config,
const ELFConfig &ELFConfig,
MemoryBuffer &In, raw_ostream &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, ELFConfig, **Obj))
return E;
return writeOutput(Config, **Obj, Out, OutputElfType);
}
Error objcopy::elf::executeObjcopyOnRawBinary(const CommonConfig &Config,
const ELFConfig &ELFConfig,
MemoryBuffer &In,
raw_ostream &Out) {
BinaryReader Reader(&In, ELFConfig.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, ELFConfig, **Obj))
return E;
return writeOutput(Config, **Obj, Out, OutputElfType);
}
Error objcopy::elf::executeObjcopyOnBinary(const CommonConfig &Config,
const ELFConfig &ELFConfig,
object::ELFObjectFileBase &In,
raw_ostream &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);
if (Error E = handleArgs(Config, ELFConfig, **Obj))
return createFileError(Config.InputFilename, std::move(E));
if (Error E = writeOutput(Config, **Obj, Out, OutputElfType))
return createFileError(Config.InputFilename, std::move(E));
return Error::success();
}
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