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//===- COFFObjcopy.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 "COFFObjcopy.h"
#include "Buffer.h"
#include "CopyConfig.h"
#include "Object.h"
#include "Reader.h"
#include "Writer.h"
#include "llvm-objcopy.h"
#include "llvm/Object/Binary.h"
#include "llvm/Object/COFF.h"
#include "llvm/Support/Errc.h"
#include "llvm/Support/JamCRC.h"
#include "llvm/Support/Path.h"
#include <cassert>
namespace llvm {
namespace objcopy {
namespace coff {
using namespace object;
using namespace COFF;
static bool isDebugSection(const Section &Sec) {
return Sec.Name.startswith(".debug");
}
static uint64_t getNextRVA(const Object &Obj) {
if (Obj.getSections().empty())
return 0;
const Section &Last = Obj.getSections().back();
return alignTo(Last.Header.VirtualAddress + Last.Header.VirtualSize,
Obj.IsPE ? Obj.PeHeader.SectionAlignment : 1);
}
static uint32_t getCRC32(StringRef Data) {
JamCRC CRC;
CRC.update(ArrayRef<char>(Data.data(), Data.size()));
// The CRC32 value needs to be complemented because the JamCRC dosn't
// finalize the CRC32 value. It also dosn't negate the initial CRC32 value
// but it starts by default at 0xFFFFFFFF which is the complement of zero.
return ~CRC.getCRC();
}
static std::vector<uint8_t> createGnuDebugLinkSectionContents(StringRef File) {
ErrorOr<std::unique_ptr<MemoryBuffer>> LinkTargetOrErr =
MemoryBuffer::getFile(File);
if (!LinkTargetOrErr)
error("'" + File + "': " + LinkTargetOrErr.getError().message());
auto LinkTarget = std::move(*LinkTargetOrErr);
uint32_t CRC32 = getCRC32(LinkTarget->getBuffer());
StringRef FileName = sys::path::filename(File);
size_t CRCPos = alignTo(FileName.size() + 1, 4);
std::vector<uint8_t> Data(CRCPos + 4);
memcpy(Data.data(), FileName.data(), FileName.size());
support::endian::write32le(Data.data() + CRCPos, CRC32);
return Data;
}
static void addGnuDebugLink(Object &Obj, StringRef DebugLinkFile) {
uint32_t StartRVA = getNextRVA(Obj);
std::vector<Section> Sections;
Section Sec;
Sec.setOwnedContents(createGnuDebugLinkSectionContents(DebugLinkFile));
Sec.Name = ".gnu_debuglink";
Sec.Header.VirtualSize = Sec.getContents().size();
Sec.Header.VirtualAddress = StartRVA;
Sec.Header.SizeOfRawData = alignTo(Sec.Header.VirtualSize,
Obj.IsPE ? Obj.PeHeader.FileAlignment : 1);
// Sec.Header.PointerToRawData is filled in by the writer.
Sec.Header.PointerToRelocations = 0;
Sec.Header.PointerToLinenumbers = 0;
// Sec.Header.NumberOfRelocations is filled in by the writer.
Sec.Header.NumberOfLinenumbers = 0;
Sec.Header.Characteristics = IMAGE_SCN_CNT_INITIALIZED_DATA |
IMAGE_SCN_MEM_READ | IMAGE_SCN_MEM_DISCARDABLE;
Sections.push_back(Sec);
Obj.addSections(Sections);
}
static Error handleArgs(const CopyConfig &Config, Object &Obj) {
// Perform the actual section removals.
Obj.removeSections([&Config](const Section &Sec) {
// Contrary to --only-keep-debug, --only-section fully removes sections that
// aren't mentioned.
if (!Config.OnlySection.empty() &&
!is_contained(Config.OnlySection, Sec.Name))
return true;
if (Config.StripDebug || Config.StripAll || Config.StripAllGNU ||
Config.DiscardMode == DiscardType::All || Config.StripUnneeded) {
if (isDebugSection(Sec) &&
(Sec.Header.Characteristics & IMAGE_SCN_MEM_DISCARDABLE) != 0)
return true;
}
if (is_contained(Config.ToRemove, Sec.Name))
return true;
return false;
});
if (Config.OnlyKeepDebug) {
// For --only-keep-debug, we keep all other sections, but remove their
// content. The VirtualSize field in the section header is kept intact.
Obj.truncateSections([](const Section &Sec) {
return !isDebugSection(Sec) && Sec.Name != ".buildid" &&
((Sec.Header.Characteristics &
(IMAGE_SCN_CNT_CODE | IMAGE_SCN_CNT_INITIALIZED_DATA)) != 0);
});
}
// StripAll removes all symbols and thus also removes all relocations.
if (Config.StripAll || Config.StripAllGNU)
for (Section &Sec : Obj.getMutableSections())
Sec.Relocs.clear();
// If we need to do per-symbol removals, initialize the Referenced field.
if (Config.StripUnneeded || Config.DiscardMode == DiscardType::All ||
!Config.SymbolsToRemove.empty())
if (Error E = Obj.markSymbols())
return E;
// Actually do removals of symbols.
Obj.removeSymbols([&](const Symbol &Sym) {
// For StripAll, all relocations have been stripped and we remove all
// symbols.
if (Config.StripAll || Config.StripAllGNU)
return true;
if (is_contained(Config.SymbolsToRemove, Sym.Name)) {
// Explicitly removing a referenced symbol is an error.
if (Sym.Referenced)
reportError(Config.OutputFilename,
createStringError(llvm::errc::invalid_argument,
"not stripping symbol '%s' because it is "
"named in a relocation",
Sym.Name.str().c_str()));
return true;
}
if (!Sym.Referenced) {
// With --strip-unneeded, GNU objcopy removes all unreferenced local
// symbols, and any unreferenced undefined external.
// With --strip-unneeded-symbol we strip only specific unreferenced
// local symbol instead of removing all of such.
if (Sym.Sym.StorageClass == IMAGE_SYM_CLASS_STATIC ||
Sym.Sym.SectionNumber == 0)
if (Config.StripUnneeded ||
is_contained(Config.UnneededSymbolsToRemove, Sym.Name))
return true;
// GNU objcopy keeps referenced local symbols and external symbols
// if --discard-all is set, similar to what --strip-unneeded does,
// but undefined local symbols are kept when --discard-all is set.
if (Config.DiscardMode == DiscardType::All &&
Sym.Sym.StorageClass == IMAGE_SYM_CLASS_STATIC &&
Sym.Sym.SectionNumber != 0)
return true;
}
return false;
});
if (!Config.AddGnuDebugLink.empty())
addGnuDebugLink(Obj, Config.AddGnuDebugLink);
if (Config.AllowBrokenLinks || !Config.BuildIdLinkDir.empty() ||
Config.BuildIdLinkInput || Config.BuildIdLinkOutput ||
!Config.SplitDWO.empty() || !Config.SymbolsPrefix.empty() ||
!Config.AllocSectionsPrefix.empty() || !Config.AddSection.empty() ||
!Config.DumpSection.empty() || !Config.KeepSection.empty() ||
!Config.SymbolsToGlobalize.empty() || !Config.SymbolsToKeep.empty() ||
!Config.SymbolsToLocalize.empty() || !Config.SymbolsToWeaken.empty() ||
!Config.SymbolsToKeepGlobal.empty() || !Config.SectionsToRename.empty() ||
!Config.SetSectionFlags.empty() || !Config.SymbolsToRename.empty() ||
Config.ExtractDWO || Config.KeepFileSymbols || Config.LocalizeHidden ||
Config.PreserveDates || Config.StripDWO || Config.StripNonAlloc ||
Config.StripSections || Config.Weaken || Config.DecompressDebugSections ||
Config.DiscardMode == DiscardType::Locals ||
!Config.SymbolsToAdd.empty() || Config.EntryExpr) {
return createStringError(llvm::errc::invalid_argument,
"option not supported by llvm-objcopy for COFF");
}
return Error::success();
}
Error executeObjcopyOnBinary(const CopyConfig &Config, COFFObjectFile &In,
Buffer &Out) {
COFFReader Reader(In);
Expected<std::unique_ptr<Object>> ObjOrErr = Reader.create();
if (!ObjOrErr)
return createFileError(Config.InputFilename, ObjOrErr.takeError());
Object *Obj = ObjOrErr->get();
assert(Obj && "Unable to deserialize COFF object");
if (Error E = handleArgs(Config, *Obj))
return createFileError(Config.InputFilename, std::move(E));
COFFWriter Writer(*Obj, Out);
if (Error E = Writer.write())
return createFileError(Config.OutputFilename, std::move(E));
return Error::success();
}
} // end namespace coff
} // end namespace objcopy
} // end namespace llvm
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