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Reland "[LLVM][llvm-objcopy] Added basic plumbing to get things started"

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As discussed on llvm-dev I've implemented the first basic steps towards
llvm-objcopy/llvm-objtool (name pending).

This change adds the ability to copy (without modification) 64-bit
little endian ELF executables that have SHT_PROGBITS, SHT_NOBITS,
SHT_NULL and SHT_STRTAB sections.

Patch by Jake Ehrlich

Differential Revision: https://reviews.llvm.org/D33964

llvm-svn: 309643
This commit is contained in:
Petr Hosek 2017-08-01 00:33:58 +00:00
parent a1127313c4
commit dd99727315
12 changed files with 825 additions and 0 deletions
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1
test/CMakeLists.txt
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@ -61,6 +61,7 @@ set(LLVM_TEST_DEPENDS
llvm-modextract llvm-modextract
llvm-mt llvm-mt
llvm-nm llvm-nm
llvm-objcopy
llvm-objdump llvm-objdump
llvm-opt-report llvm-opt-report
llvm-pdbutil llvm-pdbutil

1
test/lit.cfg
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@ -302,6 +302,7 @@ for pattern in [r"\bbugpoint\b(?!-)",
r"\bllvm-mcmarkup\b", r"\bllvm-mcmarkup\b",
r"\bllvm-modextract\b", r"\bllvm-modextract\b",
r"\bllvm-nm\b", r"\bllvm-nm\b",
r"\bllvm-objcopy\b",
r"\bllvm-objdump\b", r"\bllvm-objdump\b",
r"\bllvm-pdbutil\b", r"\bllvm-pdbutil\b",
r"\bllvm-profdata\b", r"\bllvm-profdata\b",

47
test/tools/llvm-objcopy/basic-copy.test Normal file
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@ -0,0 +1,47 @@
# RUN: yaml2obj %s > %t
# RUN: llvm-objcopy %t %t2
# RUN: llvm-readobj -sections %t2 | FileCheck %s
!ELF
FileHeader:
Class: ELFCLASS64
Data: ELFDATA2LSB
Type: ET_EXEC
Machine: EM_X86_64
Sections:
- Name: .bss
Type: SHT_NOBITS
Flags: [ SHF_ALLOC ]
AddressAlign: 0x0000000000000010
Size: 64
- Name: .text
Type: SHT_PROGBITS
Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
AddressAlign: 0x0000000000000010
Content: "00000000"
# CHECK: Type: SHT_NULL
# CHECK: Name: .bss
# CHECK-NEXT: Type: SHT_NOBITS
# CHECK-NEXT: Flags [
# CHECK-NEXT: SHF_ALLOC
# CHECK-NEXT: ]
# CHECK-NEXT: Address:
# CHECK-NEXT: Offset: [[OFFSET:0x[0-9A-F]+]]
# CHECK-NEXT: Size: 64
# CHECK: Name: .text
# CHECK-NEXT: Type: SHT_PROGBITS
# CHECK-NEXT: Flags [
# CHECK-NEXT: SHF_ALLOC
# CHECK-NEXT: SHF_EXECINSTR
# CHECK-NEXT: ]
# CHECK-NEXT: Address:
# CHECK-NEXT: Offset: [[OFFSET]]
# CHECK-NEXT: Size: 4
# CHECK: Name: .shstrtab
# CHECK-NEXT: Type: SHT_STRTAB
# CHECK-NEXT: Flags [
# CHECK-NEXT: ]

55
test/tools/llvm-objcopy/empty-section.test Normal file
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@ -0,0 +1,55 @@
# RUN: yaml2obj %s > %t
# RUN: llvm-objcopy %t %t2
# RUN: llvm-readobj -sections %t2 | FileCheck %s
!ELF
FileHeader:
Class: ELFCLASS64
Data: ELFDATA2LSB
Type: ET_EXEC
Machine: EM_X86_64
Sections:
- Name: .text
Type: SHT_PROGBITS
Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
Address: 0x0
AddressAlign: 0x0000000000001000
Content: "00000000"
- Name: .empty
Type: SHT_PROGBITS
Flags: [ SHF_ALLOC ]
Address: 0x1000
AddressAlign: 0x0000000000001000
Content: ""
- Name: .data
Type: SHT_PROGBITS
Flags: [ SHF_ALLOC ]
Address: 0x1000
AddressAlign: 0x0000000000001000
Content: "00000000"
# CHECK: Name: .text
# CHECK-NEXT: Type: SHT_PROGBITS
# CHECK-NEXT: Flags [
# CHECK-NEXT: SHF_ALLOC
# CHECK-NEXT: SHF_EXECINSTR
# CHECK-NEXT: ]
# CHECK: Name: .empty
# CHECK-NEXT: Type: SHT_PROGBITS
# CHECK-NEXT: Flags [
# CHECK-NEXT: SHF_ALLOC
# CHECK-NEXT: ]
# CHECK-NEXT: Address: 0x1000
# CHECK-NEXT: Offset: 0x2000
# CHECK-NEXT: Size: 0
# CHECK: Name: .data
# CHECK-NEXT: Type: SHT_PROGBITS
# CHECK-NEXT: Flags [
# CHECK-NEXT: SHF_ALLOC
# CHECK-NEXT: ]
# CHECK-NEXT: Address: 0x1000
# CHECK-NEXT: Offset: 0x2000
# CHECK-NEXT: Size: 4

71
test/tools/llvm-objcopy/program-headers.test Normal file
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@ -0,0 +1,71 @@
# RUN: yaml2obj %s -o %t
# RUN: llvm-objcopy %t %t2
# RUN: llvm-readobj -program-headers %t2 | FileCheck %s
!ELF
FileHeader:
Class: ELFCLASS64
Data: ELFDATA2LSB
Type: ET_EXEC
Machine: EM_X86_64
Sections:
- Name: .text
Type: SHT_PROGBITS
Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
Address: 0xAAAA1000
AddressAlign: 0x0000000000001000
Content: "00000000"
- Name: .init
Type: SHT_PROGBITS
Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
Content: "00000000"
Address: 0xAAAA1010
AddressAlign: 0x0000000000000010
- Name: .data
Type: SHT_PROGBITS
Flags: [ SHF_ALLOC ]
Content: "00000000"
Address: 0xAAAA2000
AddressAlign: 0x0000000000001000
ProgramHeaders:
- Type: PT_LOAD
Flags: [ PF_X, PF_R ]
VAddr: 0xAAAA1000
PAddr: 0xFFFF1000
Sections:
- Section: .text
- Section: .init
- Type: PT_LOAD
Flags: [ PF_R ]
VAddr: 0xAAAA2000
PAddr: 0xFFFF2000
Sections:
- Section: .data
#CHECK: ProgramHeaders [
#CHECK-NEXT: ProgramHeader {
#CHECK-NEXT: Type: PT_LOAD
#CHECK-NEXT: Offset: 0x1000
#CHECK-NEXT: VirtualAddress: 0xAAAA1000
#CHECK-NEXT: PhysicalAddress: 0xFFFF1000
#CHECK-NEXT: FileSize: 20
#CHECK-NEXT: MemSize: 20
#CHECK-NEXT: Flags [
#CHECK-NEXT: PF_R
#CHECK-NEXT: PF_X
#CHECK-NEXT: ]
#CHECK-NEXT: Alignment: 4096
#CHECK-NEXT: }
#CHECK-NEXT: ProgramHeader {
#CHECK-NEXT: Type: PT_LOAD
#CHECK-NEXT: Offset: 0x2000
#CHECK-NEXT: VirtualAddress: 0xAAAA2000
#CHECK-NEXT: PhysicalAddress: 0xFFFF2000
#CHECK-NEXT: FileSize: 4
#CHECK-NEXT: MemSize: 4
#CHECK-NEXT: Flags [
#CHECK-NEXT: PF_R
#CHECK-NEXT: ]
#CHECK-NEXT: Alignment: 4096
#CHECK-NEXT: }
#CHECK-NEXT:]

1
tools/LLVMBuild.txt
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@ -40,6 +40,7 @@ subdirectories =
llvm-modextract llvm-modextract
llvm-mt llvm-mt
llvm-nm llvm-nm
llvm-objcopy
llvm-objdump llvm-objdump
llvm-pdbutil llvm-pdbutil
llvm-profdata llvm-profdata

9
tools/llvm-objcopy/CMakeLists.txt Normal file
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@ -0,0 +1,9 @@
set(LLVM_LINK_COMPONENTS
Object
Support
MC
)
add_llvm_tool(llvm-objcopy
llvm-objcopy.cpp
Object.cpp
)

21
tools/llvm-objcopy/LLVMBuild.txt Normal file
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@ -0,0 +1,21 @@
;===- ./tools/llvm-objcopy/LLVMBuild.txt -----------------------*- Conf -*--===;
;
; The LLVM Compiler Infrastructure
;
; This file is distributed under the University of Illinois Open Source
; License. See LICENSE.TXT for details.
;
;===------------------------------------------------------------------------===;
;
; This is an LLVMBuild description file for the components in this subdirectory.
;
; For more information on the LLVMBuild system, please see:
;
; http://llvm.org/docs/LLVMBuild.html
;
;===------------------------------------------------------------------------===;
[component_0]
type = Tool
name = llvm-objcopy
parent = Tools
required_libraries = Object MC

341
tools/llvm-objcopy/Object.cpp Normal file
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@ -0,0 +1,341 @@
//===- Object.cpp -----------------------------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "Object.h"
#include "llvm-objcopy.h"
using namespace llvm;
using namespace object;
using namespace ELF;
template <class ELFT> void Segment::writeHeader(FileOutputBuffer &Out) const {
typedef typename ELFT::Ehdr Elf_Ehdr;
typedef typename ELFT::Phdr Elf_Phdr;
uint8_t *Buf = Out.getBufferStart();
Buf += sizeof(Elf_Ehdr) + Index * sizeof(Elf_Phdr);
Elf_Phdr &Phdr = *reinterpret_cast<Elf_Phdr *>(Buf);
Phdr.p_type = Type;
Phdr.p_flags = Flags;
Phdr.p_offset = Offset;
Phdr.p_vaddr = VAddr;
Phdr.p_paddr = PAddr;
Phdr.p_filesz = FileSize;
Phdr.p_memsz = MemSize;
Phdr.p_align = Align;
}
void Segment::finalize() {
auto FirstSec = firstSection();
if (FirstSec) {
// It is possible for a gap to be at the begining of a segment. Because of
// this we need to compute the new offset based on how large this gap was
// in the source file. Section layout should have already ensured that this
// space is not used for something else.
uint64_t OriginalOffset = Offset;
Offset = FirstSec->Offset - (FirstSec->OriginalOffset - OriginalOffset);
}
}
void SectionBase::finalize() {}
template <class ELFT>
void SectionBase::writeHeader(FileOutputBuffer &Out) const {
uint8_t *Buf = Out.getBufferStart();
Buf += HeaderOffset;
typename ELFT::Shdr &Shdr = *reinterpret_cast<typename ELFT::Shdr *>(Buf);
Shdr.sh_name = NameIndex;
Shdr.sh_type = Type;
Shdr.sh_flags = Flags;
Shdr.sh_addr = Addr;
Shdr.sh_offset = Offset;
Shdr.sh_size = Size;
Shdr.sh_link = Link;
Shdr.sh_info = Info;
Shdr.sh_addralign = Align;
Shdr.sh_entsize = EntrySize;
}
void Section::writeSection(FileOutputBuffer &Out) const {
if (Type == SHT_NOBITS)
return;
uint8_t *Buf = Out.getBufferStart() + Offset;
std::copy(std::begin(Contents), std::end(Contents), Buf);
}
void StringTableSection::addString(StringRef Name) {
StrTabBuilder.add(Name);
Size = StrTabBuilder.getSize();
}
uint32_t StringTableSection::findIndex(StringRef Name) const {
return StrTabBuilder.getOffset(Name);
}
void StringTableSection::finalize() { StrTabBuilder.finalize(); }
void StringTableSection::writeSection(FileOutputBuffer &Out) const {
StrTabBuilder.write(Out.getBufferStart() + Offset);
}
// Returns true IFF a section is wholly inside the range of a segment
static bool sectionWithinSegment(const SectionBase &Section,
const Segment &Segment) {
// If a section is empty it should be treated like it has a size of 1. This is
// to clarify the case when an empty section lies on a boundary between two
// segments and ensures that the section "belongs" to the second segment and
// not the first.
uint64_t SecSize = Section.Size ? Section.Size : 1;
return Segment.Offset <= Section.OriginalOffset &&
Segment.Offset + Segment.FileSize >= Section.OriginalOffset + SecSize;
}
template <class ELFT>
void Object<ELFT>::readProgramHeaders(const ELFFile<ELFT> &ElfFile) {
uint32_t Index = 0;
for (const auto &Phdr : unwrapOrError(ElfFile.program_headers())) {
Segments.emplace_back(llvm::make_unique<Segment>());
Segment &Seg = *Segments.back();
Seg.Type = Phdr.p_type;
Seg.Flags = Phdr.p_flags;
Seg.Offset = Phdr.p_offset;
Seg.VAddr = Phdr.p_vaddr;
Seg.PAddr = Phdr.p_paddr;
Seg.FileSize = Phdr.p_filesz;
Seg.MemSize = Phdr.p_memsz;
Seg.Align = Phdr.p_align;
Seg.Index = Index++;
for (auto &Section : Sections) {
if (sectionWithinSegment(*Section, Seg)) {
Seg.addSection(&*Section);
if (!Section->ParentSegment ||
Section->ParentSegment->Offset > Seg.Offset) {
Section->ParentSegment = &Seg;
}
}
}
}
}
template <class ELFT>
std::unique_ptr<SectionBase>
Object<ELFT>::makeSection(const llvm::object::ELFFile<ELFT> &ElfFile,
const Elf_Shdr &Shdr) {
ArrayRef<uint8_t> Data;
switch (Shdr.sh_type) {
case SHT_STRTAB:
return llvm::make_unique<StringTableSection>();
case SHT_NOBITS:
return llvm::make_unique<Section>(Data);
default:
Data = unwrapOrError(ElfFile.getSectionContents(&Shdr));
return llvm::make_unique<Section>(Data);
};
}
template <class ELFT>
void Object<ELFT>::readSectionHeaders(const ELFFile<ELFT> &ElfFile) {
uint32_t Index = 0;
for (const auto &Shdr : unwrapOrError(ElfFile.sections())) {
if (Index == 0) {
++Index;
continue;
}
SecPtr Sec = makeSection(ElfFile, Shdr);
Sec->Name = unwrapOrError(ElfFile.getSectionName(&Shdr));
Sec->Type = Shdr.sh_type;
Sec->Flags = Shdr.sh_flags;
Sec->Addr = Shdr.sh_addr;
Sec->Offset = Shdr.sh_offset;
Sec->OriginalOffset = Shdr.sh_offset;
Sec->Size = Shdr.sh_size;
Sec->Link = Shdr.sh_link;
Sec->Info = Shdr.sh_info;
Sec->Align = Shdr.sh_addralign;
Sec->EntrySize = Shdr.sh_entsize;
Sec->Index = Index++;
Sections.push_back(std::move(Sec));
}
}
template <class ELFT> size_t Object<ELFT>::totalSize() const {
// We already have the section header offset so we can calculate the total
// size by just adding up the size of each section header.
return SHOffset + Sections.size() * sizeof(Elf_Shdr) + sizeof(Elf_Shdr);
}
template <class ELFT> Object<ELFT>::Object(const ELFObjectFile<ELFT> &Obj) {
const auto &ElfFile = *Obj.getELFFile();
const auto &Ehdr = *ElfFile.getHeader();
std::copy(Ehdr.e_ident, Ehdr.e_ident + 16, Ident);
Type = Ehdr.e_type;
Machine = Ehdr.e_machine;
Version = Ehdr.e_version;
Entry = Ehdr.e_entry;
Flags = Ehdr.e_flags;
readSectionHeaders(ElfFile);
readProgramHeaders(ElfFile);
SectionNames =
dyn_cast<StringTableSection>(Sections[Ehdr.e_shstrndx - 1].get());
}
template <class ELFT> void Object<ELFT>::sortSections() {
// Put all sections in offset order. Maintain the ordering as closely as
// possible while meeting that demand however.
auto CompareSections = [](const SecPtr &A, const SecPtr &B) {
return A->OriginalOffset < B->OriginalOffset;
};
std::stable_sort(std::begin(Sections), std::end(Sections), CompareSections);
}
template <class ELFT> void Object<ELFT>::assignOffsets() {
// Decide file offsets and indexes.
size_t PhdrSize = Segments.size() * sizeof(Elf_Phdr);
// We can put section data after the ELF header and the program headers.
uint64_t Offset = sizeof(Elf_Ehdr) + PhdrSize;
uint64_t Index = 1;
for (auto &Section : Sections) {
// The segment can have a different alignment than the section. In the case
// that there is a parent segment then as long as we satisfy the alignment
// of the segment it should follow that that the section is aligned.
if (Section->ParentSegment) {
auto FirstInSeg = Section->ParentSegment->firstSection();
if (FirstInSeg == Section.get()) {
Offset = alignTo(Offset, Section->ParentSegment->Align);
// There can be gaps at the start of a segment before the first section.
// So first we assign the alignment of the segment and then assign the
// location of the section from there
Section->Offset =
Offset + Section->OriginalOffset - Section->ParentSegment->Offset;
}
// We should respect interstitial gaps of allocated sections. We *must*
// maintain the memory image so that addresses are preserved. As, with the
// exception of SHT_NOBITS sections at the end of segments, the memory
// image is a copy of the file image, we preserve the file image as well.
// There's a strange case where a thread local SHT_NOBITS can cause the
// memory image and file image to not be the same. This occurs, on some
// systems, when a thread local SHT_NOBITS is between two SHT_PROGBITS
// and the thread local SHT_NOBITS section is at the end of a TLS segment.
// In this case to faithfully copy the segment file image we must use
// relative offsets. In any other case this would be the same as using the
// relative addresses so this should maintian the memory image as desired.
Offset = FirstInSeg->Offset + Section->OriginalOffset -
FirstInSeg->OriginalOffset;
}
// Alignment should have already been handled by the above if statement if
// this if this section is in a segment. Technically this shouldn't do
// anything bad if the alignments of the sections are all correct and the
// file image isn't corrupted. Still in sticking with the motto "maintain
// the file image" we should avoid messing up the file image if the
// alignment disagrees with the file image.
if (!Section->ParentSegment && Section->Align)
Offset = alignTo(Offset, Section->Align);
Section->Offset = Offset;
Section->Index = Index++;
if (Section->Type != SHT_NOBITS)
Offset += Section->Size;
}
// 'offset' should now be just after all the section data so we should set the
// section header table offset to be exactly here. This spot might not be
// aligned properly however so we should align it as needed. For 32-bit ELF
// this needs to be 4-byte aligned and on 64-bit it needs to be 8-byte aligned
// so the size of ELFT::Addr is used to ensure this.
Offset = alignTo(Offset, sizeof(typename ELFT::Addr));
SHOffset = Offset;
}
template <class ELFT> void Object<ELFT>::finalize() {
for (auto &Section : Sections)
SectionNames->addString(Section->Name);
sortSections();
assignOffsets();
// Finalize SectionNames first so that we can assign name indexes.
SectionNames->finalize();
// Finally now that all offsets and indexes have been set we can finalize any
// remaining issues.
uint64_t Offset = SHOffset + sizeof(Elf_Shdr);
for (auto &Section : Sections) {
Section->HeaderOffset = Offset;
Offset += sizeof(Elf_Shdr);
Section->NameIndex = SectionNames->findIndex(Section->Name);
Section->finalize();
}
for (auto &Segment : Segments)
Segment->finalize();
}
template <class ELFT>
void Object<ELFT>::writeHeader(FileOutputBuffer &Out) const {
uint8_t *Buf = Out.getBufferStart();
Elf_Ehdr &Ehdr = *reinterpret_cast<Elf_Ehdr *>(Buf);
std::copy(Ident, Ident + 16, Ehdr.e_ident);
Ehdr.e_type = Type;
Ehdr.e_machine = Machine;
Ehdr.e_version = Version;
Ehdr.e_entry = Entry;
Ehdr.e_phoff = sizeof(Elf_Ehdr);
Ehdr.e_shoff = SHOffset;
Ehdr.e_flags = Flags;
Ehdr.e_ehsize = sizeof(Elf_Ehdr);
Ehdr.e_phentsize = sizeof(Elf_Phdr);
Ehdr.e_phnum = Segments.size();
Ehdr.e_shentsize = sizeof(Elf_Shdr);
Ehdr.e_shnum = Sections.size() + 1;
Ehdr.e_shstrndx = SectionNames->Index;
}
template <class ELFT>
void Object<ELFT>::writeProgramHeaders(FileOutputBuffer &Out) const {
for (auto &Phdr : Segments)
Phdr->template writeHeader<ELFT>(Out);
}
template <class ELFT>
void Object<ELFT>::writeSectionHeaders(FileOutputBuffer &Out) const {
uint8_t *Buf = Out.getBufferStart() + SHOffset;
// This reference serves to write the dummy section header at the begining
// of the file.
Elf_Shdr &Shdr = *reinterpret_cast<Elf_Shdr *>(Buf);
Shdr.sh_name = 0;
Shdr.sh_type = SHT_NULL;
Shdr.sh_flags = 0;
Shdr.sh_addr = 0;
Shdr.sh_offset = 0;
Shdr.sh_size = 0;
Shdr.sh_link = 0;
Shdr.sh_info = 0;
Shdr.sh_addralign = 0;
Shdr.sh_entsize = 0;
for (auto &Section : Sections)
Section->template writeHeader<ELFT>(Out);
}
template <class ELFT>
void Object<ELFT>::writeSectionData(FileOutputBuffer &Out) const {
for (auto &Section : Sections)
Section->writeSection(Out);
}
template <class ELFT> void Object<ELFT>::write(FileOutputBuffer &Out) {
writeHeader(Out);
writeProgramHeaders(Out);
writeSectionData(Out);
writeSectionHeaders(Out);
}
template class Object<ELF64LE>;
template class Object<ELF64BE>;
template class Object<ELF32LE>;
template class Object<ELF32BE>;

150
tools/llvm-objcopy/Object.h Normal file
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@ -0,0 +1,150 @@
//===- Object.h -------------------------------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_OBJCOPY_OBJECT_H
#define LLVM_OBJCOPY_OBJECT_H
#include "llvm/MC/StringTableBuilder.h"
#include "llvm/Object/ELFObjectFile.h"
#include "llvm/Support/FileOutputBuffer.h"
#include <memory>
#include <set>
class Segment;
class SectionBase {
public:
llvm::StringRef Name;
Segment *ParentSegment = nullptr;
uint64_t HeaderOffset;
uint64_t OriginalOffset;
uint32_t Index;
uint64_t Addr = 0;
uint64_t Align = 1;
uint32_t EntrySize = 0;
uint64_t Flags = 0;
uint64_t Info = 0;
uint64_t Link = llvm::ELF::SHN_UNDEF;
uint64_t NameIndex = 0;
uint64_t Offset = 0;
uint64_t Size = 0;
uint64_t Type = llvm::ELF::SHT_NULL;
virtual ~SectionBase() {}
virtual void finalize();
template <class ELFT> void writeHeader(llvm::FileOutputBuffer &Out) const;
virtual void writeSection(llvm::FileOutputBuffer &Out) const = 0;
};
class Segment {
private:
struct SectionCompare {
bool operator()(const SectionBase *Lhs, const SectionBase *Rhs) const {
// Some sections might have the same address if one of them is empty. To
// fix this we can use the lexicographic ordering on ->Addr and the
// address of the actully stored section.
if (Lhs->OriginalOffset == Rhs->OriginalOffset)
return Lhs < Rhs;
return Lhs->OriginalOffset < Rhs->OriginalOffset;
}
};
std::set<const SectionBase *, SectionCompare> Sections;
public:
uint64_t Align;
uint64_t FileSize;
uint32_t Flags;
uint32_t Index;
uint64_t MemSize;
uint64_t Offset;
uint64_t PAddr;
uint64_t Type;
uint64_t VAddr;
void finalize();
const SectionBase *firstSection() const {
if (!Sections.empty())
return *Sections.begin();
return nullptr;
}
void addSection(const SectionBase *sec) { Sections.insert(sec); }
template <class ELFT> void writeHeader(llvm::FileOutputBuffer &Out) const;
};
class Section : public SectionBase {
private:
llvm::ArrayRef<uint8_t> Contents;
public:
Section(llvm::ArrayRef<uint8_t> Data) : Contents(Data) {}
void writeSection(llvm::FileOutputBuffer &Out) const override;
};
// This is just a wraper around a StringTableBuilder that implements SectionBase
class StringTableSection : public SectionBase {
private:
llvm::StringTableBuilder StrTabBuilder;
public:
StringTableSection() : StrTabBuilder(llvm::StringTableBuilder::ELF) {
Type = llvm::ELF::SHT_STRTAB;
}
void addString(llvm::StringRef Name);
uint32_t findIndex(llvm::StringRef Name) const;
void finalize() override;
void writeSection(llvm::FileOutputBuffer &Out) const override;
static bool classof(const SectionBase *S) {
return S->Type == llvm::ELF::SHT_STRTAB;
}
};
template <class ELFT> class Object {
private:
typedef std::unique_ptr<SectionBase> SecPtr;
typedef std::unique_ptr<Segment> SegPtr;
typedef typename ELFT::Shdr Elf_Shdr;
typedef typename ELFT::Ehdr Elf_Ehdr;
typedef typename ELFT::Phdr Elf_Phdr;
StringTableSection *SectionNames;
std::vector<SecPtr> Sections;
std::vector<SegPtr> Segments;
void sortSections();
void assignOffsets();
SecPtr makeSection(const llvm::object::ELFFile<ELFT> &ElfFile,
const Elf_Shdr &Shdr);
void readProgramHeaders(const llvm::object::ELFFile<ELFT> &ElfFile);
void readSectionHeaders(const llvm::object::ELFFile<ELFT> &ElfFile);
void writeHeader(llvm::FileOutputBuffer &Out) const;
void writeProgramHeaders(llvm::FileOutputBuffer &Out) const;
void writeSectionData(llvm::FileOutputBuffer &Out) const;
void writeSectionHeaders(llvm::FileOutputBuffer &Out) const;
public:
uint8_t Ident[16];
uint64_t Entry;
uint64_t SHOffset;
uint32_t Type;
uint32_t Machine;
uint32_t Version;
uint32_t Flags;
Object(const llvm::object::ELFObjectFile<ELFT> &Obj);
size_t totalSize() const;
void finalize();
void write(llvm::FileOutputBuffer &Out);
};
#endif

96
tools/llvm-objcopy/llvm-objcopy.cpp Normal file
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@ -0,0 +1,96 @@
//===- llvm-objcopy.cpp -----------------------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "llvm-objcopy.h"
#include "Object.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/FileOutputBuffer.h"
#include "llvm/Support/PrettyStackTrace.h"
#include "llvm/Support/Signals.h"
#include "llvm/Support/ToolOutputFile.h"
#include <memory>
#include <string>
#include <system_error>
using namespace llvm;
using namespace object;
using namespace ELF;
// The name this program was invoked as.
static StringRef ToolName;
namespace llvm {
LLVM_ATTRIBUTE_NORETURN void error(Twine Message) {
errs() << ToolName << ": " << Message << ".\n";
errs().flush();
exit(1);
}
LLVM_ATTRIBUTE_NORETURN void reportError(StringRef File, std::error_code EC) {
assert(EC);
errs() << ToolName << ": '" << File << "': " << EC.message() << ".\n";
exit(1);
}
LLVM_ATTRIBUTE_NORETURN void reportError(StringRef File, llvm::Error E) {
assert(E);
std::string Buf;
raw_string_ostream OS(Buf);
logAllUnhandledErrors(std::move(E), OS, "");
OS.flush();
errs() << ToolName << ": '" << File << "': " << Buf;
exit(1);
}
}
cl::opt<std::string> InputFilename(cl::Positional, cl::desc("<input>"));
cl::opt<std::string> OutputFilename(cl::Positional, cl::desc("<output>"),
cl::init("-"));
void CopyBinary(const ELFObjectFile<ELF64LE> &ObjFile) {
std::unique_ptr<FileOutputBuffer> Buffer;
Object<ELF64LE> Obj{ObjFile};
Obj.finalize();
ErrorOr<std::unique_ptr<FileOutputBuffer>> BufferOrErr =
FileOutputBuffer::create(OutputFilename, Obj.totalSize(),
FileOutputBuffer::F_executable);
if (BufferOrErr.getError())
error("failed to open " + OutputFilename);
else
Buffer = std::move(*BufferOrErr);
std::error_code EC;
if (EC)
report_fatal_error(EC.message());
Obj.write(*Buffer);
if (auto EC = Buffer->commit())
reportError(OutputFilename, EC);
}
int main(int argc, char **argv) {
// Print a stack trace if we signal out.
sys::PrintStackTraceOnErrorSignal(argv[0]);
PrettyStackTraceProgram X(argc, argv);
llvm_shutdown_obj Y; // Call llvm_shutdown() on exit.
cl::ParseCommandLineOptions(argc, argv, "llvm objcopy utility\n");
ToolName = argv[0];
if (InputFilename.empty()) {
cl::PrintHelpMessage();
return 2;
}
Expected<OwningBinary<Binary>> BinaryOrErr = createBinary(InputFilename);
if (!BinaryOrErr)
reportError(InputFilename, BinaryOrErr.takeError());
Binary &Binary = *BinaryOrErr.get().getBinary();
if (ELFObjectFile<ELF64LE> *o = dyn_cast<ELFObjectFile<ELF64LE>>(&Binary)) {
CopyBinary(*o);
return 0;
}
reportError(InputFilename, object_error::invalid_file_type);
}

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tools/llvm-objcopy/llvm-objcopy.h Normal file
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//===- llvm-objcopy.h -------------------------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_OBJCOPY_H
#define LLVM_OBJCOPY_H
#include "llvm/ADT/Twine.h"
#include "llvm/Support/Error.h"
namespace llvm {
LLVM_ATTRIBUTE_NORETURN extern void error(Twine Message);
// This is taken from llvm-readobj.
// [see here](llvm/tools/llvm-readobj/llvm-readobj.h:38)
template <class T> T unwrapOrError(Expected<T> EO) {
if (EO)
return *EO;
std::string Buf;
raw_string_ostream OS(Buf);
logAllUnhandledErrors(EO.takeError(), OS, "");
OS.flush();
error(Buf);
}
}
#endif