llvm/tools/obj2yaml/elf2yaml.cpp
Alexander Richardson 229871c696 [obj2yaml] Don't crash for input files without symbol table
Summary: Previously we would dereference Symtab without checking for null.

Reviewers: davide, atanasyan, rafael

Reviewed By: davide, atanasyan

Differential Revision: https://reviews.llvm.org/D38080

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@313970 91177308-0d34-0410-b5e6-96231b3b80d8
2017-09-22 09:30:40 +00:00

533 lines
17 KiB
C++

//===------ utils/elf2yaml.cpp - obj2yaml conversion tool -------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "Error.h"
#include "obj2yaml.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Object/ELFObjectFile.h"
#include "llvm/ObjectYAML/ELFYAML.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/YAMLTraits.h"
using namespace llvm;
namespace {
template <class ELFT>
class ELFDumper {
typedef object::Elf_Sym_Impl<ELFT> Elf_Sym;
typedef typename object::ELFFile<ELFT>::Elf_Shdr Elf_Shdr;
typedef typename object::ELFFile<ELFT>::Elf_Word Elf_Word;
typedef typename object::ELFFile<ELFT>::Elf_Rel Elf_Rel;
typedef typename object::ELFFile<ELFT>::Elf_Rela Elf_Rela;
ArrayRef<Elf_Shdr> Sections;
// If the file has multiple sections with the same name, we add a
// suffix to make them unique.
unsigned Suffix = 0;
DenseSet<StringRef> UsedSectionNames;
std::vector<std::string> SectionNames;
Expected<StringRef> getUniquedSectionName(const Elf_Shdr *Sec);
Expected<StringRef> getSymbolName(const Elf_Sym *Sym, StringRef StrTable,
const Elf_Shdr *SymTab);
const object::ELFFile<ELFT> &Obj;
ArrayRef<Elf_Word> ShndxTable;
std::error_code dumpSymbol(const Elf_Sym *Sym, const Elf_Shdr *SymTab,
StringRef StrTable, ELFYAML::Symbol &S);
std::error_code dumpCommonSection(const Elf_Shdr *Shdr, ELFYAML::Section &S);
std::error_code dumpCommonRelocationSection(const Elf_Shdr *Shdr,
ELFYAML::RelocationSection &S);
template <class RelT>
std::error_code dumpRelocation(const RelT *Rel, const Elf_Shdr *SymTab,
ELFYAML::Relocation &R);
ErrorOr<ELFYAML::RelocationSection *> dumpRelSection(const Elf_Shdr *Shdr);
ErrorOr<ELFYAML::RelocationSection *> dumpRelaSection(const Elf_Shdr *Shdr);
ErrorOr<ELFYAML::RawContentSection *>
dumpContentSection(const Elf_Shdr *Shdr);
ErrorOr<ELFYAML::NoBitsSection *> dumpNoBitsSection(const Elf_Shdr *Shdr);
ErrorOr<ELFYAML::Group *> dumpGroup(const Elf_Shdr *Shdr);
ErrorOr<ELFYAML::MipsABIFlags *> dumpMipsABIFlags(const Elf_Shdr *Shdr);
public:
ELFDumper(const object::ELFFile<ELFT> &O);
ErrorOr<ELFYAML::Object *> dump();
};
}
template <class ELFT>
ELFDumper<ELFT>::ELFDumper(const object::ELFFile<ELFT> &O)
: Obj(O) {}
template <class ELFT>
Expected<StringRef>
ELFDumper<ELFT>::getUniquedSectionName(const Elf_Shdr *Sec) {
unsigned SecIndex = Sec - &Sections[0];
assert(&Sections[SecIndex] == Sec);
if (!SectionNames[SecIndex].empty())
return SectionNames[SecIndex];
auto NameOrErr = Obj.getSectionName(Sec);
if (!NameOrErr)
return NameOrErr;
StringRef Name = *NameOrErr;
std::string &Ret = SectionNames[SecIndex];
Ret = Name;
while (!UsedSectionNames.insert(Ret).second)
Ret = (Name + to_string(++Suffix)).str();
return Ret;
}
template <class ELFT>
Expected<StringRef> ELFDumper<ELFT>::getSymbolName(const Elf_Sym *Sym,
StringRef StrTable,
const Elf_Shdr *SymTab) {
Expected<StringRef> SymbolNameOrErr = Sym->getName(StrTable);
if (!SymbolNameOrErr)
return SymbolNameOrErr;
StringRef Name = *SymbolNameOrErr;
if (Name.empty() && Sym->getType() == ELF::STT_SECTION) {
auto ShdrOrErr = Obj.getSection(Sym, SymTab, ShndxTable);
if (!ShdrOrErr)
return ShdrOrErr.takeError();
return getUniquedSectionName(*ShdrOrErr);
}
return Name;
}
template <class ELFT> ErrorOr<ELFYAML::Object *> ELFDumper<ELFT>::dump() {
auto Y = make_unique<ELFYAML::Object>();
// Dump header
Y->Header.Class = ELFYAML::ELF_ELFCLASS(Obj.getHeader()->getFileClass());
Y->Header.Data = ELFYAML::ELF_ELFDATA(Obj.getHeader()->getDataEncoding());
Y->Header.OSABI = Obj.getHeader()->e_ident[ELF::EI_OSABI];
Y->Header.Type = Obj.getHeader()->e_type;
Y->Header.Machine = Obj.getHeader()->e_machine;
Y->Header.Flags = Obj.getHeader()->e_flags;
Y->Header.Entry = Obj.getHeader()->e_entry;
const Elf_Shdr *Symtab = nullptr;
// Dump sections
auto SectionsOrErr = Obj.sections();
if (!SectionsOrErr)
return errorToErrorCode(SectionsOrErr.takeError());
Sections = *SectionsOrErr;
SectionNames.resize(Sections.size());
for (const Elf_Shdr &Sec : Sections) {
switch (Sec.sh_type) {
case ELF::SHT_NULL:
case ELF::SHT_DYNSYM:
case ELF::SHT_STRTAB:
// Do not dump these sections.
break;
case ELF::SHT_SYMTAB:
Symtab = &Sec;
break;
case ELF::SHT_SYMTAB_SHNDX: {
auto TableOrErr = Obj.getSHNDXTable(Sec);
if (!TableOrErr)
return errorToErrorCode(TableOrErr.takeError());
ShndxTable = *TableOrErr;
break;
}
case ELF::SHT_RELA: {
ErrorOr<ELFYAML::RelocationSection *> S = dumpRelaSection(&Sec);
if (std::error_code EC = S.getError())
return EC;
Y->Sections.push_back(std::unique_ptr<ELFYAML::Section>(S.get()));
break;
}
case ELF::SHT_REL: {
ErrorOr<ELFYAML::RelocationSection *> S = dumpRelSection(&Sec);
if (std::error_code EC = S.getError())
return EC;
Y->Sections.push_back(std::unique_ptr<ELFYAML::Section>(S.get()));
break;
}
case ELF::SHT_GROUP: {
ErrorOr<ELFYAML::Group *> G = dumpGroup(&Sec);
if (std::error_code EC = G.getError())
return EC;
Y->Sections.push_back(std::unique_ptr<ELFYAML::Section>(G.get()));
break;
}
case ELF::SHT_MIPS_ABIFLAGS: {
ErrorOr<ELFYAML::MipsABIFlags *> G = dumpMipsABIFlags(&Sec);
if (std::error_code EC = G.getError())
return EC;
Y->Sections.push_back(std::unique_ptr<ELFYAML::Section>(G.get()));
break;
}
case ELF::SHT_NOBITS: {
ErrorOr<ELFYAML::NoBitsSection *> S = dumpNoBitsSection(&Sec);
if (std::error_code EC = S.getError())
return EC;
Y->Sections.push_back(std::unique_ptr<ELFYAML::Section>(S.get()));
break;
}
default: {
ErrorOr<ELFYAML::RawContentSection *> S = dumpContentSection(&Sec);
if (std::error_code EC = S.getError())
return EC;
Y->Sections.push_back(std::unique_ptr<ELFYAML::Section>(S.get()));
}
}
}
// Dump symbols
if (!Symtab)
return Y.release(); // if the symbol table is missing return early
auto StrTableOrErr = Obj.getStringTableForSymtab(*Symtab);
if (!StrTableOrErr)
return errorToErrorCode(StrTableOrErr.takeError());
StringRef StrTable = *StrTableOrErr;
bool IsFirstSym = true;
auto SymtabOrErr = Obj.symbols(Symtab);
if (!SymtabOrErr)
return errorToErrorCode(SymtabOrErr.takeError());
for (const Elf_Sym &Sym : *SymtabOrErr) {
if (IsFirstSym) {
IsFirstSym = false;
continue;
}
ELFYAML::Symbol S;
if (std::error_code EC =
ELFDumper<ELFT>::dumpSymbol(&Sym, Symtab, StrTable, S))
return EC;
switch (Sym.getBinding())
{
case ELF::STB_LOCAL:
Y->Symbols.Local.push_back(S);
break;
case ELF::STB_GLOBAL:
Y->Symbols.Global.push_back(S);
break;
case ELF::STB_WEAK:
Y->Symbols.Weak.push_back(S);
break;
default:
llvm_unreachable("Unknown ELF symbol binding");
}
}
return Y.release();
}
template <class ELFT>
std::error_code
ELFDumper<ELFT>::dumpSymbol(const Elf_Sym *Sym, const Elf_Shdr *SymTab,
StringRef StrTable, ELFYAML::Symbol &S) {
S.Type = Sym->getType();
S.Value = Sym->st_value;
S.Size = Sym->st_size;
S.Other = Sym->st_other;
Expected<StringRef> SymbolNameOrErr = getSymbolName(Sym, StrTable, SymTab);
if (!SymbolNameOrErr)
return errorToErrorCode(SymbolNameOrErr.takeError());
S.Name = SymbolNameOrErr.get();
auto ShdrOrErr = Obj.getSection(Sym, SymTab, ShndxTable);
if (!ShdrOrErr)
return errorToErrorCode(ShdrOrErr.takeError());
const Elf_Shdr *Shdr = *ShdrOrErr;
if (!Shdr)
return obj2yaml_error::success;
auto NameOrErr = getUniquedSectionName(Shdr);
if (!NameOrErr)
return errorToErrorCode(NameOrErr.takeError());
S.Section = NameOrErr.get();
return obj2yaml_error::success;
}
template <class ELFT>
template <class RelT>
std::error_code ELFDumper<ELFT>::dumpRelocation(const RelT *Rel,
const Elf_Shdr *SymTab,
ELFYAML::Relocation &R) {
R.Type = Rel->getType(Obj.isMips64EL());
R.Offset = Rel->r_offset;
R.Addend = 0;
auto SymOrErr = Obj.getRelocationSymbol(Rel, SymTab);
if (!SymOrErr)
return errorToErrorCode(SymOrErr.takeError());
const Elf_Sym *Sym = *SymOrErr;
auto StrTabSec = Obj.getSection(SymTab->sh_link);
if (!StrTabSec)
return errorToErrorCode(StrTabSec.takeError());
auto StrTabOrErr = Obj.getStringTable(*StrTabSec);
if (!StrTabOrErr)
return errorToErrorCode(StrTabOrErr.takeError());
StringRef StrTab = *StrTabOrErr;
if (Sym) {
Expected<StringRef> NameOrErr = getSymbolName(Sym, StrTab, SymTab);
if (!NameOrErr)
return errorToErrorCode(NameOrErr.takeError());
R.Symbol = NameOrErr.get();
} else {
// We have some edge cases of relocations without a symbol associated,
// e.g. an object containing the invalid (according to the System V
// ABI) R_X86_64_NONE reloc. Create a symbol with an empty name instead
// of crashing.
R.Symbol = "";
}
return obj2yaml_error::success;
}
template <class ELFT>
std::error_code ELFDumper<ELFT>::dumpCommonSection(const Elf_Shdr *Shdr,
ELFYAML::Section &S) {
S.Type = Shdr->sh_type;
S.Flags = Shdr->sh_flags;
S.Address = Shdr->sh_addr;
S.AddressAlign = Shdr->sh_addralign;
auto NameOrErr = getUniquedSectionName(Shdr);
if (!NameOrErr)
return errorToErrorCode(NameOrErr.takeError());
S.Name = NameOrErr.get();
if (Shdr->sh_link != ELF::SHN_UNDEF) {
auto LinkSection = Obj.getSection(Shdr->sh_link);
if (LinkSection.takeError())
return errorToErrorCode(LinkSection.takeError());
NameOrErr = getUniquedSectionName(*LinkSection);
if (!NameOrErr)
return errorToErrorCode(NameOrErr.takeError());
S.Link = NameOrErr.get();
}
return obj2yaml_error::success;
}
template <class ELFT>
std::error_code
ELFDumper<ELFT>::dumpCommonRelocationSection(const Elf_Shdr *Shdr,
ELFYAML::RelocationSection &S) {
if (std::error_code EC = dumpCommonSection(Shdr, S))
return EC;
auto InfoSection = Obj.getSection(Shdr->sh_info);
if (!InfoSection)
return errorToErrorCode(InfoSection.takeError());
auto NameOrErr = getUniquedSectionName(*InfoSection);
if (!NameOrErr)
return errorToErrorCode(NameOrErr.takeError());
S.Info = NameOrErr.get();
return obj2yaml_error::success;
}
template <class ELFT>
ErrorOr<ELFYAML::RelocationSection *>
ELFDumper<ELFT>::dumpRelSection(const Elf_Shdr *Shdr) {
assert(Shdr->sh_type == ELF::SHT_REL && "Section type is not SHT_REL");
auto S = make_unique<ELFYAML::RelocationSection>();
if (std::error_code EC = dumpCommonRelocationSection(Shdr, *S))
return EC;
auto SymTabOrErr = Obj.getSection(Shdr->sh_link);
if (!SymTabOrErr)
return errorToErrorCode(SymTabOrErr.takeError());
const Elf_Shdr *SymTab = *SymTabOrErr;
auto Rels = Obj.rels(Shdr);
if (!Rels)
return errorToErrorCode(Rels.takeError());
for (const Elf_Rel &Rel : *Rels) {
ELFYAML::Relocation R;
if (std::error_code EC = dumpRelocation(&Rel, SymTab, R))
return EC;
S->Relocations.push_back(R);
}
return S.release();
}
template <class ELFT>
ErrorOr<ELFYAML::RelocationSection *>
ELFDumper<ELFT>::dumpRelaSection(const Elf_Shdr *Shdr) {
assert(Shdr->sh_type == ELF::SHT_RELA && "Section type is not SHT_RELA");
auto S = make_unique<ELFYAML::RelocationSection>();
if (std::error_code EC = dumpCommonRelocationSection(Shdr, *S))
return EC;
auto SymTabOrErr = Obj.getSection(Shdr->sh_link);
if (!SymTabOrErr)
return errorToErrorCode(SymTabOrErr.takeError());
const Elf_Shdr *SymTab = *SymTabOrErr;
auto Rels = Obj.relas(Shdr);
if (!Rels)
return errorToErrorCode(Rels.takeError());
for (const Elf_Rela &Rel : *Rels) {
ELFYAML::Relocation R;
if (std::error_code EC = dumpRelocation(&Rel, SymTab, R))
return EC;
R.Addend = Rel.r_addend;
S->Relocations.push_back(R);
}
return S.release();
}
template <class ELFT>
ErrorOr<ELFYAML::RawContentSection *>
ELFDumper<ELFT>::dumpContentSection(const Elf_Shdr *Shdr) {
auto S = make_unique<ELFYAML::RawContentSection>();
if (std::error_code EC = dumpCommonSection(Shdr, *S))
return EC;
auto ContentOrErr = Obj.getSectionContents(Shdr);
if (!ContentOrErr)
return errorToErrorCode(ContentOrErr.takeError());
S->Content = yaml::BinaryRef(ContentOrErr.get());
S->Size = S->Content.binary_size();
return S.release();
}
template <class ELFT>
ErrorOr<ELFYAML::NoBitsSection *>
ELFDumper<ELFT>::dumpNoBitsSection(const Elf_Shdr *Shdr) {
auto S = make_unique<ELFYAML::NoBitsSection>();
if (std::error_code EC = dumpCommonSection(Shdr, *S))
return EC;
S->Size = Shdr->sh_size;
return S.release();
}
template <class ELFT>
ErrorOr<ELFYAML::Group *> ELFDumper<ELFT>::dumpGroup(const Elf_Shdr *Shdr) {
auto S = make_unique<ELFYAML::Group>();
if (std::error_code EC = dumpCommonSection(Shdr, *S))
return EC;
// Get sh_info which is the signature.
auto SymtabOrErr = Obj.getSection(Shdr->sh_link);
if (!SymtabOrErr)
return errorToErrorCode(SymtabOrErr.takeError());
const Elf_Shdr *Symtab = *SymtabOrErr;
auto SymOrErr = Obj.getSymbol(Symtab, Shdr->sh_info);
if (!SymOrErr)
return errorToErrorCode(SymOrErr.takeError());
const Elf_Sym *symbol = *SymOrErr;
auto StrTabOrErr = Obj.getStringTableForSymtab(*Symtab);
if (!StrTabOrErr)
return errorToErrorCode(StrTabOrErr.takeError());
StringRef StrTab = *StrTabOrErr;
auto sectionContents = Obj.getSectionContents(Shdr);
if (!sectionContents)
return errorToErrorCode(sectionContents.takeError());
Expected<StringRef> symbolName = getSymbolName(symbol, StrTab, Symtab);
if (!symbolName)
return errorToErrorCode(symbolName.takeError());
S->Info = *symbolName;
const Elf_Word *groupMembers =
reinterpret_cast<const Elf_Word *>(sectionContents->data());
const long count = (Shdr->sh_size) / sizeof(Elf_Word);
ELFYAML::SectionOrType s;
for (int i = 0; i < count; i++) {
if (groupMembers[i] == llvm::ELF::GRP_COMDAT) {
s.sectionNameOrType = "GRP_COMDAT";
} else {
auto sHdr = Obj.getSection(groupMembers[i]);
if (!sHdr)
return errorToErrorCode(sHdr.takeError());
auto sectionName = getUniquedSectionName(*sHdr);
if (!sectionName)
return errorToErrorCode(sectionName.takeError());
s.sectionNameOrType = *sectionName;
}
S->Members.push_back(s);
}
return S.release();
}
template <class ELFT>
ErrorOr<ELFYAML::MipsABIFlags *>
ELFDumper<ELFT>::dumpMipsABIFlags(const Elf_Shdr *Shdr) {
assert(Shdr->sh_type == ELF::SHT_MIPS_ABIFLAGS &&
"Section type is not SHT_MIPS_ABIFLAGS");
auto S = make_unique<ELFYAML::MipsABIFlags>();
if (std::error_code EC = dumpCommonSection(Shdr, *S))
return EC;
auto ContentOrErr = Obj.getSectionContents(Shdr);
if (!ContentOrErr)
return errorToErrorCode(ContentOrErr.takeError());
auto *Flags = reinterpret_cast<const object::Elf_Mips_ABIFlags<ELFT> *>(
ContentOrErr.get().data());
S->Version = Flags->version;
S->ISALevel = Flags->isa_level;
S->ISARevision = Flags->isa_rev;
S->GPRSize = Flags->gpr_size;
S->CPR1Size = Flags->cpr1_size;
S->CPR2Size = Flags->cpr2_size;
S->FpABI = Flags->fp_abi;
S->ISAExtension = Flags->isa_ext;
S->ASEs = Flags->ases;
S->Flags1 = Flags->flags1;
S->Flags2 = Flags->flags2;
return S.release();
}
template <class ELFT>
static std::error_code elf2yaml(raw_ostream &Out,
const object::ELFFile<ELFT> &Obj) {
ELFDumper<ELFT> Dumper(Obj);
ErrorOr<ELFYAML::Object *> YAMLOrErr = Dumper.dump();
if (std::error_code EC = YAMLOrErr.getError())
return EC;
std::unique_ptr<ELFYAML::Object> YAML(YAMLOrErr.get());
yaml::Output Yout(Out);
Yout << *YAML;
return std::error_code();
}
std::error_code elf2yaml(raw_ostream &Out, const object::ObjectFile &Obj) {
if (const auto *ELFObj = dyn_cast<object::ELF32LEObjectFile>(&Obj))
return elf2yaml(Out, *ELFObj->getELFFile());
if (const auto *ELFObj = dyn_cast<object::ELF32BEObjectFile>(&Obj))
return elf2yaml(Out, *ELFObj->getELFFile());
if (const auto *ELFObj = dyn_cast<object::ELF64LEObjectFile>(&Obj))
return elf2yaml(Out, *ELFObj->getELFFile());
if (const auto *ELFObj = dyn_cast<object::ELF64BEObjectFile>(&Obj))
return elf2yaml(Out, *ELFObj->getELFFile());
return obj2yaml_error::unsupported_obj_file_format;
}