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Compute the section table lazily. 

As a consequence this move a bunch of error checking out of the constructor.

llvm-svn: 285815
This commit is contained in:
Rafael Espindola 2016-11-02 15:15:59 +00:00
parent e3bb72ea78
commit d7160056dc
1 changed files with 52 additions and 55 deletions
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107
llvm/include/llvm/Object/ELF.h
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@ -71,7 +71,6 @@ private:
StringRef Buf;
const Elf_Ehdr *Header;
const Elf_Shdr *SectionHeaderTable = nullptr;
public:
template<typename T>
@ -147,8 +146,8 @@ public:
return makeArrayRef(program_header_begin(), program_header_end());
}
uintX_t getNumSections() const;
ErrorOr<StringRef> getSectionStringTable() const;
ErrorOr<StringRef> getSectionStringTable(Elf_Shdr_Range Sections) const;
uint32_t getExtendedSymbolTableIndex(const Elf_Sym *Sym,
const Elf_Shdr *SymTab,
ArrayRef<Elf_Word> ShndxTable) const;
@ -286,26 +285,25 @@ ELFFile<ELFT>::getRelocationSymbol(const Elf_Rel *Rel,
}
template <class ELFT>
typename ELFT::uint ELFFile<ELFT>::getNumSections() const {
assert(Header && "Header not initialized!");
if (Header->e_shnum == ELF::SHN_UNDEF && Header->e_shoff > 0) {
assert(SectionHeaderTable && "SectionHeaderTable not initialized!");
return SectionHeaderTable->sh_size;
}
return Header->e_shnum;
ErrorOr<StringRef> ELFFile<ELFT>::getSectionStringTable() const {
auto SectionsOrErr = sections();
if (std::error_code EC = SectionsOrErr.getError())
return EC;
return getSectionStringTable(*SectionsOrErr);
}
template <class ELFT>
ErrorOr<StringRef> ELFFile<ELFT>::getSectionStringTable() const {
ErrorOr<StringRef>
ELFFile<ELFT>::getSectionStringTable(Elf_Shdr_Range Sections) const {
uint32_t Index = Header->e_shstrndx;
if (Index == ELF::SHN_XINDEX)
Index = SectionHeaderTable->sh_link;
Index = Sections[0].sh_link;
if (!Index) // no section string table.
return "";
ErrorOr<const Elf_Shdr *> StrTabSecOrErr = getSection(Index);
if (std::error_code EC = StrTabSecOrErr.getError())
return EC;
return getStringTable(*StrTabSecOrErr);
if (Index >= Sections.size())
return object_error::parse_failed;
return getStringTable(&Sections[Index]);
}
template <class ELFT>
@ -328,37 +326,6 @@ ELFFile<ELFT>::ELFFile(StringRef Object, std::error_code &EC) : Buf(Object) {
return;
}
const uint64_t SectionTableOffset = Header->e_shoff;
if (SectionTableOffset + sizeof(Elf_Shdr) > FileSize) {
// Section header table goes past end of file!
EC = object_error::parse_failed;
return;
}
if (SectionTableOffset & (alignof(Elf_Shdr) - 1)) {
// Invalid address alignment of section headers
EC = object_error::parse_failed;
return;
}
// The getNumSections() call below depends on SectionHeaderTable being set.
SectionHeaderTable =
reinterpret_cast<const Elf_Shdr *>(base() + SectionTableOffset);
if (getNumSections() > UINT64_MAX / Header->e_shentsize) {
// Section table goes past end of file!
EC = object_error::parse_failed;
return;
}
const uint64_t SectionTableSize = getNumSections() * Header->e_shentsize;
if (SectionTableOffset + SectionTableSize > FileSize) {
// Section table goes past end of file!
EC = object_error::parse_failed;
return;
}
EC = std::error_code();
}
@ -369,11 +336,42 @@ static bool compareAddr(uint64_t VAddr, const Elf_Phdr_Impl<ELFT> *Phdr) {
template <class ELFT>
ErrorOr<typename ELFT::ShdrRange> ELFFile<ELFT>::sections() const {
const uintX_t SectionTableOffset = Header->e_shoff;
if (SectionTableOffset == 0)
return ArrayRef<Elf_Shdr>();
// Invalid section header entry size (e_shentsize) in ELF header
if (Header->e_shentsize != sizeof(Elf_Shdr))
return object_error::parse_failed;
auto *Begin = reinterpret_cast<const Elf_Shdr *>(base() + Header->e_shoff);
return makeArrayRef(Begin, Begin + getNumSections());
const uint64_t FileSize = Buf.size();
// Section header table goes past end of file!
if (SectionTableOffset + sizeof(Elf_Shdr) > FileSize)
return object_error::parse_failed;
// Invalid address alignment of section headers
if (SectionTableOffset & (alignof(Elf_Shdr) - 1))
return object_error::parse_failed;
const Elf_Shdr *First =
reinterpret_cast<const Elf_Shdr *>(base() + SectionTableOffset);
uintX_t NumSections = Header->e_shnum;
if (NumSections == 0)
NumSections = First->sh_size;
// Section table goes past end of file!
if (NumSections > UINT64_MAX / sizeof(Elf_Shdr))
return object_error::parse_failed;
const uint64_t SectionTableSize = NumSections * sizeof(Elf_Shdr);
// Section table goes past end of file!
if (SectionTableOffset + SectionTableSize > FileSize)
return object_error::parse_failed;
return makeArrayRef(First, NumSections);
}
template <class ELFT>
@ -396,14 +394,13 @@ const T *ELFFile<ELFT>::getEntry(const Elf_Shdr *Section,
template <class ELFT>
ErrorOr<const typename ELFFile<ELFT>::Elf_Shdr *>
ELFFile<ELFT>::getSection(uint32_t Index) const {
assert(SectionHeaderTable && "SectionHeaderTable not initialized!");
if (Index >= getNumSections())
auto TableOrErr = sections();
if (std::error_code EC = TableOrErr.getError())
return EC;
ArrayRef<Elf_Shdr> Table = *TableOrErr;
if (Index >= Table.size())
return object_error::invalid_section_index;
const Elf_Shdr *Addr = SectionHeaderTable + Index;
if (reinterpret_cast<const uint8_t *>(Addr) >= base() + getBufSize())
return object_error::invalid_section_index;
return Addr;
return &Table[Index];
}
template <class ELFT>