maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity
llvm-project/llvm/tools/llvm-objcopy/COFF/Writer.cpp

418 lines
15 KiB
C++
Raw Blame History

//===- Writer.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 "Writer.h"
#include "Object.h"
#include "llvm-objcopy.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/BinaryFormat/COFF.h"
#include "llvm/Object/COFF.h"
#include "llvm/Support/ErrorHandling.h"
#include <cstddef>
#include <cstdint>
namespace llvm {
namespace objcopy {
namespace coff {
using namespace object;
using namespace COFF;
Error COFFWriter::finalizeRelocTargets() {
for (Section &Sec : Obj.getMutableSections()) {
for (Relocation &R : Sec.Relocs) {
const Symbol *Sym = Obj.findSymbol(R.Target);
if (Sym == nullptr)
return createStringError(object_error::invalid_symbol_index,
"Relocation target '%s' (%zu) not found",
R.TargetName.str().c_str(), R.Target);
R.Reloc.SymbolTableIndex = Sym->RawIndex;
}
}
return Error::success();
}
Error COFFWriter::finalizeSymbolContents() {
for (Symbol &Sym : Obj.getMutableSymbols()) {
if (Sym.TargetSectionId <= 0) {
// Undefined, or a special kind of symbol. These negative values
// are stored in the SectionNumber field which is unsigned.
Sym.Sym.SectionNumber = static_cast<uint32_t>(Sym.TargetSectionId);
} else {
const Section *Sec = Obj.findSection(Sym.TargetSectionId);
if (Sec == nullptr)
return createStringError(object_error::invalid_symbol_index,
"Symbol '%s' points to a removed section",
Sym.Name.str().c_str());
Sym.Sym.SectionNumber = Sec->Index;
if (Sym.Sym.NumberOfAuxSymbols == 1 &&
Sym.Sym.StorageClass == IMAGE_SYM_CLASS_STATIC) {
coff_aux_section_definition *SD =
reinterpret_cast<coff_aux_section_definition *>(
Sym.AuxData[0].Opaque);
uint32_t SDSectionNumber;
if (Sym.AssociativeComdatTargetSectionId == 0) {
// Not a comdat associative section; just set the Number field to
// the number of the section itself.
SDSectionNumber = Sec->Index;
} else {
Sec = Obj.findSection(Sym.AssociativeComdatTargetSectionId);
if (Sec == nullptr)
return createStringError(
object_error::invalid_symbol_index,
"Symbol '%s' is associative to a removed section",
Sym.Name.str().c_str());
SDSectionNumber = Sec->Index;
}
// Update the section definition with the new section number.
SD->NumberLowPart = static_cast<uint16_t>(SDSectionNumber);
SD->NumberHighPart = static_cast<uint16_t>(SDSectionNumber >> 16);
}
}
// Check that we actually have got AuxData to match the weak symbol target
// we want to set. Only >= 1 would be required, but only == 1 makes sense.
if (Sym.WeakTargetSymbolId && Sym.Sym.NumberOfAuxSymbols == 1) {
coff_aux_weak_external *WE =
reinterpret_cast<coff_aux_weak_external *>(Sym.AuxData[0].Opaque);
const Symbol *Target = Obj.findSymbol(*Sym.WeakTargetSymbolId);
if (Target == nullptr)
return createStringError(object_error::invalid_symbol_index,
"Symbol '%s' is missing its weak target",
Sym.Name.str().c_str());
WE->TagIndex = Target->RawIndex;
}
}
return Error::success();
}
void COFFWriter::layoutSections() {
for (auto &S : Obj.getMutableSections()) {
if (S.Header.SizeOfRawData > 0)
S.Header.PointerToRawData = FileSize;
FileSize += S.Header.SizeOfRawData; // For executables, this is already
// aligned to FileAlignment.
S.Header.NumberOfRelocations = S.Relocs.size();
S.Header.PointerToRelocations =
S.Header.NumberOfRelocations > 0 ? FileSize : 0;
FileSize += S.Relocs.size() * sizeof(coff_relocation);
FileSize = alignTo(FileSize, FileAlignment);
if (S.Header.Characteristics & IMAGE_SCN_CNT_INITIALIZED_DATA)
SizeOfInitializedData += S.Header.SizeOfRawData;
}
}
size_t COFFWriter::finalizeStringTable() {
for (const auto &S : Obj.getSections())
if (S.Name.size() > COFF::NameSize)
StrTabBuilder.add(S.Name);
for (const auto &S : Obj.getSymbols())
if (S.Name.size() > COFF::NameSize)
StrTabBuilder.add(S.Name);
StrTabBuilder.finalize();
for (auto &S : Obj.getMutableSections()) {
if (S.Name.size() > COFF::NameSize) {
memset(S.Header.Name, 0, sizeof(S.Header.Name));
snprintf(S.Header.Name, sizeof(S.Header.Name), "/%d",
(int)StrTabBuilder.getOffset(S.Name));
} else {
strncpy(S.Header.Name, S.Name.data(), COFF::NameSize);
}
}
for (auto &S : Obj.getMutableSymbols()) {
if (S.Name.size() > COFF::NameSize) {
S.Sym.Name.Offset.Zeroes = 0;
S.Sym.Name.Offset.Offset = StrTabBuilder.getOffset(S.Name);
} else {
strncpy(S.Sym.Name.ShortName, S.Name.data(), COFF::NameSize);
}
}
return StrTabBuilder.getSize();
}
template <class SymbolTy>
std::pair<size_t, size_t> COFFWriter::finalizeSymbolTable() {
size_t RawSymIndex = 0;
for (auto &S : Obj.getMutableSymbols()) {
// Symbols normally have NumberOfAuxSymbols set correctly all the time.
// For file symbols, we need to know the output file's symbol size to be
// able to calculate the number of slots it occupies.
if (!S.AuxFile.empty())
S.Sym.NumberOfAuxSymbols =
alignTo(S.AuxFile.size(), sizeof(SymbolTy)) / sizeof(SymbolTy);
S.RawIndex = RawSymIndex;
RawSymIndex += 1 + S.Sym.NumberOfAuxSymbols;
}
return std::make_pair(RawSymIndex * sizeof(SymbolTy), sizeof(SymbolTy));
}
Error COFFWriter::finalize(bool IsBigObj) {
size_t SymTabSize, SymbolSize;
std::tie(SymTabSize, SymbolSize) = IsBigObj
? finalizeSymbolTable<coff_symbol32>()
: finalizeSymbolTable<coff_symbol16>();
if (Error E = finalizeRelocTargets())
return E;
if (Error E = finalizeSymbolContents())
return E;
size_t SizeOfHeaders = 0;
FileAlignment = 1;
size_t PeHeaderSize = 0;
if (Obj.IsPE) {
Obj.DosHeader.AddressOfNewExeHeader =
sizeof(Obj.DosHeader) + Obj.DosStub.size();
SizeOfHeaders += Obj.DosHeader.AddressOfNewExeHeader + sizeof(PEMagic);
FileAlignment = Obj.PeHeader.FileAlignment;
Obj.PeHeader.NumberOfRvaAndSize = Obj.DataDirectories.size();
PeHeaderSize = Obj.Is64 ? sizeof(pe32plus_header) : sizeof(pe32_header);
SizeOfHeaders +=
PeHeaderSize + sizeof(data_directory) * Obj.DataDirectories.size();
}
Obj.CoffFileHeader.NumberOfSections = Obj.getSections().size();
SizeOfHeaders +=
IsBigObj ? sizeof(coff_bigobj_file_header) : sizeof(coff_file_header);
SizeOfHeaders += sizeof(coff_section) * Obj.getSections().size();
SizeOfHeaders = alignTo(SizeOfHeaders, FileAlignment);
Obj.CoffFileHeader.SizeOfOptionalHeader =
PeHeaderSize + sizeof(data_directory) * Obj.DataDirectories.size();
FileSize = SizeOfHeaders;
SizeOfInitializedData = 0;
layoutSections();
if (Obj.IsPE) {
Obj.PeHeader.SizeOfHeaders = SizeOfHeaders;
Obj.PeHeader.SizeOfInitializedData = SizeOfInitializedData;
if (!Obj.getSections().empty()) {
const Section &S = Obj.getSections().back();
Obj.PeHeader.SizeOfImage =
alignTo(S.Header.VirtualAddress + S.Header.VirtualSize,
Obj.PeHeader.SectionAlignment);
}
// If the PE header had a checksum, clear it, since it isn't valid
// any longer. (We don't calculate a new one.)
Obj.PeHeader.CheckSum = 0;
}
size_t StrTabSize = finalizeStringTable();
size_t PointerToSymbolTable = FileSize;
// StrTabSize <= 4 is the size of an empty string table, only consisting
// of the length field.
if (SymTabSize == 0 && StrTabSize <= 4 && Obj.IsPE) {
// For executables, don't point to the symbol table and skip writing
// the length field, if both the symbol and string tables are empty.
PointerToSymbolTable = 0;
StrTabSize = 0;
}
size_t NumRawSymbols = SymTabSize / SymbolSize;
Obj.CoffFileHeader.PointerToSymbolTable = PointerToSymbolTable;
Obj.CoffFileHeader.NumberOfSymbols = NumRawSymbols;
FileSize += SymTabSize + StrTabSize;
FileSize = alignTo(FileSize, FileAlignment);
return Error::success();
}
void COFFWriter::writeHeaders(bool IsBigObj) {
uint8_t *Ptr = Buf.getBufferStart();
if (Obj.IsPE) {
memcpy(Ptr, &Obj.DosHeader, sizeof(Obj.DosHeader));
Ptr += sizeof(Obj.DosHeader);
memcpy(Ptr, Obj.DosStub.data(), Obj.DosStub.size());
Ptr += Obj.DosStub.size();
memcpy(Ptr, PEMagic, sizeof(PEMagic));
Ptr += sizeof(PEMagic);
}
if (!IsBigObj) {
memcpy(Ptr, &Obj.CoffFileHeader, sizeof(Obj.CoffFileHeader));
Ptr += sizeof(Obj.CoffFileHeader);
} else {
// Generate a coff_bigobj_file_header, filling it in with the values
// from Obj.CoffFileHeader. All extra fields that don't exist in
// coff_file_header can be set to hardcoded values.
coff_bigobj_file_header BigObjHeader;
BigObjHeader.Sig1 = IMAGE_FILE_MACHINE_UNKNOWN;
BigObjHeader.Sig2 = 0xffff;
BigObjHeader.Version = BigObjHeader::MinBigObjectVersion;
BigObjHeader.Machine = Obj.CoffFileHeader.Machine;
BigObjHeader.TimeDateStamp = Obj.CoffFileHeader.TimeDateStamp;
memcpy(BigObjHeader.UUID, BigObjMagic, sizeof(BigObjMagic));
BigObjHeader.unused1 = 0;
BigObjHeader.unused2 = 0;
BigObjHeader.unused3 = 0;
BigObjHeader.unused4 = 0;
// The value in Obj.CoffFileHeader.NumberOfSections is truncated, thus
// get the original one instead.
BigObjHeader.NumberOfSections = Obj.getSections().size();
BigObjHeader.PointerToSymbolTable = Obj.CoffFileHeader.PointerToSymbolTable;
BigObjHeader.NumberOfSymbols = Obj.CoffFileHeader.NumberOfSymbols;
memcpy(Ptr, &BigObjHeader, sizeof(BigObjHeader));
Ptr += sizeof(BigObjHeader);
}
if (Obj.IsPE) {
if (Obj.Is64) {
memcpy(Ptr, &Obj.PeHeader, sizeof(Obj.PeHeader));
Ptr += sizeof(Obj.PeHeader);
} else {
pe32_header PeHeader;
copyPeHeader(PeHeader, Obj.PeHeader);
// The pe32plus_header (stored in Object) lacks the BaseOfData field.
PeHeader.BaseOfData = Obj.BaseOfData;
memcpy(Ptr, &PeHeader, sizeof(PeHeader));
Ptr += sizeof(PeHeader);
}
for (const auto &DD : Obj.DataDirectories) {
memcpy(Ptr, &DD, sizeof(DD));
Ptr += sizeof(DD);
}
}
for (const auto &S : Obj.getSections()) {
memcpy(Ptr, &S.Header, sizeof(S.Header));
Ptr += sizeof(S.Header);
}
}
void COFFWriter::writeSections() {
for (const auto &S : Obj.getSections()) {
uint8_t *Ptr = Buf.getBufferStart() + S.Header.PointerToRawData;
ArrayRef<uint8_t> Contents = S.getContents();
std::copy(Contents.begin(), Contents.end(), Ptr);
// For executable sections, pad the remainder of the raw data size with
// 0xcc, which is int3 on x86.
if ((S.Header.Characteristics & IMAGE_SCN_CNT_CODE) &&
S.Header.SizeOfRawData > Contents.size())
memset(Ptr + Contents.size(), 0xcc,
S.Header.SizeOfRawData - Contents.size());
Ptr += S.Header.SizeOfRawData;
for (const auto &R : S.Relocs) {
memcpy(Ptr, &R.Reloc, sizeof(R.Reloc));
Ptr += sizeof(R.Reloc);
}
}
}
template <class SymbolTy> void COFFWriter::writeSymbolStringTables() {
uint8_t *Ptr = Buf.getBufferStart() + Obj.CoffFileHeader.PointerToSymbolTable;
for (const auto &S : Obj.getSymbols()) {
// Convert symbols back to the right size, from coff_symbol32.
copySymbol<SymbolTy, coff_symbol32>(*reinterpret_cast<SymbolTy *>(Ptr),
S.Sym);
Ptr += sizeof(SymbolTy);
if (!S.AuxFile.empty()) {
// For file symbols, just write the string into the aux symbol slots,
// assuming that the unwritten parts are initialized to zero in the memory
// mapped file.
std::copy(S.AuxFile.begin(), S.AuxFile.end(), Ptr);
Ptr += S.Sym.NumberOfAuxSymbols * sizeof(SymbolTy);
} else {
// For other auxillary symbols, write their opaque payload into one symbol
// table slot each. For big object files, the symbols are larger than the
// opaque auxillary symbol struct and we leave padding at the end of each
// entry.
for (const AuxSymbol &AuxSym : S.AuxData) {
ArrayRef<uint8_t> Ref = AuxSym.getRef();
std::copy(Ref.begin(), Ref.end(), Ptr);
Ptr += sizeof(SymbolTy);
}
}
}
if (StrTabBuilder.getSize() > 4 || !Obj.IsPE) {
// Always write a string table in object files, even an empty one.
StrTabBuilder.write(Ptr);
Ptr += StrTabBuilder.getSize();
}
}
Error COFFWriter::write(bool IsBigObj) {
if (Error E = finalize(IsBigObj))
return E;
if (Error E = Buf.allocate(FileSize))
return E;
writeHeaders(IsBigObj);
writeSections();
if (IsBigObj)
writeSymbolStringTables<coff_symbol32>();
else
writeSymbolStringTables<coff_symbol16>();
if (Obj.IsPE)
if (Error E = patchDebugDirectory())
return E;
return Buf.commit();
}
// Locate which sections contain the debug directories, iterate over all
// the debug_directory structs in there, and set the PointerToRawData field
// in all of them, according to their new physical location in the file.
Error COFFWriter::patchDebugDirectory() {
if (Obj.DataDirectories.size() < DEBUG_DIRECTORY)
return Error::success();
const data_directory *Dir = &Obj.DataDirectories[DEBUG_DIRECTORY];
if (Dir->Size <= 0)
return Error::success();
for (const auto &S : Obj.getSections()) {
if (Dir->RelativeVirtualAddress >= S.Header.VirtualAddress &&
Dir->RelativeVirtualAddress <
S.Header.VirtualAddress + S.Header.SizeOfRawData) {
if (Dir->RelativeVirtualAddress + Dir->Size >
S.Header.VirtualAddress + S.Header.SizeOfRawData)
return createStringError(object_error::parse_failed,
"Debug directory extends past end of section");
size_t Offset = Dir->RelativeVirtualAddress - S.Header.VirtualAddress;
uint8_t *Ptr = Buf.getBufferStart() + S.Header.PointerToRawData + Offset;
uint8_t *End = Ptr + Dir->Size;
while (Ptr < End) {
debug_directory *Debug = reinterpret_cast<debug_directory *>(Ptr);
Debug->PointerToRawData =
S.Header.PointerToRawData + Offset + sizeof(debug_directory);
Ptr += sizeof(debug_directory) + Debug->SizeOfData;
Offset += sizeof(debug_directory) + Debug->SizeOfData;
}
// Debug directory found and patched, all done.
return Error::success();
}
}
return createStringError(object_error::parse_failed,
"Debug directory not found");
}
Error COFFWriter::write() {
bool IsBigObj = Obj.getSections().size() > MaxNumberOfSections16;
if (IsBigObj && Obj.IsPE)
return createStringError(object_error::parse_failed,
"Too many sections for executable");
return write(IsBigObj);
}
} // end namespace coff
} // end namespace objcopy
} // end namespace llvm
Reference in New Issue View Git Blame Copy Permalink