llvm-capstone/lld/MachO/ObjC.cpp
Jez Ng 001ba65375 [lld-macho] De-templatize mach_header operations
@thakis pointed out that `mach_header` and `mach_header_64`
actually have the same set of (used) fields, with the 64-bit version
having extra padding. So we can access the fields we need using the
single `mach_header` type instead of using templates to switch between
the two.

I also spotted a potential issue where hasObjCSection tries to parse a
file w/o checking if it does indeed match the target arch... As such,
I've added a quick magic number check to ensure we don't access invalid
memory during `findCommand()`.

Addresses PR50180.

Reviewed By: #lld-macho, thakis

Differential Revision: https://reviews.llvm.org/D101724
2021-05-03 18:31:23 -04:00

55 lines
1.7 KiB
C++

//===- ObjC.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 "ObjC.h"
#include "InputFiles.h"
#include "InputSection.h"
#include "OutputSegment.h"
#include "Target.h"
#include "llvm/BinaryFormat/MachO.h"
using namespace llvm;
using namespace llvm::MachO;
using namespace lld;
using namespace lld::macho;
template <class LP> static bool hasObjCSection(MemoryBufferRef mb) {
using Section = typename LP::section;
auto *hdr =
reinterpret_cast<const typename LP::mach_header *>(mb.getBufferStart());
if (hdr->magic != LP::magic)
return false;
if (const auto *c =
findCommand<typename LP::segment_command>(hdr, LP::segmentLCType)) {
auto sectionHeaders =
ArrayRef<Section>{reinterpret_cast<const Section *>(c + 1), c->nsects};
for (const Section &sec : sectionHeaders) {
StringRef sectname(sec.sectname,
strnlen(sec.sectname, sizeof(sec.sectname)));
StringRef segname(sec.segname, strnlen(sec.segname, sizeof(sec.segname)));
if ((segname == segment_names::data &&
sectname == section_names::objcCatList) ||
(segname == segment_names::text &&
sectname == section_names::swift)) {
return true;
}
}
}
return false;
}
bool macho::hasObjCSection(MemoryBufferRef mb) {
if (target->wordSize == 8)
return ::hasObjCSection<LP64>(mb);
else
return ::hasObjCSection<ILP32>(mb);
}