ObjectFile.cpp revision 353358 
1//===- ObjectFile.cpp - File format independent object file ---------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file defines a file format independent ObjectFile class.
10//
11//===----------------------------------------------------------------------===//
12
13#include "llvm/Object/ObjectFile.h"
14#include "llvm/ADT/StringRef.h"
15#include "llvm/BinaryFormat/Magic.h"
16#include "llvm/Object/Binary.h"
17#include "llvm/Object/COFF.h"
18#include "llvm/Object/Error.h"
19#include "llvm/Object/MachO.h"
20#include "llvm/Object/Wasm.h"
21#include "llvm/Support/Error.h"
22#include "llvm/Support/ErrorHandling.h"
23#include "llvm/Support/ErrorOr.h"
24#include "llvm/Support/FileSystem.h"
25#include "llvm/Support/MemoryBuffer.h"
26#include "llvm/Support/raw_ostream.h"
27#include <algorithm>
28#include <cstdint>
29#include <memory>
30#include <system_error>
31
32using namespace llvm;
33using namespace object;
34
35void ObjectFile::anchor() {}
36
37ObjectFile::ObjectFile(unsigned int Type, MemoryBufferRef Source)
38    : SymbolicFile(Type, Source) {}
39
40bool SectionRef::containsSymbol(SymbolRef S) const {
41  Expected<section_iterator> SymSec = S.getSection();
42  if (!SymSec) {
43    // TODO: Actually report errors helpfully.
44    consumeError(SymSec.takeError());
45    return false;
46  }
47  return *this == **SymSec;
48}
49
50uint64_t ObjectFile::getSymbolValue(DataRefImpl Ref) const {
51  uint32_t Flags = getSymbolFlags(Ref);
52  if (Flags & SymbolRef::SF_Undefined)
53    return 0;
54  if (Flags & SymbolRef::SF_Common)
55    return getCommonSymbolSize(Ref);
56  return getSymbolValueImpl(Ref);
57}
58
59Error ObjectFile::printSymbolName(raw_ostream &OS, DataRefImpl Symb) const {
60  Expected<StringRef> Name = getSymbolName(Symb);
61  if (!Name)
62    return Name.takeError();
63  OS << *Name;
64  return Error::success();
65}
66
67uint32_t ObjectFile::getSymbolAlignment(DataRefImpl DRI) const { return 0; }
68
69bool ObjectFile::isSectionBitcode(DataRefImpl Sec) const {
70  if (Expected<StringRef> NameOrErr = getSectionName(Sec))
71    return *NameOrErr == ".llvmbc";
72  return false;
73}
74
75bool ObjectFile::isSectionStripped(DataRefImpl Sec) const { return false; }
76
77bool ObjectFile::isBerkeleyText(DataRefImpl Sec) const {
78  return isSectionText(Sec);
79}
80
81bool ObjectFile::isBerkeleyData(DataRefImpl Sec) const {
82  return isSectionData(Sec);
83}
84
85section_iterator ObjectFile::getRelocatedSection(DataRefImpl Sec) const {
86  return section_iterator(SectionRef(Sec, this));
87}
88
89Triple ObjectFile::makeTriple() const {
90  Triple TheTriple;
91  auto Arch = getArch();
92  TheTriple.setArch(Triple::ArchType(Arch));
93
94  // For ARM targets, try to use the build attributes to build determine
95  // the build target. Target features are also added, but later during
96  // disassembly.
97  if (Arch == Triple::arm || Arch == Triple::armeb)
98    setARMSubArch(TheTriple);
99
100  // TheTriple defaults to ELF, and COFF doesn't have an environment:
101  // the best we can do here is indicate that it is mach-o.
102  if (isMachO())
103    TheTriple.setObjectFormat(Triple::MachO);
104
105  if (isCOFF()) {
106    const auto COFFObj = dyn_cast<COFFObjectFile>(this);
107    if (COFFObj->getArch() == Triple::thumb)
108      TheTriple.setTriple("thumbv7-windows");
109  }
110
111  return TheTriple;
112}
113
114Expected<std::unique_ptr<ObjectFile>>
115ObjectFile::createObjectFile(MemoryBufferRef Object, file_magic Type) {
116  StringRef Data = Object.getBuffer();
117  if (Type == file_magic::unknown)
118    Type = identify_magic(Data);
119
120  switch (Type) {
121  case file_magic::unknown:
122  case file_magic::bitcode:
123  case file_magic::coff_cl_gl_object:
124  case file_magic::archive:
125  case file_magic::macho_universal_binary:
126  case file_magic::windows_resource:
127  case file_magic::pdb:
128  case file_magic::minidump:
129    return errorCodeToError(object_error::invalid_file_type);
130  case file_magic::elf:
131  case file_magic::elf_relocatable:
132  case file_magic::elf_executable:
133  case file_magic::elf_shared_object:
134  case file_magic::elf_core:
135    return createELFObjectFile(Object);
136  case file_magic::macho_object:
137  case file_magic::macho_executable:
138  case file_magic::macho_fixed_virtual_memory_shared_lib:
139  case file_magic::macho_core:
140  case file_magic::macho_preload_executable:
141  case file_magic::macho_dynamically_linked_shared_lib:
142  case file_magic::macho_dynamic_linker:
143  case file_magic::macho_bundle:
144  case file_magic::macho_dynamically_linked_shared_lib_stub:
145  case file_magic::macho_dsym_companion:
146  case file_magic::macho_kext_bundle:
147    return createMachOObjectFile(Object);
148  case file_magic::coff_object:
149  case file_magic::coff_import_library:
150  case file_magic::pecoff_executable:
151    return createCOFFObjectFile(Object);
152  case file_magic::xcoff_object_32:
153    return createXCOFFObjectFile(Object, Binary::ID_XCOFF32);
154  case file_magic::xcoff_object_64:
155    return createXCOFFObjectFile(Object, Binary::ID_XCOFF64);
156  case file_magic::wasm_object:
157    return createWasmObjectFile(Object);
158  }
159  llvm_unreachable("Unexpected Object File Type");
160}
161
162Expected<OwningBinary<ObjectFile>>
163ObjectFile::createObjectFile(StringRef ObjectPath) {
164  ErrorOr<std::unique_ptr<MemoryBuffer>> FileOrErr =
165      MemoryBuffer::getFile(ObjectPath);
166  if (std::error_code EC = FileOrErr.getError())
167    return errorCodeToError(EC);
168  std::unique_ptr<MemoryBuffer> Buffer = std::move(FileOrErr.get());
169
170  Expected<std::unique_ptr<ObjectFile>> ObjOrErr =
171      createObjectFile(Buffer->getMemBufferRef());
172  if (Error Err = ObjOrErr.takeError())
173    return std::move(Err);
174  std::unique_ptr<ObjectFile> Obj = std::move(ObjOrErr.get());
175
176  return OwningBinary<ObjectFile>(std::move(Obj), std::move(Buffer));
177}
178