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