1 //===- lib/ReaderWriter/MachO/Atoms.h ---------------------------*- C++ -*-===//
2 //
3 //                             The LLVM Linker
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #ifndef LLD_READER_WRITER_MACHO_ATOMS_H
11 #define LLD_READER_WRITER_MACHO_ATOMS_H
12 
13 #include "lld/Core/Atom.h"
14 #include "lld/Core/DefinedAtom.h"
15 #include "lld/Core/SharedLibraryAtom.h"
16 #include "lld/Core/Simple.h"
17 #include "llvm/ADT/ArrayRef.h"
18 #include "llvm/ADT/StringRef.h"
19 #include <cstdint>
20 #include <string>
21 
22 namespace lld {
23 
24 class File;
25 
26 namespace mach_o {
27 
28 class MachODefinedAtom : public SimpleDefinedAtom {
29 public:
MachODefinedAtom(const File & f,const StringRef name,Scope scope,ContentType type,Merge merge,bool thumb,bool noDeadStrip,const ArrayRef<uint8_t> content,Alignment align)30   MachODefinedAtom(const File &f, const StringRef name, Scope scope,
31                    ContentType type, Merge merge, bool thumb, bool noDeadStrip,
32                    const ArrayRef<uint8_t> content, Alignment align)
33       : SimpleDefinedAtom(f), _name(name), _content(content),
34         _align(align), _contentType(type), _scope(scope), _merge(merge),
35         _thumb(thumb), _noDeadStrip(noDeadStrip) {}
36 
37   // Constructor for zero-fill content
MachODefinedAtom(const File & f,const StringRef name,Scope scope,ContentType type,uint64_t size,bool noDeadStrip,Alignment align)38   MachODefinedAtom(const File &f, const StringRef name, Scope scope,
39                    ContentType type, uint64_t size, bool noDeadStrip,
40                    Alignment align)
41       : SimpleDefinedAtom(f), _name(name),
42         _content(ArrayRef<uint8_t>(nullptr, size)), _align(align),
43         _contentType(type), _scope(scope), _merge(mergeNo), _thumb(false),
44         _noDeadStrip(noDeadStrip) {}
45 
46   ~MachODefinedAtom() override = default;
47 
size()48   uint64_t size() const override { return _content.size(); }
49 
contentType()50   ContentType contentType() const override { return _contentType; }
51 
alignment()52   Alignment alignment() const override { return _align; }
53 
name()54   StringRef name() const override { return _name; }
55 
scope()56   Scope scope() const override { return _scope; }
57 
merge()58   Merge merge() const override { return _merge; }
59 
deadStrip()60   DeadStripKind deadStrip() const override {
61     if (_contentType == DefinedAtom::typeInitializerPtr)
62       return deadStripNever;
63     if (_contentType == DefinedAtom::typeTerminatorPtr)
64       return deadStripNever;
65     if (_noDeadStrip)
66       return deadStripNever;
67     return deadStripNormal;
68   }
69 
rawContent()70   ArrayRef<uint8_t> rawContent() const override {
71     // Note: Zerofill atoms have a content pointer which is null.
72     return _content;
73   }
74 
isThumb()75   bool isThumb() const { return _thumb; }
76 
77 private:
78   const StringRef _name;
79   const ArrayRef<uint8_t> _content;
80   const DefinedAtom::Alignment _align;
81   const ContentType _contentType;
82   const Scope _scope;
83   const Merge _merge;
84   const bool _thumb;
85   const bool _noDeadStrip;
86 };
87 
88 class MachODefinedCustomSectionAtom : public MachODefinedAtom {
89 public:
MachODefinedCustomSectionAtom(const File & f,const StringRef name,Scope scope,ContentType type,Merge merge,bool thumb,bool noDeadStrip,const ArrayRef<uint8_t> content,StringRef sectionName,Alignment align)90   MachODefinedCustomSectionAtom(const File &f, const StringRef name,
91                                 Scope scope, ContentType type, Merge merge,
92                                 bool thumb, bool noDeadStrip,
93                                 const ArrayRef<uint8_t> content,
94                                 StringRef sectionName, Alignment align)
95       : MachODefinedAtom(f, name, scope, type, merge, thumb, noDeadStrip,
96                          content, align),
97         _sectionName(sectionName) {}
98 
99   ~MachODefinedCustomSectionAtom() override = default;
100 
sectionChoice()101   SectionChoice sectionChoice() const override {
102     return DefinedAtom::sectionCustomRequired;
103   }
104 
customSectionName()105   StringRef customSectionName() const override {
106     return _sectionName;
107   }
108 private:
109   StringRef _sectionName;
110 };
111 
112 class MachOTentativeDefAtom : public SimpleDefinedAtom {
113 public:
MachOTentativeDefAtom(const File & f,const StringRef name,Scope scope,uint64_t size,DefinedAtom::Alignment align)114   MachOTentativeDefAtom(const File &f, const StringRef name, Scope scope,
115                         uint64_t size, DefinedAtom::Alignment align)
116       : SimpleDefinedAtom(f), _name(name), _scope(scope), _size(size),
117         _align(align) {}
118 
119   ~MachOTentativeDefAtom() override = default;
120 
size()121   uint64_t size() const override { return _size; }
122 
merge()123   Merge merge() const override { return DefinedAtom::mergeAsTentative; }
124 
contentType()125   ContentType contentType() const override { return DefinedAtom::typeZeroFill; }
126 
alignment()127   Alignment alignment() const override { return _align; }
128 
name()129   StringRef name() const override { return _name; }
130 
scope()131   Scope scope() const override { return _scope; }
132 
rawContent()133   ArrayRef<uint8_t> rawContent() const override { return ArrayRef<uint8_t>(); }
134 
135 private:
136   const std::string _name;
137   const Scope _scope;
138   const uint64_t _size;
139   const DefinedAtom::Alignment _align;
140 };
141 
142 class MachOSharedLibraryAtom : public SharedLibraryAtom {
143 public:
MachOSharedLibraryAtom(const File & file,StringRef name,StringRef dylibInstallName,bool weakDef)144   MachOSharedLibraryAtom(const File &file, StringRef name,
145                          StringRef dylibInstallName, bool weakDef)
146       : SharedLibraryAtom(), _file(file), _name(name),
147         _dylibInstallName(dylibInstallName) {}
148   ~MachOSharedLibraryAtom() override = default;
149 
loadName()150   StringRef loadName() const override { return _dylibInstallName; }
151 
canBeNullAtRuntime()152   bool canBeNullAtRuntime() const override {
153     // FIXME: this may actually be changeable. For now, all symbols are strongly
154     // defined though.
155     return false;
156   }
157 
file()158   const File &file() const override { return _file; }
159 
name()160   StringRef name() const override { return _name; }
161 
type()162   Type type() const override {
163     // Unused in MachO (I think).
164     return Type::Unknown;
165   }
166 
size()167   uint64_t size() const override {
168     // Unused in MachO (I think)
169     return 0;
170   }
171 
172 private:
173   const File &_file;
174   StringRef _name;
175   StringRef _dylibInstallName;
176 };
177 
178 } // end namespace mach_o
179 } // end namespace lld
180 
181 #endif // LLD_READER_WRITER_MACHO_ATOMS_H
182