1 //===- lld/Core/Reader.h - Abstract File Format Reading Interface ---------===//
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
7 //===----------------------------------------------------------------------===//
9 #ifndef LLD_CORE_READER_H
10 #define LLD_CORE_READER_H
12 #include "lld/Common/LLVM.h"
13 #include "lld/Core/Reference.h"
14 #include "llvm/ADT/StringRef.h"
15 #include "llvm/BinaryFormat/Magic.h"
16 #include "llvm/Support/ErrorOr.h"
17 #include "llvm/Support/FileSystem.h"
18 #include "llvm/Support/MemoryBuffer.h"
25 } // end namespace yaml
26 } // end namespace llvm
32 class MachOLinkingContext;
34 /// An abstract class for reading object files, library files, and
37 /// Each file format (e.g. mach-o, etc) has a concrete subclass of Reader.
40 virtual ~Reader() = default;
42 /// Sniffs the file to determine if this Reader can parse it.
43 /// The method is called with:
44 /// 1) the file_magic enumeration returned by identify_magic()
45 /// 2) the whole file content buffer if the above is not enough.
46 virtual bool canParse(llvm::file_magic magic, MemoryBufferRef mb) const = 0;
48 /// Parse a supplied buffer (already filled with the contents of a
49 /// file) and create a File object.
50 /// The resulting File object takes ownership of the MemoryBuffer.
51 virtual ErrorOr<std::unique_ptr<File>>
52 loadFile(std::unique_ptr<MemoryBuffer> mb, const class Registry &) const = 0;
55 /// An abstract class for handling alternate yaml representations
58 /// The YAML syntax allows "tags" which are used to specify the type of
59 /// the YAML node. In lld, top level YAML documents can be in many YAML
60 /// representations (e.g mach-o encoded as yaml, etc). A tag is used to
61 /// specify which representation is used in the following YAML document.
62 /// To work, there must be a YamlIOTaggedDocumentHandler registered that
63 /// handles each tag type.
64 class YamlIOTaggedDocumentHandler {
66 virtual ~YamlIOTaggedDocumentHandler();
68 /// This method is called on each registered YamlIOTaggedDocumentHandler
69 /// until one returns true. If the subclass handles tag type !xyz, then
70 /// this method should call io.mapTag("!xzy") to see if that is the current
71 /// document type, and if so, process the rest of the document using
72 /// YAML I/O, then convert the result into an lld::File* and return it.
73 virtual bool handledDocTag(llvm::yaml::IO &io, const lld::File *&f) const = 0;
76 /// A registry to hold the list of currently registered Readers and
77 /// tables which map Reference kind values to strings.
78 /// The linker does not directly invoke Readers. Instead, it registers
79 /// Readers based on it configuration and command line options, then calls
80 /// the Registry object to parse files.
85 /// Walk the list of registered Readers and find one that can parse the
86 /// supplied file and parse it.
87 ErrorOr<std::unique_ptr<File>>
88 loadFile(std::unique_ptr<MemoryBuffer> mb) const;
90 /// Walk the list of registered kind tables to convert a Reference Kind
92 bool referenceKindFromString(StringRef inputStr, Reference::KindNamespace &ns,
93 Reference::KindArch &a,
94 Reference::KindValue &value) const;
96 /// Walk the list of registered kind tables to convert a Reference Kind
97 /// value to a string.
98 bool referenceKindToString(Reference::KindNamespace ns, Reference::KindArch a,
99 Reference::KindValue value, StringRef &) const;
101 /// Walk the list of registered tag handlers and have the one that handles
102 /// the current document type process the yaml into an lld::File*.
103 bool handleTaggedDoc(llvm::yaml::IO &io, const lld::File *&file) const;
105 // These methods are called to dynamically add support for various file
106 // formats. The methods are also implemented in the appropriate lib*.a
107 // library, so that the code for handling a format is only linked in, if this
108 // method is used. Any options that a Reader might need must be passed
109 // as parameters to the addSupport*() method.
110 void addSupportArchives(bool logLoading);
111 void addSupportYamlFiles();
112 void addSupportMachOObjects(MachOLinkingContext &);
114 /// To convert between kind values and names, the registry walks the list
115 /// of registered kind tables. Each table is a zero terminated array of
116 /// KindStrings elements.
118 Reference::KindValue value;
122 /// A Reference Kind value is a tuple of <namespace, arch, value>. All
123 /// entries in a conversion table have the same <namespace, arch>. The
124 /// array then contains the value/name pairs.
125 void addKindTable(Reference::KindNamespace ns, Reference::KindArch arch,
126 const KindStrings array[]);
130 Reference::KindNamespace ns;
131 Reference::KindArch arch;
132 const KindStrings *array;
135 void add(std::unique_ptr<Reader>);
136 void add(std::unique_ptr<YamlIOTaggedDocumentHandler>);
138 std::vector<std::unique_ptr<Reader>> _readers;
139 std::vector<std::unique_ptr<YamlIOTaggedDocumentHandler>> _yamlHandlers;
140 std::vector<KindEntry> _kindEntries;
143 // Utilities for building a KindString table. For instance:
144 // static const Registry::KindStrings table[] = {
145 // LLD_KIND_STRING_ENTRY(R_VAX_ADDR16),
146 // LLD_KIND_STRING_ENTRY(R_VAX_DATA16),
147 // LLD_KIND_STRING_END
149 #define LLD_KIND_STRING_ENTRY(name) { name, #name }
150 #define LLD_KIND_STRING_END { 0, "" }
152 } // end namespace lld
154 #endif // LLD_CORE_READER_H