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| //===- lld/Core/Reader.h - Abstract File Format Reading Interface ---------===//
//
// 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
//
//===----------------------------------------------------------------------===//
#ifndef LLD_CORE_READER_H
#define LLD_CORE_READER_H
#include "lld/Common/LLVM.h"
#include "lld/Core/Reference.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/BinaryFormat/Magic.h"
#include "llvm/Support/ErrorOr.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/MemoryBuffer.h"
#include <memory>
#include <vector>
namespace llvm {
namespace yaml {
class IO;
} // end namespace yaml
} // end namespace llvm
namespace lld {
class File;
class LinkingContext;
class MachOLinkingContext;
/// An abstract class for reading object files, library files, and
/// executable files.
///
/// Each file format (e.g. mach-o, etc) has a concrete subclass of Reader.
class Reader {
public:
virtual ~Reader() = default;
/// Sniffs the file to determine if this Reader can parse it.
/// The method is called with:
/// 1) the file_magic enumeration returned by identify_magic()
/// 2) the whole file content buffer if the above is not enough.
virtual bool canParse(llvm::file_magic magic, MemoryBufferRef mb) const = 0;
/// Parse a supplied buffer (already filled with the contents of a
/// file) and create a File object.
/// The resulting File object takes ownership of the MemoryBuffer.
virtual ErrorOr<std::unique_ptr<File>>
loadFile(std::unique_ptr<MemoryBuffer> mb, const class Registry &) const = 0;
};
/// An abstract class for handling alternate yaml representations
/// of object files.
///
/// The YAML syntax allows "tags" which are used to specify the type of
/// the YAML node. In lld, top level YAML documents can be in many YAML
/// representations (e.g mach-o encoded as yaml, etc). A tag is used to
/// specify which representation is used in the following YAML document.
/// To work, there must be a YamlIOTaggedDocumentHandler registered that
/// handles each tag type.
class YamlIOTaggedDocumentHandler {
public:
virtual ~YamlIOTaggedDocumentHandler();
/// This method is called on each registered YamlIOTaggedDocumentHandler
/// until one returns true. If the subclass handles tag type !xyz, then
/// this method should call io.mapTag("!xzy") to see if that is the current
/// document type, and if so, process the rest of the document using
/// YAML I/O, then convert the result into an lld::File* and return it.
virtual bool handledDocTag(llvm::yaml::IO &io, const lld::File *&f) const = 0;
};
/// A registry to hold the list of currently registered Readers and
/// tables which map Reference kind values to strings.
/// The linker does not directly invoke Readers. Instead, it registers
/// Readers based on it configuration and command line options, then calls
/// the Registry object to parse files.
class Registry {
public:
Registry();
/// Walk the list of registered Readers and find one that can parse the
/// supplied file and parse it.
ErrorOr<std::unique_ptr<File>>
loadFile(std::unique_ptr<MemoryBuffer> mb) const;
/// Walk the list of registered kind tables to convert a Reference Kind
/// name to a value.
bool referenceKindFromString(StringRef inputStr, Reference::KindNamespace &ns,
Reference::KindArch &a,
Reference::KindValue &value) const;
/// Walk the list of registered kind tables to convert a Reference Kind
/// value to a string.
bool referenceKindToString(Reference::KindNamespace ns, Reference::KindArch a,
Reference::KindValue value, StringRef &) const;
/// Walk the list of registered tag handlers and have the one that handles
/// the current document type process the yaml into an lld::File*.
bool handleTaggedDoc(llvm::yaml::IO &io, const lld::File *&file) const;
// These methods are called to dynamically add support for various file
// formats. The methods are also implemented in the appropriate lib*.a
// library, so that the code for handling a format is only linked in, if this
// method is used. Any options that a Reader might need must be passed
// as parameters to the addSupport*() method.
void addSupportArchives(bool logLoading);
void addSupportYamlFiles();
void addSupportMachOObjects(MachOLinkingContext &);
/// To convert between kind values and names, the registry walks the list
/// of registered kind tables. Each table is a zero terminated array of
/// KindStrings elements.
struct KindStrings {
Reference::KindValue value;
StringRef name;
};
/// A Reference Kind value is a tuple of <namespace, arch, value>. All
/// entries in a conversion table have the same <namespace, arch>. The
/// array then contains the value/name pairs.
void addKindTable(Reference::KindNamespace ns, Reference::KindArch arch,
const KindStrings array[]);
private:
struct KindEntry {
Reference::KindNamespace ns;
Reference::KindArch arch;
const KindStrings *array;
};
void add(std::unique_ptr<Reader>);
void add(std::unique_ptr<YamlIOTaggedDocumentHandler>);
std::vector<std::unique_ptr<Reader>> _readers;
std::vector<std::unique_ptr<YamlIOTaggedDocumentHandler>> _yamlHandlers;
std::vector<KindEntry> _kindEntries;
};
// Utilities for building a KindString table. For instance:
// static const Registry::KindStrings table[] = {
// LLD_KIND_STRING_ENTRY(R_VAX_ADDR16),
// LLD_KIND_STRING_ENTRY(R_VAX_DATA16),
// LLD_KIND_STRING_END
// };
#define LLD_KIND_STRING_ENTRY(name) { name, #name }
#define LLD_KIND_STRING_END { 0, "" }
} // end namespace lld
#endif // LLD_CORE_READER_H
|