ELFObjHandler.cpp | Explore in Territory

//===- ELFObjHandler.cpp --------------------------------------------------===//
//
// 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
//
//===-----------------------------------------------------------------------===/

#include "llvm/InterfaceStub/ELFObjHandler.h"
#include "llvm/InterfaceStub/IFSStub.h"
#include "llvm/MC/StringTableBuilder.h"
#include "llvm/Object/Binary.h"
#include "llvm/Object/ELFObjectFile.h"
#include "llvm/Object/ELFTypes.h"
#include "llvm/Support/Errc.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/FileOutputBuffer.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/MemoryBuffer.h"
#include <optional>

ELFObjectFile;

usingnamespacellvm;
usingnamespacellvm::object;
usingnamespacellvm::ELF;

namespace llvm {
namespace ifs {

// Simple struct to hold relevant .dynamic entries.
struct DynamicEntries { … };

/// This initializes an ELF file header with information specific to a binary
/// dynamic shared object.
/// Offsets, indexes, links, etc. for section and program headers are just
/// zero-initialized as they will be updated elsewhere.
///
/// @param ElfHeader Target ELFT::Ehdr to populate.
/// @param Machine Target architecture (e_machine from ELF specifications).
template <class ELFT>
static void initELFHeader(typename ELFT::Ehdr &ElfHeader, uint16_t Machine) { … }

namespace {
template <class ELFT> struct OutputSection { … };

template <class T, class ELFT>
struct ContentSection : public OutputSection<ELFT> { … };

// This class just wraps StringTableBuilder for the purpose of adding a
// default constructor.
class ELFStringTableBuilder : public StringTableBuilder { … };

template <class ELFT> class ELFSymbolTableBuilder { … };

template <class ELFT> class ELFDynamicTableBuilder { … };

template <class ELFT> class ELFStubBuilder { … };

/// This function takes an error, and appends a string of text to the end of
/// that error. Since "appending" to an Error isn't supported behavior of an
/// Error, this function technically creates a new error with the combined
/// message and consumes the old error.
///
/// @param Err Source error.
/// @param After Text to append at the end of Err's error message.
Error appendToError(Error Err, StringRef After) { … }

template <class ELFT> class DynSym { … };
} // end anonymous namespace

/// This function behaves similarly to StringRef::substr(), but attempts to
/// terminate the returned StringRef at the first null terminator. If no null
/// terminator is found, an error is returned.
///
/// @param Str Source string to create a substring from.
/// @param Offset The start index of the desired substring.
static Expected<StringRef> terminatedSubstr(StringRef Str, size_t Offset) { … }

/// This function populates a DynamicEntries struct using an ELFT::DynRange.
/// After populating the struct, the members are validated with
/// some basic correctness checks.
///
/// @param Dyn Target DynamicEntries struct to populate.
/// @param DynTable Source dynamic table.
template <class ELFT>
static Error populateDynamic(DynamicEntries &Dyn,
                             typename ELFT::DynRange DynTable) { … }

/// This function creates an IFSSymbol and populates all members using
/// information from a binary ELFT::Sym.
///
/// @param SymName The desired name of the IFSSymbol.
/// @param RawSym ELFT::Sym to extract symbol information from.
template <class ELFT>
static IFSSymbol createELFSym(StringRef SymName,
                              const typename ELFT::Sym &RawSym) { … }

/// This function populates an IFSStub with symbols using information read
/// from an ELF binary.
///
/// @param TargetStub IFSStub to add symbols to.
/// @param DynSym Range of dynamic symbols to add to TargetStub.
/// @param DynStr StringRef to the dynamic string table.
template <class ELFT>
static Error populateSymbols(IFSStub &TargetStub,
                             const typename ELFT::SymRange DynSym,
                             StringRef DynStr) { … }

/// Returns a new IFSStub with all members populated from an ELFObjectFile.
/// @param ElfObj Source ELFObjectFile.
template <class ELFT>
static Expected<std::unique_ptr<IFSStub>>
buildStub(const ELFObjectFile<ELFT> &ElfObj) { … }

/// This function opens a file for writing and then writes a binary ELF stub to
/// the file.
///
/// @param FilePath File path for writing the ELF binary.
/// @param Stub Source InterFace Stub to generate a binary ELF stub from.
template <class ELFT>
static Error writeELFBinaryToFile(StringRef FilePath, const IFSStub &Stub,
                                  bool WriteIfChanged) { … }

Expected<std::unique_ptr<IFSStub>> readELFFile(MemoryBufferRef Buf) { … }

// This function wraps the ELFT writeELFBinaryToFile() so writeBinaryStub()
// can be called without having to use ELFType templates directly.
Error writeBinaryStub(StringRef FilePath, const IFSStub &Stub,
                      bool WriteIfChanged) { … }

} // end namespace ifs
} // end namespace llvm
llvm/llvm/lib/InterfaceStub/ELFObjHandler.cpp
