llvm-6502/tools/dsymutil/BinaryHolder.h
Frederic Riss 5a0743e1e8 [dsymutil] Implement the BinaryHolder object and gain archive support.
This object is meant to own the ObjectFiles and their underlying
MemoryBuffer. It is basically the equivalent of an OwningBinary
except that it efficiently handles Archives. It is optimized for
efficiently providing mappings of members of the same archive when
they are opened successively (which is standard in Darwin debug
maps, objects from the same archive will be contiguous).

Of course, the BinaryHolder will also be used by the DWARF linker
once it is commited, but for now only the debug map parser uses it.

With this change, you can run llvm-dsymutil on your Darwin debug build
of clang and get a complete debug map for it.

Differential Revision: http://reviews.llvm.org/D6690

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225207 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-05 21:29:28 +00:00

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//===-- BinaryHolder.h - Utility class for accessing binaries -------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This program is a utility that aims to be a dropin replacement for
// Darwin's dsymutil.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_TOOLS_DSYMUTIL_BINARYHOLDER_H
#define LLVM_TOOLS_DSYMUTIL_BINARYHOLDER_H
#include "llvm/Object/Archive.h"
#include "llvm/Object/Error.h"
#include "llvm/Object/ObjectFile.h"
#include "llvm/Support/Errc.h"
#include "llvm/Support/ErrorOr.h"
namespace llvm {
namespace dsymutil {
/// \brief The BinaryHolder class is responsible for creating and
/// owning ObjectFile objects and their underlying MemoryBuffer. This
/// is different from a simple OwningBinary in that it handles
/// accessing to archive members.
///
/// As an optimization, this class will reuse an already mapped and
/// parsed Archive object if 2 successive requests target the same
/// archive file (Which is always the case in debug maps).
/// Currently it only owns one memory buffer at any given time,
/// meaning that a mapping request will invalidate the previous memory
/// mapping.
class BinaryHolder {
std::unique_ptr<object::Archive> CurrentArchive;
std::unique_ptr<MemoryBuffer> CurrentMemoryBuffer;
std::unique_ptr<object::ObjectFile> CurrentObjectFile;
bool Verbose;
/// \brief Get the MemoryBufferRef for the file specification in \p
/// Filename from the current archive.
///
/// This function performs no system calls, it just looks up a
/// potential match for the given \p Filename in the currently
/// mapped archive if there is one.
ErrorOr<MemoryBufferRef> GetArchiveMemberBuffer(StringRef Filename);
/// \brief Interpret Filename as an archive member specification,
/// map the corresponding archive to memory and return the
/// MemoryBufferRef corresponding to the described member.
ErrorOr<MemoryBufferRef> MapArchiveAndGetMemberBuffer(StringRef Filename);
/// \brief Return the MemoryBufferRef that holds the memory
/// mapping for the given \p Filename. This function will try to
/// parse archive member specifications of the form
/// /path/to/archive.a(member.o).
///
/// The returned MemoryBufferRef points to a buffer owned by this
/// object. The buffer is valid until the next call to
/// GetMemoryBufferForFile() on this object.
ErrorOr<MemoryBufferRef> GetMemoryBufferForFile(StringRef Filename);
public:
BinaryHolder(bool Verbose) : Verbose(Verbose) {}
/// \brief Get the ObjectFile designated by the \p Filename. This
/// might be an archive member specification of the form
/// /path/to/archive.a(member.o).
///
/// Calling this function invalidates the previous mapping owned by
/// the BinaryHolder.
ErrorOr<const object::ObjectFile &> GetObjectFile(StringRef Filename);
/// \brief Wraps GetObjectFile() to return a derived ObjectFile type.
template <typename ObjectFileType>
ErrorOr<const ObjectFileType &> GetFileAs(StringRef Filename) {
auto ErrOrObjFile = GetObjectFile(Filename);
if (auto Err = ErrOrObjFile.getError())
return Err;
if (const auto *Derived = dyn_cast<ObjectFileType>(CurrentObjectFile.get()))
return *Derived;
return make_error_code(object::object_error::invalid_file_type);
}
/// \brief Access the currently owned ObjectFile. As successfull
/// call to GetObjectFile() or GetFileAs() must have been performed
/// before calling this.
const object::ObjectFile &Get() {
assert(CurrentObjectFile);
return *CurrentObjectFile;
}
/// \brief Access to a derived version of the currently owned
/// ObjectFile. The conversion must be known to be valid.
template <typename ObjectFileType> const ObjectFileType &GetAs() {
return cast<ObjectFileType>(*CurrentObjectFile);
}
};
}
}
#endif