// balst_objectfileformat.h -*-C++-*-
// ----------------------------------------------------------------------------
// NOTICE
//
// This component is not up to date with current BDE coding standards, and
// should not be used as an example for new development.
// ----------------------------------------------------------------------------
#ifndef INCLUDED_BALST_OBJECTFILEFORMAT
#define INCLUDED_BALST_OBJECTFILEFORMAT
#include <bsls_ident.h>
BSLS_IDENT("$Id: $")
//@PURPOSE: Provide platform-dependent object file format trait definitions.
//
//@CLASSES:
// balst::ObjectFileFormat: namespace for object file format traits
//
//@SEE_ALSO:
//
//@DESCRIPTION: This component defines a set of traits that identify and
// describe a platform's object file format properties. For example, the
// 'balst::ObjectFileFormat::ResolverPolicy' trait is ascribed a "value" (i.e.,
// 'Elf' or 'Xcoff') appropriate for each supported platform. The various
// stack trace traits are actually types declared in the
// 'bdescu_ObjectFileFormat' 'struct'. These types are intended to be used in
// specializing template implementations or to enable function overloading
// based on the prevalent system's characteristics. #defines are also
// provided by this component to facilitate conditional compilation depending
// upon object file formats.
//
///DWARF Information
///-----------------
// DWARF is a format for detailed debugging information. It is not a complete
// format, but is used within other formats. It is used within ELF on Linux,
// but not (yet) on Solaris at Bloomberg (currently the ELF format on Solaris
// still uses STABS). It is used within the Mach-O format (also known as the
// 'Dladdr' format in this file) used on Darwin. It is also used by the Clang
// compiler (which uses ELF).
//
// For all these platforms, parsing the DWARF information is necessary for the
// stack trace to get source file names and line numbers (the ELF format gives
// source file names, but only in the case of file-scope static functions).
//
// DWARF is implemented for g++ versions earlier than 7.1.0 on Linux.
//
///Implementation Note
///- - - - - - - - - -
// Linux g++ 7.1.0 uses DWARF version 4, while g++ 5.4.0 and before use DWARF
// version 3. At the moment the required system header, 'dwarf.h', is not
// available in the Bloomberg production build 'chroot' environment, so
// support for dwarf formats is disabled.
//
// DWARF support on Clang is problematic and not currrently implemented, see
// the long comment in balst_stacktraceresolverimpl_elf.cpp, which explains
// exactly how it could be implemented when that becomes a priority.
//
// We have not yet investigated implementing DWARF for Dladdr (Darwin).
//
///Usage
///-----
// In this section we show the intended usage of this component.
//
///Example 1: Accessing 'balst::ObjectFileFormat' Information at Run Time
/// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
// The templated (specialized) 'typeTest' function returns a unique, non-zero
// value when passed an object of types
// 'balst::ObjectFileFormat::{Elf,Xcoff,Windows}', and 0 otherwise.
//..
// template <typename TYPE>
// int typeTest(const TYPE &)
// {
// return 0;
// }
//
// int typeTest(const balst::ObjectFileFormat::Elf &)
// {
// return 1;
// }
//
// int typeTest(const balst::ObjectFileFormat::Xcoff &)
// {
// return 2;
// }
//
// int typeTest(const balst::ObjectFileFormat::Windows &)
// {
// return 3;
// }
//
// int main() ...
//..
// We define an object 'policy' of type 'balst::ObjectFileFormat::Policy',
// which will be of type '...::Elf', '...::Xcoff', or '...::Windows'
// appropriate for the platform.
//..
// balst::ObjectFileFormat::Policy policy;
//..
// We now test it using 'typeTest':
//..
// assert(typeTest(policy) > 0);
//
// #if defined(BALST_OBJECTFILEFORMAT_RESOLVER_ELF)
// assert(1 == typeTest(policy));
// #endif
//
// #if defined(BALST_OBJECTFILEFORMAT_RESOLVER_XCOFF)
// assert(2 == typeTest(policy));
// #endif
//
// #if defined(BALST_OBJECTFILEFORMAT_RESOLVER_WINDOWS)
// assert(3 == typeTest(policy));
// #endif
// }
//..
#include <balscm_version.h>
#include <bsls_platform.h>
namespace BloombergLP {
namespace balst {
// ======================
// class ObjectFileFormat
// ======================
struct ObjectFileFormat {
// This 'struct' is named 'ObjectFileFormat' for historical reasons, what
// it really determines is resolving strategy. Linux, for example, can be
// resolved using either the 'Elf' or 'Dladdr' policies. We choose 'Elf'
// for linux because that mode of resolving yields more information.
struct Elf {}; // resolve as elf object
struct Xcoff {}; // resolve as xcoff object
struct Windows {}; // format used on Microsoft Windows platform
struct Dladdr {}; // resolve using the 'dladdr' call
struct Dummy {};
#if defined(BSLS_PLATFORM_OS_SOLARIS) || \
defined(BSLS_PLATFORM_OS_LINUX)
typedef Elf Policy;
# define BALST_OBJECTFILEFORMAT_RESOLVER_ELF 1
# if defined(BSLS_PLATFORM_OS_LINUX) && defined(BSLS_PLATFORM_CMP_GNU)
# define BALST_OBJECTFILEFORMAT_RESOLVER_DWARF 1
# endif
#elif defined(BSLS_PLATFORM_OS_AIX)
typedef Xcoff Policy;
# define BALST_OBJECTFILEFORMAT_RESOLVER_XCOFF 1
#elif defined(BSLS_PLATFORM_OS_WINDOWS)
typedef Windows Policy;
# define BALST_OBJECTFILEFORMAT_RESOLVER_WINDOWS 1
#elif defined(BSLS_PLATFORM_OS_DARWIN)
typedef Dladdr Policy;
# define BALST_OBJECTFILEFORMAT_RESOLVER_DLADDR 1
#else
typedef Dummy Policy;
# error unrecognized platform
# define BALST_OBJECTFILEFORMAT_RESOLVER_UNIMPLEMENTED 1
#endif
};
} // close package namespace
} // close enterprise namespace
#endif
// ----------------------------------------------------------------------------
// Copyright 2015 Bloomberg Finance L.P.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// ----------------------------- END-OF-FILE ----------------------------------