folly/folly/Demangle.cpp

/*
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * 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.
 */

#include <folly/Demangle.h>

#include <algorithm>
#include <cstring>

#include <folly/CPortability.h>
#include <folly/CppAttributes.h>
#include <folly/Utility.h>
#include <folly/functional/Invoke.h>
#include <folly/lang/CString.h>

#if __has_include(<cxxabi.h>)
#include <cxxabi.h>
#endif

//  The headers <libiberty.h> (binutils) and <string.h> (glibc) both declare the
//  symbol basename. Unfortunately, the declarations are different. So including
//  both headers in the same translation unit fails due to the two conflicting
//  declarations. Since <demangle.h> includes <libiberty.h> we must be careful.
#if __has_include(<demangle.h>)
#pragma push_macro("HAVE_DECL_BASENAME")
#define HAVE_DECL_BASENAME …
#include <demangle.h> // @manual
#pragma pop_macro("HAVE_DECL_BASENAME")
#endif

//  try to find cxxabi demangle
//
//  prefer using a weakref

#if __has_include(<cxxabi.h>)

[[gnu::weakref("__cxa_demangle")]] static char* cxxabi_demangle(
    char const*, char*, size_t*, int*);

#else // __has_include(<cxxabi.h>)

static constexpr auto cxxabi_demangle = static_cast<char* (*)(...)>(nullptr);

#endif // __has_include(<cxxabi.h>)

//  try to find liberty demangle
//
//  cannot use a weak symbol since it may be the only referenced symbol in
//  liberty
//
//  in contrast with cxxabi, where there are certainly other referenced symbols
//
//  for rust_demangle_callback, detect its declaration in the header

#if __has_include(<demangle.h>)

namespace {
struct poison {};

[[maybe_unused]] FOLLY_ERASE void rust_demangle_callback(poison);

[[maybe_unused]] FOLLY_ERASE int rust_demangle_callback_fallback(
    const char*, int, demangle_callbackref, void*) {
  return 0;
}

FOLLY_CREATE_QUAL_INVOKER(
    invoke_rust_demangle_primary, ::rust_demangle_callback);
FOLLY_CREATE_QUAL_INVOKER(
    invoke_rust_demangle_fallback, rust_demangle_callback_fallback);

using invoke_rust_demangle_fn = folly::invoke_first_match<
    invoke_rust_demangle_primary,
    invoke_rust_demangle_fallback>;
constexpr invoke_rust_demangle_fn invoke_rust_demangle;

int call_rust_demangle_callback(
    const char* mangled, int options, demangle_callbackref cb, void* opaque) {
  return invoke_rust_demangle(mangled, options, cb, opaque);
}

} // namespace

using liberty_demangle_t = int(const char*, int, demangle_callbackref, void*);

static constexpr liberty_demangle_t* liberty_cplus_demangle =
    cplus_demangle_v3_callback;
static constexpr liberty_demangle_t* liberty_rust_demangle =
    call_rust_demangle_callback;

#if defined(DMGL_NO_RECURSE_LIMIT)
static constexpr auto liberty_demangle_options_no_recurse_limit =
    DMGL_NO_RECURSE_LIMIT;
#else
static constexpr auto liberty_demangle_options_no_recurse_limit = 0;
#endif

static constexpr auto liberty_demangle_options = //
    DMGL_PARAMS | DMGL_ANSI | DMGL_TYPES | //
    liberty_demangle_options_no_recurse_limit;

#else // __has_include(<demangle.h>)

liberty_demangle_t;

static constexpr liberty_demangle_t* liberty_cplus_demangle = …;
static constexpr liberty_demangle_t* liberty_rust_demangle = …;
static constexpr auto liberty_demangle_options = …;

#endif // __has_include(<demangle.h>)

//  implementations

namespace folly {

bool const demangle_build_has_cxxabi = …;
bool const demangle_build_has_liberty = …//
    to_bool(liberty_cplus_demangle) && //
    to_bool(liberty_rust_demangle);

namespace {
void demangleStringCallback(const char* str, size_t size, void* p) { … }
} // namespace

fbstring demangle(const char* name) { … }

namespace {

struct DemangleBuf { … };

void demangleBufCallback(const char* str, size_t size, void* p) { … }

} // namespace

size_t demangle(const char* name, char* out, size_t outSize) { … }

} // namespace folly