mirror of
https://github.com/jart/cosmopolitan.git
synced 2025-01-31 03:27:39 +00:00
127 lines
3.9 KiB
C++
127 lines
3.9 KiB
C++
//===----------------------------------------------------------------------===//
|
|
//
|
|
// 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 _LIBCPP_REFSTRING_H
|
|
#define _LIBCPP_REFSTRING_H
|
|
|
|
#include "atomic_support.h"
|
|
#include <__config>
|
|
#include <cstddef>
|
|
#include <cstring>
|
|
#include <stdexcept>
|
|
|
|
// MacOS and iOS used to ship with libstdc++, and still support old applications
|
|
// linking against libstdc++. The libc++ and libstdc++ exceptions are supposed
|
|
// to be ABI compatible, such that they can be thrown from one library and caught
|
|
// in the other.
|
|
//
|
|
// For that reason, we must look for libstdc++ in the same process and if found,
|
|
// check the string stored in the exception object to see if it is the GCC empty
|
|
// string singleton before manipulating the reference count. This is done so that
|
|
// if an exception is created with a zero-length string in libstdc++, libc++abi
|
|
// won't try to delete the memory.
|
|
#if defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) || defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__)
|
|
# define _LIBCPP_CHECK_FOR_GCC_EMPTY_STRING_STORAGE
|
|
# include <dlfcn.h>
|
|
# include <mach-o/dyld.h>
|
|
#endif
|
|
|
|
_LIBCPP_BEGIN_NAMESPACE_STD
|
|
|
|
namespace __refstring_imp {
|
|
namespace {
|
|
typedef int count_t;
|
|
|
|
struct _Rep_base {
|
|
std::size_t len;
|
|
std::size_t cap;
|
|
count_t count;
|
|
};
|
|
|
|
inline _Rep_base* rep_from_data(const char* data_) noexcept {
|
|
char* data = const_cast<char*>(data_);
|
|
return reinterpret_cast<_Rep_base*>(data - sizeof(_Rep_base));
|
|
}
|
|
|
|
inline char* data_from_rep(_Rep_base* rep) noexcept {
|
|
char* data = reinterpret_cast<char*>(rep);
|
|
return data + sizeof(*rep);
|
|
}
|
|
|
|
#if defined(_LIBCPP_CHECK_FOR_GCC_EMPTY_STRING_STORAGE)
|
|
inline const char* compute_gcc_empty_string_storage() noexcept {
|
|
void* handle = dlopen("/usr/lib/libstdc++.6.dylib", RTLD_NOLOAD);
|
|
if (handle == nullptr)
|
|
return nullptr;
|
|
void* sym = dlsym(handle, "_ZNSs4_Rep20_S_empty_rep_storageE");
|
|
if (sym == nullptr)
|
|
return nullptr;
|
|
return data_from_rep(reinterpret_cast<_Rep_base*>(sym));
|
|
}
|
|
|
|
inline const char* get_gcc_empty_string_storage() noexcept {
|
|
static const char* p = compute_gcc_empty_string_storage();
|
|
return p;
|
|
}
|
|
#endif
|
|
|
|
} // namespace
|
|
} // namespace __refstring_imp
|
|
|
|
using namespace __refstring_imp;
|
|
|
|
inline __libcpp_refstring::__libcpp_refstring(const char* msg) {
|
|
std::size_t len = strlen(msg);
|
|
_Rep_base* rep = static_cast<_Rep_base*>(::operator new(sizeof(*rep) + len + 1));
|
|
rep->len = len;
|
|
rep->cap = len;
|
|
rep->count = 0;
|
|
char* data = data_from_rep(rep);
|
|
std::memcpy(data, msg, len + 1);
|
|
__imp_ = data;
|
|
}
|
|
|
|
inline __libcpp_refstring::__libcpp_refstring(const __libcpp_refstring& s) noexcept : __imp_(s.__imp_) {
|
|
if (__uses_refcount())
|
|
__libcpp_atomic_add(&rep_from_data(__imp_)->count, 1);
|
|
}
|
|
|
|
inline __libcpp_refstring& __libcpp_refstring::operator=(__libcpp_refstring const& s) noexcept {
|
|
bool adjust_old_count = __uses_refcount();
|
|
struct _Rep_base* old_rep = rep_from_data(__imp_);
|
|
__imp_ = s.__imp_;
|
|
if (__uses_refcount())
|
|
__libcpp_atomic_add(&rep_from_data(__imp_)->count, 1);
|
|
if (adjust_old_count) {
|
|
if (__libcpp_atomic_add(&old_rep->count, count_t(-1)) < 0) {
|
|
::operator delete(old_rep);
|
|
}
|
|
}
|
|
return *this;
|
|
}
|
|
|
|
inline __libcpp_refstring::~__libcpp_refstring() {
|
|
if (__uses_refcount()) {
|
|
_Rep_base* rep = rep_from_data(__imp_);
|
|
if (__libcpp_atomic_add(&rep->count, count_t(-1)) < 0) {
|
|
::operator delete(rep);
|
|
}
|
|
}
|
|
}
|
|
|
|
inline bool __libcpp_refstring::__uses_refcount() const {
|
|
#if defined(_LIBCPP_CHECK_FOR_GCC_EMPTY_STRING_STORAGE)
|
|
return __imp_ != get_gcc_empty_string_storage();
|
|
#else
|
|
return true;
|
|
#endif
|
|
}
|
|
|
|
_LIBCPP_END_NAMESPACE_STD
|
|
|
|
#endif //_LIBCPP_REFSTRING_H
|