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/*
* Copyright (c) 2019-2020, Andrew Kaster <andrewdkaster@gmail.com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <AK/Debug.h>
#include <AK/Format.h>
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/internals.h>
#include <sys/mman.h>
#include <unistd.h>
extern "C" {
struct AtExitEntry {
AtExitFunction method { nullptr };
void* parameter { nullptr };
void* dso_handle { nullptr };
bool has_been_called { false };
};
static constexpr size_t max_atexit_entry_count = PAGE_SIZE / sizeof(AtExitEntry);
static AtExitEntry* atexit_entries;
static size_t atexit_entry_count = 0;
static void lock_atexit_handlers()
{
if (mprotect(atexit_entries, PAGE_SIZE, PROT_READ) < 0) {
perror("lock_atexit_handlers");
_exit(1);
}
}
static void unlock_atexit_handlers()
{
if (mprotect(atexit_entries, PAGE_SIZE, PROT_READ | PROT_WRITE) < 0) {
perror("unlock_atexit_handlers");
_exit(1);
}
}
int __cxa_atexit(AtExitFunction exit_function, void* parameter, void* dso_handle)
{
if (atexit_entry_count >= max_atexit_entry_count)
return -1;
if (!atexit_entries) {
atexit_entries = (AtExitEntry*)mmap(nullptr, PAGE_SIZE, PROT_READ, MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
if (atexit_entries == MAP_FAILED) {
perror("__cxa_atexit mmap");
_exit(1);
}
}
unlock_atexit_handlers();
atexit_entries[atexit_entry_count++] = { exit_function, parameter, dso_handle, false };
lock_atexit_handlers();
return 0;
}
void __cxa_finalize(void* dso_handle)
{
// From the itanium abi, https://itanium-cxx-abi.github.io/cxx-abi/abi.html#dso-dtor-runtime-api
//
// When __cxa_finalize(d) is called, it should walk the termination function list, calling each in turn
// if d matches __dso_handle for the termination function entry. If d == NULL, it should call all of them.
// Multiple calls to __cxa_finalize shall not result in calling termination function entries multiple times;
// the implementation may either remove entries or mark them finished.
ssize_t entry_index = atexit_entry_count;
dbgln_if(GLOBAL_DTORS_DEBUG, "__cxa_finalize: {} entries in the finalizer list", entry_index);
while (--entry_index >= 0) {
auto& exit_entry = atexit_entries[entry_index];
bool needs_calling = !exit_entry.has_been_called && (!dso_handle || dso_handle == exit_entry.dso_handle);
if (needs_calling) {
dbgln_if(GLOBAL_DTORS_DEBUG, "__cxa_finalize: calling entry[{}] {:p}({:p}) dso: {:p}", entry_index, exit_entry.method, exit_entry.parameter, exit_entry.dso_handle);
unlock_atexit_handlers();
exit_entry.has_been_called = true;
lock_atexit_handlers();
exit_entry.method(exit_entry.parameter);
}
}
}
[[noreturn]] void __cxa_pure_virtual()
{
VERIFY_NOT_REACHED();
}
} // extern "C"
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