mirror of
https://github.com/RGBCube/serenity
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112 lines
3.4 KiB
C++
112 lines
3.4 KiB
C++
/*
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* Copyright (c) 2019-2020, Andrew Kaster <akaster@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <AK/Debug.h>
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#include <AK/Format.h>
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#include <LibC/bits/pthread_integration.h>
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#include <assert.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <sys/internals.h>
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#include <sys/mman.h>
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#include <unistd.h>
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extern "C" {
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struct AtExitEntry {
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AtExitFunction method { nullptr };
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void* parameter { nullptr };
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void* dso_handle { nullptr };
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bool has_been_called { false };
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};
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static constexpr size_t max_atexit_entry_count = PAGE_SIZE / sizeof(AtExitEntry);
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static AtExitEntry* atexit_entries;
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static size_t atexit_entry_count = 0;
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static pthread_mutex_t atexit_mutex = __PTHREAD_MUTEX_INITIALIZER;
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static void lock_atexit_handlers()
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{
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if (mprotect(atexit_entries, PAGE_SIZE, PROT_READ) < 0) {
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perror("lock_atexit_handlers");
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_exit(1);
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}
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}
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static void unlock_atexit_handlers()
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{
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if (mprotect(atexit_entries, PAGE_SIZE, PROT_READ | PROT_WRITE) < 0) {
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perror("unlock_atexit_handlers");
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_exit(1);
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}
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}
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int __cxa_atexit(AtExitFunction exit_function, void* parameter, void* dso_handle)
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{
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__pthread_mutex_lock(&atexit_mutex);
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if (atexit_entry_count >= max_atexit_entry_count) {
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__pthread_mutex_unlock(&atexit_mutex);
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return -1;
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}
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if (!atexit_entries) {
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atexit_entries = (AtExitEntry*)mmap(nullptr, PAGE_SIZE, PROT_READ, MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
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if (atexit_entries == MAP_FAILED) {
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__pthread_mutex_unlock(&atexit_mutex);
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perror("__cxa_atexit mmap");
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_exit(1);
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}
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}
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unlock_atexit_handlers();
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atexit_entries[atexit_entry_count++] = { exit_function, parameter, dso_handle, false };
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lock_atexit_handlers();
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__pthread_mutex_unlock(&atexit_mutex);
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return 0;
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}
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void __cxa_finalize(void* dso_handle)
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{
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// From the itanium abi, https://itanium-cxx-abi.github.io/cxx-abi/abi.html#dso-dtor-runtime-api
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//
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// When __cxa_finalize(d) is called, it should walk the termination function list, calling each in turn
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// if d matches __dso_handle for the termination function entry. If d == NULL, it should call all of them.
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// Multiple calls to __cxa_finalize shall not result in calling termination function entries multiple times;
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// the implementation may either remove entries or mark them finished.
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__pthread_mutex_lock(&atexit_mutex);
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ssize_t entry_index = atexit_entry_count;
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dbgln_if(GLOBAL_DTORS_DEBUG, "__cxa_finalize: {} entries in the finalizer list", entry_index);
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while (--entry_index >= 0) {
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auto& exit_entry = atexit_entries[entry_index];
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bool needs_calling = !exit_entry.has_been_called && (!dso_handle || dso_handle == exit_entry.dso_handle);
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if (needs_calling) {
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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);
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unlock_atexit_handlers();
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exit_entry.has_been_called = true;
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lock_atexit_handlers();
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__pthread_mutex_unlock(&atexit_mutex);
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exit_entry.method(exit_entry.parameter);
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__pthread_mutex_lock(&atexit_mutex);
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}
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}
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__pthread_mutex_unlock(&atexit_mutex);
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}
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__attribute__((noreturn)) void __cxa_pure_virtual()
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{
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VERIFY_NOT_REACHED();
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}
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} // extern "C"
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