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LibC: Make atexit handlers thread-safe

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Gunnar Beutner 2021-04-17 18:35:14 +02:00 • committed by Andreas Kling
parent 4075b306f8
commit ebca6aabc0
1 changed files with 16 additions and 1 deletions
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17
Userland/Libraries/LibC/cxxabi.cpp
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@ -26,6 +26,7 @@
#include <AK/Debug.h> #include <AK/Debug.h>
#include <AK/Format.h> #include <AK/Format.h>
#include <LibC/bits/pthread_integration.h>
#include <assert.h> #include <assert.h>
#include <stdio.h> #include <stdio.h>
#include <stdlib.h> #include <stdlib.h>
@ -46,6 +47,7 @@ static constexpr size_t max_atexit_entry_count = PAGE_SIZE / sizeof(AtExitEntry)
static AtExitEntry* atexit_entries; static AtExitEntry* atexit_entries;
static size_t atexit_entry_count = 0; static size_t atexit_entry_count = 0;
static pthread_mutex_t atexit_mutex = __PTHREAD_MUTEX_INITIALIZER;
static void lock_atexit_handlers() static void lock_atexit_handlers()
{ {
@ -65,12 +67,17 @@ static void unlock_atexit_handlers()
int __cxa_atexit(AtExitFunction exit_function, void* parameter, void* dso_handle) int __cxa_atexit(AtExitFunction exit_function, void* parameter, void* dso_handle)
{ {
if (atexit_entry_count >= max_atexit_entry_count) __pthread_mutex_lock(&atexit_mutex);
if (atexit_entry_count >= max_atexit_entry_count) {
__pthread_mutex_unlock(&atexit_mutex);
return -1; return -1;
}
if (!atexit_entries) { if (!atexit_entries) {
atexit_entries = (AtExitEntry*)mmap(nullptr, PAGE_SIZE, PROT_READ, MAP_ANONYMOUS | MAP_PRIVATE, 0, 0); atexit_entries = (AtExitEntry*)mmap(nullptr, PAGE_SIZE, PROT_READ, MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
if (atexit_entries == MAP_FAILED) { if (atexit_entries == MAP_FAILED) {
__pthread_mutex_unlock(&atexit_mutex);
perror("__cxa_atexit mmap"); perror("__cxa_atexit mmap");
_exit(1); _exit(1);
} }
@ -80,6 +87,8 @@ int __cxa_atexit(AtExitFunction exit_function, void* parameter, void* dso_handle
atexit_entries[atexit_entry_count++] = { exit_function, parameter, dso_handle, false }; atexit_entries[atexit_entry_count++] = { exit_function, parameter, dso_handle, false };
lock_atexit_handlers(); lock_atexit_handlers();
__pthread_mutex_unlock(&atexit_mutex);
return 0; return 0;
} }
@ -92,6 +101,8 @@ void __cxa_finalize(void* dso_handle)
// Multiple calls to __cxa_finalize shall not result in calling termination function entries multiple times; // 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. // the implementation may either remove entries or mark them finished.
__pthread_mutex_lock(&atexit_mutex);
ssize_t entry_index = atexit_entry_count; ssize_t entry_index = atexit_entry_count;
dbgln_if(GLOBAL_DTORS_DEBUG, "__cxa_finalize: {} entries in the finalizer list", entry_index); dbgln_if(GLOBAL_DTORS_DEBUG, "__cxa_finalize: {} entries in the finalizer list", entry_index);
@ -104,9 +115,13 @@ void __cxa_finalize(void* dso_handle)
unlock_atexit_handlers(); unlock_atexit_handlers();
exit_entry.has_been_called = true; exit_entry.has_been_called = true;
lock_atexit_handlers(); lock_atexit_handlers();
__pthread_mutex_unlock(&atexit_mutex);
exit_entry.method(exit_entry.parameter); exit_entry.method(exit_entry.parameter);
__pthread_mutex_lock(&atexit_mutex);
} }
} }
__pthread_mutex_unlock(&atexit_mutex);
} }
[[noreturn]] void __cxa_pure_virtual() [[noreturn]] void __cxa_pure_virtual()