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Fix Zend signals unblocking

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There are a few parts here:
 * opcache should not be blocking signals while invoking compile_file,
   otherwise signals may remain blocked on a compile error. While at
   it, also protect SHM memory during compile_file.
 * We should deactivate Zend signals at the end of the request, to make
   sure that we gracefully recover from a missing unblock and signals
   don't remain blocked forever.
 * We don't use a critical section in deactivation, because it should
   not be necessary. Additionally we want to clean up the signal queue,
   if it is non-empty.
 * Enable SIGG(check) in debug builds so we notice issues in the future.
This commit is contained in:
Nikita Popov 2019-07-23 10:38:23 +02:00
parent 68fd435ba8
commit 38f1288b64
3 changed files with 31 additions and 6 deletions
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21
Zend/zend_signal.c
View file

@ -330,13 +330,13 @@ void zend_signal_activate(void)
SIGG(active) = 1;
SIGG(depth) = 0;
SIGG(check) = ZEND_DEBUG;
} /* }}} */
/* {{{ zend_signal_deactivate
* */
void zend_signal_deactivate(void)
{
if (SIGG(check)) {
size_t x;
struct sigaction sa;
@ -344,21 +344,32 @@ void zend_signal_deactivate(void)
if (SIGG(depth) != 0) {
zend_error(E_CORE_WARNING, "zend_signal: shutdown with non-zero blocking depth (%d)", SIGG(depth));
}
/* did anyone steal our installed handler */
for (x = 0; x < sizeof(zend_sigs) / sizeof(*zend_sigs); x++) {
sigaction(zend_sigs[x], NULL, &sa);
if (sa.sa_sigaction != zend_signal_handler_defer) {
if (sa.sa_sigaction != zend_signal_handler_defer &&
sa.sa_sigaction != (void *) SIG_IGN) {
zend_error(E_CORE_WARNING, "zend_signal: handler was replaced for signal (%d) after startup", zend_sigs[x]);
}
}
}
SIGNAL_BEGIN_CRITICAL();
SIGG(active) = 0;
/* After active=0 is set, signal handlers will be called directly and other
* state that is reset below will not be accessed. */
*((volatile int *) &SIGG(active)) = 0;
SIGG(running) = 0;
SIGG(blocked) = 0;
SIGG(depth) = 0;
SIGNAL_END_CRITICAL();
/* If there are any queued signals because of a missed unblock, drop them. */
if (SIGG(phead) && SIGG(ptail)) {
SIGG(ptail)->next = SIGG(pavail);
SIGG(pavail) = SIGG(phead);
SIGG(phead) = NULL;
SIGG(ptail) = NULL;
}
}
/* }}} */

11
ext/opcache/ZendAccelerator.c
View file

@ -1570,7 +1570,9 @@ static zend_persistent_script *opcache_compile_file(zend_file_handle *file_handl
/* check blacklist right after ensuring that file was opened */
if (file_handle->opened_path && zend_accel_blacklist_is_blacklisted(&accel_blacklist, ZSTR_VAL(file_handle->opened_path))) {
SHM_UNPROTECT();
ZCSG(blacklist_misses)++;
SHM_PROTECT();
*op_array_p = accelerator_orig_compile_file(file_handle, type);
return NULL;
}
@ -1601,7 +1603,9 @@ static zend_persistent_script *opcache_compile_file(zend_file_handle *file_handl
}
if (ZCG(accel_directives).max_file_size > 0 && size > (size_t)ZCG(accel_directives).max_file_size) {
SHM_UNPROTECT();
ZCSG(blacklist_misses)++;
SHM_PROTECT();
*op_array_p = accelerator_orig_compile_file(file_handle, type);
return NULL;
}
@ -2003,11 +2007,16 @@ zend_op_array *persistent_compile_file(zend_file_handle *file_handle, int type)
return accelerator_orig_compile_file(file_handle, type);
}
SHM_PROTECT();
HANDLE_UNBLOCK_INTERRUPTIONS();
persistent_script = opcache_compile_file(file_handle, type, key, &op_array);
HANDLE_BLOCK_INTERRUPTIONS();
SHM_UNPROTECT();
/* Try and cache the script and assume that it is returned from_shared_memory.
* If it isn't compile_and_cache_file() changes the flag to 0
*/
from_shared_memory = 0;
persistent_script = opcache_compile_file(file_handle, type, key, &op_array);
if (persistent_script) {
persistent_script = cache_script_in_shared_memory(persistent_script, key, key ? key_length : 0, &from_shared_memory);
}

5
main/main.c
View file

@ -1932,6 +1932,11 @@ void php_request_shutdown(void *dummy)
zend_unset_timeout();
} zend_end_try();
/* 17. Deactivate Zend signals */
#ifdef ZEND_SIGNALS
zend_signal_deactivate();
#endif
#ifdef PHP_WIN32
if (PG(com_initialized)) {
CoUninitialize();