Introduce new zend_module_entry hook: child_startup_func

UPGRADING

@@ -45,6 +45,10 @@ PHP 8.4 UPGRADE NOTES
     object. This is no longer possible, and cloning a DOMXPath object now throws
     an error.
 
+- FFI:
+  . Using FFI::load() during preloading ("opcache.preload") is not supported
+    anymore. Use "ffi.preload" instead.
+
 - MBString:
   . mb_encode_numericentity() and mb_decode_numericentity() now check that
     the $map is only composed of integers, if not a ValueError is thrown.

UPGRADING.INTERNALS

@@ -40,6 +40,12 @@ PHP 8.4 INTERNALS UPGRADE NOTES
 * The inet_aton() and win32/inet.h on Windows have been removed. Use Windows
   native inet_pton() from ws2tcpip.h.
 
+* It is recommended that extensions initializing external libraries or starting
+  threads during module startup (MINIT) do so in the child startup hook (CHINIT)
+  instead. A child startup hook can be declared by using the
+  PHP_MODULE_SET_CHINIT_FUNC() macro during module startup. See
+  ext/curl/interface.c for an example.
+
 ========================
 2. Build system changes
 ========================
@@ -147,3 +153,7 @@ PHP 8.4 INTERNALS UPGRADE NOTES
 ========================
 5. SAPI changes
 ========================
+
+* SAPIs must call php_module_child_startup() once per request-handling process,
+  any time before handling the first request of the process, and must not fork
+  (without exec()) after that.

Zend/zend_API.c

@@ -34,6 +34,16 @@
 #include "zend_observer.h"
 
 #include <stdarg.h>
+#if ZEND_DEBUG
+# if __linux__
+#  include <sys/types.h>
+#  include <dirent.h>
+# elif __APPLE__
+#  include <mach/mach_init.h>
+#  include <mach/task.h>
+#  include <mach/vm_map.h>
+# endif /* __APPLE__ */
+#endif
 
 /* these variables are true statics/globals, and have to be mutex'ed on every access */
 ZEND_API HashTable module_registry;
@@ -2292,6 +2302,64 @@ ZEND_API void add_property_zval_ex(zval *arg, const char *key, size_t key_len, z
 }
 /* }}} */
 
+#if ZEND_DEBUG
+# if __linux__
+static int zend_thread_count(void)
+{
+	pid_t pid = getpid();
+	char path[64];
+	int len = snprintf(path, sizeof(path), "/proc/%d/task", (int)pid);
+	if (len == -1 || len >= sizeof(path)) {
+		return -1;
+	}
+
+	DIR *d = opendir(path);
+	if (d == NULL) {
+		return -1;
+	}
+
+	struct dirent *entry;
+	int nthreads = 0;
+	while ((entry = readdir(d))){
+		nthreads++;
+	}
+
+	closedir(d);
+
+	return nthreads;
+}
+# elif __APPLE__
+static int zend_thread_count(void)
+{
+	pid_t pid = getpid();
+	mach_port_t me = mach_task_self();
+	mach_port_t task;
+	kern_return_t res;
+	thread_array_t threads;
+	mach_msg_type_number_t nthreads;
+
+	res = task_for_pid(me, pid, &task);
+	if (res != KERN_SUCCESS) {
+		return -1;
+	}
+
+	res = task_threads(task, &threads, &nthreads);
+	if (res != KERN_SUCCESS) {
+		return -1;
+	}
+
+	vm_deallocate(me, (vm_address_t)threads, nthreads * sizeof(*threads));
+
+	return (int) nthreads;
+}
+# else
+static int zend_thread_count(void)
+{
+	return 0;
+}
+# endif /* __APPLE__ */
+#endif
+
 ZEND_API zend_result zend_startup_module_ex(zend_module_entry *module) /* {{{ */
 {
 	size_t name_len;
@@ -2338,14 +2406,29 @@ ZEND_API zend_result zend_startup_module_ex(zend_module_entry *module) /* {{{ */
 #endif
 	}
 	if (module->module_startup_func) {
+#if ZEND_DEBUG
+		int thread_count = zend_thread_count();
+#endif
 		EG(current_module) = module;
 		if (module->module_startup_func(module->type, module->module_number)==FAILURE) {
 			zend_error_noreturn(E_CORE_ERROR,"Unable to start %s module", module->name);
 			EG(current_module) = NULL;
 			return FAILURE;
 		}
 		EG(current_module) = NULL;
+#if ZEND_DEBUG
+		if (zend_thread_count() > thread_count) {
+			zend_error_noreturn(E_CORE_ERROR,
+					"Thread count increased during the initialization of %s"
+					" module. This is unsafe as the process may be forked after"
+					" initialization. Modules whishing to start threads should"
+					" do so in child_startup_func.",
+					module->name);
+			abort();
+		}
+#endif
 	}
+
 	return SUCCESS;
 }
 /* }}} */
@@ -2491,6 +2574,40 @@ ZEND_API void zend_destroy_modules(void) /* {{{ */
 }
 /* }}} */
 
+ZEND_API void zend_child_startup_modules(void) /* {{{ */
+{
+	zend_module_entry *module;
+
+	ZEND_HASH_MAP_FOREACH_PTR(&module_registry, module) {
+		if (module->child_startup_func) {
+			if (module->child_startup_func(module->type, module->module_number)==FAILURE) {
+				zend_error(E_CORE_ERROR, "child_startup() for %s module failed", module->name);
+				exit(1);
+			}
+		}
+	} ZEND_HASH_FOREACH_END();
+}
+/* }}} */
+
+ZEND_API void zend_module_set_child_startup_func(INIT_FUNC_ARGS, zend_result (*child_startup_func)(INIT_FUNC_ARGS)) /* {{{ */
+{
+	if (!EG(current_module)) {
+		zend_error(E_CORE_ERROR, "Can not set child startup func after startup");
+		abort();
+	}
+
+	if (EG(current_module)->module_number != module_number) {
+		zend_error(E_CORE_ERROR,
+				"Invalid module_number passed to zend_set_child_startup_func"
+				" during statup of %s module",
+				EG(current_module)->name);
+		abort();
+	}
+
+	EG(current_module)->child_startup_func = child_startup_func;
+}
+/* }}} */
+
 ZEND_API zend_module_entry* zend_register_module_ex(zend_module_entry *module, int module_type) /* {{{ */
 {
 	size_t name_len;

Zend/zend_API.h

@@ -221,6 +221,7 @@ typedef struct _zend_fcall_info_cache {
 /* Name macros */
 #define ZEND_MODULE_STARTUP_N(module)       zm_startup_##module
 #define ZEND_MODULE_SHUTDOWN_N(module)		zm_shutdown_##module
+#define ZEND_MODULE_CHILD_STARTUP_N(module) zm_child_startup_##module
 #define ZEND_MODULE_ACTIVATE_N(module)		zm_activate_##module
 #define ZEND_MODULE_DEACTIVATE_N(module)	zm_deactivate_##module
 #define ZEND_MODULE_POST_ZEND_DEACTIVATE_N(module)	zm_post_zend_deactivate_##module
@@ -231,6 +232,7 @@ typedef struct _zend_fcall_info_cache {
 /* Declaration macros */
 #define ZEND_MODULE_STARTUP_D(module)		zend_result ZEND_MODULE_STARTUP_N(module)(INIT_FUNC_ARGS)
 #define ZEND_MODULE_SHUTDOWN_D(module)		zend_result ZEND_MODULE_SHUTDOWN_N(module)(SHUTDOWN_FUNC_ARGS)
+#define ZEND_MODULE_CHILD_STARTUP_D(module)	zend_result ZEND_MODULE_CHILD_STARTUP_N(module)(INIT_FUNC_ARGS)
 #define ZEND_MODULE_ACTIVATE_D(module)		zend_result ZEND_MODULE_ACTIVATE_N(module)(INIT_FUNC_ARGS)
 #define ZEND_MODULE_DEACTIVATE_D(module)	zend_result ZEND_MODULE_DEACTIVATE_N(module)(SHUTDOWN_FUNC_ARGS)
 #define ZEND_MODULE_POST_ZEND_DEACTIVATE_D(module)	zend_result ZEND_MODULE_POST_ZEND_DEACTIVATE_N(module)(void)
@@ -243,6 +245,9 @@ typedef struct _zend_fcall_info_cache {
 	ZEND_DLEXPORT zend_module_entry *get_module(void) { return &name##_module_entry; }\
     END_EXTERN_C()
 
+#define ZEND_MODULE_SET_CHILD_STARTUP_FUNC(func) \
+	zend_module_set_child_startup_func(INIT_FUNC_ARGS_PASSTHRU, func)
+
 #define ZEND_BEGIN_MODULE_GLOBALS(module_name)		\
 	typedef struct _zend_##module_name##_globals {
 #define ZEND_END_MODULE_GLOBALS(module_name)		\
@@ -384,6 +389,8 @@ ZEND_API zend_result zend_startup_module_ex(zend_module_entry *module);
 ZEND_API void zend_startup_modules(void);
 ZEND_API void zend_collect_module_handlers(void);
 ZEND_API void zend_destroy_modules(void);
+ZEND_API void zend_child_startup_modules(void);
+ZEND_API void zend_module_set_child_startup_func(INIT_FUNC_ARGS, zend_result (*child_startup_func)(INIT_FUNC_ARGS));
 ZEND_API void zend_check_magic_method_implementation(
 		const zend_class_entry *ce, const zend_function *fptr, zend_string *lcname, int error_type);
 ZEND_API void zend_add_magic_method(zend_class_entry *ce, zend_function *fptr, zend_string *lcname);

Zend/zend_modules.h

@@ -46,7 +46,7 @@
 
 #define ZEND_MODULE_BUILD_ID "API" ZEND_TOSTR(ZEND_MODULE_API_NO) ZEND_BUILD_TS ZEND_BUILD_DEBUG ZEND_BUILD_SYSTEM ZEND_BUILD_EXTRA
 
-#define STANDARD_MODULE_PROPERTIES_EX 0, 0, NULL, 0, ZEND_MODULE_BUILD_ID
+#define STANDARD_MODULE_PROPERTIES_EX NULL, 0, 0, NULL, 0, ZEND_MODULE_BUILD_ID
 
 #define NO_MODULE_GLOBALS 0, NULL, NULL, NULL
 
@@ -77,8 +77,12 @@ struct _zend_module_entry {
 	const struct _zend_module_dep *deps;
 	const char *name;
 	const struct _zend_function_entry *functions;
+	/* Called once per process, excluding forked processes. This function
+	 * must not start threads. Calling external libraries from this function is
+	 * not recommended. */
 	zend_result (*module_startup_func)(INIT_FUNC_ARGS);
 	zend_result (*module_shutdown_func)(SHUTDOWN_FUNC_ARGS);
+	/* Called once per request */
 	zend_result (*request_startup_func)(INIT_FUNC_ARGS);
 	zend_result (*request_shutdown_func)(SHUTDOWN_FUNC_ARGS);
 	void (*info_func)(ZEND_MODULE_INFO_FUNC_ARGS);
@@ -92,6 +96,8 @@ struct _zend_module_entry {
 	void (*globals_ctor)(void *global);
 	void (*globals_dtor)(void *global);
 	zend_result (*post_deactivate_func)(void);
+	/* Called once per request-handling process */
+	zend_result (*child_startup_func)(INIT_FUNC_ARGS);
 	int module_started;
 	unsigned char type;
 	void *handle;

ext/curl/interface.c

@@ -365,10 +365,22 @@ PHP_MINFO_FUNCTION(curl)
 }
 /* }}} */
 
+/* {{{ PHP_CHINIT_FUNCTION */
+PHP_CHINIT_FUNCTION(curl)
+{
+	if (curl_global_init(CURL_GLOBAL_DEFAULT) != CURLE_OK) {
+		return FAILURE;
+	}
+
+	return SUCCESS;
+}
+/* }}} */
+
 /* {{{ PHP_MINIT_FUNCTION */
 PHP_MINIT_FUNCTION(curl)
 {
 	REGISTER_INI_ENTRIES();
+	PHP_MODULE_SET_CHINIT_FUNC(PHP_CHINIT(curl));
 
 	register_curl_symbols(module_number);
 
@@ -390,10 +402,6 @@ PHP_MINIT_FUNCTION(curl)
 	}
 #endif
 
-	if (curl_global_init(CURL_GLOBAL_DEFAULT) != CURLE_OK) {
-		return FAILURE;
-	}
-
 	curl_ce = register_class_CurlHandle();
 	curl_ce->create_object = curl_create_object;
 	curl_ce->default_object_handlers = &curl_object_handlers;

ext/ffi/ffi.c

@@ -3537,7 +3537,7 @@ ZEND_METHOD(FFI, load) /* {{{ */
 	ZEND_PARSE_PARAMETERS_END();
 
 	if (CG(compiler_options) & ZEND_COMPILE_PRELOAD_IN_CHILD) {
-		zend_throw_error(zend_ffi_exception_ce, "FFI::load() doesn't work in conjunction with \"opcache.preload_user\". Use \"ffi.preload\" instead.");
+		zend_throw_error(zend_ffi_exception_ce, "FFI::load() doesn't work in conjunction with \"opcache.preload\". Use \"ffi.preload\" instead.");
 		RETURN_THROWS();
 	}
 

ext/ffi/tests/bug78761.phpt

@@ -2,15 +2,8 @@
 Bug #78761 (Zend memory heap corruption with preload and casting)
 --EXTENSIONS--
 ffi
-posix
---SKIPIF--
-<?php
-if (PHP_OS_FAMILY == 'Windows') die('skip Preloading is not supported on Windows');
-if (posix_geteuid() == 0) die('skip Cannot run test as root.');
-?>
 --INI--
-opcache.enable_cli=1
-opcache.preload={PWD}/bug78761_preload.php
+ffi.preload={PWD}/bug78761_preload.h
 --FILE--
 <?php
 try {