ext/standard/filestat: omit access()/stat() system calls for cached scripts

Author: MaxKellermann

ext/opcache/ZendAccelerator.c

@@ -216,6 +216,29 @@ ZEND_ATTRIBUTE_PURE static bool check_validate_timestamps_fh(const zend_file_han
 	return check_validate_timestamps_zstr(path);
 }
 
+bool is_persistent_script(const zend_string *filename)
+{
+	if (!IS_ABSOLUTE_PATH(ZSTR_VAL(filename), ZSTR_LEN(filename)))
+		return false;
+
+	zend_string *key = normalize_path(filename);
+	const zend_persistent_script *const persistent_script = zend_accel_hash_find(&ZCSG(hash), key);
+	zend_string_efree(key);
+	if (persistent_script == NULL || persistent_script->corrupted)
+		return false;
+
+	if (persistent_script->timestamp == 0)
+		/* preloaded, no validation */
+		return true;
+
+	if (check_validate_timestamps_zstr(filename) &&
+	    (ZCG(accel_directives).revalidate_freq == 0 ||
+	     persistent_script->dynamic_members.revalidate < ZCG(request_time)))
+		return false;
+
+	return true;
+}
+
 /* O+ overrides PHP chdir() function and remembers the current working directory
  * in ZCG(cwd) and ZCG(cwd_len). Later accel_getcwd() can use stored value and
  * avoid getcwd() call.

ext/opcache/ZendAccelerator.h

@@ -330,6 +330,11 @@ BEGIN_EXTERN_C()
 
 ZEND_ATTRIBUTE_PURE bool check_validate_timestamps_zstr(const zend_string *filename);
 
+/**
+ * Is the specified filename a cached script whose time stamp does not
+ * need to be revalidated currently?
+ */
+ZEND_ATTRIBUTE_PURE bool is_persistent_script(const zend_string *filename);
 
 void accel_shutdown(void);
 zend_result accel_activate(INIT_FUNC_ARGS);

ext/standard/filestat.c

@@ -18,6 +18,8 @@
 #include "fopen_wrappers.h"
 #include "php_globals.h"
 
+#include "ext/opcache/ZendAccelerator.h" // for is_persistent_script()
+
 #include <stdlib.h>
 #include <sys/stat.h>
 #include <string.h>
@@ -736,6 +738,18 @@ PHPAPI void php_stat(zend_string *filename, int type, zval *return_value)
 	const char *local = NULL;
 	php_stream_wrapper *wrapper = NULL;
 
+	if ((type == FS_EXISTS || type == FS_IS_R || type == FS_IS_FILE) &&
+	    /* is an absolute path that ends with ".php" */
+	    ZSTR_LEN(filename) >= 6 &&
+	    ZSTR_VAL(filename)[0] == '/' &&
+	    memcmp(ZSTR_VAL(filename) + ZSTR_LEN(filename) - 4, ".php", 4) == 0 &&
+	    is_persistent_script(filename)) {
+		/* this is a cached script and its time stamp does not
+		 * need revalidation - we can safely pretend it exists
+		 * and it is a regular file */
+		RETURN_TRUE;
+	}
+
 	if (IS_ACCESS_CHECK(type)) {
 		if (!ZSTR_LEN(filename) || CHECK_NULL_PATH(ZSTR_VAL(filename), ZSTR_LEN(filename))) {
 			if (ZSTR_LEN(filename) && !IS_EXISTS_CHECK(type)) {