Feature Request #28790 Add php.ini option to disable stat cache

Zend/zend_virtual_cwd.c

@@ -146,6 +146,7 @@ static void cwd_globals_ctor(virtual_cwd_globals *cwd_g) /* {{{ */
 	cwd_g->realpath_cache_size = 0;
 	cwd_g->realpath_cache_size_limit = REALPATH_CACHE_SIZE;
 	cwd_g->realpath_cache_ttl = REALPATH_CACHE_TTL;
+	cwd_g->enable_stat_cache = true;
 	memset(cwd_g->realpath_cache, 0, sizeof(cwd_g->realpath_cache));
 }
 /* }}} */

Zend/zend_virtual_cwd.h

@@ -223,6 +223,7 @@ typedef struct _virtual_cwd_globals {
 	zend_long                   realpath_cache_size;
 	zend_long                   realpath_cache_size_limit;
 	zend_long                   realpath_cache_ttl;
+	bool                   enable_stat_cache;
 	realpath_cache_bucket *realpath_cache[1024];
 } virtual_cwd_globals;
 

ext/standard/filestat.c

@@ -784,20 +784,22 @@ PHPAPI void php_stat(zend_string *filename, int type, zval *return_value)
 	}
 
 	do {
-		/* Try to hit the cache first */
-		if (flags & PHP_STREAM_URL_STAT_LINK) {
-			if (filename == BG(CurrentLStatFile)
-			 || (BG(CurrentLStatFile)
-			  && zend_string_equal_content(filename, BG(CurrentLStatFile)))) {
-				memcpy(&ssb, &BG(lssb), sizeof(php_stream_statbuf));
-				break;
-			}
-		} else {
-			if (filename == BG(CurrentStatFile)
-			 || (BG(CurrentStatFile)
-			  && zend_string_equal_content(filename, BG(CurrentStatFile)))) {
-				memcpy(&ssb, &BG(ssb), sizeof(php_stream_statbuf));
-				break;
+		if (CWDG(enable_stat_cache)) {
+			/* Try to hit the cache first */
+			if (flags & PHP_STREAM_URL_STAT_LINK) {
+				if (filename == BG(CurrentLStatFile)
+				 || (BG(CurrentLStatFile)
+				  && zend_string_equal_content(filename, BG(CurrentLStatFile)))) {
+					memcpy(&ssb, &BG(lssb), sizeof(php_stream_statbuf));
+					break;
+				}
+			} else {
+				if (filename == BG(CurrentStatFile)
+				 || (BG(CurrentStatFile)
+				  && zend_string_equal_content(filename, BG(CurrentStatFile)))) {
+					memcpy(&ssb, &BG(ssb), sizeof(php_stream_statbuf));
+					break;
+				}
 			}
 		}
 
@@ -825,21 +827,23 @@ PHPAPI void php_stat(zend_string *filename, int type, zval *return_value)
 			RETURN_FALSE;
 		}
 
-		/* Drop into cache */
-		if (flags & PHP_STREAM_URL_STAT_LINK) {
-			if (BG(CurrentLStatFile)) {
-				zend_string_release(BG(CurrentLStatFile));
+		if (CWDG(enable_stat_cache)) {
+			/* Drop into cache */
+			if (flags & PHP_STREAM_URL_STAT_LINK) {
+				if (BG(CurrentLStatFile)) {
+					zend_string_release(BG(CurrentLStatFile));
+				}
+				BG(CurrentLStatFile) = zend_string_copy(filename);
+				memcpy(&BG(lssb), &ssb, sizeof(php_stream_statbuf));
 			}
-			BG(CurrentLStatFile) = zend_string_copy(filename);
-			memcpy(&BG(lssb), &ssb, sizeof(php_stream_statbuf));
-		}
-		if (!(flags & PHP_STREAM_URL_STAT_LINK)
-		 || !S_ISLNK(ssb.sb.st_mode)) {
-			if (BG(CurrentStatFile)) {
-				zend_string_release(BG(CurrentStatFile));
+			if (!(flags & PHP_STREAM_URL_STAT_LINK)
+			 || !S_ISLNK(ssb.sb.st_mode)) {
+				if (BG(CurrentStatFile)) {
+					zend_string_release(BG(CurrentStatFile));
+				}
+				BG(CurrentStatFile) = zend_string_copy(filename);
+				memcpy(&BG(ssb), &ssb, sizeof(php_stream_statbuf));
 			}
-			BG(CurrentStatFile) = zend_string_copy(filename);
-			memcpy(&BG(ssb), &ssb, sizeof(php_stream_statbuf));
 		}
 	} while (0);
 

ext/standard/tests/file/bug28790.cache.phpt

@@ -0,0 +1,60 @@
+--TEST--
+Bug #28790: Add php.ini option to disable stat cache (with cache)
+--FILE--
+<?php
+
+$php = '"'.getenv('TEST_PHP_EXECUTABLE').'"';
+$phpfile = getenv('TEST_PHP_EXECUTABLE');
+$impossiblefile = __FILE__.DIRECTORY_SEPARATOR.'bug28790.impossible';
+$testfile = __DIR__.DIRECTORY_SEPARATOR.'bug28790.file';
+
+function all_the_stats($filename, $message) {
+    if (@lstat($filename)) {
+        print("lstat: $message.\n");
+    }
+    if (@stat($filename)) {
+        print("stat: $message.\n");
+    }
+}
+
+# Windows can use / for dir separators, so let's do that.
+$qtestfile = str_replace("\\", "/", "$testfile");
+
+# This creates a file and should emit stat & lstat messages.
+passthru($php.' -n -r "touch(\\"'.$qtestfile.'\\");"');
+all_the_stats("$testfile", "testfile exists");
+
+# This deletes the file and shouldn't emit stat & lstat messages (but does).
+passthru($php.' -n -r "unlink(\\"'.$qtestfile.'\\");"');
+all_the_stats("$testfile", "testfile exists (it shouldn't)");
+
+# This stats a non-existent file; still stat/lstats the deleted testfile (shouldn't).
+if (!@stat("$impossiblefile")) {
+    print("stat impossiblefile does not exist.\n");
+}
+all_the_stats("$testfile", "testfile exists (it shouldn't)");
+
+# This is_files an existing file; still can lstat the deleted testfile (shouldn't).
+if (is_file("$phpfile")) {
+    print("is_file(stat): php binary exists.\n");
+}
+all_the_stats("$testfile", "testfile exists (it shouldn't)");
+
+# This lstats an existing file; finally can't stat or lstat the deleted testfile.
+if (lstat("$phpfile")) {
+    print("lstat: php binary exists.\n");
+}
+all_the_stats("$testfile", "testfile exists (it shouldn't)");
+
+?>
+--EXPECT--
+lstat: testfile exists.
+stat: testfile exists.
+lstat: testfile exists (it shouldn't).
+stat: testfile exists (it shouldn't).
+stat impossiblefile does not exist.
+lstat: testfile exists (it shouldn't).
+stat: testfile exists (it shouldn't).
+is_file(stat): php binary exists.
+lstat: testfile exists (it shouldn't).
+lstat: php binary exists.

ext/standard/tests/file/bug28790.no-cache.phpt

@@ -0,0 +1,57 @@
+--TEST--
+Bug #28790: Add php.ini option to disable stat cache (without cache)
+--INI--
+enable_stat_cache = False
+--FILE--
+<?php
+
+$php = '"'.getenv('TEST_PHP_EXECUTABLE').'"';
+$phpfile = getenv('TEST_PHP_EXECUTABLE');
+$impossiblefile = __FILE__.DIRECTORY_SEPARATOR.'bug28790.impossible';
+$testfile = __DIR__.DIRECTORY_SEPARATOR.'bug28790.file';
+
+function all_the_stats($filename, $message) {
+    if (@lstat($filename)) {
+        print("lstat: $message.\n");
+    }
+    if (@stat($filename)) {
+        print("stat: $message.\n");
+    }
+}
+
+# Windows can use / for dir separators, so let's do that.
+$qtestfile = str_replace("\\", "/", "$testfile");
+
+# This creates a file and should emit stat & lstat messages.
+passthru($php.' -n -r "touch(\\"'.$qtestfile.'\\");"');
+all_the_stats("$testfile", "testfile exists");
+
+# This deletes the file and shouldn't emit stat or lstat messages.
+passthru($php.' -n -r "unlink(\\"'.$qtestfile.'\\");"');
+all_the_stats("$testfile", "testfile exists (it shouldn't)");
+
+# This stats a non-existent file; still no testfile stat or lstat messages.
+if (!@stat("$impossiblefile")) {
+    print("stat impossiblefile does not exist.\n");
+}
+all_the_stats("$testfile", "testfile exists (it shouldn't)");
+
+# This is_files an existing file; still no testfile stat or lstat messages.
+if (is_file("$phpfile")) {
+    print("is_file(stat): php binary exists.\n");
+}
+all_the_stats("$testfile", "testfile exists (it shouldn't)");
+
+# This lstats an existing file; still no testfile stat or lstat messages.
+if (lstat("$phpfile")) {
+    print("lstat: php binary exists.\n");
+}
+all_the_stats("$testfile", "testfile exists (it shouldn't)");
+
+?>
+--EXPECT--
+lstat: testfile exists.
+stat: testfile exists.
+stat impossiblefile does not exist.
+is_file(stat): php binary exists.
+lstat: php binary exists.

main/main.c

@@ -739,6 +739,7 @@ PHP_INI_BEGIN()
 
 	STD_PHP_INI_ENTRY("realpath_cache_size",	"4096K",	PHP_INI_SYSTEM,		OnUpdateLong,	realpath_cache_size_limit,	virtual_cwd_globals,	cwd_globals)
 	STD_PHP_INI_ENTRY("realpath_cache_ttl",		"120",		PHP_INI_SYSTEM,		OnUpdateLong,	realpath_cache_ttl,			virtual_cwd_globals,	cwd_globals)
+	STD_PHP_INI_BOOLEAN("enable_stat_cache",	"1",		PHP_INI_SYSTEM,		OnUpdateBool,	enable_stat_cache,			virtual_cwd_globals,	cwd_globals)
 
 	STD_PHP_INI_ENTRY("user_ini.filename",		".user.ini",	PHP_INI_SYSTEM,		OnUpdateString,		user_ini_filename,	php_core_globals,		core_globals)
 	STD_PHP_INI_ENTRY("user_ini.cache_ttl",		"300",			PHP_INI_SYSTEM,		OnUpdateLong,		user_ini_cache_ttl,	php_core_globals,		core_globals)

php.ini-development

@@ -356,6 +356,12 @@ disable_classes =
 ; https://php.net/realpath-cache-ttl
 ;realpath_cache_ttl = 120
 
+; Allows user to disable the "stat cache". By default php remembers the
+; results of the last call to stat() and lstat() and functions that call
+; it underneath.  Setting this to Off disables that behaviour.
+; http://php.net/enable-stat-cache
+;enable_stat_cache = On
+
 ; Enables or disables the circular reference collector.
 ; https://php.net/zend.enable-gc
 zend.enable_gc = On

php.ini-production

@@ -356,6 +356,12 @@ disable_classes =
 ; https://php.net/realpath-cache-ttl
 ;realpath_cache_ttl = 120
 
+; Allows user to disable the "stat cache". By default php remembers the
+; results of the last call to stat() and lstat() and functions that call
+; it underneath.  Setting this to Off disables that behaviour.
+; http://php.net/enable-stat-cache
+;enable_stat_cache = On
+
 ; Enables or disables the circular reference collector.
 ; https://php.net/zend.enable-gc
 zend.enable_gc = On