Implement #72653: SQLite should allow opening with empty filename

From the [sqlite3_open](https://www.sqlite.org/c3ref/open.html) docs:

| If the filename is an empty string, then a private, temporary on-disk
| database will be created. This private database will be automatically
| deleted as soon as the database connection is closed.

We make that facility available to userland.

While we're at it, we also do some minor optimizations, remove the
unnecessary check for NUL characters in filename, which is already catered
to by ZPP(p), and add a missing `return` in case db_obj isn't initialized.

Author: cmb69

NEWS

@@ -65,6 +65,10 @@ PHP                                                                        NEWS
   . Fixed bug #72646 (SplFileObject::getCsvControl does not return the escape
     character). (cmb)
 
+- SQLite3:
+  . Implemented FR #72653 (SQLite should allow opening with empty filename).
+    (cmb)
+
 21 Jul 2016, PHP 5.6.24
 
 - Core:

ext/sqlite3/sqlite3.c

@@ -118,13 +118,11 @@ PHP_METHOD(sqlite3, open)
 
 	if (db_obj->initialised) {
 		zend_throw_exception(zend_exception_get_default(TSRMLS_C), "Already initialised DB Object", 0 TSRMLS_CC);
-	}
-
-	if (strlen(filename) != filename_len) {
 		return;
 	}
-	if (filename_len != sizeof(":memory:")-1 ||
-			memcmp(filename, ":memory:", sizeof(":memory:")-1) != 0) {
+
+	if (filename_len != 0 && (filename_len != sizeof(":memory:")-1 ||
+			memcmp(filename, ":memory:", sizeof(":memory:")-1) != 0)) {
 		if (!(fullpath = expand_filepath(filename, NULL TSRMLS_CC))) {
 			zend_throw_exception(zend_exception_get_default(TSRMLS_C), "Unable to expand filepath", 0 TSRMLS_CC);
 			return;
@@ -144,7 +142,8 @@ PHP_METHOD(sqlite3, open)
 			return;
 		}
 	} else {
-		fullpath = estrdup(filename);
+		/* filename equals "" or ":memory:" */
+		fullpath = filename;
 	}
 
 #if SQLITE_VERSION_NUMBER >= 3005000
@@ -153,7 +152,7 @@ PHP_METHOD(sqlite3, open)
 	if (sqlite3_open(fullpath, &(db_obj->db)) != SQLITE_OK) {
 #endif
 		zend_throw_exception_ex(zend_exception_get_default(TSRMLS_C), 0 TSRMLS_CC, "Unable to open database: %s", sqlite3_errmsg(db_obj->db));
-		if (fullpath) {
+		if (fullpath != filename) {
 			efree(fullpath);
 		}
 		return;
@@ -178,7 +177,7 @@ PHP_METHOD(sqlite3, open)
 		sqlite3_set_authorizer(db_obj->db, php_sqlite3_authorizer, NULL);
 	}
 
-	if (fullpath) {
+	if (fullpath != filename) {
 		efree(fullpath);
 	}
 }

ext/sqlite3/tests/sqlite3_open_empty_string.phpt

@@ -7,13 +7,8 @@ Thijs Feryn <[email protected]>
 <?php require_once(dirname(__FILE__) . '/skipif.inc'); ?>
 --FILE--
 <?php
-try{
-    $db = new SQLite3('');
-} catch(Exception $e) {
-    echo $e->getMessage().PHP_EOL;
-}
+$db = new SQLite3('');
 echo "Done\n";
 ?>
---EXPECTF--
-Unable to expand filepath
+--EXPECT--
 Done