fix(agent): Resolve mysqli deprecation warnings on PHP 8.1+ (#750)

Certain wrapped mysqli functions allow null values to be passed for
optional values on PHP 8.1+.
This PR fixes the issue of the agent not properly expecting these null
values in zpp resulting in deprecation warnings being thrown.

agent/php_internal_instrument.c

@@ -643,14 +643,28 @@ NR_INNER_WRAPPER(mysqli_construct) {
   zval* mysqli_obj = NULL;
   int zcaught = 0;
 
+#if ZEND_MODULE_API_NO >= ZEND_8_1_X_API_NO
+  bool port_is_null = 1;
+  const char *type_spec = "|s!s!s!s!l!s!";
   if (FAILURE
       == zend_parse_parameters_ex(
-          ZEND_PARSE_PARAMS_QUIET, ZEND_NUM_ARGS() TSRMLS_CC, "|ssssls", &host,
+          ZEND_PARSE_PARAMS_QUIET, ZEND_NUM_ARGS() TSRMLS_CC, type_spec, &host,
+          &host_len, &username, &username_len, &password, &password_len,
+          &database, &database_len, &port, &port_is_null, &socket, &socket_len)) {
+    nr_wrapper->oldhandler(INTERNAL_FUNCTION_PARAM_PASSTHRU);
+    return;
+  }
+#else
+  const char *type_spec =  "|ssssls";
+  if (FAILURE
+      == zend_parse_parameters_ex(
+          ZEND_PARSE_PARAMS_QUIET, ZEND_NUM_ARGS() TSRMLS_CC, type_spec, &host,
           &host_len, &username, &username_len, &password, &password_len,
           &database, &database_len, &port, &socket, &socket_len)) {
     nr_wrapper->oldhandler(INTERNAL_FUNCTION_PARAM_PASSTHRU);
     return;
   }
+#endif
 
   zcaught = nr_zend_call_old_handler(nr_wrapper->oldhandler,
                                      INTERNAL_FUNCTION_PARAM_PASSTHRU);
@@ -794,20 +808,29 @@ NR_INNER_WRAPPER(mysqli_commit) {
   zend_long flags = 0;
   nr_string_len_t name_len = 0;
 
+#if ZEND_MODULE_API_NO >= ZEND_8_1_X_API_NO
+  const char *proc_type_spec = "o|ls!";
+  const char *oo_type_spec = "|ls!";
+#else
+  const char *proc_type_spec = "o|ls";
+  const char *oo_type_spec = "|ls";
+#endif
+
   if (FAILURE
       == zend_parse_parameters_ex(ZEND_PARSE_PARAMS_QUIET,
-                                  ZEND_NUM_ARGS() TSRMLS_CC, "o|ls",
+                                  ZEND_NUM_ARGS() TSRMLS_CC, proc_type_spec,
                                   &mysqli_obj, &flags, &name, &name_len)) {
     if (FAILURE
         == zend_parse_parameters_ex(ZEND_PARSE_PARAMS_QUIET,
-                                    ZEND_NUM_ARGS() TSRMLS_CC, "|ls", &flags,
+                                    ZEND_NUM_ARGS() TSRMLS_CC, oo_type_spec, &flags,
                                     &name, &name_len)) {
       nr_wrapper->oldhandler(INTERNAL_FUNCTION_PARAM_PASSTHRU);
       return;
     } else {
       mysqli_obj = NR_PHP_INTERNAL_FN_THIS();
     }
   }
+
   nr_php_instrument_datastore_operation_call(nr_wrapper, NR_DATASTORE_MYSQL,
                                              "commit", instance,
                                              INTERNAL_FUNCTION_PARAM_PASSTHRU);
@@ -849,15 +872,47 @@ NR_INNER_WRAPPER(mysqli_real_connect) {
   zval* mysqli_obj = NULL;
   int zcaught = 0;
 
+  /* PHP 8.1 and later will report a deprecation warning if null is sent where
+   * a non-null argument value is expected.  For these PHP versions we use the
+   * same argument type specification as the mysqli::real_connect() extension
+   * uses to avoid creating this deprecation warning.
+   * For older PHPs continue to use the same specification string as previously
+   * to minimize any chances of introducing new problems.
+   */
+#if ZEND_MODULE_API_NO >= ZEND_8_1_X_API_NO
+  bool port_is_null = 1;
+  const char *proc_type_spec = "o|s!s!s!s!l!s!l";
+  const char *oo_type_spec = "|s!s!s!s!l!s!l";
   if (FAILURE
       == zend_parse_parameters_ex(
-          ZEND_PARSE_PARAMS_QUIET, ZEND_NUM_ARGS() TSRMLS_CC, "o|sssslsl",
+          ZEND_PARSE_PARAMS_QUIET, ZEND_NUM_ARGS() TSRMLS_CC, proc_type_spec,
+          &mysqli_obj, &host, &host_len, &username, &username_len, &password,
+          &password_len, &database, &database_len, &port, &port_is_null, &socket, &socket_len,
+          &flags)) {
+    if (FAILURE
+        == zend_parse_parameters_ex(
+            ZEND_PARSE_PARAMS_QUIET, ZEND_NUM_ARGS() TSRMLS_CC, oo_type_spec,
+            &host, &host_len, &username, &username_len, &password,
+            &password_len, &database, &database_len, &port, &port_is_null, &socket,
+            &socket_len, &flags)) {
+      nr_wrapper->oldhandler(INTERNAL_FUNCTION_PARAM_PASSTHRU);
+      return;
+    } else {
+      mysqli_obj = NR_PHP_INTERNAL_FN_THIS();
+    }
+  }
+#else
+  const char *proc_type_spec = "o|sssslsl";
+  const char *oo_type_spec = "|sssslsl";
+  if (FAILURE
+      == zend_parse_parameters_ex(
+          ZEND_PARSE_PARAMS_QUIET, ZEND_NUM_ARGS() TSRMLS_CC, proc_type_spec,
           &mysqli_obj, &host, &host_len, &username, &username_len, &password,
           &password_len, &database, &database_len, &port, &socket, &socket_len,
           &flags)) {
     if (FAILURE
         == zend_parse_parameters_ex(
-            ZEND_PARSE_PARAMS_QUIET, ZEND_NUM_ARGS() TSRMLS_CC, "|sssslsl",
+            ZEND_PARSE_PARAMS_QUIET, ZEND_NUM_ARGS() TSRMLS_CC, oo_type_spec,
             &host, &host_len, &username, &username_len, &password,
             &password_len, &database, &database_len, &port, &socket,
             &socket_len, &flags)) {
@@ -867,6 +922,7 @@ NR_INNER_WRAPPER(mysqli_real_connect) {
       mysqli_obj = NR_PHP_INTERNAL_FN_THIS();
     }
   }
+#endif
 
   zcaught = nr_zend_call_old_handler(nr_wrapper->oldhandler,
                                      INTERNAL_FUNCTION_PARAM_PASSTHRU);
@@ -1339,9 +1395,14 @@ NR_INNER_WRAPPER(mysqli_stmt_construct) {
   char* sqlstr = NULL;
   nr_string_len_t sqlstrlen = 0;
 
+#if ZEND_MODULE_API_NO >= ZEND_8_1_X_API_NO
+  const char *type_spec = "o|s!";
+#else
+  const char *type_spec = "o|s";
+#endif
   if (FAILURE
       == zend_parse_parameters_ex(ZEND_PARSE_PARAMS_QUIET,
-                                  ZEND_NUM_ARGS() TSRMLS_CC, "o|s", &mysqli_obj,
+                                  ZEND_NUM_ARGS() TSRMLS_CC, type_spec, &mysqli_obj,
                                   &sqlstr, &sqlstrlen)) {
     nr_wrapper->oldhandler(INTERNAL_FUNCTION_PARAM_PASSTHRU);
     return;

tests/integration/mysqli/test_null_connect_proc.php

@@ -0,0 +1,36 @@
+<?php
+/*
+ * Copyright 2020 New Relic Corporation. All rights reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/*DESCRIPTION
+The agent should not cause a deprecation warning to be thrown when passing null
+to optional arguments for mysqli_connect on PHP 8.1+
+*/
+
+/*SKIPIF
+<?php require("skipif.inc");
+
+if (version_compare(PHP_VERSION, "8.1", "<")) {
+  die("skip: Deprecation warning PHP 8.1+ specific\n");
+}
+*/
+
+/*INI
+error_reporting = E_DEPRECATION
+*/
+
+/*EXPECT
+*/
+
+require_once(realpath (dirname ( __FILE__ )) . '/../../include/config.php');
+
+$link = mysqli_connect(null, null, null, null, null, null);
+
+if (mysqli_connect_errno()) {
+  echo mysqli_connect_error() . "\n";
+  exit(1);
+}
+
+mysqli_close($link);

tests/integration/mysqli/test_null_construct_oo.php

@@ -0,0 +1,36 @@
+<?php
+/*
+ * Copyright 2020 New Relic Corporation. All rights reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/*DESCRIPTION
+The agent should not cause a deprecation warning to be thrown when passing null
+to optional arguments for mysqli::__construct on PHP 8.1+
+*/
+
+/*SKIPIF
+<?php require("skipif.inc");
+
+if (version_compare(PHP_VERSION, "8.1", "<")) {
+  die("skip: Deprecation warning PHP 8.1+ specific\n");
+}
+*/
+
+/*INI
+error_reporting = E_DEPRECATION
+*/
+
+/*EXPECT
+*/
+
+require_once(realpath (dirname ( __FILE__ )) . '/../../include/config.php');
+
+$link = new mysqli(null, null, null, null, null, null);
+
+if (mysqli_connect_errno()) {
+  echo mysqli_connect_error() . "\n";
+  exit(1);
+}
+
+mysqli_close($link);

tests/integration/mysqli/test_null_rc_oo.php

@@ -0,0 +1,38 @@
+<?php
+/*
+ * Copyright 2020 New Relic Corporation. All rights reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/*DESCRIPTION
+The agent should not cause a deprecation warning to be thrown when passing null
+to optional arguments for mysqli::real_connect on PHP 8.1+
+*/
+
+/*SKIPIF
+<?php require("skipif.inc");
+
+if (version_compare(PHP_VERSION, "8.1", "<")) {
+  die("skip: Deprecation warning PHP 8.1+ specific\n");
+}
+*/
+
+/*INI
+error_reporting = E_DEPRECATION
+*/
+
+/*EXPECT
+*/
+
+require_once(realpath (dirname ( __FILE__ )) . '/../../include/config.php');
+
+$link = mysqli_init();
+$link->options(MYSQLI_OPT_CONNECT_TIMEOUT, 10);
+$link->real_connect(null, null, null, null, null, null);
+
+if (mysqli_connect_errno()) {
+  echo mysqli_connect_error() . "\n";
+  exit(1);
+}
+
+mysqli_close($link);

tests/integration/mysqli/test_null_rc_proc.php

@@ -0,0 +1,39 @@
+<?php
+/*
+ * Copyright 2020 New Relic Corporation. All rights reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/*DESCRIPTION
+The agent should not cause a deprecation warning to be thrown when passing null
+to optional arguments for mysqli_real_connect on PHP 8.1+
+*/
+
+/*SKIPIF
+<?php require("skipif.inc");
+
+if (version_compare(PHP_VERSION, "8.1", "<")) {
+  die("skip: Deprecation warning PHP 8.1+ specific\n");
+}
+*/
+
+/*INI
+error_reporting = E_DEPRECATION
+*/
+
+/*EXPECT
+*/
+
+require_once(realpath (dirname ( __FILE__ )) . '/../../include/config.php');
+
+$link = mysqli_init();
+mysqli_options($link, MYSQLI_OPT_CONNECT_TIMEOUT, 10);
+
+mysqli_real_connect($link, null, null, null, null, null, null);
+
+if (mysqli_connect_errno()) {
+  echo mysqli_connect_error() . "\n";
+  exit(1);
+}
+
+mysqli_close($link);

tests/integration/mysqli/test_null_stmt_construct.php

@@ -0,0 +1,60 @@
+<?php
+/*
+ * Copyright 2020 New Relic Corporation. All rights reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/*DESCRIPTION
+The agent should not cause a deprecation warning to be thrown when passing null
+to optional arguments for mysqli_stmt:__construct on PHP 8.1+
+*/
+
+/*SKIPIF
+<?php require("skipif.inc");
+
+if (version_compare(PHP_VERSION, "8.1", "<")) {
+  die("skip: Deprecation warning PHP 8.1+ specific\n");
+}
+*/
+
+/*INI
+error_reporting = E_ALL
+*/
+
+/*EXPECT
+STATISTICS
+*/
+
+require_once(realpath (dirname ( __FILE__ )) . '/../../include/config.php');
+
+function test_stmt_prepare($link)
+{
+  $stmt = new mysqli_stmt($link, null);
+  $name = 'STATISTICS';
+
+  $query = "SELECT TABLE_NAME FROM information_schema.tables WHERE table_name=?";
+  if (FALSE === $stmt->prepare($query) ||
+      FALSE === $stmt->bind_param('s', $name) ||
+      FALSE === $stmt->execute() ||
+      FALSE === $stmt->bind_result($name)) {
+    echo mysqli_stmt_error($stmt) . "\n";
+    mysqli_stmt_close($stmt);
+    return;
+  }
+
+  while (mysqli_stmt_fetch($stmt)) {
+    echo $name . "\n";
+  }
+
+  mysqli_stmt_close($stmt);
+}
+
+$link = mysqli_connect($MYSQL_HOST, $MYSQL_USER, $MYSQL_PASSWD, $MYSQL_DB, $MYSQL_PORT, $MYSQL_SOCKET);
+if (mysqli_connect_errno()) {
+  echo mysqli_connect_error() . "\n";
+  exit(1);
+}
+
+test_stmt_prepare($link);
+mysqli_close($link);
+