MySQLnd: Support cursors in store/get result

This fixes two related issues:

1. When a PS with cursor is used in store_result/get_result,
   perform a COM_FETCH with maximum number of rows rather than
   silently switching to an unbuffered result set (in the case of
   store_result) or erroring (in the case of get_result).
   In the future, we might want to make get_result unbuffered for
   PS with cursors, as using cursors with buffered result sets
   doesn't really make sense. Unlike store_result, get_result
   isn't very explicit about what kind of result set is desired.
2. If the client did not request a cursor, but the server reports
   that a cursor exists, ignore this and treat the PS as if it
   has no cursor (i.e. to not use COM_FETCH). It appears to be a
   server side bug that a cursor used inside an SP will be reported
   to the client, even though the client cannot use the cursor.

Fixes bug #64638, bug #72862, bug #77935.

Closes GH-6518.

3 files changed, 153 insertions, 33 deletions

diff --git a/ext/mysqli/tests/bug77935.phpt b/ext/mysqli/tests/bug77935.phpt
new file mode 100644
index 0000000000..7a39ac0065
--- /dev/null
+++ b/ext/mysqli/tests/bug77935.phpt
@@ -0,0 +1,38 @@
+--TEST--
+Bug #77935: Crash in mysqlnd_fetch_stmt_row_cursor when calling an SP with a cursor
+--SKIPIF--
+<?php
+require_once('skipif.inc');
+require_once('skipifconnectfailure.inc');
+?>
+--FILE--
+<?php
+require_once(__DIR__ . '/connect.inc');
+
+mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
+$db = my_mysqli_connect($host, $user, $passwd, $db, $port, $socket);
+$db->query('DROP PROCEDURE IF EXISTS testSp');
+$db->query(<<<'SQL'
+CREATE
+    PROCEDURE `testSp`()
+	BEGIN
+		DECLARE `cur` CURSOR FOR SELECT 1;
+		OPEN `cur`;
+		CLOSE `cur`;
+		SELECT 1;
+	END;
+SQL);
+
+$stmt = $db->prepare("CALL testSp()");
+$stmt->execute();
+$result = $stmt->get_result();
+while ($row = $result->fetch_assoc()) {
+    var_dump($row);
+}
+
+?>
+--EXPECT--
+array(1) {
+  [1]=>
+  int(1)
+}
diff --git a/ext/mysqli/tests/mysqli_stmt_get_result.phpt b/ext/mysqli/tests/mysqli_stmt_get_result.phpt
index 712537a10b..fc07a1d2a2 100644
--- a/ext/mysqli/tests/mysqli_stmt_get_result.phpt
+++ b/ext/mysqli/tests/mysqli_stmt_get_result.phpt
@@ -110,21 +110,7 @@ if (!function_exists('mysqli_stmt_get_result'))
 
     mysqli_stmt_close($stmt);
 
-    if (!$stmt = mysqli_stmt_init($link))
-        printf("[032] [%d] %s\n", mysqli_errno($link), mysqli_error($link));
-
-    if (!mysqli_stmt_prepare($stmt, "SELECT id, label FROM test ORDER BY id LIMIT 2"))
-        printf("[033] [%d] %s\n", mysqli_stmt_errno($stmt), mysqli_stmt_error($stmt));
-
-    if (!mysqli_stmt_execute($stmt))
-        printf("[034] [%d] %s\n", mysqli_stmt_errno($stmt), mysqli_stmt_error($stmt));
-
-    $id = NULL;
-    $label = NULL;
-    if (true !== ($tmp = mysqli_stmt_bind_result($stmt, $id, $label)))
-        printf("[035] Expecting boolean/true, got %s/%s\n", gettype($tmp), var_export($tmp, 1));
-
-    // get_result cannot be used in PS cursor mode
+    // get_result can be used in PS cursor mode
     if (!$stmt = mysqli_stmt_init($link))
         printf("[030] [%d] %s\n", mysqli_errno($link), mysqli_error($link));
 
@@ -137,23 +123,10 @@ if (!function_exists('mysqli_stmt_get_result'))
     if (!mysqli_stmt_execute($stmt))
         printf("[033] [%d] %s\n", mysqli_stmt_errno($stmt), mysqli_stmt_error($stmt));
 
-    mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
-    try {
-        $res = mysqli_stmt_get_result($stmt);
-        // we expect no segfault if we try to fetch a row because get_result should throw an error or return false
-        mysqli_fetch_assoc($res);
-    } catch (\mysqli_sql_exception $e) {
-        echo $e->getMessage() . "\n";
-    }
-
-    try {
-        $res = $stmt->get_result();
-        // we expect no segfault if we try to fetch a row because get_result should throw an error or return false
-        $res->fetch_assoc();
-    } catch (\mysqli_sql_exception $e) {
-        echo $e->getMessage() . "\n";
+    $result = mysqli_stmt_get_result($stmt);
+    while ($row = mysqli_fetch_assoc($result)) {
+        var_dump($row);
     }
-    mysqli_report(MYSQLI_REPORT_OFF);
 
     if (!$stmt = mysqli_stmt_init($link))
         printf("[034] [%d] %s\n", mysqli_errno($link), mysqli_error($link));
@@ -213,8 +186,18 @@ Warning: mysqli_stmt_fetch(): invalid object or resource mysqli_stmt
 
 Warning: mysqli_stmt_get_result(): invalid object or resource mysqli_stmt
  in %s on line %d
-mysqli_stmt_get_result() cannot be used with cursors
-get_result() cannot be used with cursors
+array(2) {
+  ["id"]=>
+  int(1)
+  ["label"]=>
+  string(1) "a"
+}
+array(2) {
+  ["id"]=>
+  int(2)
+  ["label"]=>
+  string(1) "b"
+}
 [040] [2014] [Commands out of sync; you can't run this command now]
 [041] [0] []
 array(2) {
diff --git a/ext/mysqli/tests/ps_cursor_multiple_result_sets.phpt b/ext/mysqli/tests/ps_cursor_multiple_result_sets.phpt
new file mode 100644
index 0000000000..ed15d10e4a
--- /dev/null
+++ b/ext/mysqli/tests/ps_cursor_multiple_result_sets.phpt
@@ -0,0 +1,99 @@
+--TEST--
+PS using cursor and returning multiple result sets
+--SKIPIF--
+<?php
+require_once('skipif.inc');
+require_once('skipifconnectfailure.inc');
+?>
+--FILE--
+<?php
+require_once(__DIR__ . '/connect.inc');
+
+mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
+$db = my_mysqli_connect($host, $user, $passwd, $db, $port, $socket);
+$db->query('DROP PROCEDURE IF EXISTS testPs');
+$db->query(<<<'SQL'
+CREATE PROCEDURE testPs() BEGIN
+    DECLARE testCursor CURSOR FOR SELECT 'stuff';
+    OPEN testCursor;
+    CLOSE testCursor;
+    SELECT 1 as a, 2 as b;
+    SELECT 3 as a, 4 as b;
+END
+SQL
+);
+
+echo "use_result:\n";
+$stmt = $db->prepare("call testPs()");
+$stmt->execute();
+$stmt->bind_result($v1, $v2);
+while ($stmt->fetch()) {
+    var_dump($v1, $v2);
+}
+
+$stmt->next_result();
+$stmt->bind_result($v1, $v2);
+while ($stmt->fetch()) {
+    var_dump($v1, $v2);
+}
+$stmt->next_result();
+
+echo "\nstore_result:\n";
+$stmt = $db->prepare("call testPs()");
+$stmt->execute();
+$stmt->store_result();
+$stmt->bind_result($v1, $v2);
+while ($stmt->fetch()) {
+    var_dump($v1, $v2);
+}
+
+$stmt->next_result();
+$stmt->store_result();
+$stmt->bind_result($v1, $v2);
+while ($stmt->fetch()) {
+    var_dump($v1, $v2);
+}
+$stmt->next_result();
+
+echo "\nget_result:\n";
+$stmt = $db->prepare("call testPs()");
+$stmt->execute();
+$result = $stmt->get_result();
+while ($row = $result->fetch_assoc()) {
+    var_dump($row);
+}
+
+$stmt->next_result();
+$result = $stmt->get_result();
+while ($row = $result->fetch_assoc()) {
+    var_dump($row);
+}
+$stmt->next_result();
+
+?>
+--EXPECT--
+use_result:
+int(1)
+int(2)
+int(3)
+int(4)
+
+store_result:
+int(1)
+int(2)
+int(3)
+int(4)
+
+get_result:
+array(2) {
+  ["a"]=>
+  int(1)
+  ["b"]=>
+  int(2)
+}
+array(2) {
+  ["a"]=>
+  int(3)
+  ["b"]=>
+  int(4)
+}