Fix GH-11982: str_getcsv returns null byte for unterminated enclosure

ext/standard/file.c

@@ -2017,7 +2017,14 @@ PHPAPI HashTable *php_fgetcsv(php_stream *stream, char delimiter, char enclosure
 								memcpy(tptr, line_end, line_end_len);
 								tptr += line_end_len;
 
+								/* nothing can be fetched if stream is NULL (e.g. str_getcsv()) */
 								if (stream == NULL) {
+									/* the enclosure is unterminated */
+									if (bptr > limit) {
+										/* if the line ends with enclosure, we need to go back by
+										 * one character so the \0 character is not copied. */
+										--bptr;
+									}
 									goto quit_loop_2;
 								}
 
@@ -2028,6 +2035,11 @@ PHPAPI HashTable *php_fgetcsv(php_stream *stream, char delimiter, char enclosure
 									 * assign all the data from the start of
 									 * the enclosure to end of data to the
 									 * last element */
+									if (bptr > limit) {
+										/* if the line ends with enclosure, we need to go back by
+										 * one character so the \0 character is not copied. */
+										--bptr;
+									}
 									goto quit_loop_2;
 								}
 

ext/standard/tests/file/fgetcsv_variation33.phpt

@@ -0,0 +1,29 @@
+--TEST--
+fgetcsv() with unterminated enclosure at the end of file
+--FILE--
+<?php
+$contents = <<<EOS
+"cell1","cell2"
+"cell1","
+EOS;
+$stream = fopen('php://memory', 'w+');
+fwrite($stream, $contents);
+rewind($stream);
+while (($data = fgetcsv($stream)) !== false) {
+    var_dump($data);
+}
+fclose($stream);
+?>
+--EXPECT--
+array(2) {
+  [0]=>
+  string(5) "cell1"
+  [1]=>
+  string(5) "cell2"
+}
+array(2) {
+  [0]=>
+  string(5) "cell1"
+  [1]=>
+  string(0) ""
+}

ext/standard/tests/strings/gh11982.phpt

@@ -0,0 +1,26 @@
+--TEST--
+GH-11982 (str_getcsv returns null byte for unterminated quoted string)
+--FILE--
+<?php
+var_dump(str_getcsv('"'));
+var_dump(str_getcsv('"field","'));
+var_dump(str_getcsv('"","a'));
+?>
+--EXPECT--
+array(1) {
+  [0]=>
+  string(0) ""
+}
+array(2) {
+  [0]=>
+  string(5) "field"
+  [1]=>
+  string(0) ""
+}
+array(2) {
+  [0]=>
+  string(0) ""
+  [1]=>
+  string(1) "a"
+}
+