Fix #75917: SplFileObject::seek broken with CSV flags

Closes GH-7697.

NEWS

@@ -5,6 +5,10 @@ PHP                                                                        NEWS
 - Core:
   . Fixed bug #81656 (GCC-11 silently ignores -R). (Michael Wallner)
 
+- Spl:
+  . Fixed bug #75917 (SplFileObject::seek broken with CSV flags). (Aliaksandr
+    Bystry)
+
 16 Dec 2021, PHP 8.0.14
 
 - Core:

ext/spl/spl_directory.c

@@ -1939,6 +1939,8 @@ static int spl_filesystem_file_read_line_ex(zval * this_ptr, spl_filesystem_obje
 
 	/* 1) use fgetcsv? 2) overloaded call the function, 3) do it directly */
 	if (SPL_HAS_FLAG(intern->flags, SPL_FILE_OBJECT_READ_CSV) || intern->u.file.func_getCurr->common.scope != spl_ce_SplFileObject) {
+		spl_filesystem_file_free_line(intern);
+
 		if (php_stream_eof(intern->u.file.stream)) {
 			if (!silent) {
 				zend_throw_exception_ex(spl_ce_RuntimeException, 0, "Cannot read from file %s", intern->file_name);

ext/spl/tests/bug75917.phpt

@@ -0,0 +1,24 @@
+--TEST--
+Bug #75917 (SplFileObject::seek broken with CSV flags)
+--FILE--
+<?php
+$expected = [
+    ['john', 'doe', 'john.doe@example.com', '0123456789'],
+    ['jane', 'doe', 'jane.doe@example.com'],
+];
+
+$tmp = new SplTempFileObject();
+foreach ($expected as $row) {
+    $tmp->fputcsv($row);
+}
+$tmp->setFlags(0);
+$tmp->seek(23);
+var_dump($tmp->current());
+
+$tmp->setFlags(SplFileObject::READ_CSV | SplFileObject::SKIP_EMPTY);
+$tmp->seek(23);
+var_dump($tmp->current());
+?>
+--EXPECT--
+bool(false)
+bool(false)