Fix #69181: READ_CSV|DROP_NEW_LINE drops newlines within fields

One may argue that `DROP_NEW_LINE` does not make sense in combination
with `READ_CSV`, but without `DROP_NEW_LINE`, `SKIP_EMPTY` does not
skip empty lines at all.  We could fix that, but do not for BC reasons.
Instead we no longer drop newlines in `spl_filesystem_file_read()` when
reading CSV, but handle that in `spl_filesystem_file_read_csv()` by
treating lines with only (CR)LF as being empty as well.

Author: cmb69

ext/spl/spl_directory.c

@@ -2045,7 +2045,7 @@ static int spl_filesystem_file_read(spl_filesystem_object *intern, int silent) /
 		intern->u.file.current_line = estrdup("");
 		intern->u.file.current_line_len = 0;
 	} else {
-		if (SPL_HAS_FLAG(intern->flags, SPL_FILE_OBJECT_DROP_NEW_LINE)) {
+		if (SPL_HAS_FLAG(intern->flags, SPL_FILE_OBJECT_DROP_NEW_LINE) && !SPL_HAS_FLAG(intern->flags, SPL_FILE_OBJECT_READ_CSV)) {
 			if (line_len > 0 && buf[line_len - 1] == '\n') {
 				line_len--;
 				if (line_len > 0 && buf[line_len - 1] == '\r') {
@@ -2125,14 +2125,24 @@ static int spl_filesystem_file_call(spl_filesystem_object *intern, zend_function
 	spl_filesystem_file_call(intern, func_ptr, pass_num_args, return_value, arg2); \
 } /* }}} */
 
+static int is_csv_line_empty(spl_filesystem_object *intern) /* {{{ */
+{
+	char *current_line = intern->u.file.current_line;
+	size_t current_line_len = intern->u.file.current_line_len;
+	return current_line_len == 0
+		|| (SPL_HAS_FLAG(intern->flags, SPL_FILE_OBJECT_READ_CSV) && SPL_HAS_FLAG(intern->flags, SPL_FILE_OBJECT_DROP_NEW_LINE)
+			&& (current_line_len == 1 && current_line[0] == '\n')
+				|| current_line_len == 2 && current_line[0] == '\r' && current_line[1] == '\n');
+} /* }}} */
+
 static int spl_filesystem_file_read_csv(spl_filesystem_object *intern, char delimiter, char enclosure, int escape, zval *return_value) /* {{{ */
 {
 	int ret = SUCCESS;
 	zval *value;
 
 	do {
 		ret = spl_filesystem_file_read(intern, 1);
-	} while (ret == SUCCESS && !intern->u.file.current_line_len && SPL_HAS_FLAG(intern->flags, SPL_FILE_OBJECT_SKIP_EMPTY));
+	} while (ret == SUCCESS && is_csv_line_empty(intern) && SPL_HAS_FLAG(intern->flags, SPL_FILE_OBJECT_SKIP_EMPTY));
 
 	if (ret == SUCCESS) {
 		size_t buf_len = intern->u.file.current_line_len;

ext/spl/tests/bug69181.phpt

@@ -0,0 +1,42 @@
+--TEST--
+Bug #69181 (READ_CSV|DROP_NEW_LINE drops newlines within fields)
+--FILE--
+<?php
+$filename = __DIR__ . "/bug69181.csv";
+$csv = <<<CSV
+"foo\nbar\nbaz",qux
+
+"foo\nbar\nbaz",qux
+CSV;
+
+file_put_contents($filename, $csv);
+
+$file = new SplFileObject($filename);
+$file->setFlags(SplFileObject::SKIP_EMPTY | SplFileObject::DROP_NEW_LINE | SplFileObject::READ_CSV);
+var_dump(iterator_to_array($file));
+?>
+--EXPECT--
+array(2) {
+  [0]=>
+  array(2) {
+    [0]=>
+    string(11) "foo
+bar
+baz"
+    [1]=>
+    string(3) "qux"
+  }
+  [2]=>
+  array(2) {
+    [0]=>
+    string(11) "foo
+bar
+baz"
+    [1]=>
+    string(3) "qux"
+  }
+}
+--CLEAN--
+<?php
+@unlink(__DIR__ . "/bug69181.csv");
+?>