Prevent an infinite loop parsing a capture name

stevenjohnstone · stevenjohnstone · commit c23d8bc65d5a · 2025-11-19T09:30:57.000Z
Fixes #3729.
diff --git a/src/prism.c b/src/prism.c
@@ -21163,6 +21163,9 @@ pm_named_capture_escape_unicode(pm_parser_t *parser, pm_buffer_t *unescaped, con
         }
 
         size_t length = pm_strspn_hexadecimal_digit(cursor, end - cursor);
+        if (length == 0) {
+            break;
+        }
         uint32_t value = escape_unicode(parser, cursor, length);
 
         (void) pm_buffer_append_unicode_codepoint(unescaped, value);

Original file line number	Diff line number	Diff line change
`@@ -21163,6 +21163,9 @@ pm_named_capture_escape_unicode(pm_parser_t parser, pm_buffer_t unescaped, con`
`21163`	`21163`	`}`
`21164`	`21164`
`21165`	`21165`	`size_t length = pm_strspn_hexadecimal_digit(cursor, end - cursor);`
	`21166`	`+ if (length == 0) {`
	`21167`	`+ break;`
	`21168`	`+ }`
`21166`	`21169`	`uint32_t value = escape_unicode(parser, cursor, length);`
`21167`	`21170`
`21168`	`21171`	`(void) pm_buffer_append_unicode_codepoint(unescaped, value);`