MFH (fixed #42085)

diff --git a/ext/mbstring/libmbfl/mbfl/mbfilter.c b/ext/mbstring/libmbfl/mbfl/mbfilter.c
index a8e3b68d33909068f52a2386fb1b32e8e1bb011d..97d2f048ccacc18608697169a566d58c9b4bab09 100644 (file)
--- a/ext/mbstring/libmbfl/mbfl/mbfilter.c
+++ b/ext/mbstring/libmbfl/mbfl/mbfilter.c
@@ -858,7 +858,7 @@ mbfl_strpos(
     int offset,
     int reverse)
 {
-       int n, result;
+       int n, result, negative_offset = 0;
        unsigned char *p;
        mbfl_convert_filter *filter;
        struct collector_strpos_data pc;
@@ -904,6 +904,12 @@ mbfl_strpos(
                mbfl_wchar_device_clear(&pc.needle);
                return -4;
        }
+
+       if (offset < 0) {
+               negative_offset = -offset-1;
+               offset = 0;
+       }
+
        pc.start = offset;
        pc.output = 0;
        pc.needle_pos = 0;
@@ -912,7 +918,7 @@ mbfl_strpos(
 
        /* feed data */
        p = haystack->val;
-       n = haystack->len;
+       n = haystack->len - negative_offset;
        if (p != NULL) {
                while (n > 0) {
                        if ((*filter->filter_function)(*p++, filter) < 0) {