Fix text_position to not scan past end of source string in multibyte

case, per report from Korea PostgreSQL Users' Group.

diff --git a/src/backend/utils/adt/varlena.c b/src/backend/utils/adt/varlena.c
index d90979029ed2a2267d34546a72e87b551aa09f77..8e2a4b66cecc9b350e69393356f937f1895a9dba 100644 (file)
--- a/src/backend/utils/adt/varlena.c
+++ b/src/backend/utils/adt/varlena.c
@@ -761,9 +761,6 @@ text_position(Datum str, Datum search_str, int matchnum)
        len1 = (VARSIZE(t1) - VARHDRSZ);
        len2 = (VARSIZE(t2) - VARHDRSZ);
 
-       /* no use in searching str past point where search_str will fit */
-       px = (len1 - len2);
-
        if (eml == 1)                           /* simple case - single byte encoding */
        {
                char       *p1,
@@ -772,6 +769,9 @@ text_position(Datum str, Datum search_str, int matchnum)
                p1 = VARDATA(t1);
                p2 = VARDATA(t2);
 
+               /* no use in searching str past point where search_str will fit */
+               px = (len1 - len2);
+
                for (p = 0; p <= px; p++)
                {
                        if ((*p2 == *p1) && (strncmp(p1, p2, len2) == 0))
@@ -799,6 +799,9 @@ text_position(Datum str, Datum search_str, int matchnum)
                (void) pg_mb2wchar_with_len((unsigned char *) VARDATA(t2), p2, len2);
                len2 = pg_wchar_strlen(p2);
 
+               /* no use in searching str past point where search_str will fit */
+               px = (len1 - len2);
+
                for (p = 0; p <= px; p++)
                {
                        if ((*p2 == *p1) && (pg_wchar_strncmp(p1, p2, len2) == 0))