Teach regex_fixed_prefix() the correct handling of advanced regex

escapes --- they aren't simply quoted characters.  Problem noted by
Antti Salmela.  Also fix problem with incorrect handling of multibyte
characters when followed by a quantifier.

diff --git a/src/backend/utils/adt/selfuncs.c b/src/backend/utils/adt/selfuncs.c
index a3f782895b9b7f765045409042adc20cbc43dc64..c388d28717e42a94ed23047949a5a702ed390ddd 100644 (file)
--- a/src/backend/utils/adt/selfuncs.c
+++ b/src/backend/utils/adt/selfuncs.c
@@ -15,7 +15,7 @@
  *
  *
  * IDENTIFICATION
- *   $PostgreSQL: pgsql/src/backend/utils/adt/selfuncs.c,v 1.167 2004/11/09 00:34:42 tgl Exp $
+ *   $PostgreSQL: pgsql/src/backend/utils/adt/selfuncs.c,v 1.168 2004/12/02 02:45:07 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -3459,6 +3459,8 @@ regex_fixed_prefix(Const *patt_const, bool case_insensitive,
    char       *match;
    int         pos,
                match_pos,
+               prev_pos,
+               prev_match_pos,
                paren_depth;
    char       *patt;
    char       *rest;
@@ -3519,11 +3521,13 @@ regex_fixed_prefix(Const *patt_const, bool case_insensitive,
 
    /* OK, allocate space for pattern */
    match = palloc(strlen(patt) + 1);
-   match_pos = 0;
+   prev_match_pos = match_pos = 0;
 
    /* note start at pos 1 to skip leading ^ */
-   for (pos = 1; patt[pos]; pos++)
+   for (prev_pos = pos = 1; patt[pos]; )
    {
+       int     len;
+
        /*
         * Check for characters that indicate multiple possible matches
         * here. XXX I suspect isalpha() is not an adequately
@@ -3537,6 +3541,14 @@ regex_fixed_prefix(Const *patt_const, bool case_insensitive,
            (case_insensitive && isalpha((unsigned char) patt[pos])))
            break;
 
+       /*
+        * In AREs, backslash followed by alphanumeric is an escape, not
+        * a quoted character.  Must treat it as having multiple possible
+        * matches.
+        */
+       if (patt[pos] == '\\' && isalnum((unsigned char) patt[pos + 1]))
+           break;
+
        /*
         * Check for quantifiers.  Except for +, this means the preceding
         * character is optional, so we must remove it from the prefix
@@ -3546,14 +3558,13 @@ regex_fixed_prefix(Const *patt_const, bool case_insensitive,
            patt[pos] == '?' ||
            patt[pos] == '{')
        {
-           if (match_pos > 0)
-               match_pos--;
-           pos--;
+           match_pos = prev_match_pos;
+           pos = prev_pos;
            break;
        }
        if (patt[pos] == '+')
        {
-           pos--;
+           pos = prev_pos;
            break;
        }
        if (patt[pos] == '\\')
@@ -3563,7 +3574,14 @@ regex_fixed_prefix(Const *patt_const, bool case_insensitive,
            if (patt[pos] == '\0')
                break;
        }
-       match[match_pos++] = patt[pos];
+       /* save position in case we need to back up on next loop cycle */
+       prev_match_pos = match_pos;
+       prev_pos = pos;
+       /* must use encoding-aware processing here */
+       len = pg_mblen(&patt[pos]);
+       memcpy(&match[match_pos], &patt[pos], len);
+       match_pos += len;
+       pos += len;
    }
 
    match[match_pos] = '\0';