Fix bogus calculation of potential output string length in translate().

diff --git a/src/backend/utils/adt/oracle_compat.c b/src/backend/utils/adt/oracle_compat.c
index db8c25a..56fe7a6 100644 (file)
--- a/src/backend/utils/adt/oracle_compat.c
+++ b/src/backend/utils/adt/oracle_compat.c
@@ -9,7 +9,7 @@
  *
  *
  * IDENTIFICATION
- *     $PostgreSQL: pgsql/src/backend/utils/adt/oracle_compat.c,v 1.72 2007/09/21 22:52:52 tgl Exp $
+ *     $PostgreSQL: pgsql/src/backend/utils/adt/oracle_compat.c,v 1.73 2007/09/22 05:35:42 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1162,30 +1162,34 @@ translate(PG_FUNCTION_ARGS)
                                tolen,
                                retlen,
                                i;
-
-       int                     str_len;
-       int                     estimate_len;
+       int                     worst_len;
        int                     len;
        int                     source_len;
        int                     from_index;
 
        m = VARSIZE_ANY_EXHDR(string);
-       
        if (m <= 0)
                PG_RETURN_TEXT_P(string);
+       source = VARDATA_ANY(string);
 
        fromlen = VARSIZE_ANY_EXHDR(from);
        from_ptr = VARDATA_ANY(from);
        tolen = VARSIZE_ANY_EXHDR(to);
        to_ptr = VARDATA_ANY(to);
 
-       str_len = VARSIZE_ANY_EXHDR(string);
-       source = VARDATA_ANY(string);
+       /*
+        * The worst-case expansion is to substitute a max-length character for
+        * a single-byte character at each position of the string.
+        */
+       worst_len = pg_database_encoding_max_length() * m;
 
-       estimate_len = (tolen * 1.0 / fromlen + 0.5) * str_len;
-       estimate_len = estimate_len > str_len ? estimate_len : str_len;
+       /* check for integer overflow */
+       if (worst_len / pg_database_encoding_max_length() != m)
+               ereport(ERROR,
+                               (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
+                                errmsg("requested length too large")));
 
-       result = (text *) palloc(estimate_len + VARHDRSZ);
+       result = (text *) palloc(worst_len + VARHDRSZ);
        target = VARDATA(result);
        retlen = 0;
 
@@ -1238,9 +1242,9 @@ translate(PG_FUNCTION_ARGS)
        SET_VARSIZE(result, retlen + VARHDRSZ);
 
        /*
-        * There may be some wasted space in the result if deletions occurred, but
-        * it's not worth reallocating it; the function result probably won't live
-        * long anyway.
+        * The function result is probably much bigger than needed, if we're
+        * using a multibyte encoding, but it's not worth reallocating it;
+        * the result probably won't live long anyway.
         */
 
        PG_RETURN_TEXT_P(result);