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 db8c25aa67770fc54c1d7c58c8e033faeffebe7a..56fe7a607f63732857a5850f564262dcd43990df 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);