Make replace(), split_part(), and string_to_array() behave somewhat sanely

when handed an invalidly-encoded pattern.  The previous coding could get
into an infinite loop if pg_mb2wchar_with_len() returned a zero-length
string after we'd tested for nonempty pattern; which is exactly what it
will do if the string consists only of an incomplete multibyte character.
This led to either an out-of-memory error or a backend crash depending
on platform.  Per report from Wiktor Wodecki.

diff --git a/src/backend/utils/adt/varlena.c b/src/backend/utils/adt/varlena.c
index 0b5b4fd16a402e92ccf6fd6b814327186884d7cf..b0c6d8b62aa83b34d7f0e58559d685b517e4ffef 100644 (file)
--- a/src/backend/utils/adt/varlena.c
+++ b/src/backend/utils/adt/varlena.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *   $PostgreSQL: pgsql/src/backend/utils/adt/varlena.c,v 1.156 2007/04/06 04:21:43 tgl Exp $
+ *   $PostgreSQL: pgsql/src/backend/utils/adt/varlena.c,v 1.157 2007/07/19 20:34:20 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -2111,8 +2111,8 @@ replace_text(PG_FUNCTION_ARGS)
    text       *src_text = PG_GETARG_TEXT_P(0);
    text       *from_sub_text = PG_GETARG_TEXT_P(1);
    text       *to_sub_text = PG_GETARG_TEXT_P(2);
-   int         src_text_len = TEXTLEN(src_text);
-   int         from_sub_text_len = TEXTLEN(from_sub_text);
+   int         src_text_len;
+   int         from_sub_text_len;
    TextPositionState state;
    text       *ret_text;
    int         start_posn;
@@ -2121,11 +2121,22 @@ replace_text(PG_FUNCTION_ARGS)
    char       *start_ptr;
    StringInfoData str;
 
-   if (src_text_len == 0 || from_sub_text_len == 0)
-       PG_RETURN_TEXT_P(src_text);
-
    text_position_setup(src_text, from_sub_text, &state);
 
+   /*
+    * Note: we check the converted string length, not the original, because
+    * they could be different if the input contained invalid encoding.
+    */
+   src_text_len = state.len1;
+   from_sub_text_len = state.len2;
+
+   /* Return unmodified source string if empty source or pattern */
+   if (src_text_len < 1 || from_sub_text_len < 1)
+   {
+       text_position_cleanup(&state);
+       PG_RETURN_TEXT_P(src_text);
+   }
+
    start_posn = 1;
    curr_posn = text_position_next(1, &state);
 
@@ -2143,6 +2154,8 @@ replace_text(PG_FUNCTION_ARGS)
 
    do
    {
+       CHECK_FOR_INTERRUPTS();
+
        /* copy the data skipped over by last text_position_next() */
        chunk_len = charlen_to_bytelen(start_ptr, curr_posn - start_posn);
        appendBinaryStringInfo(&str, start_ptr, chunk_len);
@@ -2449,8 +2462,8 @@ split_text(PG_FUNCTION_ARGS)
    text       *inputstring = PG_GETARG_TEXT_P(0);
    text       *fldsep = PG_GETARG_TEXT_P(1);
    int         fldnum = PG_GETARG_INT32(2);
-   int         inputstring_len = TEXTLEN(inputstring);
-   int         fldsep_len = TEXTLEN(fldsep);
+   int         inputstring_len;
+   int         fldsep_len;
    TextPositionState state;
    int         start_posn;
    int         end_posn;
@@ -2462,13 +2475,26 @@ split_text(PG_FUNCTION_ARGS)
                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                 errmsg("field position must be greater than zero")));
 
+   text_position_setup(inputstring, fldsep, &state);
+
+   /*
+    * Note: we check the converted string length, not the original, because
+    * they could be different if the input contained invalid encoding.
+    */
+   inputstring_len = state.len1;
+   fldsep_len = state.len2;
+
    /* return empty string for empty input string */
    if (inputstring_len < 1)
+   {
+       text_position_cleanup(&state);
        PG_RETURN_TEXT_P(PG_STR_GET_TEXT(""));
+   }
 
    /* empty field separator */
    if (fldsep_len < 1)
    {
+       text_position_cleanup(&state);
        /* if first field, return input string, else empty string */
        if (fldnum == 1)
            PG_RETURN_TEXT_P(inputstring);
@@ -2476,8 +2502,6 @@ split_text(PG_FUNCTION_ARGS)
            PG_RETURN_TEXT_P(PG_STR_GET_TEXT(""));
    }
 
-   text_position_setup(inputstring, fldsep, &state);
-
    /* identify bounds of first field */
    start_posn = 1;
    end_posn = text_position_next(1, &state);
@@ -2537,8 +2561,8 @@ text_to_array(PG_FUNCTION_ARGS)
 {
    text       *inputstring = PG_GETARG_TEXT_P(0);
    text       *fldsep = PG_GETARG_TEXT_P(1);
-   int         inputstring_len = TEXTLEN(inputstring);
-   int         fldsep_len = TEXTLEN(fldsep);
+   int         inputstring_len;
+   int         fldsep_len;
    TextPositionState state;
    int         fldnum;
    int         start_posn;
@@ -2548,19 +2572,32 @@ text_to_array(PG_FUNCTION_ARGS)
    text       *result_text;
    ArrayBuildState *astate = NULL;
 
+   text_position_setup(inputstring, fldsep, &state);
+
+   /*
+    * Note: we check the converted string length, not the original, because
+    * they could be different if the input contained invalid encoding.
+    */
+   inputstring_len = state.len1;
+   fldsep_len = state.len2;
+
    /* return NULL for empty input string */
    if (inputstring_len < 1)
+   {
+       text_position_cleanup(&state);
        PG_RETURN_NULL();
+   }
 
    /*
     * empty field separator return one element, 1D, array using the input
     * string
     */
    if (fldsep_len < 1)
+   {
+       text_position_cleanup(&state);
        PG_RETURN_ARRAYTYPE_P(create_singleton_array(fcinfo, TEXTOID,
                                           PointerGetDatum(inputstring), 1));
-
-   text_position_setup(inputstring, fldsep, &state);
+   }
 
    start_posn = 1;
    /* start_ptr points to the start_posn'th character of inputstring */
@@ -2568,6 +2605,8 @@ text_to_array(PG_FUNCTION_ARGS)
 
    for (fldnum = 1;; fldnum++) /* field number is 1 based */
    {
+       CHECK_FOR_INTERRUPTS();
+
        end_posn = text_position_next(start_posn, &state);
 
        if (end_posn == 0)