Fix bogus code in contrib/ tsearch dictionary examples.

Both dict_int and dict_xsyn were blithely assuming that whatever memory
palloc gives back will be pre-zeroed.  This would typically work for
just about long enough to run their regression tests, and no longer :-(.

The pre-9.0 code in dict_xsyn was even lamer than that, as it would
happily give back a pointer to the result of palloc(0), encouraging
its caller to access off the end of memory.  Again, this would just
barely fail to fail as long as memory contained nothing but zeroes.

Per a report from Rodrigo Hjort that code based on these examples
didn't work reliably.

diff --git a/contrib/dict_int/dict_int.c b/contrib/dict_int/dict_int.c
index e555cdb89351c7efeda2b04d513ba576ec4f923f..fcc154a9a40bb3ece2acfeb4a57a2e61cc228007 100644 (file)
--- a/contrib/dict_int/dict_int.c
+++ b/contrib/dict_int/dict_int.c
@@ -73,7 +73,7 @@ dintdict_lexize(PG_FUNCTION_ARGS)
        DictInt    *d = (DictInt *) PG_GETARG_POINTER(0);
        char       *in = (char *) PG_GETARG_POINTER(1);
        char       *txt = pnstrdup(in, PG_GETARG_INT32(2));
-       TSLexeme   *res = palloc(sizeof(TSLexeme) * 2);
+       TSLexeme   *res = palloc0(sizeof(TSLexeme) * 2);
 
        res[1].lexeme = NULL;
        if (PG_GETARG_INT32(2) > d->maxlen)

diff --git a/contrib/dict_xsyn/dict_xsyn.c b/contrib/dict_xsyn/dict_xsyn.c
index 511ef271e3e68a0630c4cb2bd5dc8272f4b0919d..1aa5e9540b1bfbf04ec2b19acf9ded9894b06ed6 100644 (file)
--- a/contrib/dict_xsyn/dict_xsyn.c
+++ b/contrib/dict_xsyn/dict_xsyn.c
@@ -200,7 +200,7 @@ dxsyn_lexize(PG_FUNCTION_ARGS)
                int                     nsyns = 0;
                bool            is_first = true;
 
-               res = palloc(0);
+               res = palloc(sizeof(TSLexeme));
 
                while (pos < value + value_length)
                {
@@ -212,13 +212,13 @@ dxsyn_lexize(PG_FUNCTION_ARGS)
                        *end = '\0';
 
                        res = repalloc(res, sizeof(TSLexeme) * (nsyns + 2));
-                       res[nsyns].lexeme = NULL;
 
                        /* first word is added to result only if KEEPORIG flag is set */
                        if (d->keeporig || !is_first)
                        {
                                res[nsyns].lexeme = pstrdup(syn);
-                               res[nsyns + 1].lexeme = NULL;
+                               res[nsyns].nvariant = 0;
+                               res[nsyns].flags = 0;
 
                                nsyns++;
                        }
@@ -228,6 +228,8 @@ dxsyn_lexize(PG_FUNCTION_ARGS)
                        pos = end + 1;
                }
 
+               res[nsyns].lexeme = NULL;
+
                pfree(value);
        }