From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Thu, 3 Nov 2011 23:18:10 +0000 (-0400)
Subject: Fix bogus code in contrib/ tsearch dictionary examples.
X-Git-Tag: REL8_3_17~13
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=0dddbbcd3178242f24d7476e12436ec7e1340f6d;p=postgresql

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 163a5029a0..d0941c66ad 100644
--- 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 68a631c17a..892983c48b 100644
--- 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);
 	}