Use psprintf to simplify gtsvectorout()

The buffer allocation was correct, but looked archaic and scary:

- It was weird to calculate the buffer size before determining which
  format string was used. With the same effort, we could've used the
  right-sized buffer for each branch.

- Commit aa0d3504560 added one more possible return string ("all true
  bits"), but didn't adjust the code at the top of the function to
  calculate the returned string's max size. It was not a live bug,
  because the new string was smaller than the existing ones, but
  seemed wrong in principle.

- Use of sprintf() is generally eyebrow-raising these days

Switch to psprintf(). psprintf() allocates a larger buffer than what
was allocated before, 128 bytes vs 80 bytes, which is acceptable as
this code is not performance or space critical.

Reviewed-by: Andres Freund
Discussion: https://www.postgresql.org/message-id/54c29fb0-edf2-48ea-9814-44e918bbd6e8@iki.fi

1 files changed, 4 insertions, 13 deletions

diff --git a/src/backend/utils/adt/tsgistidx.c b/src/backend/utils/adt/tsgistidx.c
index 5698ee5502b..1438ff35209 100644
--- a/src/backend/utils/adt/tsgistidx.c
+++ b/src/backend/utils/adt/tsgistidx.c
@@ -96,34 +96,25 @@ gtsvectorin(PG_FUNCTION_ARGS)
 	PG_RETURN_VOID();			/* keep compiler quiet */
 }
 
-#define SINGOUTSTR	"%d true bits, %d false bits"
-#define ARROUTSTR	"%d unique words"
-#define EXTRALEN	( 2*13 )
-
-static int	outbuf_maxlen = 0;
-
 Datum
 gtsvectorout(PG_FUNCTION_ARGS)
 {
 	SignTSVector *key = (SignTSVector *) PG_DETOAST_DATUM(PG_GETARG_DATUM(0));
 	char	   *outbuf;
 
-	if (outbuf_maxlen == 0)
-		outbuf_maxlen = 2 * EXTRALEN + Max(strlen(SINGOUTSTR), strlen(ARROUTSTR)) + 1;
-	outbuf = palloc(outbuf_maxlen);
-
 	if (ISARRKEY(key))
-		sprintf(outbuf, ARROUTSTR, (int) ARRNELEM(key));
+		outbuf = psprintf("%d unique words", (int) ARRNELEM(key));
 	else
 	{
 		if (ISALLTRUE(key))
-			sprintf(outbuf, "all true bits");
+			outbuf = pstrdup("all true bits");
 		else
 		{
 			int			siglen = GETSIGLEN(key);
 			int			cnttrue = sizebitvec(GETSIGN(key), siglen);
 
-			sprintf(outbuf, SINGOUTSTR, cnttrue, (int) SIGLENBIT(siglen) - cnttrue);
+			outbuf = psprintf("%d true bits, %d false bits",
+							  cnttrue, (int) SIGLENBIT(siglen) - cnttrue);
 		}
 	}