utils-std

commit: 78fcb7b90d11100be507ea8a9870a5a5cdc37920
parent 40c908cd00a9f61fc669ff92ced34b99f7423f3f
Author: Haelwenn (lanodan) Monnier <contact@hacktivis.me>
Date:   Thu, 24 Apr 2025 21:37:33 +0200

cmd/expr: use snprintf instead of length estimate + sprintf

Diffstat:
M
cmd/expr.y
23
++++++++++++-----------
M
test-cmd/expr.sh
5
++++-

2 files changed, 16 insertions(+), 12 deletions(-)
diff --git a/cmd/expr.y b/cmd/expr.y
@@ -202,22 +202,23 @@ assert_to_integer(struct val *vp)
 static void
 to_string(struct val *vp)
 {
-	char *tmp;
-
 	if (vp->type == string || vp->type == numeric_string)
 		return;
 
-	/*
-	 * log_10(x) ~= 0.3 * log_2(x).  Rounding up gives the number
-	 * of digits; add one each for the sign and terminating null
-	 * character, respectively.
-	 */
-#define	NDIGITS(x) (3 * (sizeof(x) * CHAR_BIT) / 10 + 1 + 1 + 1)
-	tmp = malloc(NDIGITS(vp->u.i));
+	int ndigits = snprintf(NULL, 0, "%jd", vp->u.i);
+	if(ndigits < 0)
+		utils_errx(ERR_EXIT, "failed to pre-format integer %jd as a string", vp->u.i);
+
+	ndigits++; // NULL terminator
+
+	char *tmp = malloc(ndigits);
 	if (tmp == NULL)
-		utils_errx(ERR_EXIT, "malloc() failed");
+		utils_errx(ERR_EXIT, "malloc(%zd) for to_string() failed", ndigits);
+
+	int ret = snprintf(tmp, ndigits, "%jd", vp->u.i);
+	if(ret < 0)
+		utils_errx(ERR_EXIT, "failed to format integer %jd as a string", vp->u.i);
 
-	sprintf(tmp, "%jd", vp->u.i);
 	vp->type = string;
 	vp->u.s  = tmp;
 }
diff --git a/test-cmd/expr.sh b/test-cmd/expr.sh
@@ -4,7 +4,7 @@
 
 WD="$(dirname "$0")/../"
 target="${WD}/cmd/expr"
-plans=41
+plans=43
 
 . "${WD}/test-cmd/tap.sh"
 
@@ -80,3 +80,6 @@ t_args add '3
 ' 1 + 2
 t_args sub '2
 ' 3 - 1
+
+t_expr_no to_string_int_no '(' 0 : 0 ')' = 'foo'
+t_expr_ok to_string_int_ok '(' 'f00bar' : 'f[0-9][0-9]bar' ')' : 6