From: Alejandro Colomar <alx@kernel.org>
Date: Sat, 19 Jul 2025 08:48:06 +0000 (+0200)
Subject: src/chfn.c: Simplify checking for a long GECOS field
X-Git-Url: http://git.ipfire.org/gitweb/gitweb.cgi?a=commitdiff_plain;h=d4b0418b4bf86787bfd8692fb2328fe39c1105a8;p=thirdparty%2Fshadow.git

src/chfn.c: Simplify checking for a long GECOS field

Use a buffer of the exact size we want, and let SNPRINTF() decide if it
fits or not.

BTW, the old check seemed to be wrong: it wasn't accounting for the
commas in the 80-character limit, but that didn't make much sense.

Signed-off-by: Alejandro Colomar <alx@kernel.org>
---

diff --git a/src/chfn.c b/src/chfn.c
index b4f913ba1..ca654e0d7 100644
--- a/src/chfn.c
+++ b/src/chfn.c
@@ -561,7 +561,8 @@ static void check_fields (void)
  */
 int main (int argc, char **argv)
 {
-	char                 new_gecos[BUFSIZ];
+	int                  ret;
+	char                 new_gecos[80];
 	char                 *user;
 	const struct passwd  *pw;
 
@@ -643,14 +644,13 @@ int main (int argc, char **argv)
 	 * Build the new GECOS field by plastering all the pieces together,
 	 * if they will fit ...
 	 */
-	if ((strlen (fullnm) + strlen (roomno) + strlen (workph) +
-	     strlen (homeph) + strlen (slop)) > (unsigned int) 80) {
+	ret = SNPRINTF(new_gecos, "%s,%s,%s,%s%s%s",
+	               fullnm, roomno, workph, homeph,
+	               (!streq(slop, "")) ? "," : "", slop);
+	if (ret == -1) {
 		fprintf (stderr, _("%s: fields too long\n"), Prog);
 		fail_exit (E_NOPERM);
 	}
-	SNPRINTF(new_gecos, "%s,%s,%s,%s%s%s",
-	         fullnm, roomno, workph, homeph,
-	         (!streq(slop, "")) ? "," : "", slop);
 
 	/* Rewrite the user's gecos in the passwd file */
 	update_gecos (user, new_gecos);