From: Alejandro Colomar <alx@kernel.org>
Date: Wed, 15 Nov 2023 21:49:13 +0000 (+0100)
Subject: lib/env.c: Replace strncpy(3) call by stpcpy(mempcpy(), "")
X-Git-Tag: 4.15.0-rc1~108
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=72060a2b2bdede62fd5874f10d523379a4dbdcc4;p=thirdparty%2Fshadow.git

lib/env.c: Replace strncpy(3) call by stpcpy(mempcpy(), "")

We were using strncpy(3), which is designed to copy from a string into a
(null-padded) fixed-size character array.  However, we were doing the
opposite: copying from a known-size array (which was a prefix of a
string), into a string.  That's why we had to manually zero the buffer
afterwards.

Use instead mempcpy(3) to copy the non-null bytes, and then terminate
with a null byte with stpcpy(..., "").

Cc: "Serge E. Hallyn" <serge@hallyn.com>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
---

diff --git a/lib/env.c b/lib/env.c
index dc35c54d9..6d6b1370c 100644
--- a/lib/env.c
+++ b/lib/env.c
@@ -192,8 +192,7 @@ void set_env (int argc, char *const *argv)
 			}
 
 			if (NULL != *p) {
-				strncpy (variable, *argv, (size_t)(cp - *argv));
-				variable[cp - *argv] = '\0';
+				stpcpy(mempcpy(variable, *argv, (size_t)(cp - *argv)), "");
 				printf (_("You may not change $%s\n"),
 					variable);
 				continue;