lib/utmp.c: ttyname_ra(): Add macro

And use it instead of its pattern.

This macro enforces correct use of ttyname_r(3) with arrays.

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

diff --git a/lib/utmp.c b/lib/utmp.c
index 98348583e028e843b4c48c391dfca877b0ef9be2..6074de3d5ef1dbfd4d959754e2d390558bbe9cb0 100644 (file)
--- a/lib/utmp.c
+++ b/lib/utmp.c
@@ -44,6 +44,9 @@
 
 #define UTX_LINESIZE  countof(memberof(struct utmpx, ut_line))
 
+// ttyname_ra - tty name re-entrant array
+#define ttyname_ra(fd, buf)  ttyname_r(fd, buf, countof(buf))
+
 
 /*
  * is_my_tty -- determine if "tty" is the same TTY stdin is using
@@ -59,7 +62,7 @@ is_my_tty(const char tty[UTX_LINESIZE])
                strcpy (full_tty, "/dev/");
        strncat(full_tty, tty, UTX_LINESIZE);
 
-       if (ttyname_r(STDIN_FILENO, my_tty, countof(my_tty)) != 0) {
+       if (ttyname_ra(STDIN_FILENO, my_tty) != 0) {
                (void) puts (_("Unable to determine your tty name."));
                exit (EXIT_FAILURE);
        }