[src/trunk]: src/lib/libc/gen Use ioctl to find the pty name directly instead...

[christos <christos%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/886d47e704bf
branches:  trunk
changeset: 571091:886d47e704bf
user:      christos <christos%NetBSD.org@localhost>
date:      Thu Nov 11 00:00:15 2004 +0000

description:
Use ioctl to find the pty name directly instead of looking it up in
the database; it is much faster, and the common case these days.

diffstat:

 lib/libc/gen/ttyname.c |  10 ++++++++--
 1 files changed, 8 insertions(+), 2 deletions(-)

diffs (44 lines):

diff -r 43984fe123f8 -r 886d47e704bf lib/libc/gen/ttyname.c
--- a/lib/libc/gen/ttyname.c    Wed Nov 10 23:59:06 2004 +0000
+++ b/lib/libc/gen/ttyname.c    Thu Nov 11 00:00:15 2004 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: ttyname.c,v 1.19 2003/08/07 16:42:58 agc Exp $ */
+/*     $NetBSD: ttyname.c,v 1.20 2004/11/11 00:00:15 christos Exp $    */
 
 /*
  * Copyright (c) 1988, 1993
@@ -34,7 +34,7 @@
 #if 0
 static char sccsid[] = "@(#)ttyname.c  8.2 (Berkeley) 1/27/94";
 #else
-__RCSID("$NetBSD: ttyname.c,v 1.19 2003/08/07 16:42:58 agc Exp $");
+__RCSID("$NetBSD: ttyname.c,v 1.20 2004/11/11 00:00:15 christos Exp $");
 #endif
 #endif /* LIBC_SCCS and not lint */
 
@@ -51,12 +51,14 @@
 #include <string.h>
 #include <termios.h>
 #include <unistd.h>
+#include <sys/ioctl.h>
 
 #ifdef __weak_alias
 __weak_alias(ttyname,_ttyname)
 #endif
 
 static char buf[sizeof(_PATH_DEV) + MAXNAMLEN] = _PATH_DEV;
+static struct ptmget ptm;
 static char *oldttyname __P((struct stat *));
 
 char *
@@ -74,6 +76,10 @@
 
        _DIAGASSERT(fd != -1);
 
+       /* If it is a pty, deal with it quickly */
+       if (ioctl(fd, TIOCPTSNAME, &ptm) != -1)
+               return ptm.sn;
+
        /* Must be a terminal. */
        if (tcgetattr(fd, &ttyb) < 0)
                return (NULL);