Add an -f option which allows one to specify a snp device to use.

Previously, watch would always use the first device it could
successfully open, but this isn't always desired.  Specifically, it
may not be desired during debugging (of snp), or if a particular snp
device has different permissions (which makes since after snp.c 1.64).

2 files changed, 30 insertions, 8 deletions

diff --git a/usr.sbin/watch/watch.8 b/usr.sbin/watch/watch.8
index 56b7343bf802..4b75dd504e70 100644
--- a/usr.sbin/watch/watch.8
+++ b/usr.sbin/watch/watch.8
@@ -2,7 +2,7 @@
 .\" @(#)watch.8		1.1 (FreeBSD) 2/17/95
 .\" $FreeBSD$
 .\"
-.Dd February 17, 1995
+.Dd November 24, 2001
 .Dt WATCH 8
 .Os
 .Sh NAME
@@ -11,6 +11,7 @@
 .Sh SYNOPSIS
 .Nm
 .Op Fl ciotnW
+.Op Fl f Ar snpdev
 .Op Ar tty
 .\"  watch [-ciotnW] [<tty name>]
 .Sh DESCRIPTION
@@ -29,6 +30,19 @@ If this option is not specified,
 .Nm
 will request a new tty if running in interactive mode or exit if running
 without a controlling tty.
+.It Fl f Ar snpdev
+If this option is specified,
+.Nm
+will use
+.Ar snpdev
+as the
+.Xr snp 4
+device.
+Without this option,
+.Nm
+will attempt to find the next available
+.Xr snp 4
+device.
 .It Fl i
 Force interactive mode.
 Interactive mode is a default if
diff --git a/usr.sbin/watch/watch.c b/usr.sbin/watch/watch.c
index 4d1c38d974db..d594ee0c7e69 100644
--- a/usr.sbin/watch/watch.c
+++ b/usr.sbin/watch/watch.c
@@ -71,6 +71,7 @@ int             opt_interactive = 1;
 int             opt_timestamp = 0;
 int		opt_write = 0;
 int		opt_no_switch = 0;
+const char	*opt_snpdev;
 
 char            dev_name[DEV_NAME_LEN];
 int             snp_io;
@@ -164,12 +165,16 @@ open_snp()
 	else
 		mode = O_RDONLY;
 
-	for (c = '0'; c <= '9'; c++) {
-		snp[8] = c;
-		if ((f = open(snp, mode)) < 0)
-			continue;
-		return f;
-	}
+	if (opt_snpdev == NULL)
+		for (c = '0'; c <= '9'; c++) {
+			snp[8] = c;
+			if ((f = open(snp, mode)) < 0)
+				continue;
+			return f;
+		}
+	else
+		if ((f = open(opt_snpdev, mode)) != -1)
+			return (f);
 	fatal(EX_OSFILE, "cannot open snoop device");
 	return (0);
 }
@@ -302,7 +307,7 @@ main(ac, av)
 		opt_interactive = 0;
 
 
-	while ((ch = getopt(ac, av, "Wciotn")) != -1)
+	while ((ch = getopt(ac, av, "Wciotnf:")) != -1)
 		switch (ch) {
 		case 'W':
 			opt_write = 1;
@@ -322,6 +327,9 @@ main(ac, av)
 		case 'n':
 			opt_no_switch = 1;
 			break;
+		case 'f':
+			opt_snpdev = optarg;
+			break;
 		case '?':
 		default:
 			usage();