From feaa48d2461847ea8493e2adf55cefd9eda50922 Mon Sep 17 00:00:00 2001
From: alfred <alfred@FreeBSD.org>
Date: Thu, 1 Nov 2012 18:59:19 +0000
Subject: Add an option to display the current dump device via dumpon -l.

MFC after:	2 weeks
---
 sbin/dumpon/dumpon.c | 43 ++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 40 insertions(+), 3 deletions(-)

(limited to 'sbin/dumpon/dumpon.c')

diff --git a/sbin/dumpon/dumpon.c b/sbin/dumpon/dumpon.c
index 73d46b0..ac73399 100644
--- a/sbin/dumpon/dumpon.c
+++ b/sbin/dumpon/dumpon.c
@@ -46,6 +46,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/sysctl.h>
 
 #include <err.h>
+#include <errno.h>
 #include <fcntl.h>
 #include <paths.h>
 #include <stdint.h>
@@ -60,9 +61,10 @@ static int	verbose;
 static void
 usage(void)
 {
-	fprintf(stderr, "%s\n%s\n",
+	fprintf(stderr, "%s\n%s\n%s\n",
 	    "usage: dumpon [-v] special_file",
-	    "       dumpon [-v] off");
+	    "       dumpon [-v] off",
+	    "       dumpon -l");
 	exit(EX_USAGE);
 }
 
@@ -92,15 +94,45 @@ check_size(int fd, const char *fn)
 	}
 }
 
+static void
+listdumpdev(void)
+{
+	char dumpdev[PATH_MAX];
+	size_t len;
+	const char *sysctlname = "kern.shutdown.dumpdevname";
+
+	len = sizeof(dumpdev);
+	if (sysctlbyname(sysctlname, &dumpdev, &len, NULL, 0) != 0) {
+		if (errno == ENOMEM) {
+			err(EX_OSERR, "Kernel returned too large of a buffer for '%s'\n",
+				sysctlname);
+		} else {
+			err(EX_OSERR, "Sysctl get '%s'\n", sysctlname);
+		}
+	}
+	if (verbose) {
+		printf("kernel dumps on ");
+	}
+	if (strlen(dumpdev) == 0) {
+		printf("%s\n", _PATH_DEVNULL);
+	} else {
+		printf("%s\n", dumpdev);
+	}
+}
+
 int
 main(int argc, char *argv[])
 {
 	int ch;
 	int i, fd;
 	u_int u;
+	int do_listdumpdev = 0;
 
-	while ((ch = getopt(argc, argv, "v")) != -1)
+	while ((ch = getopt(argc, argv, "lv")) != -1)
 		switch((char)ch) {
+		case 'l':
+			do_listdumpdev = 1;
+			break;
 		case 'v':
 			verbose = 1;
 			break;
@@ -111,6 +143,11 @@ main(int argc, char *argv[])
 	argc -= optind;
 	argv += optind;
 
+	if (do_listdumpdev) {
+		listdumpdev();
+		exit(EX_OK);
+	}
+
 	if (argc != 1)
 		usage();
 
-- 
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