From: Matthew Dillon <dillon@apollo.backplane.com>
Date: Tue, 29 Nov 2011 21:41:54 +0000 (-0800)
Subject: dmesg - Don't fail when the kernel is adding to the dmesg quickly
X-Git-Tag: v3.0.0~532
X-Git-Url: http://gitweb.dragonflybsd.org/dragonfly.git/commitdiff_plain/35bb81cee37e18ff19a165bb1ec20e52fadbe0b9

dmesg - Don't fail when the kernel is adding to the dmesg quickly

* If the kernel is quickly adding to the dmesg buffer and has not started
  recycling the FIFO the increasing size of the buffer will exceed the
  probed size.

* Add another 4K to the probed size to try to deal with this case.
---

diff --git a/sbin/dmesg/dmesg.c b/sbin/dmesg/dmesg.c
index 09da87f..93e7cf5 100644
--- a/sbin/dmesg/dmesg.c
+++ b/sbin/dmesg/dmesg.c
@@ -98,6 +98,7 @@ main(int argc, char **argv)
 		/* Running kernel. Use sysctl. */
 		if (sysctlbyname("kern.msgbuf", NULL, &buflen, NULL, 0) == -1)
 			err(1, "sysctl kern.msgbuf");
+		buflen += 4096;		/* add some slop */
 		if ((bp = malloc(buflen)) == NULL)
 			errx(1, "malloc failed");
 		if (sysctlbyname("kern.msgbuf", bp, &buflen, NULL, 0) == -1)