Author: ian
Date: Mon Mar 16 21:09:11 2015
New Revision: 280156
URL: https://svnweb.freebsd.org/changeset/base/280156

Log:
  Fix minor fallout from sysctl strings being nulterminated now.  The dmesg
  code can read the buffer via sysctl or from a core file.  In the core file
  case there will be no nulterm, and the code copes with that, but now in the
  sysctl case there is a nulterm (there didn't used to be).  The least
  disruptive way to restore the old behavior (and eliminate a spurious '\000'
  at the end of the output) is to remove the nulterm (by decrementing the
  buffer length) in the sysctl case.

Modified:
  head/sbin/dmesg/dmesg.c

Modified: head/sbin/dmesg/dmesg.c
==============================================================================
--- head/sbin/dmesg/dmesg.c     Mon Mar 16 20:24:37 2015        (r280155)
+++ head/sbin/dmesg/dmesg.c     Mon Mar 16 21:09:11 2015        (r280156)
@@ -111,8 +111,10 @@ main(int argc, char *argv[])
 
        if (memf == NULL) {
                /*
-                * Running kernel.  Use sysctl.  This gives an unwrapped
-                * buffer as a side effect.
+                * Running kernel.  Use sysctl.  This gives an unwrapped buffer
+                * as a side effect.  Remove nulterm (if present) so the value
+                * returned by sysctl is formatted as the rest of the code
+                * expects (the same as the value read from a core file below).
                 */
                if (sysctlbyname("kern.msgbuf", NULL, &buflen, NULL, 0) == -1)
                        err(1, "sysctl kern.msgbuf");
@@ -120,6 +122,8 @@ main(int argc, char *argv[])
                        errx(1, "malloc failed");
                if (sysctlbyname("kern.msgbuf", bp, &buflen, NULL, 0) == -1)
                        err(1, "sysctl kern.msgbuf");
+               if (buflen > 0 && bp[buflen - 1] == '\0')
+                       buflen--;
                if (clear)
                        if (sysctlbyname("kern.msgbuf_clear", NULL, NULL, 
&clear, sizeof(int)))
                                err(1, "sysctl kern.msgbuf_clear");
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