[src/trunk]: src/lib/libkvm When using /dev/ksyms, don't keep it open more th...

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

details:   https://anonhg.NetBSD.org/src/rev/341287f71bc0
branches:  trunk
changeset: 554918:341287f71bc0
user:      cube <cube%NetBSD.org@localhost>
date:      Tue Nov 04 14:59:10 2003 +0000

description:
When using /dev/ksyms, don't keep it open more than strictly necessary.
This allows LKM manipulation while an application using libkvm, such as
vmstat or gkrellm, is running.

Patch reviewed by Anders Magnusson.

diffstat:

 lib/libkvm/kvm.c |  37 +++++++++++++++++++++++++++++++++----
 1 files changed, 33 insertions(+), 4 deletions(-)

diffs (71 lines):

diff -r 33e6f17ba8a5 -r 341287f71bc0 lib/libkvm/kvm.c
--- a/lib/libkvm/kvm.c  Tue Nov 04 14:52:22 2003 +0000
+++ b/lib/libkvm/kvm.c  Tue Nov 04 14:59:10 2003 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: kvm.c,v 1.81 2003/08/07 16:44:36 agc Exp $     */
+/*     $NetBSD: kvm.c,v 1.82 2003/11/04 14:59:10 cube Exp $    */
 
 /*-
  * Copyright (c) 1989, 1992, 1993
@@ -38,7 +38,7 @@
 #if 0
 static char sccsid[] = "@(#)kvm.c      8.2 (Berkeley) 2/13/94";
 #else
-__RCSID("$NetBSD: kvm.c,v 1.81 2003/08/07 16:44:36 agc Exp $");
+__RCSID("$NetBSD: kvm.c,v 1.82 2003/11/04 14:59:10 cube Exp $");
 #endif
 #endif /* LIBC_SCCS and not lint */
 
@@ -337,6 +337,16 @@
                                _kvm_syserr(kd, kd->program, "%s", uf);
                                goto failed;
                        }
+               } else {
+                       /*
+                        * We're here because /dev/ksyms was opened
+                        * successfully.  However, we don't want to keep it
+                        * open, so we close it now.  Later, we will open
+                        * it again, since it will be the only case where
+                        * kd->nlfd is negative.
+                        */
+                       close(kd->nlfd);
+                       kd->nlfd = -1;
                }
        } else {
                /*
@@ -733,14 +743,33 @@
        kvm_t *kd;
        struct nlist *nl;
 {
-       int rv;
+       int rv, nlfd;
+
+       /*
+        * kd->nlfd might be negative when we get here, and in that
+        * case that means that we're using /dev/ksyms.
+        * So open it again, just for the time we retrieve the list.
+        */
+       if (kd->nlfd < 0) {
+               nlfd = open_cloexec(_PATH_KSYMS, O_RDONLY, 0);
+               if (nlfd < 0) {
+                       _kvm_err(kd, 0, "failed to open %s", _PATH_KSYMS);
+                       return (nlfd);
+               }
+       } else
+               nlfd = kd->nlfd;
 
        /*
         * Call the nlist(3) routines to retrieve the given namelist.
         */
-       rv = __fdnlist(kd->nlfd, nl);
+       rv = __fdnlist(nlfd, nl);
+
        if (rv == -1)
                _kvm_err(kd, 0, "bad namelist");
+
+       if (kd->nlfd < 0)
+               close(nlfd);
+
        return (rv);
 }