In snmpd_metrics process keep file descriptors 0 1 2 open.

stdin, stdout, stderr are reserverd.  They should point to a terminal,
a redirect file or pipe, or /dev/null.  Closing them and allocating
arbitrary files in those places is not good.  Call closefrom with
4 to keep /dev/null open in snmpd_metrics.

OK martijn@

diff --git a/usr.sbin/snmpd/snmpd.c b/usr.sbin/snmpd/snmpd.c
index c48b2a9..60af191 100644 (file)
--- a/usr.sbin/snmpd/snmpd.c
+++ b/usr.sbin/snmpd/snmpd.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: snmpd.c,v 1.51 2024/04/08 13:18:54 tobhe Exp $        */
+/*     $OpenBSD: snmpd.c,v 1.52 2024/04/12 14:17:42 bluhm Exp $        */
 
 /*
  * Copyright (c) 2007, 2008, 2012 Reyk Floeter <reyk@openbsd.org>
@@ -358,14 +358,10 @@ snmpd_backend(struct snmpd *env)
        }
        if (env->sc_flags & SNMPD_F_VERBOSE)
                argv[i++] = "-vv";
-       if (env->sc_flags & SNMPD_F_DEBUG) {
+       if (env->sc_flags & SNMPD_F_DEBUG)
                argv[i++] = "-d";
-               argv[i++] = "-x";
-               argv[i++] = "3";
-       } else {
-               argv[i++] = "-x";
-               argv[i++] = "0";
-       }
+       argv[i++] = "-x";
+       argv[i++] = "3";
        argv[i] = NULL;
        while ((file = readdir(dir)) != NULL) {
                if (file->d_name[0] == '.')
@@ -377,10 +373,9 @@ snmpd_backend(struct snmpd *env)
                        fatal("fork");
                case 0:
                        close(pair[1]);
-                       if (dup2(pair[0],
-                           env->sc_flags & SNMPD_F_DEBUG ? 3 : 0) == -1)
+                       if (dup2(pair[0], 3) == -1)
                                fatal("dup2");
-                       if (closefrom(env->sc_flags & SNMPD_F_DEBUG ? 4 : 1) == -1)
+                       if (closefrom(4) == -1)
                                fatal("closefrom");
                        (void)snprintf(execpath, sizeof(execpath), "%s/%s",
                            SNMPD_BACKEND, file->d_name);