2 * Copyright (c) 2014 Nicira, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at:
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
18 #include "daemon-private.h"
24 VLOG_DEFINE_THIS_MODULE(daemon);
26 /* For each of the standard file descriptors, whether to replace it by
27 * /dev/null (if false) or keep it for the daemon to use (if true). */
28 static bool save_fds[3];
30 /* Will daemonize() really detach? */
37 /* If configured with set_pidfile() or set_detach(), creates the pid file and
38 * detaches from the foreground session. */
46 /* Sets up a following call to daemonize() to create a pidfile named 'name'.
47 * If 'name' begins with '/' (or contains ':' in windows), then it is treated
48 * as an absolute path. Otherwise, it is taken relative to RUNDIR,
49 * which is $(prefix)/var/run by default.
51 * If 'name' is null, then program_name followed by ".pid" is used. */
53 set_pidfile(const char *name)
55 assert_single_threaded();
57 pidfile = make_pidfile_name(name);
60 /* A daemon doesn't normally have any use for the file descriptors for stdin,
61 * stdout, and stderr after it detaches. To keep these file descriptors from
62 * e.g. holding an SSH session open, by default detaching replaces each of
63 * these file descriptors by /dev/null. But a few daemons expect the user to
64 * redirect stdout or stderr to a file, in which case it is desirable to keep
65 * these file descriptors. This function, therefore, disables replacing 'fd'
66 * by /dev/null when the daemon detaches. */
68 daemon_save_fd(int fd)
70 ovs_assert(fd == STDIN_FILENO ||
71 fd == STDOUT_FILENO ||
76 /* Returns a readable and writable fd for /dev/null, if successful, otherwise
77 * a negative errno value. The caller must not close the returned fd (because
78 * the same fd will be handed out to subsequent callers). */
84 char *device = "/dev/null";
90 null_fd = open(device, O_RDWR);
93 VLOG_ERR("could not open %s: %s", device, ovs_strerror(error));
101 /* Close standard file descriptors (except any that the client has requested we
102 * leave open by calling daemon_save_fd()). If we're started from e.g. an SSH
103 * session, then this keeps us from holding that session open artificially. */
105 close_standard_fds(void)
107 int null_fd = get_null_fd();
111 for (fd = 0; fd < 3; fd++) {
118 /* Disable logging to stderr to avoid wasting CPU time. */
119 vlog_set_levels(NULL, VLF_CONSOLE, VLL_OFF);