2 * daemon.c by Kern Sibbald
6 * this code is inspired by the Prentice Hall book
7 * "Unix Network Programming" by W. Richard Stevens
8 * and later updated from his book "Advanced Programming
9 * in the UNIX Environment"
11 * Initialize a daemon process completely detaching us from
12 * any terminal processes.
16 Copyright (C) 2000-2005 Kern Sibbald
18 This program is free software; you can redistribute it and/or
19 modify it under the terms of the GNU General Public License
20 version 2 as amended with additional clauses defined in the
21 file LICENSE in the main source directory.
23 This program is distributed in the hope that it will be useful,
24 but WITHOUT ANY WARRANTY; without even the implied warranty of
25 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
26 the file LICENSE for additional details.
32 extern int debug_level;
37 #if !defined(HAVE_CYGWIN) && !defined(HAVE_WIN32)
50 Dmsg0(900, "Enter daemon_start\n");
51 if ( (cpid = fork() ) < 0) {
53 Emsg1(M_ABORT, 0, _("Cannot fork to become daemon: %s\n"), be.strerror());
54 } else if (cpid > 0) {
55 exit(0); /* parent exits */
61 /* In the PRODUCTION system, we close ALL
62 * file descriptors except stdin, stdout, and stderr.
64 if (debug_level > 0) {
65 low_fd = 2; /* don't close debug output */
67 for (i=sysconf(_SC_OPEN_MAX)-1; i > low_fd; i--) {
71 /* Move to root directory. For debug we stay
72 * in current directory so dumps go there.
79 * Avoid creating files 666 but don't override any
80 * more restrictive mask set by the user.
88 * Make sure we have fd's 0, 1, 2 open
89 * If we don't do this one of our sockets may open
90 * there and if we then use stdout, it could
91 * send total garbage to our socket.
95 fd = open("/dev/null", O_RDONLY, 0644);
99 for(i=1; fd + i <= 2; i++) {
104 #endif /* HAVE_CYGWIN */
105 Dmsg0(900, "Exit daemon_start\n");