1 /*****************************************************************************\
2 * daemonize.c - daemonization routine
3 *****************************************************************************
4 * Copyright (C) 2002 The Regents of the University of California.
5 * Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
6 * Written by Mark A. Grondona <mgrondona@llnl.gov>.
7 * CODE-OCEC-09-009. All rights reserved.
8 *
9 * This file is part of Slurm, a resource management program.
10 * For details, see <https://slurm.schedmd.com/>.
11 * Please also read the included file: DISCLAIMER.
12 *
13 * Slurm is free software; you can redistribute it and/or modify it under
14 * the terms of the GNU General Public License as published by the Free
15 * Software Foundation; either version 2 of the License, or (at your option)
16 * any later version.
17 *
18 * In addition, as a special exception, the copyright holders give permission
19 * to link the code of portions of this program with the OpenSSL library under
20 * certain conditions as described in each individual source file, and
21 * distribute linked combinations including the two. You must obey the GNU
22 * General Public License in all respects for all of the code used other than
23 * OpenSSL. If you modify file(s) with this exception, you may extend this
24 * exception to your version of the file(s), but you are not obligated to do
25 * so. If you do not wish to do so, delete this exception statement from your
26 * version. If you delete this exception statement from all source files in
27 * the program, then also delete it here.
28 *
29 * Slurm is distributed in the hope that it will be useful, but WITHOUT ANY
30 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
31 * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
32 * details.
33 *
34 * You should have received a copy of the GNU General Public License along
35 * with Slurm; if not, write to the Free Software Foundation, Inc.,
36 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
37 \*****************************************************************************/
38
39 #include <config.h>
40
41 #define _GNU_SOURCE
42
43 #include <fcntl.h>
44 #include <sys/resource.h>
45 #include <sys/stat.h>
46 #include <sys/types.h>
47 #include <unistd.h>
48
49 #include "src/common/daemonize.h"
50 #include "src/common/fd.h"
51 #include "src/common/log.h"
52 #include "src/common/macros.h"
53 #include "src/common/xassert.h"
54
55 /*
56 * Double-fork and go into background.
57 * Caller is responsible for umasks
58 */
xdaemon(void)59 int xdaemon(void)
60 {
61 int devnull;
62
63 switch (fork()) {
64 case 0 : break; /* child */
65 case -1 : return -1;
66 default : _exit(0); /* exit parent */
67 }
68
69 if (setsid() < 0)
70 return -1;
71
72 switch (fork()) {
73 case 0 : break; /* child */
74 case -1: return -1;
75 default: _exit(0); /* exit parent */
76 }
77
78 /*
79 * dup stdin, stdout, and stderr onto /dev/null
80 */
81 devnull = open("/dev/null", O_RDWR);
82 if (devnull < 0)
83 error("Unable to open /dev/null: %m");
84 if (dup2(devnull, STDIN_FILENO) < 0)
85 error("Unable to dup /dev/null onto stdin: %m");
86 if (dup2(devnull, STDOUT_FILENO) < 0)
87 error("Unable to dup /dev/null onto stdout: %m");
88 if (dup2(devnull, STDERR_FILENO) < 0)
89 error("Unable to dup /dev/null onto stderr: %m");
90 if (close(devnull) < 0)
91 error("Unable to close /dev/null: %m");
92
93 return 0;
94 }
95
96 /*
97 * Read and return pid stored in pidfile.
98 * Returns 0 if file doesn't exist or pid cannot be read.
99 * If pidfd != NULL, the file will be kept open and the fd
100 * returned.
101 */
102 pid_t
read_pidfile(const char * pidfile,int * pidfd)103 read_pidfile(const char *pidfile, int *pidfd)
104 {
105 int fd;
106 FILE *fp = NULL;
107 unsigned long pid;
108 pid_t lpid;
109
110 if ((fd = open(pidfile, O_RDONLY)) < 0)
111 return ((pid_t) 0);
112
113 if (!(fp = fdopen(fd, "r"))) {
114 error ("Unable to access old pidfile at `%s': %m", pidfile);
115 (void) close(fd);
116 return ((pid_t) 0);
117 }
118
119 if (fscanf(fp, "%lu", &pid) < 1) {
120 error ("Possible corrupt pidfile `%s'", pidfile);
121 (void) close(fd);
122 return ((pid_t) 0);
123 }
124
125 if ((lpid = fd_is_read_lock_blocked(fd)) == (pid_t) 0) {
126 verbose ("pidfile not locked, assuming no running daemon");
127 (void) close(fd);
128 return ((pid_t) 0);
129 }
130
131 if (lpid != (pid_t) pid)
132 fatal ("pidfile locked by %lu but contains pid=%lu",
133 (unsigned long) lpid, (unsigned long) pid);
134
135 if (pidfd != NULL)
136 *pidfd = fd;
137 else
138 (void) close(fd);
139
140 /* fclose(fp); NOTE: DO NOT CLOSE, "fd" CONTAINS FILE DESCRIPTOR */
141 return (lpid);
142 }
143
144
145
146 int
create_pidfile(const char * pidfile,uid_t uid)147 create_pidfile(const char *pidfile, uid_t uid)
148 {
149 FILE *fp;
150 int fd;
151
152 xassert(pidfile != NULL);
153 xassert(pidfile[0] == '/');
154
155 fd = open(pidfile, O_CREAT | O_WRONLY | O_TRUNC | O_CLOEXEC,
156 S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
157 if (fd < 0) {
158 error("Unable to open pidfile `%s': %m", pidfile);
159 return -1;
160 }
161
162 if (!(fp = fdopen(fd, "w"))) {
163 error("Unable to access pidfile at `%s': %m", pidfile);
164 (void) close(fd);
165 return -1;
166 }
167
168 if (fd_get_write_lock(fd) < 0) {
169 error ("Unable to lock pidfile `%s': %m", pidfile);
170 goto error;
171 }
172
173 if (fprintf(fp, "%lu\n", (unsigned long) getpid()) == EOF) {
174 error("Unable to write to pidfile `%s': %m", pidfile);
175 goto error;
176 }
177
178 fflush(fp);
179
180 if (uid && (fchown(fd, uid, -1) < 0))
181 error ("Unable to reset owner of pidfile: %m");
182
183 /* fclose(fp); NOTE: DO NOT CLOSE, "fd" CONTAINS FILE DESCRIPTOR */
184 return fd;
185
186 error:
187 (void)fclose(fp); /* Ignore errors */
188
189 if (unlink(pidfile) < 0)
190 error("Unable to remove pidfile `%s': %m", pidfile);
191 return -1;
192 }
193
194 void
test_core_limit(void)195 test_core_limit(void)
196 {
197 #ifdef RLIMIT_CORE
198 struct rlimit rlim[1];
199 if (getrlimit(RLIMIT_CORE, rlim) < 0)
200 error("Unable to get core limit");
201 else if (rlim->rlim_cur != RLIM_INFINITY) {
202 rlim->rlim_cur /= 1024; /* bytes to KB */
203 if (rlim->rlim_cur < 2048) {
204 verbose("Warning: Core limit is only %ld KB",
205 (long int) rlim->rlim_cur);
206 }
207 }
208 #endif
209 return;
210 }
211