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99ed9c43 MD |
1 | /* |
2 | * Copyright (C) 2013 - David Goulet <dgoulet@efficios.com> | |
3 | * Copyright (C) 2014 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
4 | * | |
5 | * This program is free software; you can redistribute it and/or modify it | |
6 | * under the terms of the GNU General Public License, version 2 only, as | |
7 | * published by the Free Software Foundation. | |
8 | * | |
9 | * This program is distributed in the hope that it will be useful, but WITHOUT | |
10 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
11 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for | |
12 | * more details. | |
13 | * | |
14 | * You should have received a copy of the GNU General Public License along with | |
15 | * this program; if not, write to the Free Software Foundation, Inc., 51 | |
16 | * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. | |
17 | */ | |
18 | ||
6c1c0768 | 19 | #define _LGPL_SOURCE |
99ed9c43 | 20 | #include <unistd.h> |
790c779e | 21 | #include <common/compat/paths.h> |
99ed9c43 MD |
22 | #include <fcntl.h> |
23 | #include <wait.h> | |
24 | #include <stdlib.h> | |
25 | ||
26 | #include <urcu/system.h> | |
27 | ||
28 | #include <src/common/daemonize.h> | |
29 | #include <src/common/error.h> | |
30 | ||
d5d51699 | 31 | LTTNG_HIDDEN |
99ed9c43 MD |
32 | int lttng_daemonize(pid_t *child_ppid, int *completion_flag, |
33 | int close_fds) | |
34 | { | |
35 | int ret; | |
36 | pid_t pid; | |
37 | ||
38 | /* Get parent pid of this process. */ | |
39 | *child_ppid = getppid(); | |
40 | ||
41 | pid = fork(); | |
42 | if (pid < 0) { | |
43 | PERROR("fork"); | |
44 | goto error; | |
45 | } else if (pid == 0) { | |
46 | int fd; | |
47 | pid_t sid; | |
48 | ||
49 | /* Child */ | |
50 | ||
51 | /* | |
52 | * Get the newly created parent pid so we can signal | |
53 | * that process when we are ready to operate. | |
54 | */ | |
55 | *child_ppid = getppid(); | |
56 | ||
57 | sid = setsid(); | |
58 | if (sid < 0) { | |
59 | PERROR("setsid"); | |
60 | goto error; | |
61 | } | |
62 | ||
63 | /* | |
64 | * Try to change directory to /. If we can't well at | |
65 | * least notify. | |
66 | */ | |
67 | ret = chdir("/"); | |
68 | if (ret < 0) { | |
69 | PERROR("chdir"); | |
70 | } | |
71 | ||
72 | if (close_fds) { | |
73 | fd = open(_PATH_DEVNULL, O_RDWR, 0); | |
74 | if (fd < 0) { | |
75 | PERROR("open %s", _PATH_DEVNULL); | |
76 | /* | |
77 | * Let 0, 1 and 2 open since we can't | |
78 | * bind them to /dev/null. | |
79 | */ | |
80 | } else { | |
81 | (void) dup2(fd, STDIN_FILENO); | |
82 | (void) dup2(fd, STDOUT_FILENO); | |
83 | (void) dup2(fd, STDERR_FILENO); | |
84 | if (fd > 2) { | |
85 | ret = close(fd); | |
86 | if (ret < 0) { | |
87 | PERROR("close"); | |
88 | } | |
89 | } | |
90 | } | |
91 | } | |
92 | goto end; | |
93 | } else { | |
94 | /* Parent */ | |
95 | ||
96 | /* | |
97 | * Waiting for child to notify this parent that it can | |
98 | * exit. Note that sleep() is interrupted before the 1 | |
99 | * second delay as soon as the signal is received, so it | |
100 | * will not cause visible delay for the user. | |
101 | */ | |
102 | while (!CMM_LOAD_SHARED(*completion_flag)) { | |
103 | int status; | |
104 | pid_t ret; | |
105 | ||
106 | /* | |
107 | * Check if child exists without blocking. If | |
108 | * so, we have to stop this parent process and | |
109 | * return an error. | |
110 | */ | |
111 | ret = waitpid(pid, &status, WNOHANG); | |
112 | if (ret < 0 || (ret != 0 && WIFEXITED(status))) { | |
113 | /* The child exited somehow or was not valid. */ | |
114 | goto error; | |
115 | } | |
116 | sleep(1); | |
117 | } | |
118 | ||
119 | /* | |
120 | * From this point on, the parent can exit and the child | |
121 | * is now an operationnal session daemon ready to serve | |
122 | * clients and applications. | |
123 | */ | |
124 | exit(EXIT_SUCCESS); | |
125 | } | |
126 | ||
127 | end: | |
128 | return 0; | |
129 | ||
130 | error: | |
131 | return -1; | |
132 | } |