1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
|
/* daemon/daemonise.c
*
* Daemonisation support code
*
* Copyright 2009-2011 Simtec Electronics
*
* For licence terms refer to the COPYING file.
*/
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <signal.h>
#include <stdbool.h>
#include "daemonise.h"
/* exported interface documented in daemonise.h */
void
do_daemonise(const char *pidfilename, bool close_all_fd)
{
int fd;
int pid;
FILE *pidfile;
int pipefds[2];
int fdlimit;
int cfd;
if (pipe(pipefds) == -1) {
perror("pipe");
exit(1);
}
switch ((pid = fork())) {
case 0:
/* Child */
break; /* logic below */
case -1:
/* Error */
perror("fork");
exit(1);
break;
default:
/* Parent */
close(pipefds[1]);
/* wait until child closes pipe */
if (read(pipefds[0], &pid, 1) < 0)
perror("read");
exit(0);
}
/* Make stdin/out/err all be /dev/null */
fd = open("/dev/null", O_RDWR);
if (fd == -1) {
perror("/dev/null open");
exit(1);
}
dup2(fd, 0);
dup2(fd, 1);
dup2(fd, 2);
close(fd);
if (chdir("/") == -1) {
perror("chdir");
exit(1);
}
if (close_all_fd) {
/* ensure any other fd are closed */
fdlimit = sysconf(_SC_OPEN_MAX);
for (cfd = 3; cfd < fdlimit ; cfd++) {
if ((cfd != pipefds[0]) &&
(cfd != pipefds[1])) {
close(cfd);
}
}
}
/* Ensure our process group is better */
setsid();
setpgid(0, 0);
/* Second fork() ensures we can never regain a controlling tty */
switch ((pid = fork())) {
case -1:
/* Error */
exit(1);
case 0:
/* Child */
close(pipefds[0]);
close(pipefds[1]); /* Signals outer-parent that we're done */
break;
default:
/* Parent */
if (pidfilename != NULL) {
pidfile = fopen(pidfilename, "w");
if (pidfile == NULL) {
perror("open");
kill(pid, SIGQUIT);
exit(2);
}
fprintf(pidfile, "%d\n", pid);
fclose(pidfile);
}
exit(0);
}
}
|
