Makefile.in: Remove special treatment of ortp_send/ortp_recv
[paraslash.git] / signal.c
1 /*
2 * Copyright (C) 2004-2006 Andre Noll <maan@systemlinux.org>
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA.
17 */
18 /** \file signal.c signal handling functions */
19
20
21
22 #include "para.h"
23 #include "fd.h"
24
25 #include <signal.h>
26
27 #include "error.h"
28 static int signal_pipe[2];
29
30 /**
31 * initialize the paraslash signal subsystem
32 *
33 * This function creates a pipe, the signal pipe, to deliver pending
34 * signals to the application (Bernstein's trick). It should be called
35 * during the application's startup part, followed by subsequent calls
36 * to para_install_sighandler() for each signal that should be caught.
37 *
38 * para_signal_init() installs a generic signal handler which is used for all
39 * signals simultaneously. When a signal arrives, this generic signal handler
40 * writes the corresponding signal number to the signal pipe so that the
41 * application can test for pending signals simply by checking the signal pipe
42 * for reading, e.g. by using the select(2) system call.
43 *
44 * \return This function either succeeds or calls exit(2) to terminate
45 * the current process. On success, the file descriptor of the signal pipe is
46 * returned.
47 */
48 int para_signal_init(void)
49 {
50 int ret = -E_SIGNAL_PIPE;
51 if (pipe(signal_pipe))
52 goto err_out;
53 ret = mark_fd_nonblock(signal_pipe[0]);
54 if (ret < 0)
55 goto err_out;
56 ret = mark_fd_nonblock(signal_pipe[1]);
57 if (ret < 0)
58 goto err_out;
59 return signal_pipe[0];
60 err_out:
61 PARA_EMERG_LOG("%s\n", PARA_STRERROR(-ret));
62 exit(EXIT_FAILURE);
63 }
64
65 /*
66 * just write one integer to signal pipe
67 */
68 static void generic_signal_handler(int s)
69 {
70 write(signal_pipe[1], &s, sizeof(int));
71 //fprintf(stderr, "got sig %i, write returned %d\n", s, ret);
72 }
73
74 /**
75 * reap one child
76 *
77 * call waitpid() and print a log message containing the pid
78 * and the cause of the child's death.
79 *
80 * \return Like \p waitpid(), this function returns the process ID of the
81 * terminated child; on error, \p -E_WAITPID is returned.
82 * \sa waitpid(2)
83 */
84 pid_t para_reap_child(void)
85 {
86 int status;
87 pid_t pid = waitpid(-1, &status, WNOHANG);
88
89 if (pid <= 0) {
90 if (pid < 0)
91 pid = -E_WAITPID;
92 return 0;
93 }
94 if (WIFEXITED(status))
95 PARA_DEBUG_LOG("child %i exited. Exit status: %i\n", pid,
96 WEXITSTATUS(status));
97 else if (WIFSIGNALED(status))
98 PARA_DEBUG_LOG("child %i was killed by signal %i\n", pid,
99 WTERMSIG(status));
100 else
101 PARA_WARNING_LOG("child %i terminated abormally\n", pid);
102 return pid;
103 }
104
105 /**
106 * paraslash's zombie killer
107 *
108 * It just calls \p para_reap_child() until there are no more children left to
109 * reap.
110 */
111 void para_reap_children(void)
112 {
113 while (para_reap_child() > 0)
114 ; /* nothing */
115 }
116
117 /**
118 * wrapper around signal(2)
119 * \param sig the number of the signal to catch
120 *
121 * This installs the generic signal handler for the given signal.
122 * \return This function returns 1 on success and \p -E_SIGNAL_SIG_ERR on errors.
123 * \sa signal(2)
124 */
125 int para_install_sighandler(int sig)
126 {
127 PARA_DEBUG_LOG("catching signal %d\n", sig);
128 return signal(sig, &generic_signal_handler) == SIG_ERR? -E_SIGNAL_SIG_ERR : 1;
129 }
130
131 /**
132 * return number of next pending signal
133 *
134 * This should be called if the fd for the signal pipe is ready for reading.
135 *
136 * \return On success, the number of the received signal is returned. \p
137 * -E_SIGNAL_READ is returned if a read error occured while reading the signal
138 * pipe. If the read was interrupted by another signal the function returns 0.
139 */
140 int para_next_signal(void)
141 {
142 int s;
143 ssize_t r;
144
145 if ((r = read(signal_pipe[0], &s, sizeof(s)) == sizeof(s)) > 0) {
146 PARA_DEBUG_LOG("next signal: %d\n", s);
147 return s;
148 }
149 return r < 0 && (errno != EAGAIN)? 0 : -E_SIGNAL_READ;
150 }