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
114
115
116
117
118
119
120
121
122
|
/*++
/* NAME
/* timed_wait 3
/* SUMMARY
/* wait operations with timeout
/* SYNOPSIS
/* #include <timed_wait.h>
/*
/* int timed_waitpid(pid, statusp, options, time_limit)
/* pid_t pid;
/* WAIT_STATUS_T *statusp;
/* int options;
/* int time_limit;
/* DESCRIPTION
/* \fItimed_waitpid\fR() waits at most \fItime_limit\fR seconds
/* for process termination.
/*
/* Arguments:
/* .IP "pid, statusp, options"
/* The process ID, status pointer and options passed to waitpid(3).
/* .IP time_limit
/* The time in seconds that timed_waitpid() will wait.
/* This must be a number > 0.
/* DIAGNOSTICS
/* Panic: interface violation.
/*
/* When the time limit is exceeded, the result is -1 and errno
/* is set to ETIMEDOUT. Otherwise, the result value is the result
/* from the underlying waitpid() routine.
/* BUGS
/* If there were a \fIportable\fR way to select() on process status
/* information, these routines would not have to use a steenkeeng
/* alarm() timer and signal() handler.
/* LICENSE
/* .ad
/* .fi
/* The Secure Mailer license must be distributed with this software.
/* AUTHOR(S)
/* Wietse Venema
/* IBM T.J. Watson Research
/* P.O. Box 704
/* Yorktown Heights, NY 10598, USA
/*--*/
/* System library. */
#include <sys_defs.h>
#include <sys/wait.h>
#include <unistd.h>
#include <signal.h>
#include <errno.h>
/* Utility library. */
#include <msg.h>
#include <posix_signals.h>
#include <timed_wait.h>
/* Application-specific. */
static int timed_wait_expired;
/* timed_wait_alarm - timeout handler */
static void timed_wait_alarm(int unused_sig)
{
/*
* WARNING WARNING WARNING.
*
* This code runs at unpredictable moments, as a signal handler. This code
* is here only so that we can break out of waitpid(). Don't put any code
* here other than for setting a global flag.
*/
timed_wait_expired = 1;
}
/* timed_waitpid - waitpid with time limit */
int timed_waitpid(pid_t pid, WAIT_STATUS_T *statusp, int options,
int time_limit)
{
const char *myname = "timed_waitpid";
struct sigaction action;
struct sigaction old_action;
int time_left;
int wpid;
/*
* Sanity checks.
*/
if (time_limit <= 0)
msg_panic("%s: bad time limit: %d", myname, time_limit);
/*
* Set up a timer.
*/
sigemptyset(&action.sa_mask);
action.sa_flags = 0;
action.sa_handler = timed_wait_alarm;
if (sigaction(SIGALRM, &action, &old_action) < 0)
msg_fatal("%s: sigaction(SIGALRM): %m", myname);
timed_wait_expired = 0;
time_left = alarm(time_limit);
/*
* Wait for only a limited amount of time.
*/
if ((wpid = waitpid(pid, statusp, options)) < 0 && timed_wait_expired)
errno = ETIMEDOUT;
/*
* Cleanup.
*/
alarm(0);
if (sigaction(SIGALRM, &old_action, (struct sigaction *) 0) < 0)
msg_fatal("%s: sigaction(SIGALRM): %m", myname);
if (time_left)
alarm(time_left);
return (wpid);
}
|
