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
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
|
/*
* Copyright (c) 2001 Markus Friedl. All rights reserved.
* Copyright (c) 2021 Darren Tucker (dtucker at dtucker net).
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "includes.h"
#ifndef HAVE_PSELECT
#include <sys/types.h>
#include <sys/time.h>
#ifdef HAVE_SYS_SELECT_H
# include <sys/select.h>
#endif
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "log.h"
#ifndef HAVE_SIGHANDLER_T
typedef void (*sighandler_t)(int);
#endif
static sighandler_t saved_sighandler[_NSIG];
static int notify_pipe[2]; /* 0 = read end, 1 = write end */
/*
* Because the debugging for this is so noisy, we only output on the first
* call, and suppress it thereafter.
*/
static int suppress_debug;
static void
pselect_set_nonblock(int fd)
{
int val;
if ((val = fcntl(fd, F_GETFL)) == -1 ||
fcntl(fd, F_SETFL, val|O_NONBLOCK) == -1)
error_f("fcntl: %s", strerror(errno));
}
/*
* we write to this pipe if a SIGCHLD is caught in order to avoid
* the race between select() and child_terminated.
*/
static int
pselect_notify_setup(void)
{
if (pipe(notify_pipe) == -1) {
error("pipe(notify_pipe) failed %s", strerror(errno));
notify_pipe[0] = notify_pipe[1] = -1;
return -1;
}
pselect_set_nonblock(notify_pipe[0]);
pselect_set_nonblock(notify_pipe[1]);
if (!suppress_debug)
debug3_f("pipe0 %d pipe1 %d", notify_pipe[0], notify_pipe[1]);
return 0;
}
static void
pselect_notify_parent(void)
{
if (notify_pipe[1] != -1)
(void)write(notify_pipe[1], "", 1);
}
static void
pselect_notify_prepare(fd_set *readset)
{
if (notify_pipe[0] != -1)
FD_SET(notify_pipe[0], readset);
}
static void
pselect_notify_done(fd_set *readset)
{
char c;
if (notify_pipe[0] != -1 && FD_ISSET(notify_pipe[0], readset)) {
while (read(notify_pipe[0], &c, 1) != -1)
debug2_f("reading");
FD_CLR(notify_pipe[0], readset);
}
(void)close(notify_pipe[0]);
(void)close(notify_pipe[1]);
}
/*ARGSUSED*/
static void
pselect_sig_handler(int sig)
{
int save_errno = errno;
pselect_notify_parent();
if (saved_sighandler[sig] != NULL)
(*saved_sighandler[sig])(sig); /* call original handler */
errno = save_errno;
}
/*
* A minimal implementation of pselect(2), built on top of select(2).
*/
int
pselect(int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
const struct timespec *timeout, const sigset_t *mask)
{
int ret, sig, saved_errno, unmasked = 0;
sigset_t osig;
struct sigaction sa, osa;
struct timeval tv, *tvp = NULL;
if (timeout != NULL) {
tv.tv_sec = timeout->tv_sec;
tv.tv_usec = timeout->tv_nsec / 1000;
tvp = &tv;
}
if (mask == NULL) /* no signal mask, just call select */
return select(nfds, readfds, writefds, exceptfds, tvp);
/* For each signal unmasked, save old handler and install ours. */
for (sig = 0; sig < _NSIG; sig++) {
saved_sighandler[sig] = NULL;
if (sig == SIGKILL || sig == SIGSTOP || sigismember(mask, sig))
continue;
if (sigaction(sig, NULL, &sa) == 0 &&
sa.sa_handler != SIG_IGN && sa.sa_handler != SIG_DFL) {
unmasked = 1;
sa.sa_handler = pselect_sig_handler;
if (sigaction(sig, &sa, &osa) == 0) {
if (!suppress_debug)
debug3_f("installed signal handler for"
" %s, previous 0x%p",
strsignal(sig), osa.sa_handler);
saved_sighandler[sig] = osa.sa_handler;
}
}
}
if (unmasked) {
if ((ret = pselect_notify_setup()) == -1) {
saved_errno = ENOMEM;
goto out;
}
pselect_notify_prepare(readfds);
nfds = MAX(nfds, notify_pipe[0] + 1);
}
/* Unmask signals, call select then restore signal mask. */
sigprocmask(SIG_SETMASK, mask, &osig);
ret = select(nfds, readfds, writefds, exceptfds, tvp);
saved_errno = errno;
sigprocmask(SIG_SETMASK, &osig, NULL);
if (unmasked)
pselect_notify_done(readfds);
out:
/* Restore signal handlers. */
for (sig = 0; sig < _NSIG; sig++) {
if (saved_sighandler[sig] == NULL)
continue;
if (sigaction(sig, NULL, &sa) == 0) {
sa.sa_handler = saved_sighandler[sig];
if (sigaction(sig, &sa, NULL) == 0) {
if (!suppress_debug)
debug3_f("restored signal handler for "
"%s", strsignal(sig));
} else {
error_f("failed to restore signal handler for "
"%s: %s", strsignal(sig), strerror(errno));
}
}
}
suppress_debug = 1;
errno = saved_errno;
return ret;
}
#endif
|
