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
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
/* Copyright (C) 2010, 2013 Free Software Foundation, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* as published by the Free Software Foundation; either version 3 of
* the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301 USA
*/
#define _GNU_SOURCE
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#include <poll.h>
#include "libguile/_scm.h"
#include "libguile/bytevectors.h"
#include "libguile/numbers.h"
#include "libguile/error.h"
#include "libguile/validate.h"
#include "libguile/poll.h"
/* {Poll}
*/
/* Poll a set of file descriptors, waiting until one or more of them is
ready to perform input or output.
This is a low-level interface. See the `(ice-9 poll)' module for a more
usable wrapper.
`pollfds' is expected to be a bytevector, laid out in contiguous blocks of 64
bits. Each block has the format of one `struct pollfd': a 32-bit int file
descriptor, a 16-bit int events mask, and a 16-bit int revents mask.
The number of pollfd structures in `pollfds' is specified in
`nfds'. `pollfds' must be at least long enough to support that number of
structures. It may be longer, in which case the trailing entries are left
untouched.
The pollfds bytevector is modified directly, setting the returned events in
the final two bytes (the revents member).
Since Scheme ports can buffer input or output in userspace, a Scheme
poll interface needs to take that into account as well. The `ports'
argument, a vector big enough for `nfds' elements, is given for this
purpose. If a pollfd entry has a corresponding open port, that port
is scanned for available input or output before dropping into the
poll. If any port has buffered I/O available, the poll syscall is
still issued, but with a timeout of 0 milliseconds, and a full port
scan occurs after the poll returns.
If timeout is given and is non-negative, the poll will return after that
number of milliseconds if no fd became active.
*/
static SCM
scm_primitive_poll (SCM pollfds, SCM nfds, SCM ports, SCM timeout)
#define FUNC_NAME "primitive-poll"
{
int rv = 0;
nfds_t i;
nfds_t c_nfds;
int c_timeout;
int have_buffered_io = 0;
struct pollfd *fds;
SCM_VALIDATE_BYTEVECTOR (SCM_ARG1, pollfds);
c_nfds = scm_to_uint32 (nfds);
c_timeout = scm_to_int (timeout);
if (SCM_UNLIKELY (SCM_BYTEVECTOR_LENGTH (pollfds)
< c_nfds * sizeof(struct pollfd)))
SCM_OUT_OF_RANGE (SCM_ARG2, nfds);
SCM_VALIDATE_VECTOR (SCM_ARG3, ports);
if (SCM_UNLIKELY (SCM_SIMPLE_VECTOR_LENGTH (ports) < c_nfds))
SCM_OUT_OF_RANGE (SCM_ARG3, ports);
fds = (struct pollfd*)SCM_BYTEVECTOR_CONTENTS (pollfds);
for (i = 0; i < c_nfds; i++)
{
SCM port = SCM_SIMPLE_VECTOR_REF (ports, i);
short int revents = 0;
if (SCM_PORTP (port))
{
if (SCM_CLOSEDP (port))
revents |= POLLERR;
else
{
scm_t_port *pt = SCM_PTAB_ENTRY (port);
if (pt->read_pos < pt->read_end)
/* Buffered input waiting to be read. */
revents |= POLLIN;
if (pt->write_pos < pt->write_end)
/* Buffered output possible. */
revents |= POLLOUT;
}
}
if (revents & fds[i].events)
{
have_buffered_io = 1;
c_timeout = 0;
break;
}
}
SCM_SYSCALL (rv = poll (fds, c_nfds, c_timeout));
if (rv == -1)
SCM_SYSERROR;
if (have_buffered_io)
for (i = 0; i < c_nfds; i++)
{
SCM port = SCM_SIMPLE_VECTOR_REF (ports, i);
short int revents = 0;
if (SCM_PORTP (port))
{
if (SCM_CLOSEDP (port))
revents |= POLLERR;
else
{
scm_t_port *pt = SCM_PTAB_ENTRY (port);
if (pt->read_pos < pt->read_end)
/* Buffered input waiting to be read. */
revents |= POLLIN;
if (SCM_OUTPUT_PORT_P (port) && pt->write_pos < pt->write_end)
/* Buffered output possible. */
revents |= POLLOUT;
}
}
/* Mask in the events we are interested, and test if any are
interesting. */
if ((revents &= fds[i].events))
{
/* Could be the underlying fd is also ready for reading. */
if (!fds[i].revents)
rv++;
/* In any case, add these events to whatever the syscall
set. */
fds[i].revents |= revents;
}
}
return scm_from_int (rv);
}
#undef FUNC_NAME
static void
scm_init_poll (void)
{
scm_c_define_gsubr ("primitive-poll", 4, 0, 0, scm_primitive_poll);
scm_c_define ("%sizeof-struct-pollfd", scm_from_size_t (sizeof (struct pollfd)));
#ifdef POLLIN
scm_c_define ("POLLIN", scm_from_int (POLLIN));
#endif
#ifdef POLLPRI
scm_c_define ("POLLPRI", scm_from_int (POLLPRI));
#endif
#ifdef POLLOUT
scm_c_define ("POLLOUT", scm_from_int (POLLOUT));
#endif
#ifdef POLLRDHUP
scm_c_define ("POLLRDHUP", scm_from_int (POLLRDHUP));
#endif
#ifdef POLLERR
scm_c_define ("POLLERR", scm_from_int (POLLERR));
#endif
#ifdef POLLHUP
scm_c_define ("POLLHUP", scm_from_int (POLLHUP));
#endif
#ifdef POLLNVAL
scm_c_define ("POLLNVAL", scm_from_int (POLLNVAL));
#endif
}
void
scm_register_poll (void)
{
scm_c_register_extension ("libguile-" SCM_EFFECTIVE_VERSION,
"scm_init_poll",
(scm_t_extension_init_func) scm_init_poll,
NULL);
}
/*
Local Variables:
c-file-style: "gnu"
End:
*/