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4c187d46 | 1 | /* Copyright (C) 2010, 2013 Free Software Foundation, Inc. |
6f81b18a AW |
2 | * |
3 | * This library is free software; you can redistribute it and/or | |
4 | * modify it under the terms of the GNU Lesser General Public License | |
5 | * as published by the Free Software Foundation; either version 3 of | |
6 | * the License, or (at your option) any later version. | |
7 | * | |
8 | * This library is distributed in the hope that it will be useful, but | |
9 | * WITHOUT ANY WARRANTY; without even the implied warranty of | |
10 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
11 | * Lesser General Public License for more details. | |
12 | * | |
13 | * You should have received a copy of the GNU Lesser General Public | |
14 | * License along with this library; if not, write to the Free Software | |
15 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA | |
16 | * 02110-1301 USA | |
17 | */ | |
18 | ||
19 | ||
20 | \f | |
21 | ||
22 | #define _GNU_SOURCE | |
23 | ||
24 | #ifdef HAVE_CONFIG_H | |
25 | # include <config.h> | |
26 | #endif | |
27 | ||
b5870f25 JE |
28 | #include <poll.h> |
29 | ||
6f81b18a AW |
30 | #include "libguile/_scm.h" |
31 | #include "libguile/bytevectors.h" | |
32 | #include "libguile/numbers.h" | |
33 | #include "libguile/error.h" | |
34 | #include "libguile/validate.h" | |
35 | ||
36 | #include "libguile/poll.h" | |
37 | ||
38 | \f | |
6f81b18a AW |
39 | |
40 | /* {Poll} | |
41 | */ | |
42 | ||
43 | /* Poll a set of file descriptors, waiting until one or more of them is | |
44 | ready to perform input or output. | |
45 | ||
46 | This is a low-level interface. See the `(ice-9 poll)' module for a more | |
47 | usable wrapper. | |
48 | ||
49 | `pollfds' is expected to be a bytevector, laid out in contiguous blocks of 64 | |
50 | bits. Each block has the format of one `struct pollfd': a 32-bit int file | |
51 | descriptor, a 16-bit int events mask, and a 16-bit int revents mask. | |
52 | ||
53 | The number of pollfd structures in `pollfds' is specified in | |
54 | `nfds'. `pollfds' must be at least long enough to support that number of | |
55 | structures. It may be longer, in which case the trailing entries are left | |
56 | untouched. | |
57 | ||
58 | The pollfds bytevector is modified directly, setting the returned events in | |
59 | the final two bytes (the revents member). | |
60 | ||
e9634465 AW |
61 | Since Scheme ports can buffer input or output in userspace, a Scheme |
62 | poll interface needs to take that into account as well. The `ports' | |
63 | argument, a vector big enough for `nfds' elements, is given for this | |
64 | purpose. If a pollfd entry has a corresponding open port, that port | |
65 | is scanned for available input or output before dropping into the | |
66 | poll. If any port has buffered I/O available, the poll syscall is | |
67 | still issued, but with a timeout of 0 milliseconds, and a full port | |
68 | scan occurs after the poll returns. | |
69 | ||
6f81b18a AW |
70 | If timeout is given and is non-negative, the poll will return after that |
71 | number of milliseconds if no fd became active. | |
72 | */ | |
6f81b18a | 73 | static SCM |
e9634465 | 74 | scm_primitive_poll (SCM pollfds, SCM nfds, SCM ports, SCM timeout) |
6f81b18a AW |
75 | #define FUNC_NAME "primitive-poll" |
76 | { | |
e9634465 AW |
77 | int rv = 0; |
78 | nfds_t i; | |
6f81b18a AW |
79 | nfds_t c_nfds; |
80 | int c_timeout; | |
e9634465 | 81 | int have_buffered_io = 0; |
6f81b18a AW |
82 | struct pollfd *fds; |
83 | ||
84 | SCM_VALIDATE_BYTEVECTOR (SCM_ARG1, pollfds); | |
85 | c_nfds = scm_to_uint32 (nfds); | |
86 | c_timeout = scm_to_int (timeout); | |
87 | ||
88 | if (SCM_UNLIKELY (SCM_BYTEVECTOR_LENGTH (pollfds) | |
89 | < c_nfds * sizeof(struct pollfd))) | |
e9634465 | 90 | SCM_OUT_OF_RANGE (SCM_ARG2, nfds); |
6f81b18a | 91 | |
e9634465 AW |
92 | SCM_VALIDATE_VECTOR (SCM_ARG3, ports); |
93 | if (SCM_UNLIKELY (SCM_SIMPLE_VECTOR_LENGTH (ports) < c_nfds)) | |
94 | SCM_OUT_OF_RANGE (SCM_ARG3, ports); | |
95 | ||
6f81b18a AW |
96 | fds = (struct pollfd*)SCM_BYTEVECTOR_CONTENTS (pollfds); |
97 | ||
e9634465 AW |
98 | for (i = 0; i < c_nfds; i++) |
99 | { | |
100 | SCM port = SCM_SIMPLE_VECTOR_REF (ports, i); | |
101 | short int revents = 0; | |
102 | ||
103 | if (SCM_PORTP (port)) | |
104 | { | |
105 | if (SCM_CLOSEDP (port)) | |
106 | revents |= POLLERR; | |
107 | else | |
108 | { | |
109 | scm_t_port *pt = SCM_PTAB_ENTRY (port); | |
110 | ||
111 | if (pt->read_pos < pt->read_end) | |
112 | /* Buffered input waiting to be read. */ | |
113 | revents |= POLLIN; | |
114 | if (pt->write_pos < pt->write_end) | |
115 | /* Buffered output possible. */ | |
116 | revents |= POLLOUT; | |
117 | } | |
118 | } | |
119 | ||
120 | if (revents & fds[i].events) | |
121 | { | |
122 | have_buffered_io = 1; | |
123 | c_timeout = 0; | |
124 | break; | |
125 | } | |
126 | } | |
127 | ||
6f81b18a AW |
128 | SCM_SYSCALL (rv = poll (fds, c_nfds, c_timeout)); |
129 | ||
130 | if (rv == -1) | |
131 | SCM_SYSERROR; | |
132 | ||
e9634465 AW |
133 | if (have_buffered_io) |
134 | for (i = 0; i < c_nfds; i++) | |
135 | { | |
136 | SCM port = SCM_SIMPLE_VECTOR_REF (ports, i); | |
137 | short int revents = 0; | |
138 | ||
139 | if (SCM_PORTP (port)) | |
140 | { | |
141 | if (SCM_CLOSEDP (port)) | |
142 | revents |= POLLERR; | |
143 | else | |
144 | { | |
145 | scm_t_port *pt = SCM_PTAB_ENTRY (port); | |
146 | ||
147 | if (pt->read_pos < pt->read_end) | |
148 | /* Buffered input waiting to be read. */ | |
149 | revents |= POLLIN; | |
557abc49 | 150 | if (SCM_OUTPUT_PORT_P (port) && pt->write_pos < pt->write_end) |
e9634465 AW |
151 | /* Buffered output possible. */ |
152 | revents |= POLLOUT; | |
153 | } | |
154 | } | |
155 | ||
557abc49 AW |
156 | /* Mask in the events we are interested, and test if any are |
157 | interesting. */ | |
158 | if ((revents &= fds[i].events)) | |
159 | { | |
160 | /* Could be the underlying fd is also ready for reading. */ | |
161 | if (!fds[i].revents) | |
162 | rv++; | |
163 | ||
164 | /* In any case, add these events to whatever the syscall | |
165 | set. */ | |
166 | fds[i].revents |= revents; | |
167 | } | |
e9634465 AW |
168 | } |
169 | ||
6f81b18a AW |
170 | return scm_from_int (rv); |
171 | } | |
172 | #undef FUNC_NAME | |
6f81b18a AW |
173 | |
174 | ||
175 | \f | |
176 | ||
177 | static void | |
178 | scm_init_poll (void) | |
179 | { | |
e9634465 | 180 | scm_c_define_gsubr ("primitive-poll", 4, 0, 0, scm_primitive_poll); |
6d346bb6 | 181 | scm_c_define ("%sizeof-struct-pollfd", scm_from_size_t (sizeof (struct pollfd))); |
6f81b18a AW |
182 | |
183 | #ifdef POLLIN | |
184 | scm_c_define ("POLLIN", scm_from_int (POLLIN)); | |
185 | #endif | |
186 | #ifdef POLLPRI | |
187 | scm_c_define ("POLLPRI", scm_from_int (POLLPRI)); | |
188 | #endif | |
189 | #ifdef POLLOUT | |
190 | scm_c_define ("POLLOUT", scm_from_int (POLLOUT)); | |
191 | #endif | |
192 | #ifdef POLLRDHUP | |
193 | scm_c_define ("POLLRDHUP", scm_from_int (POLLRDHUP)); | |
194 | #endif | |
195 | #ifdef POLLERR | |
196 | scm_c_define ("POLLERR", scm_from_int (POLLERR)); | |
197 | #endif | |
198 | #ifdef POLLHUP | |
199 | scm_c_define ("POLLHUP", scm_from_int (POLLHUP)); | |
200 | #endif | |
201 | #ifdef POLLNVAL | |
202 | scm_c_define ("POLLNVAL", scm_from_int (POLLNVAL)); | |
203 | #endif | |
204 | ||
205 | } | |
206 | ||
207 | void | |
208 | scm_register_poll (void) | |
209 | { | |
210 | scm_c_register_extension ("libguile-" SCM_EFFECTIVE_VERSION, | |
211 | "scm_init_poll", | |
212 | (scm_t_extension_init_func) scm_init_poll, | |
213 | NULL); | |
214 | } | |
215 | ||
216 | /* | |
217 | Local Variables: | |
218 | c-file-style: "gnu" | |
219 | End: | |
220 | */ |