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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: sel.h,v 1.6 1999/08/31 17:42:22 mdw Exp $ |
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4 | * |
5 | * I/O multiplexing support |
6 | * |
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7 | * (c) 1999 Straylight/Edgeware |
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8 | */ |
9 | |
10 | /*----- Licensing notice --------------------------------------------------* |
11 | * |
12 | * This file is part of the mLib utilities library. |
13 | * |
14 | * mLib is free software; you can redistribute it and/or modify |
15 | * it under the terms of the GNU Library General Public License as |
16 | * published by the Free Software Foundation; either version 2 of the |
17 | * License, or (at your option) any later version. |
18 | * |
19 | * mLib is distributed in the hope that it will be useful, |
20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
22 | * GNU Library General Public License for more details. |
23 | * |
24 | * You should have received a copy of the GNU Library General Public |
25 | * License along with mLib; if not, write to the Free |
26 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
27 | * MA 02111-1307, USA. |
28 | */ |
29 | |
30 | /*----- Revision history --------------------------------------------------* |
31 | * |
32 | * $Log: sel.h,v $ |
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33 | * Revision 1.6 1999/08/31 17:42:22 mdw |
34 | * New function `sel_force' to force a descriptor to be `selected'. |
35 | * |
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36 | * Revision 1.5 1999/08/19 18:30:26 mdw |
37 | * Implement hooks for foreign select-using systems (currently not well |
38 | * tested). |
39 | * |
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40 | * Revision 1.4 1999/05/22 13:39:15 mdw |
41 | * Change spelling of `multiplexor'. ;-) |
42 | * |
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43 | * Revision 1.3 1999/05/17 20:36:36 mdw |
44 | * Make the selector type symbols an enumeration rather than a bunch of |
45 | * #defines. |
46 | * |
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47 | * Revision 1.2 1999/05/15 10:33:32 mdw |
48 | * Fix copyright notices. |
49 | * |
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50 | * Revision 1.1 1999/05/14 21:01:15 mdw |
51 | * Integrated `select' handling bits from the background resolver project. |
52 | * |
53 | */ |
54 | |
55 | #ifndef SEL_H |
56 | #define SEL_H |
57 | |
58 | #ifdef __cplusplus |
59 | extern "C" { |
60 | #endif |
61 | |
62 | /*----- Theory lesson -----------------------------------------------------* |
63 | * |
64 | * Things which are expecting to do I/O or go off at a certain time are |
65 | * called `selectors'. There are two types of selectors: `file selectors' |
66 | * wait patiently for a file to become readable or writable; `timeout |
67 | * selectors' wait for a certain amount of time to elapse. There is also a |
68 | * `multiplexor' which copes with managing all of this stuff. |
69 | * |
70 | * Multiplexors aren't actually very interesting. You initialize them with |
71 | * @sel_init@, and then add and remove selectors as you go. When you want to |
72 | * wait for something to happen, call @sel_select@. |
73 | * |
74 | * A file selector can *either* read *or* write. It can't do both. This is |
75 | * because you quite often want to read a socket but not write it; during |
76 | * those times you don't want to write, you just don't install a write |
77 | * selector. |
78 | * |
79 | * File selectors are called when their files are available for reading or |
80 | * writing as appropriate, and given their file descriptor, the state of the |
81 | * file, and a pointer that was registered along with the selector. |
82 | * |
83 | * File selectors are set up in two phases. First, they're `initialized' |
84 | * with @sel_initfile@. An initialized file selector doesn't do anything. |
85 | * It needs to be added to a multiplexor using `sel_addfile'. It can later |
86 | * be removed using `sel_rmfile'. You can carry on adding and removing as |
87 | * you wish. Just don't try adding it twice in a row. |
88 | * |
89 | * Timeout selectors are called at a certain time. (Actually, they're called |
90 | * *after* a certain time.) There's no separate initialization step with |
91 | * timouts: you just add them and they work. If you decide you don't want a |
92 | * timeout to go off, then you just remove it. (Adding and removing the |
93 | * *same* timeout isn't something you do very often. You usually use a |
94 | * different expiry time each time.) |
95 | */ |
96 | |
97 | /*----- Header files ------------------------------------------------------*/ |
98 | |
99 | #include <sys/types.h> |
100 | #include <sys/time.h> |
101 | #include <unistd.h> |
102 | |
103 | /*----- Data structures ---------------------------------------------------*/ |
104 | |
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105 | /* --- A multiplexor --- * |
106 | * |
107 | * The files are sorted in reverse order of file descriptor number; the |
108 | * timers are in normal order of occurrence. Thus, the interesting one |
109 | * is always at the front of the list. |
110 | */ |
111 | |
112 | enum { |
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113 | SEL_READ, /* File is ready to read */ |
114 | SEL_WRITE, /* File is ready to write */ |
115 | SEL_EXC, /* Something odd has happened */ |
116 | SEL_MODES /* Number of modes available */ |
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117 | }; |
118 | |
119 | typedef struct sel_state { |
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120 | struct sel_file *files[SEL_MODES]; /* Lists of interesting files */ |
121 | struct sel_timer *timers; /* List of timers */ |
122 | struct sel_hook *hooks; /* List of hook functions applied */ |
123 | fd_set fd[SEL_MODES]; /* Quick reference table for files */ |
124 | struct sel_args *args; /* Pointer to arguments */ |
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125 | } sel_state; |
126 | |
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127 | /* --- Listening for a file --- */ |
128 | |
129 | typedef struct sel_file { |
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130 | struct sel_file *next; /* Next file in the list */ |
131 | struct sel_file *prev; /* Previous file in the list */ |
132 | struct sel_state *s; /* Pointer to select multiplexor */ |
133 | int fd; /* File descriptor */ |
134 | unsigned mode; /* Interesting event for file */ |
135 | void (*func)(int /*fd*/, unsigned /*mode*/, void */*p*/); /* Handler */ |
136 | void *p; /* Argument for the handler */ |
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137 | } sel_file; |
138 | |
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139 | /* --- Waiting for a timeout --- */ |
140 | |
141 | typedef struct sel_timer { |
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142 | struct sel_timer *next; /* Next timer in the list */ |
143 | struct sel_timer *prev; /* Previous timer in the list */ |
144 | struct timeval tv; /* Real time when timer should go */ |
145 | void (*func)(struct timeval */*tv*/, void */*p*/); /* Handler function */ |
146 | void *p; /* Argument for the handler */ |
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147 | } sel_timer; |
148 | |
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149 | /* --- A select argument block --- */ |
150 | |
151 | typedef struct sel_args { |
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152 | int maxfd; /* Highest-numbered file */ |
153 | fd_set fd[SEL_MODES]; /* Bit flags for all the files */ |
154 | struct timeval tv, *tvp; /* Time to return */ |
155 | struct timeval now; /* Current time */ |
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156 | } sel_args; |
157 | |
158 | /* --- A selector hook --- * |
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159 | * |
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160 | * The hooks are called (in arbitrary order) on each select. |
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161 | */ |
162 | |
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163 | typedef void (*sel_hookfn)(sel_state */*s*/, |
164 | sel_args */*a*/, |
165 | void */*p*/); |
166 | |
167 | typedef struct sel_hook { |
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168 | struct sel_hook *next; /* Next hook in the list */ |
169 | struct sel_hook *prev; /* Previous hook in the list */ |
170 | sel_hookfn before, after; /* Hook functions */ |
171 | void *p; /* Argument for the hook functions */ |
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172 | } sel_hook; |
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173 | |
174 | /*----- Functions provided ------------------------------------------------*/ |
175 | |
176 | /* --- @sel_init@ --- * |
177 | * |
178 | * Arguments: @sel_state *s@ = pointer to a state block to initialize |
179 | * |
180 | * Returns: --- |
181 | * |
182 | * Use: Initializes a select state block. |
183 | */ |
184 | |
185 | extern void sel_init(sel_state */*s*/); |
186 | |
187 | /* --- @sel_initfile@ --- * |
188 | * |
189 | * Arguments: @sel_state *s@ = select state to attach to |
190 | * @sel_file *f@ = pointer to a file block to initialize |
191 | * @int fd@ = the file descriptor to listen to |
192 | * @unsigned mode@ = what to listen for |
193 | * @void (*func)(int fd, unsigned mode, void *p)@ = handler |
194 | * @void *p@ = argument to pass to handler |
195 | * |
196 | * Returns: --- |
197 | * |
198 | * Use: Initializes a file block ready for use. The file block |
199 | * isn't added to the list of things to do until a call to |
200 | * @sel_addfile@. |
201 | */ |
202 | |
203 | extern void sel_initfile(sel_state */*s*/, sel_file */*f*/, |
204 | int /*fd*/, unsigned /*mode*/, |
205 | void (*/*func*/)(int /*fd*/, |
206 | unsigned /*mode*/, |
207 | void */*p*/), |
208 | void */*p*/); |
209 | |
210 | /* --- @sel_addfile@ --- * |
211 | * |
212 | * Arguments: @sel_file *f@ = pointer to a file block |
213 | * |
214 | * Returns: --- |
215 | * |
216 | * Use: Adds a file block into the list of things to listen to. |
217 | */ |
218 | |
219 | extern void sel_addfile(sel_file */*f*/); |
220 | |
221 | /* --- @sel_rmfile@ --- * |
222 | * |
223 | * Arguments: @sel_file *f@ = pointer to a file block |
224 | * |
225 | * Returns: --- |
226 | * |
227 | * Use: Removes a file block from the list of things to listen to. |
228 | */ |
229 | |
230 | extern void sel_rmfile(sel_file */*f*/); |
231 | |
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232 | /* --- @sel_force@ --- * |
233 | * |
234 | * Arguments: @sel_file *f@ = pointer to file selector |
235 | * |
236 | * Returns: --- |
237 | * |
238 | * Use: Forces a file selector to be considered ready. This is only |
239 | * useful during a call to @sel_select@. Of particular use is |
240 | * forcing a write selector when there's something interesting |
241 | * ready for it. |
242 | */ |
243 | |
244 | extern void sel_force(sel_file */*f*/); |
245 | |
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246 | /* --- @sel_addtimer@ --- * |
247 | * |
248 | * Arguments: @sel_state *s@ = pointer to a state block |
249 | * @sel_timer *t@ = pointer to a timer block |
250 | * @struct timeval *tv@ = pointer to time to activate |
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251 | * @void *p@ = argument for handler function |
252 | * |
253 | * Returns: --- |
254 | * |
255 | * Use: Registers and sets up a timer. |
256 | */ |
257 | |
258 | extern void sel_addtimer(sel_state */*s*/, sel_timer */*t*/, |
259 | struct timeval */*tv*/, |
260 | void (*/*func*/)(struct timeval */*tv*/, |
261 | void */*p*/), |
262 | void */*p*/); |
263 | |
264 | /* --- @sel_rmtimer@ --- * |
265 | * |
266 | * Arguments: @sel_timer *t@ = pointer to timer block |
267 | * |
268 | * Returns: --- |
269 | * |
270 | * Use: Removes a timer from the list of timers. |
271 | */ |
272 | |
273 | extern void sel_rmtimer(sel_timer */*t*/); |
274 | |
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275 | /* --- @sel_addhook@ --- * |
276 | * |
277 | * Arguments: @sel_state *s@ = pointer to state block |
278 | * @sel_hook *h@ = pointer to hook block |
279 | * @sel_hookfn before, after@ = hook functions |
280 | * @void *p@ = pointer argument to pass to hook functions |
281 | * |
282 | * Returns: --- |
283 | * |
284 | * Use: Registers hook functions to be called on each select call. |
285 | */ |
286 | |
287 | extern void sel_addhook(sel_state */*s*/, sel_hook */*h*/, |
288 | sel_hookfn /*before*/, sel_hookfn /*after*/, |
289 | void */*p*/); |
290 | |
291 | /* --- @sel_rmhook@ --- * |
292 | * |
293 | * Arguments: @sel_hook *h@ = pointer to hook block |
294 | * |
295 | * Returns: --- |
296 | * |
297 | * Use: Removes hook functions. |
298 | */ |
299 | |
300 | extern void sel_rmhook(sel_hook */*h*/); |
301 | |
302 | /* --- @sel_fdmerge@ --- * |
303 | * |
304 | * Arguments: @fd_set *dest@ = destination FD set |
305 | * @fd_set *fd@ = pointer to set to merge |
306 | * @int maxfd@ = highest numbered descriptor in @fd@ + 1 |
307 | * |
308 | * Returns: Actual highest numbered descriptor. |
309 | * |
310 | * Use: Merges file descriptor sets, and returns an accurate @maxfd@ |
311 | * value. |
312 | */ |
313 | |
314 | extern int sel_fdmerge(fd_set */*dest*/, fd_set */*fd*/, int /*maxfd*/); |
315 | |
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316 | /* --- @sel_select@ --- * |
317 | * |
318 | * Arguments: @sel_state *s@ = pointer to state block |
319 | * |
320 | * Returns: Zero if all OK, -1 on error. |
321 | * |
322 | * Use: Does a @select@ call (or equivalent @poll@). |
323 | */ |
324 | |
325 | extern int sel_select(sel_state */*s*/); |
326 | |
327 | /*----- That's all, folks -------------------------------------------------*/ |
328 | |
329 | #ifdef __cplusplus |
330 | } |
331 | #endif |
332 | |
333 | #endif |