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1 24 jeremybenn
/*
2
 * (c) Copyright 1990-1996 OPEN SOFTWARE FOUNDATION, INC.
3
 * (c) Copyright 1990-1996 HEWLETT-PACKARD COMPANY
4
 * (c) Copyright 1990-1996 DIGITAL EQUIPMENT CORPORATION
5
 * (c) Copyright 1991, 1992 Siemens-Nixdorf Information Systems
6
 * To anyone who acknowledges that this file is provided "AS IS" without
7
 * any express or implied warranty: permission to use, copy, modify, and
8
 * distribute this file for any purpose is hereby granted without fee,
9
 * provided that the above copyright notices and this notice appears in
10
 * all source code copies, and that none of the names listed above be used
11
 * in advertising or publicity pertaining to distribution of the software
12
 * without specific, written prior permission.  None of these organizations
13
 * makes any representations about the suitability of this software for
14
 * any purpose.
15
 */
16
/*
17
 *      Header file for thread synchrounous I/O
18
 */
19
 
20
#ifndef CMA_THREAD_IO
21
#define CMA_THREAD_IO
22
 
23
/*
24
 *  INCLUDE FILES
25
 */
26
 
27
#include <cma_config.h>
28
#include <sys/select.h>
29
#include <cma.h>
30
#include <sys/types.h>
31
#include <sys/time.h>
32
#include <cma_init.h>
33
#include <cma_errors.h>
34
 
35
/*
36
 * CONSTANTS
37
 */
38
 
39
/*
40
 * Maximum number of files (ie, max_fd+1)
41
 */
42
#define cma__c_mx_file  FD_SETSIZE
43
 
44
/*
45
 * Number of bits per file descriptor bit mask (ie number of bytes * bits/byte)
46
 */
47
#define cma__c_nbpm     NFDBITS
48
 
49
/*
50
 * TYPE DEFINITIONS
51
 */
52
 
53
typedef enum CMA__T_IO_TYPE {
54
    cma__c_io_read   = 0,
55
    cma__c_io_write  = 1,
56
    cma__c_io_except = 2
57
    } cma__t_io_type;
58
#define cma__c_max_io_type      2
59
 
60
/*
61
 * From our local <sys/types.h>:
62
 *
63
 *  typedef long    fd_mask;
64
 *
65
 *  typedef struct fd_set {
66
 *          fd_mask fds_bits[howmany(FD_SETSIZE, NFDBITS)];
67
 *  } fd_set;
68
 *
69
 */
70
typedef fd_mask cma__t_mask;
71
typedef fd_set  cma__t_file_mask;
72
 
73
 
74
 
75
/*
76
 *  GLOBAL DATA
77
 */
78
 
79
/*
80
 * Maximum number of files (ie, max_fd+1) as determined by getdtablesize().
81
 */
82
extern int      cma__g_mx_file;
83
 
84
/*
85
 * Number of submasks (ie "int" sized chunks) per file descriptor mask as
86
 * determined by getdtablesize().
87
 */
88
extern int      cma__g_nspm;
89
 
90
/*
91
 * MACROS
92
 */
93
 
94
/*
95
 * Define a constant for the errno value which indicates that the requested
96
 * operation was not performed because it would block the process.
97
 */
98
# define cma__is_blocking(s) \
99
    ((s == EAGAIN) || (s == EWOULDBLOCK) || (s == EINPROGRESS) || \
100
     (s == EALREADY) || (s == EDEADLK))
101
 
102
/*
103
*       It is necessary to issue an I/O function, before calling cma__io_wait()
104
*       in the following cases:
105
*
106
*               *       This file descriptor has been set non-blocking by CMA
107
*               *       This file descriptor has been set non-blocking by the user.
108
*/
109
 
110
#define cma__issue_io_call(fd)                                  \
111
        ( (cma__g_file[fd]->non_blocking) || \
112
          (cma__g_file[fd]->user_fl.user_non_blocking) )
113
 
114
 
115
#define cma__set_user_nonblocking(flags) \
116
 
117
/*
118
 * Determine if the file is open
119
 */
120
/*
121
 * If the file gets closed while waiting for the mutex cma__g_file[rfd]
122
 * gets set to null. This results in a crash if NDEBUG is set to 0
123
 * since cma__int_lock tries to dereference it to set the mutex ownership
124
 * after it gets the mutex. The following will still set the ownership
125
 * in cma__int_lock so we'll set it back to noone if cma__g_file is null
126
 * when we come back just in case it matters. It shouldn't since its no
127
 * longer in use but.....
128
 * Callers of this should recheck cma__g_file after the reservation to
129
 * make sure continueing makes sense.
130
 */
131
#define cma__fd_reserve(rfd)    \
132
                { \
133
                cma__t_int_mutex *__mutex__; \
134
                __mutex__ = cma__g_file[rfd]->mutex; \
135
                cma__int_lock (__mutex__); \
136
                if(cma__g_file[rfd] == (cma__t_file_obj *)cma_c_null_ptr) \
137
                        cma__int_unlock(__mutex__); \
138
                }
139
 
140
 
141
/*
142
 * Unreserve a file descriptor
143
 */
144
#define cma__fd_unreserve(ufd)  cma__int_unlock (cma__g_file[ufd]->mutex)
145
 
146
/*
147
 * AND together two select file descriptor masks
148
 */
149
#define cma__fdm_and(target,a,b)                                        \
150
        {                                                               \
151
        int __i__ = cma__g_nspm;                                        \
152
        while (__i__--)                                                 \
153
            (target)->fds_bits[__i__] =                                 \
154
                (a)->fds_bits[__i__] & (b)->fds_bits[__i__];            \
155
        }
156
 
157
/*
158
 * Clear a bit in a select file descriptor mask
159
 *
160
 * FD_CLR(n, p)  :=  ((p)->fds_bits[(n)/NFDBITS] &= ~(1 << ((n) % NFDBITS)))
161
 */
162
#define cma__fdm_clr_bit(n,p)   FD_CLR (n, p)
163
 
164
/*
165
 * Copy the contents of one file descriptor mask into another.  If the
166
 * destination operand is null, do nothing; if the source operand is null,
167
 * simply zero the destination.
168
 */
169
#define cma__fdm_copy(src,dst,nfds) {                                   \
170
        if (dst)                                                        \
171
            if (src) {                                                  \
172
                cma__t_mask *__s__ = (cma__t_mask *)(src);              \
173
                cma__t_mask *__d__ = (cma__t_mask *)(dst);              \
174
                int __i__;                                              \
175
                for (__i__ = 0; __i__ < (nfds); __i__ += cma__c_nbpm)    \
176
                    *__d__++ = *__s__++;                                \
177
                }                                                       \
178
            else                                                        \
179
                cma__fdm_zero (dst);                                    \
180
            }
181
 
182
/*
183
 * To increment count for each bit set in fd - mask
184
 */
185
#define cma__fdm_count_bits(map,count)                                  \
186
        {                                                               \
187
        int     __i__ = cma__g_nspm;                                    \
188
        while (__i__--) {                                               \
189
            cma__t_mask    __tm__;                                      \
190
            __tm__ = (map)->fds_bits[__i__];                            \
191
            while(__tm__) {                                             \
192
                (count)++;                                              \
193
                __tm__ &= ~(__tm__ & (-__tm__)); /* Assumes 2's comp */ \
194
                }                                                       \
195
            }                                                           \
196
        }
197
 
198
/*
199
 * Test if a bit is set in a select file descriptor mask
200
 *
201
 * FD_ISSET(n,p)  :=  ((p)->fds_bits[(n)/NFDBITS] & (1 << ((n) % NFDBITS)))
202
 */
203
#define cma__fdm_is_set(n,p)    FD_ISSET (n, p)
204
 
205
/*
206
 * OR together two select file descriptor masks
207
 */
208
#define cma__fdm_or(target,a,b)                                         \
209
        {                                                               \
210
        int __i__ = cma__g_nspm;                                        \
211
        while (__i__--)                                                 \
212
            (target)->fds_bits[__i__] =                                 \
213
                (a)->fds_bits[__i__] | (b)->fds_bits[__i__];            \
214
        }
215
 
216
/*
217
 * Set a bit in a select file descriptor mask
218
 *
219
 * FD_SET(n,p)  :=  ((p)->fds_bits[(n)/NFDBITS] |= (1 << ((n) % NFDBITS)))
220
 */
221
#define cma__fdm_set_bit(n,p)   FD_SET (n, p)
222
 
223
/*
224
 * Clear a select file descriptor mask.
225
 */
226
#define cma__fdm_zero(n)                                                \
227
        cma__memset ((char *) n, 0, cma__g_nspm * sizeof(cma__t_mask))
228
 
229
 
230
 
231
 
232
 
233
/*
234
 * CMA "thread-synchronous" I/O read/write operations
235
 */
236
 
237
    /*
238
     * Since all CMA "thread-synchronous" I/O (read or write) operations on
239
     * U*ix follow the exact same structure, the wrapper routines have been
240
     * condensed into a macro.
241
     *
242
     * The steps performed are as follows:
243
     *  1. Check that the file descriptor is a legitimate value.
244
     *  2. Check that the entry in the CMA file "database" which corresponds to
245
     *      the file descriptor indicates that the "file" was "opened" by CMA.
246
     *  3. Reserve the file, to serialized access to files.  This not only
247
     *      simplifies things, but also defends against non-reentrancy.
248
     *  4. If the "file" is "set" for non-blocking I/O, check if we
249
     *      have actually set the file non-blocking yet, and if not do so.
250
     *      Then, issue the I/O operantion.
251
     *      Success or failure is returned immediately, after unreserving the
252
     *      file.  If the error indicates that the operation would have caused
253
     *      the process to block, continue to the next step.
254
     *  5. The I/O prolog adds this "file" to the global bit mask, which
255
     *      represents all "files" which have threads waiting to perform I/O on
256
     *      them, and causes the thread to block on the condition variable for
257
     *      this "file".  Periodically, a select is done on this global bit
258
     *      mask, and the condition variables corresponding to "files" which
259
     *      are ready for I/O are signaled, releasing those waiting threads to
260
     *      perform their I/O.
261
     *  6. When the thread returns from the I/O prolog, it can (hopefully)
262
     *      perform its operation without blocking the process.
263
     *  7. The I/O epilog clears the bit in the global mask and/or signals the
264
     *      the next thread waiting for this "file", as appropriate.
265
     *  8. If the I/O failed, continue to loop.
266
     *  9. Finally, the "file" is unreserved, as we're done with it, and the
267
     *      result of the operation is returned.
268
     *
269
     *
270
     * Note:  currently, we believe that timeslicing which is based on the
271
     *      virtual-time timer does not cause system calls to return EINTR.
272
     *      Threfore, any EINTR returns are relayed directly to the caller.
273
     *      On platforms which do not support a virtual-time timer, the code
274
     *      should probably catch EINTR returns and restart the system call.
275
     */
276
 
277
/*
278
 * This macro is used for both read-type and write-type functions.
279
 *
280
 * Note:  the second call to "func" may require being bracketed in a
281
 *        cma__interrupt_disable/cma__interrupt_enable pair, but we'll
282
 *        wait and see if this is necessary.
283
 */
284
#define cma__ts_func(func,fd,arglist,type,post_process) { \
285
    cma_t_integer   __res__; \
286
    cma_t_boolean   __done__ = cma_c_false; \
287
    if ((fd < 0) || (fd >= cma__g_mx_file)) return (cma__set_errno (EBADF), -1); \
288
    if (!cma__is_open(fd)) return (cma__set_errno (EBADF), -1); \
289
    cma__fd_reserve (fd); \
290
    if (!cma__is_open(fd)) return (cma__set_errno (EBADF), -1); \
291
    if (cma__issue_io_call(fd)) {\
292
        if ((!cma__g_file[fd]->set_non_blocking) && \
293
                (cma__g_file[fd]->non_blocking == cma_c_true)) \
294
            cma__set_nonblocking(fd); \
295
        cma__interrupt_disable (0); \
296
        TRY { \
297
            __res__ = func arglist; \
298
            } \
299
        CATCH_ALL { \
300
            cma__interrupt_enable (0); \
301
            cma__fd_unreserve (fd); \
302
            RERAISE; \
303
            } \
304
        ENDTRY \
305
        cma__interrupt_enable (0); \
306
        if ((__res__ != -1) \
307
                || (!cma__is_blocking (errno)) \
308
                || (cma__g_file[fd]->user_fl.user_non_blocking)) \
309
            __done__ = cma_c_true; \
310
        } \
311
    if (__done__) { \
312
        cma__fd_unreserve (fd); \
313
        } \
314
    else { \
315
        TRY { \
316
            cma__io_prolog (type, fd); \
317
            while (!__done__) { \
318
                cma__io_wait (type, fd); \
319
                __res__ = func arglist; \
320
                if ((__res__ != -1) \
321
                        || (!cma__is_blocking (errno)) \
322
                        || (cma__g_file[fd]->user_fl.user_non_blocking)) \
323
                    __done__ = cma_c_true; \
324
                } \
325
            } \
326
        FINALLY { \
327
            cma__io_epilog (type, fd); \
328
            cma__fd_unreserve (fd); \
329
            } \
330
        ENDTRY \
331
        } \
332
    if (__res__ != -1)  post_process; \
333
    return __res__;  \
334
    }
335
 
336
    /*
337
     * Since most CMA "thread-synchronous" I/O ("open"-type) operations on
338
     * U*ix follow the exact same structure, the wrapper routines have been
339
     * condensed into a macro.
340
     *
341
     * The steps performed are as follows:
342
     *  1. Issue the open function.
343
     *  2. If the value returned indicates an error, return it to the caller.
344
     *  3. If the file descriptor returned is larger than what we think is the
345
     *      maximum value (ie if it is too big for our database) then bugcheck.
346
     *  4. "Open" the "file" in the CMA file database.
347
     *  5. Return the file descriptor value to the caller.
348
     *
349
     * FIX-ME: for the time being, if the I/O operation returns EINTR, we
350
     *      simply return it to the caller; eventually, we should catch this
351
     *      and "do the right thing" (if we can figure out what that is).
352
     */
353
 
354
/*
355
 * This macro is used for all "open"-type functions which return a single file
356
 * desciptor by immediate value.
357
 */
358
#define cma__ts_open(func,arglist,post_process)  {              \
359
    int __fd__;                                                 \
360
    TRY {                                                       \
361
        cma__int_init ();                                       \
362
        cma__int_lock (cma__g_io_data_mutex);                   \
363
        __fd__ = func arglist;                                  \
364
        cma__int_unlock (cma__g_io_data_mutex);                 \
365
        if (__fd__ >= 0 && __fd__ < cma__g_mx_file)              \
366
            post_process;                                       \
367
        }                                                       \
368
    CATCH_ALL                                                   \
369
        {                                                       \
370
        cma__set_errno (EBADF);                                 \
371
        __fd__ = -1;                                            \
372
        }                                                       \
373
    ENDTRY                                                      \
374
    if (__fd__ >= cma__g_mx_file)                               \
375
        cma__bugcheck ("cma__ts_open:  fd is too large");       \
376
    return __fd__;                                              \
377
    }
378
/*
379
 * This macro is used for all "open"-type functions which return a pair of file
380
 * desciptors by reference parameter.
381
 */
382
#define cma__ts_open2(func,fdpair,arglist,post_process)  {              \
383
    int     __res__;                                                    \
384
    TRY {                                                               \
385
        cma__int_init ();                                               \
386
        cma__int_lock (cma__g_io_data_mutex);                           \
387
        __res__ = func arglist;                                         \
388
        cma__int_unlock (cma__g_io_data_mutex);                         \
389
        if (__res__ >= 0 && fdpair[0] < cma__g_mx_file                    \
390
                && fdpair[1] < cma__g_mx_file)                          \
391
            post_process;                                               \
392
        }                                                               \
393
    CATCH_ALL                                                           \
394
        {                                                               \
395
        cma__set_errno (EBADF);                                         \
396
        __res__ = -1;                                                   \
397
        }                                                               \
398
    ENDTRY                                                              \
399
    if ((fdpair[0] >= cma__g_mx_file) || (fdpair[1] >= cma__g_mx_file)) \
400
        cma__bugcheck ("cma__ts_open2:  one of fd's is too large"); \
401
    return __res__;                                                     \
402
    }
403
 
404
/*
405
 * INTERNAL INTERFACES
406
 */
407
extern void cma__close_general (int);
408
 
409
extern void
410
cma__init_thread_io (void);
411
 
412
extern cma_t_boolean cma__io_available  (cma__t_io_type,int,struct timeval *);
413
 
414
extern void cma__io_epilog  (cma__t_io_type,int);
415
 
416
extern void cma__io_prolog  (cma__t_io_type,int);
417
 
418
extern void cma__io_wait  (cma__t_io_type,int);
419
 
420
extern void cma__open_general  (int);
421
 
422
extern void cma__reinit_thread_io  (int);
423
 
424
extern void cma__set_nonblocking  (int);
425
 
426
extern void cma__set_user_nonblock_flags  (int,int);
427
 
428
extern cma_t_boolean
429
cma__is_open (int fd);
430
 
431
 
432
#endif
433
 
434
 

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