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

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