gdb/osf-share/HP800/cma_thread_io.h

   1 /*
   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 \f
 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