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)) 231 232 233 234 235 236 /* 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 433