src/main/select.c

   1 /* File descriptors managment and switching */
   2
   3 #ifdef HAVE_CONFIG_H
   4 #include "config.h"
   5 #endif
   6
   7 #include <errno.h>
   8 #include <signal.h>
   9 #include <string.h> /* FreeBSD FD_ZERO() macro calls bzero() */
  10 #ifdef HAVE_SYS_SIGNAL_H
  11 #include <sys/signal.h>
  12 #endif
  13 #include <sys/types.h>
  14 #ifdef HAVE_SYS_WAIT_H
  15 #include <sys/wait.h>
  16 #endif
  17 #ifdef HAVE_UNISTD_H
  18 #include <unistd.h>
  19 #endif
  20
  21 /* This must be here, thanks to BSD. */
  22 #ifdef HAVE_INTTYPES_H
  23 #include <inttypes.h> /* OMG */
  24 #endif
  25 #ifdef HAVE_SYS_SELECT_H
  26 #include <sys/select.h>
  27 #endif
  28
  29 #include "elinks.h"
  30
  31 #include "intl/gettext/libintl.h"
  32 #include "main/main.h"
  33 #include "main/select.h"
  34 #include "main/timer.h"
  35 #include "osdep/signals.h"
  36 #include "terminal/terminal.h"
  37 #include "util/error.h"
  38 #include "util/memory.h"
  39 #include "util/time.h"
  40
  41
  42 #ifndef FD_SETSIZE
  43 #define FD_SETSIZE 1024
  44 #endif
  45
  46 struct thread {
  47         select_handler_T read_func;
  48         select_handler_T write_func;
  49         select_handler_T error_func;
  50         void *data;
  51 };
  52
  53 static struct thread threads[FD_SETSIZE];
  54
  55 static fd_set w_read;
  56 static fd_set w_write;
  57 static fd_set w_error;
  58
  59 static fd_set x_read;
  60 static fd_set x_write;
  61 static fd_set x_error;
  62
  63 static int w_max;
  64
  65 int
  66 get_file_handles_count(void)
  67 {
  68         int i = 0, j;
  69
  70         for (j = 0; j < FD_SETSIZE; j++)
  71                 if (threads[j].read_func
  72                     || threads[j].write_func
  73                     || threads[j].error_func)
  74                         i++;
  75         return i;
  76 }
  77
  78 struct bottom_half {
  79         LIST_HEAD(struct bottom_half);
  80
  81         select_handler_T fn;
  82         void *data;
  83 };
  84
  85 static INIT_LIST_OF(struct bottom_half, bottom_halves);
  86
  87 int
  88 register_bottom_half_do(select_handler_T fn, void *data)
  89 {
  90         struct bottom_half *bh;
  91
  92         foreach (bh, bottom_halves)
  93                 if (bh->fn == fn && bh->data == data)
  94                         return 0;
  95
  96         bh = mem_alloc(sizeof(*bh));
  97         if (!bh) return -1;
  98         bh->fn = fn;
  99         bh->data = data;
 100         add_to_list(bottom_halves, bh);
 101
 102         return 0;
 103 }
 104
 105 void
 106 check_bottom_halves(void)
 107 {
 108         while (!list_empty(bottom_halves)) {
 109                 struct bottom_half *bh = bottom_halves.prev;
 110                 select_handler_T fn = bh->fn;
 111                 void *data = bh->data;
 112
 113                 del_from_list(bh);
 114                 mem_free(bh);
 115                 fn(data);
 116         }
 117 }
 118
 119 select_handler_T
 120 get_handler(int fd, enum select_handler_type tp)
 121 {
 122 #ifndef CONFIG_OS_WIN32
 123         assertm(fd >= 0 && fd < FD_SETSIZE,
 124                 "get_handler: handle %d >= FD_SETSIZE %d",
 125                 fd, FD_SETSIZE);
 126         if_assert_failed return NULL;
 127 #endif
 128         switch (tp) {
 129                 case SELECT_HANDLER_READ:       return threads[fd].read_func;
 130                 case SELECT_HANDLER_WRITE:      return threads[fd].write_func;
 131                 case SELECT_HANDLER_ERROR:      return threads[fd].error_func;
 132                 case SELECT_HANDLER_DATA:       return threads[fd].data;
 133         }
 134
 135         INTERNAL("get_handler: bad type %d", tp);
 136         return NULL;
 137 }
 138
 139 void
 140 set_handlers(int fd, select_handler_T read_func, select_handler_T write_func,
 141              select_handler_T error_func, void *data)
 142 {
 143 #ifndef CONFIG_OS_WIN32
 144         assertm(fd >= 0 && fd < FD_SETSIZE,
 145                 "set_handlers: handle %d >= FD_SETSIZE %d",
 146                 fd, FD_SETSIZE);
 147         if_assert_failed return;
 148 #endif
 149         threads[fd].read_func = read_func;
 150         threads[fd].write_func = write_func;
 151         threads[fd].error_func = error_func;
 152         threads[fd].data = data;
 153
 154         if (read_func) {
 155                 FD_SET(fd, &w_read);
 156         } else {
 157                 FD_CLR(fd, &w_read);
 158                 FD_CLR(fd, &x_read);
 159         }
 160
 161         if (write_func) {
 162                 FD_SET(fd, &w_write);
 163         } else {
 164                 FD_CLR(fd, &w_write);
 165                 FD_CLR(fd, &x_write);
 166         }
 167
 168         if (error_func) {
 169                 FD_SET(fd, &w_error);
 170         } else {
 171                 FD_CLR(fd, &w_error);
 172                 FD_CLR(fd, &x_error);
 173         }
 174
 175         if (read_func || write_func || error_func) {
 176                 if (fd >= w_max) w_max = fd + 1;
 177         } else if (fd == w_max - 1) {
 178                 int i;
 179
 180                 for (i = fd - 1; i >= 0; i--)
 181                         if (FD_ISSET(i, &w_read)
 182                             || FD_ISSET(i, &w_write)
 183                             || FD_ISSET(i, &w_error))
 184                                 break;
 185                 w_max = i + 1;
 186         }
 187 }
 188
 189 void
 190 select_loop(void (*init)(void))
 191 {
 192         timeval_T last_time;
 193         int select_errors = 0;
 194
 195         clear_signal_mask_and_handlers();
 196         FD_ZERO(&w_read);
 197         FD_ZERO(&w_write);
 198         FD_ZERO(&w_error);
 199         w_max = 0;
 200         timeval_now(&last_time);
 201 #ifdef SIGPIPE
 202         signal(SIGPIPE, SIG_IGN);
 203 #endif
 204         init();
 205         check_bottom_halves();
 206
 207         while (!program.terminate) {
 208                 struct timeval *timeout = NULL;
 209                 int n, i, has_timer;
 210                 timeval_T t;
 211
 212                 check_signals();
 213                 check_timers(&last_time);
 214                 redraw_all_terminals();
 215
 216                 memcpy(&x_read, &w_read, sizeof(fd_set));
 217                 memcpy(&x_write, &w_write, sizeof(fd_set));
 218                 memcpy(&x_error, &w_error, sizeof(fd_set));
 219
 220                 if (program.terminate) break;
 221
 222                 has_timer = get_next_timer_time(&t);
 223                 if (!w_max && !has_timer) break;
 224                 critical_section = 1;
 225
 226                 if (check_signals()) {
 227                         critical_section = 0;
 228                         continue;
 229                 }
 230 #if 0
 231                 {
 232                         int i;
 233
 234                         printf("\nR:");
 235                         for (i = 0; i < 256; i++)
 236                                 if (FD_ISSET(i, &x_read)) printf("%d,", i);
 237                         printf("\nW:");
 238                         for (i = 0; i < 256; i++)
 239                                 if (FD_ISSET(i, &x_write)) printf("%d,", i);
 240                         printf("\nE:");
 241                         for (i = 0; i < 256; i++)
 242                                 if (FD_ISSET(i, &x_error)) printf("%d,", i);
 243                         fflush(stdout);
 244                 }
 245 #endif
 246                 if (has_timer) {
 247                         /* Be sure timeout is not negative. */
 248                         timeval_limit_to_zero_or_one(&t);
 249                         timeout = (struct timeval *) &t;
 250                 }
 251
 252                 n = select(w_max, &x_read, &x_write, &x_error, timeout);
 253                 if (n < 0) {
 254                         /* The following calls (especially gettext)
 255                          * might change errno.  */
 256                         const int errno_from_select = errno;
 257
 258                         critical_section = 0;
 259                         uninstall_alarm();
 260                         if (errno_from_select != EINTR) {
 261                                 ERROR(gettext("The call to %s failed: %d (%s)"),
 262                                       "select()", errno_from_select, (unsigned char *) strerror(errno_from_select));
 263                                 if (++select_errors > 10) /* Infinite loop prevention. */
 264                                         INTERNAL(gettext("%d select() failures."),
 265                                                  select_errors);
 266                         }
 267                         continue;
 268                 }
 269
 270                 select_errors = 0;
 271                 critical_section = 0;
 272                 uninstall_alarm();
 273                 check_signals();
 274                 /*printf("sel: %d\n", n);*/
 275                 check_timers(&last_time);
 276
 277                 i = -1;
 278                 while (n > 0 && ++i < w_max) {
 279                         int k = 0;
 280
 281 #if 0
 282                         printf("C %d : %d,%d,%d\n", i, FD_ISSET(i, &w_read),
 283                                FD_ISSET(i, &w_write), FD_ISSET(i, &w_error));
 284                         printf("A %d : %d,%d,%d\n", i, FD_ISSET(i, &x_read),
 285                                FD_ISSET(i, &x_write), FD_ISSET(i, &x_error));
 286 #endif
 287                         if (FD_ISSET(i, &x_read)) {
 288                                 if (threads[i].read_func) {
 289                                         threads[i].read_func(threads[i].data);
 290                                         check_bottom_halves();
 291                                 }
 292                                 k = 1;
 293                         }
 294
 295                         if (FD_ISSET(i, &x_write)) {
 296                                 if (threads[i].write_func) {
 297                                         threads[i].write_func(threads[i].data);
 298                                         check_bottom_halves();
 299                                 }
 300                                 k = 1;
 301                         }
 302
 303                         if (FD_ISSET(i, &x_error)) {
 304                                 if (threads[i].error_func) {
 305                                         threads[i].error_func(threads[i].data);
 306                                         check_bottom_halves();
 307                                 }
 308                                 k = 1;
 309                         }
 310
 311                         n -= k;
 312                 }
 313         }
 314 }
 315
 316 static int
 317 can_read_or_write(int fd, int write)
 318 {
 319         struct timeval tv = {0, 0};
 320         fd_set fds;
 321         fd_set *rfds = NULL;
 322         fd_set *wfds = NULL;
 323
 324         FD_ZERO(&fds);
 325         FD_SET(fd, &fds);
 326
 327         if (write)
 328                 wfds = &fds;
 329         else
 330                 rfds = &fds;
 331
 332         return select(fd + 1, rfds, wfds, NULL, &tv);
 333 }
 334
 335 int
 336 can_read(int fd)
 337 {
 338         return can_read_or_write(fd, 0);
 339 }
 340
 341 int
 342 can_write(int fd)
 343 {
 344         return can_read_or_write(fd, 1);
 345 }