poll.c 5.2 KB

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204
  1. /* Copyright (C) 1994,1996,1997,1998,1999,2001,2002
  2. Free Software Foundation, Inc.
  3. This file is part of the GNU C Library.
  4. The GNU C Library is free software; you can redistribute it and/or
  5. modify it under the terms of the GNU Lesser General Public
  6. License as published by the Free Software Foundation; either
  7. version 2.1 of the License, or (at your option) any later version.
  8. The GNU C Library is distributed in the hope that it will be useful,
  9. but WITHOUT ANY WARRANTY; without even the implied warranty of
  10. MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  11. Lesser General Public License for more details.
  12. You should have received a copy of the GNU Lesser General Public
  13. License along with the GNU C Library; if not, write to the Free
  14. Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  15. 02111-1307 USA. */
  16. #ifdef __NR_poll
  17. #include "syscalls.h"
  18. #include <sys/poll.h>
  19. _syscall3(int, poll, struct pollfd *, fds,
  20. unsigned long int, nfds, int, timeout);
  21. #else
  22. #include <alloca.h>
  23. #include <sys/poll.h>
  24. #include <sys/types.h>
  25. #include <errno.h>
  26. #include <string.h>
  27. #include <sys/time.h>
  28. #include <sys/param.h>
  29. #include <unistd.h>
  30. /* uClinux 2.0 doesn't have poll, emulate it using select */
  31. /* Poll the file descriptors described by the NFDS structures starting at
  32. FDS. If TIMEOUT is nonzero and not -1, allow TIMEOUT milliseconds for
  33. an event to occur; if TIMEOUT is -1, block until an event occurs.
  34. Returns the number of file descriptors with events, zero if timed out,
  35. or -1 for errors. */
  36. int poll(struct pollfd *fds, nfds_t nfds, int timeout)
  37. {
  38. static int max_fd_size;
  39. struct timeval tv;
  40. fd_set *rset, *wset, *xset;
  41. struct pollfd *f;
  42. int ready;
  43. int maxfd = 0;
  44. int bytes;
  45. if (!max_fd_size)
  46. max_fd_size = getdtablesize ();
  47. bytes = howmany (max_fd_size, __NFDBITS);
  48. rset = alloca (bytes);
  49. wset = alloca (bytes);
  50. xset = alloca (bytes);
  51. /* We can't call FD_ZERO, since FD_ZERO only works with sets
  52. of exactly __FD_SETSIZE size. */
  53. bzero (rset, bytes);
  54. bzero (wset, bytes);
  55. bzero (xset, bytes);
  56. for (f = fds; f < &fds[nfds]; ++f)
  57. {
  58. f->revents = 0;
  59. if (f->fd >= 0)
  60. {
  61. if (f->fd >= max_fd_size)
  62. {
  63. /* The user provides a file descriptor number which is higher
  64. than the maximum we got from the `getdtablesize' call.
  65. Maybe this is ok so enlarge the arrays. */
  66. fd_set *nrset, *nwset, *nxset;
  67. int nbytes;
  68. max_fd_size = roundup (f->fd, __NFDBITS);
  69. nbytes = howmany (max_fd_size, __NFDBITS);
  70. nrset = alloca (nbytes);
  71. nwset = alloca (nbytes);
  72. nxset = alloca (nbytes);
  73. bzero ((char *) nrset + bytes, nbytes - bytes);
  74. bzero ((char *) nwset + bytes, nbytes - bytes);
  75. bzero ((char *) nxset + bytes, nbytes - bytes);
  76. rset = memcpy (nrset, rset, bytes);
  77. wset = memcpy (nwset, wset, bytes);
  78. xset = memcpy (nxset, xset, bytes);
  79. bytes = nbytes;
  80. }
  81. if (f->events & POLLIN)
  82. FD_SET (f->fd, rset);
  83. if (f->events & POLLOUT)
  84. FD_SET (f->fd, wset);
  85. if (f->events & POLLPRI)
  86. FD_SET (f->fd, xset);
  87. if (f->fd > maxfd && (f->events & (POLLIN|POLLOUT|POLLPRI)))
  88. maxfd = f->fd;
  89. }
  90. }
  91. tv.tv_sec = timeout / 1000;
  92. tv.tv_usec = (timeout % 1000) * 1000;
  93. while (1)
  94. {
  95. ready = select (maxfd + 1, rset, wset, xset,
  96. timeout == -1 ? NULL : &tv);
  97. /* It might be that one or more of the file descriptors is invalid.
  98. We now try to find and mark them and then try again. */
  99. if (ready == -1 && errno == EBADF)
  100. {
  101. fd_set *sngl_rset = alloca (bytes);
  102. fd_set *sngl_wset = alloca (bytes);
  103. fd_set *sngl_xset = alloca (bytes);
  104. struct timeval sngl_tv;
  105. /* Clear the original set. */
  106. bzero (rset, bytes);
  107. bzero (wset, bytes);
  108. bzero (xset, bytes);
  109. /* This means we don't wait for input. */
  110. sngl_tv.tv_sec = 0;
  111. sngl_tv.tv_usec = 0;
  112. maxfd = -1;
  113. /* Reset the return value. */
  114. ready = 0;
  115. for (f = fds; f < &fds[nfds]; ++f)
  116. if (f->fd != -1 && (f->events & (POLLIN|POLLOUT|POLLPRI))
  117. && (f->revents & POLLNVAL) == 0)
  118. {
  119. int n;
  120. bzero (sngl_rset, bytes);
  121. bzero (sngl_wset, bytes);
  122. bzero (sngl_xset, bytes);
  123. if (f->events & POLLIN)
  124. FD_SET (f->fd, sngl_rset);
  125. if (f->events & POLLOUT)
  126. FD_SET (f->fd, sngl_wset);
  127. if (f->events & POLLPRI)
  128. FD_SET (f->fd, sngl_xset);
  129. n = select (f->fd + 1, sngl_rset, sngl_wset, sngl_xset,
  130. &sngl_tv);
  131. if (n != -1)
  132. {
  133. /* This descriptor is ok. */
  134. if (f->events & POLLIN)
  135. FD_SET (f->fd, rset);
  136. if (f->events & POLLOUT)
  137. FD_SET (f->fd, wset);
  138. if (f->events & POLLPRI)
  139. FD_SET (f->fd, xset);
  140. if (f->fd > maxfd)
  141. maxfd = f->fd;
  142. if (n > 0)
  143. /* Count it as being available. */
  144. ++ready;
  145. }
  146. else if (errno == EBADF)
  147. f->revents |= POLLNVAL;
  148. }
  149. /* Try again. */
  150. continue;
  151. }
  152. break;
  153. }
  154. if (ready > 0)
  155. for (f = fds; f < &fds[nfds]; ++f)
  156. {
  157. if (f->fd >= 0)
  158. {
  159. if (FD_ISSET (f->fd, rset))
  160. f->revents |= POLLIN;
  161. if (FD_ISSET (f->fd, wset))
  162. f->revents |= POLLOUT;
  163. if (FD_ISSET (f->fd, xset))
  164. f->revents |= POLLPRI;
  165. }
  166. }
  167. return ready;
  168. }
  169. #endif