poll.c 5.5 KB

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  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. #include "syscalls.h"
  17. #include <sys/poll.h>
  18. extern __typeof(poll) __libc_poll;
  19. #ifdef __NR_poll
  20. # define __NR___libc_poll __NR_poll
  21. _syscall3(int, __libc_poll, struct pollfd *, fds,
  22. unsigned long int, nfds, int, timeout);
  23. #else
  24. #include <alloca.h>
  25. #include <sys/types.h>
  26. #include <errno.h>
  27. #include <string.h>
  28. #include <sys/time.h>
  29. #include <sys/param.h>
  30. #include <unistd.h>
  31. libc_hidden_proto(memcpy)
  32. libc_hidden_proto(memset)
  33. libc_hidden_proto(getdtablesize)
  34. libc_hidden_proto(select)
  35. /* uClinux 2.0 doesn't have poll, emulate it using select */
  36. /* Poll the file descriptors described by the NFDS structures starting at
  37. FDS. If TIMEOUT is nonzero and not -1, allow TIMEOUT milliseconds for
  38. an event to occur; if TIMEOUT is -1, block until an event occurs.
  39. Returns the number of file descriptors with events, zero if timed out,
  40. or -1 for errors. */
  41. int __libc_poll(struct pollfd *fds, nfds_t nfds, int timeout)
  42. {
  43. static int max_fd_size;
  44. struct timeval tv;
  45. fd_set *rset, *wset, *xset;
  46. struct pollfd *f;
  47. int ready;
  48. int maxfd = 0;
  49. int bytes;
  50. if (!max_fd_size)
  51. max_fd_size = getdtablesize ();
  52. bytes = howmany (max_fd_size, __NFDBITS);
  53. rset = alloca (bytes);
  54. wset = alloca (bytes);
  55. xset = alloca (bytes);
  56. /* We can't call FD_ZERO, since FD_ZERO only works with sets
  57. of exactly __FD_SETSIZE size. */
  58. memset (rset, 0, bytes);
  59. memset (wset, 0, bytes);
  60. memset (xset, 0, bytes);
  61. for (f = fds; f < &fds[nfds]; ++f)
  62. {
  63. f->revents = 0;
  64. if (f->fd >= 0)
  65. {
  66. if (f->fd >= max_fd_size)
  67. {
  68. /* The user provides a file descriptor number which is higher
  69. than the maximum we got from the `getdtablesize' call.
  70. Maybe this is ok so enlarge the arrays. */
  71. fd_set *nrset, *nwset, *nxset;
  72. int nbytes;
  73. max_fd_size = roundup (f->fd, __NFDBITS);
  74. nbytes = howmany (max_fd_size, __NFDBITS);
  75. nrset = alloca (nbytes);
  76. nwset = alloca (nbytes);
  77. nxset = alloca (nbytes);
  78. memset ((char *) nrset + bytes, 0, nbytes - bytes);
  79. memset ((char *) nwset + bytes, 0, nbytes - bytes);
  80. memset ((char *) nxset + bytes, 0, nbytes - bytes);
  81. rset = memcpy (nrset, rset, bytes);
  82. wset = memcpy (nwset, wset, bytes);
  83. xset = memcpy (nxset, xset, bytes);
  84. bytes = nbytes;
  85. }
  86. if (f->events & POLLIN)
  87. FD_SET (f->fd, rset);
  88. if (f->events & POLLOUT)
  89. FD_SET (f->fd, wset);
  90. if (f->events & POLLPRI)
  91. FD_SET (f->fd, xset);
  92. if (f->fd > maxfd && (f->events & (POLLIN|POLLOUT|POLLPRI)))
  93. maxfd = f->fd;
  94. }
  95. }
  96. tv.tv_sec = timeout / 1000;
  97. tv.tv_usec = (timeout % 1000) * 1000;
  98. while (1)
  99. {
  100. ready = select (maxfd + 1, rset, wset, xset,
  101. timeout == -1 ? NULL : &tv);
  102. /* It might be that one or more of the file descriptors is invalid.
  103. We now try to find and mark them and then try again. */
  104. if (ready == -1 && errno == EBADF)
  105. {
  106. fd_set *sngl_rset = alloca (bytes);
  107. fd_set *sngl_wset = alloca (bytes);
  108. fd_set *sngl_xset = alloca (bytes);
  109. struct timeval sngl_tv;
  110. /* Clear the original set. */
  111. memset (rset, 0, bytes);
  112. memset (wset, 0, bytes);
  113. memset (xset, 0, bytes);
  114. /* This means we don't wait for input. */
  115. sngl_tv.tv_sec = 0;
  116. sngl_tv.tv_usec = 0;
  117. maxfd = -1;
  118. /* Reset the return value. */
  119. ready = 0;
  120. for (f = fds; f < &fds[nfds]; ++f)
  121. if (f->fd != -1 && (f->events & (POLLIN|POLLOUT|POLLPRI))
  122. && (f->revents & POLLNVAL) == 0)
  123. {
  124. int n;
  125. memset (sngl_rset, 0, bytes);
  126. memset (sngl_wset, 0, bytes);
  127. memset (sngl_xset, 0, bytes);
  128. if (f->events & POLLIN)
  129. FD_SET (f->fd, sngl_rset);
  130. if (f->events & POLLOUT)
  131. FD_SET (f->fd, sngl_wset);
  132. if (f->events & POLLPRI)
  133. FD_SET (f->fd, sngl_xset);
  134. n = select (f->fd + 1, sngl_rset, sngl_wset, sngl_xset,
  135. &sngl_tv);
  136. if (n != -1)
  137. {
  138. /* This descriptor is ok. */
  139. if (f->events & POLLIN)
  140. FD_SET (f->fd, rset);
  141. if (f->events & POLLOUT)
  142. FD_SET (f->fd, wset);
  143. if (f->events & POLLPRI)
  144. FD_SET (f->fd, xset);
  145. if (f->fd > maxfd)
  146. maxfd = f->fd;
  147. if (n > 0)
  148. /* Count it as being available. */
  149. ++ready;
  150. }
  151. else if (errno == EBADF)
  152. f->revents |= POLLNVAL;
  153. }
  154. /* Try again. */
  155. continue;
  156. }
  157. break;
  158. }
  159. if (ready > 0)
  160. for (f = fds; f < &fds[nfds]; ++f)
  161. {
  162. if (f->fd >= 0)
  163. {
  164. if (FD_ISSET (f->fd, rset))
  165. f->revents |= POLLIN;
  166. if (FD_ISSET (f->fd, wset))
  167. f->revents |= POLLOUT;
  168. if (FD_ISSET (f->fd, xset))
  169. f->revents |= POLLPRI;
  170. }
  171. }
  172. return ready;
  173. }
  174. #endif
  175. libc_hidden_proto(poll)
  176. weak_alias(__libc_poll,poll)
  177. libc_hidden_weak(poll)