libguile/poll.c

   1 /* Copyright (C) 2010 Free Software Foundation, Inc.
   2  *
   3  * This library is free software; you can redistribute it and/or
   4  * modify it under the terms of the GNU Lesser General Public License
   5  * as published by the Free Software Foundation; either version 3 of
   6  * the License, or (at your option) any later version.
   7  *
   8  * This library is distributed in the hope that it will be useful, but
   9  * 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  *
  13  * You should have received a copy of the GNU Lesser General Public
  14  * License along with this library; if not, write to the Free Software
  15  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  16  * 02110-1301 USA
  17  */
  18
  19
  20 \f
  21
  22 #define _GNU_SOURCE
  23
  24 #ifdef HAVE_CONFIG_H
  25 #  include <config.h>
  26 #endif
  27
  28 #include "libguile/_scm.h"
  29 #include "libguile/bytevectors.h"
  30 #include "libguile/numbers.h"
  31 #include "libguile/error.h"
  32 #include "libguile/validate.h"
  33
  34 #include "libguile/poll.h"
  35
  36 \f
  37 #ifdef HAVE_POLL_H
  38 #include <poll.h>
  39 #endif
  40
  41 \f
  42
  43 /* {Poll}
  44  */
  45
  46 /* Poll a set of file descriptors, waiting until one or more of them is
  47    ready to perform input or output.
  48
  49    This is a low-level interface.  See the `(ice-9 poll)' module for a more
  50    usable wrapper.
  51
  52    `pollfds' is expected to be a bytevector, laid out in contiguous blocks of 64
  53    bits.  Each block has the format of one `struct pollfd': a 32-bit int file
  54    descriptor, a 16-bit int events mask, and a 16-bit int revents mask.
  55
  56    The number of pollfd structures in `pollfds' is specified in
  57    `nfds'. `pollfds' must be at least long enough to support that number of
  58    structures. It may be longer, in which case the trailing entries are left
  59    untouched.
  60
  61    The pollfds bytevector is modified directly, setting the returned events in
  62    the final two bytes (the revents member).
  63
  64    If timeout is given and is non-negative, the poll will return after that
  65    number of milliseconds if no fd became active.
  66    */
  67 #ifdef HAVE_POLL
  68 static SCM
  69 scm_primitive_poll (SCM pollfds, SCM nfds, SCM timeout)
  70 #define FUNC_NAME "primitive-poll"
  71 {
  72   int rv;
  73   nfds_t c_nfds;
  74   int c_timeout;
  75   struct pollfd *fds;
  76
  77   SCM_VALIDATE_BYTEVECTOR (SCM_ARG1, pollfds);
  78   c_nfds = scm_to_uint32 (nfds);
  79   c_timeout = scm_to_int (timeout);
  80
  81   if (SCM_UNLIKELY (SCM_BYTEVECTOR_LENGTH (pollfds)
  82                     < c_nfds * sizeof(struct pollfd)))
  83     SCM_OUT_OF_RANGE (SCM_ARG1, nfds);
  84
  85   fds = (struct pollfd*)SCM_BYTEVECTOR_CONTENTS (pollfds);
  86
  87   SCM_SYSCALL (rv = poll (fds, c_nfds, c_timeout));
  88
  89   if (rv == -1)
  90     SCM_SYSERROR;
  91
  92   return scm_from_int (rv);
  93 }
  94 #undef FUNC_NAME
  95 #endif /* HAVE_POLL */
  96
  97
  98 \f
  99
 100 static void
 101 scm_init_poll (void)
 102 {
 103 #if HAVE_POLL
 104   scm_c_define_gsubr ("primitive-poll", 3, 0, 0, scm_primitive_poll);
 105 #else
 106   scm_misc_error ("%init-poll", "`poll' unavailable on this platform", SCM_EOL);
 107 #endif
 108
 109 #ifdef POLLIN
 110   scm_c_define ("POLLIN", scm_from_int (POLLIN));
 111 #endif
 112 #ifdef POLLPRI
 113   scm_c_define ("POLLPRI", scm_from_int (POLLPRI));
 114 #endif
 115 #ifdef POLLOUT
 116   scm_c_define ("POLLOUT", scm_from_int (POLLOUT));
 117 #endif
 118 #ifdef POLLRDHUP
 119   scm_c_define ("POLLRDHUP", scm_from_int (POLLRDHUP));
 120 #endif
 121 #ifdef POLLERR
 122   scm_c_define ("POLLERR", scm_from_int (POLLERR));
 123 #endif
 124 #ifdef POLLHUP
 125   scm_c_define ("POLLHUP", scm_from_int (POLLHUP));
 126 #endif
 127 #ifdef POLLNVAL
 128   scm_c_define ("POLLNVAL", scm_from_int (POLLNVAL));
 129 #endif
 130
 131 }
 132
 133 void
 134 scm_register_poll (void)
 135 {
 136   scm_c_register_extension ("libguile-" SCM_EFFECTIVE_VERSION,
 137                             "scm_init_poll",
 138                             (scm_t_extension_init_func) scm_init_poll,
 139                             NULL);
 140 }
 141
 142 /*
 143   Local Variables:
 144   c-file-style: "gnu"
 145   End:
 146 */