include/sys/select.h

   1 /* `fd_set' type and related macros, and `select'/`pselect' declarations.
   2    Copyright (C) 1996,97,98,99,2000,01,02,2003 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 /*      POSIX 1003.1g: 6.2 Select from File Descriptor Sets <sys/select.h>  */
  20
  21 #ifndef _SYS_SELECT_H
  22 #define _SYS_SELECT_H   1
  23
  24 #include <features.h>
  25
  26 /* Get definition of needed basic types.  */
  27 #include <bits/types.h>
  28
  29 /* Get __FD_* definitions.  */
  30 #include <bits/select.h>
  31
  32 /* Get __sigset_t.  */
  33 #include <bits/sigset.h>
  34
  35 #ifndef __sigset_t_defined
  36 # define __sigset_t_defined
  37 typedef __sigset_t sigset_t;
  38 #endif
  39
  40 /* Get definition of timer specification structures.  */
  41 #define __need_time_t
  42 #define __need_timespec
  43 #include <time.h>
  44 #define __need_timeval
  45 #include <bits/time.h>
  46
  47 #ifndef __suseconds_t_defined
  48 typedef __suseconds_t suseconds_t;
  49 # define __suseconds_t_defined
  50 #endif
  51
  52
  53 /* The fd_set member is required to be an array of longs.  */
  54 typedef long int __fd_mask;
  55
  56 /* Some versions of <linux/posix_types.h> define these macros.  */
  57 #undef  __NFDBITS
  58 #undef  __FDELT
  59 #undef  __FDMASK
  60 /* It's easier to assume 8-bit bytes than to get CHAR_BIT.  */
  61 #define __NFDBITS       (8 * sizeof (__fd_mask))
  62 #define __FDELT(d)      ((d) / __NFDBITS)
  63 #define __FDMASK(d)     ((__fd_mask) 1 << ((d) % __NFDBITS))
  64
  65 /* fd_set for select and pselect.  */
  66 typedef struct
  67   {
  68     /* XPG4.2 requires this member name.  Otherwise avoid the name
  69        from the global namespace.  */
  70 #ifdef __USE_XOPEN
  71     __fd_mask fds_bits[__FD_SETSIZE / __NFDBITS];
  72 # define __FDS_BITS(set) ((set)->fds_bits)
  73 #else
  74     __fd_mask __fds_bits[__FD_SETSIZE / __NFDBITS];
  75 # define __FDS_BITS(set) ((set)->__fds_bits)
  76 #endif
  77   } fd_set;
  78
  79 /* Maximum number of file descriptors in `fd_set'.  */
  80 #define FD_SETSIZE              __FD_SETSIZE
  81
  82 #ifdef __USE_MISC
  83 /* Sometimes the fd_set member is assumed to have this type.  */
  84 typedef __fd_mask fd_mask;
  85
  86 /* Number of bits per word of `fd_set' (some code assumes this is 32).  */
  87 # define NFDBITS                __NFDBITS
  88 #endif
  89
  90
  91 /* Access macros for `fd_set'.  */
  92 #define FD_SET(fd, fdsetp)      __FD_SET (fd, fdsetp)
  93 #define FD_CLR(fd, fdsetp)      __FD_CLR (fd, fdsetp)
  94 #define FD_ISSET(fd, fdsetp)    __FD_ISSET (fd, fdsetp)
  95 #define FD_ZERO(fdsetp)         __FD_ZERO (fdsetp)
  96
  97
  98 __BEGIN_DECLS
  99
 100 /* Check the first NFDS descriptors each in READFDS (if not NULL) for read
 101    readiness, in WRITEFDS (if not NULL) for write readiness, and in EXCEPTFDS
 102    (if not NULL) for exceptional conditions.  If TIMEOUT is not NULL, time out
 103    after waiting the interval specified therein.  Returns the number of ready
 104    descriptors, or -1 for errors.
 105
 106    This function is a cancellation point and therefore not marked with
 107    __THROW.  */
 108 extern int select (int __nfds, fd_set *__restrict __readfds,
 109                    fd_set *__restrict __writefds,
 110                    fd_set *__restrict __exceptfds,
 111                    struct timeval *__restrict __timeout);
 112 #ifdef _LIBC
 113 extern __typeof(select) __select_nocancel attribute_hidden;
 114 libc_hidden_proto(select)
 115 #endif
 116
 117 #ifdef __USE_XOPEN2K
 118 /* Same as above only that the TIMEOUT value is given with higher
 119    resolution and a sigmask which is been set temporarily.  This version
 120    should be used.
 121
 122    This function is a cancellation point and therefore not marked with
 123    __THROW.  */
 124 extern int pselect (int __nfds, fd_set *__restrict __readfds,
 125                     fd_set *__restrict __writefds,
 126                     fd_set *__restrict __exceptfds,
 127                     const struct timespec *__restrict __timeout,
 128                     const __sigset_t *__restrict __sigmask);
 129 #endif
 130
 131 __END_DECLS
 132
 133 #endif /* sys/select.h */