misc/sys/select.h

   1 /* `fd_set' type and related macros, and `select'/`pselect' declarations.
   2    Copyright (C) 1996-2013 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 this macros.  */
  57 #undef  __NFDBITS
  58 /* It's easier to assume 8-bit bytes than to get CHAR_BIT.  */
  59 #define __NFDBITS       (8 * (int) sizeof (__fd_mask))
  60 #define __FD_ELT(d)     ((d) / __NFDBITS)
  61 #define __FD_MASK(d)    ((__fd_mask) 1 << ((d) % __NFDBITS))
  62
  63 /* fd_set for select and pselect.  */
  64 typedef struct
  65   {
  66     /* XPG4.2 requires this member name.  Otherwise avoid the name
  67        from the global namespace.  */
  68 #ifdef __USE_XOPEN
  69     __fd_mask fds_bits[__FD_SETSIZE / __NFDBITS];
  70 # define __FDS_BITS(set) ((set)->fds_bits)
  71 #else
  72     __fd_mask __fds_bits[__FD_SETSIZE / __NFDBITS];
  73 # define __FDS_BITS(set) ((set)->__fds_bits)
  74 #endif
  75   } fd_set;
  76
  77 /* Maximum number of file descriptors in `fd_set'.  */
  78 #define FD_SETSIZE              __FD_SETSIZE
  79
  80 #ifdef __USE_MISC
  81 /* Sometimes the fd_set member is assumed to have this type.  */
  82 typedef __fd_mask fd_mask;
  83
  84 /* Number of bits per word of `fd_set' (some code assumes this is 32).  */
  85 # define NFDBITS                __NFDBITS
  86 #endif
  87
  88
  89 /* Access macros for `fd_set'.  */
  90 #define FD_SET(fd, fdsetp)      __FD_SET (fd, fdsetp)
  91 #define FD_CLR(fd, fdsetp)      __FD_CLR (fd, fdsetp)
  92 #define FD_ISSET(fd, fdsetp)    __FD_ISSET (fd, fdsetp)
  93 #define FD_ZERO(fdsetp)         __FD_ZERO (fdsetp)
  94
  95
  96 __BEGIN_DECLS
  97
  98 /* Check the first NFDS descriptors each in READFDS (if not NULL) for read
  99    readiness, in WRITEFDS (if not NULL) for write readiness, and in EXCEPTFDS
 100    (if not NULL) for exceptional conditions.  If TIMEOUT is not NULL, time out
 101    after waiting the interval specified therein.  Returns the number of ready
 102    descriptors, or -1 for errors.
 103
 104    This function is a cancellation point and therefore not marked with
 105    __THROW.  */
 106 extern int select (int __nfds, fd_set *__restrict __readfds,
 107                    fd_set *__restrict __writefds,
 108                    fd_set *__restrict __exceptfds,
 109                    struct timeval *__restrict __timeout);
 110
 111 #ifdef __USE_XOPEN2K
 112 /* Same as above only that the TIMEOUT value is given with higher
 113    resolution and a sigmask which is been set temporarily.  This version
 114    should be used.
 115
 116    This function is a cancellation point and therefore not marked with
 117    __THROW.  */
 118 extern int pselect (int __nfds, fd_set *__restrict __readfds,
 119                     fd_set *__restrict __writefds,
 120                     fd_set *__restrict __exceptfds,
 121                     const struct timespec *__restrict __timeout,
 122                     const __sigset_t *__restrict __sigmask);
 123 #endif
 124
 125
 126 /* Define some inlines helping to catch common problems.  */
 127 #if __USE_FORTIFY_LEVEL > 0 && defined __GNUC__
 128 # include <bits/select2.h>
 129 #endif
 130
 131 __END_DECLS
 132
 133 #endif /* sys/select.h */