bsd/man/man2/pathconf.2

   1 .\"     $NetBSD: pathconf.2,v 1.2 1995/02/27 12:35:22 cgd Exp $
   2 .\"
   3 .\" Copyright (c) 1993
   4 .\"     The Regents of the University of California.  All rights reserved.
   5 .\"
   6 .\" Redistribution and use in source and binary forms, with or without
   7 .\" modification, are permitted provided that the following conditions
   8 .\" are met:
   9 .\" 1. Redistributions of source code must retain the above copyright
  10 .\"    notice, this list of conditions and the following disclaimer.
  11 .\" 2. Redistributions in binary form must reproduce the above copyright
  12 .\"    notice, this list of conditions and the following disclaimer in the
  13 .\"    documentation and/or other materials provided with the distribution.
  14 .\" 3. All advertising materials mentioning features or use of this software
  15 .\"    must display the following acknowledgement:
  16 .\"     This product includes software developed by the University of
  17 .\"     California, Berkeley and its contributors.
  18 .\" 4. Neither the name of the University nor the names of its contributors
  19 .\"    may be used to endorse or promote products derived from this software
  20 .\"    without specific prior written permission.
  21 .\"
  22 .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  23 .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24 .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25 .\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26 .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27 .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28 .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29 .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30 .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32 .\" SUCH DAMAGE.
  33 .\"
  34 .\"     @(#)pathconf.2  8.1 (Berkeley) 6/4/93
  35 .\"
  36 .Dd June 4, 1993
  37 .Dt PATHCONF 2
  38 .Os BSD 4
  39 .Sh NAME
  40 .Nm fpathconf ,
  41 .Nm pathconf
  42 .Nd get configurable pathname variables
  43 .Sh SYNOPSIS
  44 .Fd #include <unistd.h>
  45 .Ft long
  46 .Fo fpathconf
  47 .Fa "int fildes"
  48 .Fa "int name"
  49 .Fc
  50 .Ft long
  51 .Fo pathconf
  52 .Fa "const char *path"
  53 .Fa "int name"
  54 .Fc
  55 .Sh DESCRIPTION
  56 .Pp
  57 The
  58 .Fn pathconf
  59 and
  60 .Fn fpathconf
  61 functions provides a method for applications to determine the current
  62 value of a configurable system limit or option variable associated
  63 with a pathname or file descriptor.
  64 .Pp
  65 For
  66 .Nm pathconf ,
  67 the
  68 .Fa path
  69 argument is the name of a file or directory.
  70 For
  71 .Nm fpathconf ,
  72 the
  73 .Fa fildes
  74 argument is an open file descriptor.
  75 The
  76 .Fa name
  77 argument specifies the system variable to be queried.
  78 Symbolic constants for each name value are found in the include file
  79 .Li <unistd.h> .
  80 .Pp
  81 The available values are as follows:
  82 .Pp
  83 .Bl -tag -width "123456"
  84 .Pp
  85 .It Li _PC_LINK_MAX
  86 The maximum file link count.
  87 .It Li _PC_MAX_CANON
  88 The maximum number of bytes in terminal canonical input line.
  89 .It Li _PC_MAX_INPUT
  90 The minimum maximum number of bytes for which space is available in
  91 a terminal input queue.
  92 .It Li _PC_NAME_MAX
  93 The maximum number of bytes in a file name.
  94 .It Li _PC_PATH_MAX
  95 The maximum number of bytes in a pathname.
  96 .It Li _PC_PIPE_BUF
  97 The maximum number of bytes which will be written atomically to a pipe.
  98 .It Li _PC_CHOWN_RESTRICTED
  99 Return 1 if appropriate privileges are required for the
 100 .Xr chown 2
 101 system call, otherwise 0.
 102 .It Li _PC_NO_TRUNC
 103 Return 1 if file names longer than KERN_NAME_MAX are truncated.
 104 .It Li _PC_VDISABLE
 105 Returns the terminal character disabling value.
 106 .El
 107 .Sh RETURN VALUES
 108 If the call to
 109 .Nm pathconf
 110 or
 111 .Nm fpathconf
 112 is not successful, \-1 is returned and
 113 .Va errno
 114 is set appropriately.
 115 Otherwise, if the variable is associated with functionality that does
 116 not have a limit in the system, \-1 is returned and
 117 .Va errno
 118 is not modified.
 119 Otherwise, the current variable value is returned.
 120 .Sh ERRORS
 121 If any of the following conditions occur, the
 122 .Nm pathconf
 123 and
 124 .Nm fpathconf
 125 functions shall return -1 and set
 126 .Va errno
 127 to the corresponding value.
 128 .Bl -tag -width ENAMETOOLONGAA
 129 .\" ===========
 130 .It Bq Er EINVAL
 131 The value of the
 132 .Fa name
 133 argument is invalid.
 134 .\" ===========
 135 .It Bq Er EINVAL
 136 The implementation does not support an association of the variable
 137 name with the associated file.
 138 .El
 139 .Pp
 140 .Fn Pathconf
 141 will fail if:
 142 .Bl -tag -width ENAMETOOLONGAA
 143 .\" ===========
 144 .It Bq Er EACCES
 145 Search permission is denied for a component of the path prefix.
 146 .\" ===========
 147 .It Bq Er EIO
 148 An I/O error occurs while reading from or writing to the file system.
 149 .\" ===========
 150 .It Bq Er ELOOP
 151 Too many symbolic links are encountered in translating the pathname.
 152 This is taken to be indicative of a looping symbolic link.
 153 .\" ===========
 154 .It Bq Er ENAMETOOLONG
 155 A component of a pathname exceeded 255 characters,
 156 or an entire path name exceeded 1023 characters.
 157 .\" ===========
 158 .It Bq Er ENOENT
 159 The named file does not exist.
 160 .\" ===========
 161 .It Bq Er ENOTDIR
 162 A component of the path prefix is not a directory.
 163 .El
 164 .Pp
 165 .Bl -tag -width ENAMETOOLONGAA
 166 .Fn Fpathconf
 167 will fail if:
 168 .\" ===========
 169 .It Bq Er EBADF
 170 .Fa fildes
 171 is not a valid open file descriptor.
 172 .\" ===========
 173 .It Bq Er EIO
 174 An I/O error occurs while reading from or writing to the file system.
 175 .El
 176 .Sh SEE ALSO
 177 .Xr sysctl 3
 178 .Sh HISTORY
 179 The
 180 .Nm pathconf
 181 and
 182 .Nm fpathconf
 183 functions first appeared in 4.4BSD.