bsd/man/man2/pathconf.2

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  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 pathconf ,
  41 .Nm fpathconf
  42 .Nd get configurable pathname variables
  43 .Sh SYNOPSIS
  44 .Fd #include <unistd.h>
  45 .Ft long
  46 .Fn pathconf "const char *path" "int name"
  47 .Ft long
  48 .Fn fpathconf "int fd" "int name"
  49 .Sh DESCRIPTION
  50 .Pp
  51 The
  52 .Fn pathconf
  53 and
  54 .Fn fpathconf
  55 functions provides a method for applications to determine the current
  56 value of a configurable system limit or option variable associated
  57 with a pathname or file descriptor.
  58 .Pp
  59 For
  60 .Nm pathconf ,
  61 the
  62 .Fa path
  63 argument is the name of a file or directory.
  64 For
  65 .Nm fpathconf ,
  66 the
  67 .Fa fd
  68 argument is an open file descriptor.
  69 The
  70 .Fa name
  71 argument specifies the system variable to be queried.
  72 Symbolic constants for each name value are found in the include file
  73 .Li <unistd.h> .
  74 .Pp
  75 The available values are as follows:
  76 .Pp
  77 .Bl -tag -width "123456"
  78 .Pp
  79 .It Li _PC_LINK_MAX
  80 The maximum file link count.
  81 .It Li _PC_MAX_CANON
  82 The maximum number of bytes in terminal canonical input line.
  83 .It Li _PC_MAX_INPUT
  84 The minimum maximum number of bytes for which space is available in
  85 a terminal input queue.
  86 .It Li _PC_NAME_MAX
  87 The maximum number of bytes in a file name.
  88 .It Li _PC_PATH_MAX
  89 The maximum number of bytes in a pathname.
  90 .It Li _PC_PIPE_BUF
  91 The maximum number of bytes which will be written atomically to a pipe.
  92 .It Li _PC_CHOWN_RESTRICTED
  93 Return 1 if appropriate privileges are required for the
  94 .Xr chown 2
  95 system call, otherwise 0.
  96 .It Li _PC_NO_TRUNC
  97 Return 1 if file names longer than KERN_NAME_MAX are truncated.
  98 .It Li _PC_VDISABLE
  99 Returns the terminal character disabling value.
 100 .El
 101 .Sh RETURN VALUES
 102 If the call to
 103 .Nm pathconf
 104 or
 105 .Nm fpathconf
 106 is not successful, \-1 is returned and
 107 .Va errno
 108 is set appropriately.
 109 Otherwise, if the variable is associated with functionality that does
 110 not have a limit in the system, \-1 is returned and
 111 .Va errno
 112 is not modified.
 113 Otherwise, the current variable value is returned.
 114 .Sh ERRORS
 115 If any of the following conditions occur, the
 116 .Nm pathconf
 117 and
 118 .Nm fpathconf
 119 functions shall return -1 and set
 120 .Va errno
 121 to the corresponding value.
 122 .Bl -tag -width Er
 123 .It Bq Er EINVAL
 124 The value of the
 125 .Fa name
 126 argument is invalid.
 127 .It Bq Er EINVAL
 128 The implementation does not support an association of the variable
 129 name with the associated file.
 130 .El
 131 .Fn Pathconf
 132 will fail if:
 133 .Bl -tag -width ENAMETOOLONGAA
 134 .It Bq Er ENOTDIR
 135 A component of the path prefix is not a directory.
 136 .It Bq Er ENAMETOOLONG
 137 A component of a pathname exceeded 255 characters,
 138 or an entire path name exceeded 1023 characters.
 139 .It Bq Er ENOENT
 140 The named file does not exist.
 141 .It Bq Er EACCES
 142 Search permission is denied for a component of the path prefix.
 143 .It Bq Er ELOOP
 144 Too many symbolic links were encountered in translating the pathname.
 145 .It Bq Er EIO
 146 An I/O error occurred while reading from or writing to the file system.
 147 .El
 148 .Pp
 149 .Bl -tag -width [EFAULT]
 150 .Fn Fpathconf
 151 will fail if:
 152 .It Bq Er EBADF
 153 .Fa fd
 154 is not a valid open file descriptor.
 155 .It Bq Er EIO
 156 An I/O error occurred while reading from or writing to the file system.
 157 .El
 158 .Sh SEE ALSO
 159 .Xr sysctl 3
 160 .Sh HISTORY
 161 The
 162 .Nm pathconf
 163 and
 164 .Nm fpathconf
 165 functions first appeared in 4.4BSD.