262 lines
7.5 KiB
Groff
262 lines
7.5 KiB
Groff
.\" Copyright (c) 1993
|
|
.\" The Regents of the University of California. All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\" 4. Neither the name of the University nor the names of its contributors
|
|
.\" may be used to endorse or promote products derived from this software
|
|
.\" without specific prior written permission.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
.\" SUCH DAMAGE.
|
|
.\"
|
|
.\" @(#)pathconf.2 8.1 (Berkeley) 6/4/93
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd July 7, 2009
|
|
.Dt PATHCONF 2
|
|
.Os
|
|
.Sh NAME
|
|
.Nm pathconf ,
|
|
.Nm lpathconf ,
|
|
.Nm fpathconf
|
|
.Nd get configurable pathname variables
|
|
.Sh LIBRARY
|
|
.Lb libc
|
|
.Sh SYNOPSIS
|
|
.In unistd.h
|
|
.Ft long
|
|
.Fn pathconf "const char *path" "int name"
|
|
.Ft long
|
|
.Fn lpathconf "const char *path" "int name"
|
|
.Ft long
|
|
.Fn fpathconf "int fd" "int name"
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Fn pathconf ,
|
|
.Fn lpathconf
|
|
and
|
|
.Fn fpathconf
|
|
system calls provide a method for applications to determine the current
|
|
value of a configurable system limit or option variable associated
|
|
with a pathname or file descriptor.
|
|
.Pp
|
|
For
|
|
.Fn pathconf
|
|
and
|
|
.Fn lpathconf ,
|
|
the
|
|
.Fa path
|
|
argument is the name of a file or directory.
|
|
For
|
|
.Fn fpathconf ,
|
|
the
|
|
.Fa fd
|
|
argument is an open file descriptor.
|
|
The
|
|
.Fa name
|
|
argument specifies the system variable to be queried.
|
|
Symbolic constants for each name value are found in the include file
|
|
.Li <unistd.h> .
|
|
.Pp
|
|
The
|
|
.Fn lpathconf
|
|
system call is like
|
|
.Fn pathconf
|
|
except in the case where the named file is a symbolic link,
|
|
in which case
|
|
.Fn lpathconf
|
|
returns information about the link,
|
|
while
|
|
.Fn pathconf
|
|
returns information about the file the link references.
|
|
.Pp
|
|
The available values are as follows:
|
|
.Bl -tag -width 6n
|
|
.It Li _PC_LINK_MAX
|
|
The maximum file link count.
|
|
.It Li _PC_MAX_CANON
|
|
The maximum number of bytes in terminal canonical input line.
|
|
.It Li _PC_MAX_INPUT
|
|
The minimum maximum number of bytes for which space is available in
|
|
a terminal input queue.
|
|
.It Li _PC_NAME_MAX
|
|
The maximum number of bytes in a file name.
|
|
.It Li _PC_PATH_MAX
|
|
The maximum number of bytes in a pathname.
|
|
.It Li _PC_PIPE_BUF
|
|
The maximum number of bytes which will be written atomically to a pipe.
|
|
.It Li _PC_CHOWN_RESTRICTED
|
|
Return 1 if appropriate privilege is required for the
|
|
.Xr chown 2
|
|
system call, otherwise 0.
|
|
.St -p1003.1-2001
|
|
requires appropriate privilege in all cases, but this behavior was optional
|
|
in prior editions of the standard.
|
|
.It Li _PC_NO_TRUNC
|
|
Return greater than zero if attempts to use pathname components longer than
|
|
.Brq Dv NAME_MAX
|
|
will result in an
|
|
.Bq Er ENAMETOOLONG
|
|
error; otherwise, such components will be truncated to
|
|
.Brq Dv NAME_MAX .
|
|
.St -p1003.1-2001
|
|
requires the error in all cases, but this behavior was optional in prior
|
|
editions of the standard, and some
|
|
.No non- Ns Tn POSIX Ns -compliant
|
|
file systems do not support this behavior.
|
|
.It Li _PC_VDISABLE
|
|
Returns the terminal character disabling value.
|
|
.It Li _PC_ASYNC_IO
|
|
Return 1 if asynchronous I/O is supported, otherwise 0.
|
|
.It Li _PC_PRIO_IO
|
|
Returns 1 if prioritised I/O is supported for this file,
|
|
otherwise 0.
|
|
.It Li _PC_SYNC_IO
|
|
Returns 1 if synchronised I/O is supported for this file, otherwise 0.
|
|
.It Li _PC_ALLOC_SIZE_MIN
|
|
Minimum number of bytes of storage allocated for any portion of a file.
|
|
.It Li _PC_FILESIZEBITS
|
|
Number of bits needed to represent the maximum file size.
|
|
.It Li _PC_REC_INCR_XFER_SIZE
|
|
Recommended increment for file transfer sizes between
|
|
.Dv _PC_REC_MIN_XFER_SIZE
|
|
and
|
|
.Dv _PC_REC_MAX_XFER_SIZE .
|
|
.It Li _PC_REC_MAX_XFER_SIZE
|
|
Maximum recommended file transfer size.
|
|
.It Li _PC_REC_MIN_XFER_SIZE
|
|
Minimum recommended file transfer size.
|
|
.It Li _PC_REC_XFER_ALIGN
|
|
Recommended file transfer buffer alignment.
|
|
.It Li _PC_SYMLINK_MAX
|
|
Maximum number of bytes in a symbolic link.
|
|
.It Li _PC_ACL_EXTENDED
|
|
Returns 1 if an Access Control List (ACL) can be set on the specified
|
|
file, otherwise 0.
|
|
.It Li _PC_ACL_NFS4
|
|
Returns 1 if an NFSv4 ACLs can be set on the specified
|
|
file, otherwise 0.
|
|
.It Li _PC_ACL_PATH_MAX
|
|
Maximum number of ACL entries per file.
|
|
.It Li _PC_CAP_PRESENT
|
|
Returns 1 if a capability state can be set on the specified file,
|
|
otherwise 0.
|
|
.It Li _PC_INF_PRESENT
|
|
Returns 1 if an information label can be set on the specified file,
|
|
otherwise 0.
|
|
.It Li _PC_MAC_PRESENT
|
|
Returns 1 if a Mandatory Access Control (MAC) label can be set on the
|
|
specified file, otherwise 0.
|
|
.It Li _PC_MIN_HOLE_SIZE
|
|
If a file system supports the reporting of holes (see
|
|
.Xr lseek 2 ) ,
|
|
.Fn pathconf
|
|
and
|
|
.Fn fpathconf
|
|
return a positive number that represents the minimum hole size returned in
|
|
bytes.
|
|
The offsets of holes returned will be aligned to this same value.
|
|
A special value of 1 is returned if the file system does not specify the minimum
|
|
hole size but still reports holes.
|
|
.El
|
|
.Sh RETURN VALUES
|
|
If the call to
|
|
.Fn pathconf
|
|
or
|
|
.Fn fpathconf
|
|
is not successful, \-1 is returned and
|
|
.Va errno
|
|
is set appropriately.
|
|
Otherwise, if the variable is associated with functionality that does
|
|
not have a limit in the system, \-1 is returned and
|
|
.Va errno
|
|
is not modified.
|
|
Otherwise, the current variable value is returned.
|
|
.Sh ERRORS
|
|
If any of the following conditions occur, the
|
|
.Fn pathconf
|
|
and
|
|
.Fn fpathconf
|
|
system calls shall return -1 and set
|
|
.Va errno
|
|
to the corresponding value.
|
|
.Bl -tag -width Er
|
|
.It Bq Er EINVAL
|
|
The value of the
|
|
.Fa name
|
|
argument is invalid.
|
|
.It Bq Er EINVAL
|
|
The implementation does not support an association of the variable
|
|
name with the associated file.
|
|
.El
|
|
.Pp
|
|
The
|
|
.Fn pathconf
|
|
system call
|
|
will fail if:
|
|
.Bl -tag -width Er
|
|
.It Bq Er ENOTDIR
|
|
A component of the path prefix is not a directory.
|
|
.It Bq Er ENAMETOOLONG
|
|
A component of a pathname exceeded
|
|
.Brq Dv NAME_MAX
|
|
characters (but see
|
|
.Dv _PC_NO_TRUNC
|
|
above),
|
|
or an entire path name exceeded
|
|
.Brq Dv PATH_MAX
|
|
characters.
|
|
.It Bq Er ENOENT
|
|
The named file does not exist.
|
|
.It Bq Er EACCES
|
|
Search permission is denied for a component of the path prefix.
|
|
.It Bq Er ELOOP
|
|
Too many symbolic links were encountered in translating the pathname.
|
|
.It Bq Er EIO
|
|
An I/O error occurred while reading from or writing to the file system.
|
|
.El
|
|
.Pp
|
|
The
|
|
.Fn fpathconf
|
|
system call
|
|
will fail if:
|
|
.Bl -tag -width Er
|
|
.It Bq Er EBADF
|
|
The
|
|
.Fa fd
|
|
argument
|
|
is not a valid open file descriptor.
|
|
.It Bq Er EIO
|
|
An I/O error occurred while reading from or writing to the file system.
|
|
.El
|
|
.Sh SEE ALSO
|
|
.Xr lseek 2 ,
|
|
.Xr sysctl 3
|
|
.Sh HISTORY
|
|
The
|
|
.Fn pathconf
|
|
and
|
|
.Fn fpathconf
|
|
system calls first appeared in
|
|
.Bx 4.4 .
|
|
The
|
|
.Fn lpathconf
|
|
system call first appeared in
|
|
.Fx 8.0 .
|