Libc-1244.50.9.tar.gz

[apple/libc.git] / gen / confstr.3

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.\"	@(#)confstr.3	8.1 (Berkeley) 6/4/93
.\" $FreeBSD: src/lib/libc/gen/confstr.3,v 1.11 2001/10/01 16:08:50 ru Exp $
.\"
.Dd June 18, 2001
.Dt CONFSTR 3
.Os
.Sh NAME
.Nm confstr
.Nd get string-valued configurable variables
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In unistd.h
.Ft size_t
.Fn confstr "int name" "char *buf" "size_t len"
.Sh DESCRIPTION
This interface is specified by
.\" .St -p1003.1-200x .
.Tn POSIX .
A more flexible (but non-portable) interface is provided by
.Xr sysctl 3 .
.Pp
The
.Fn confstr
function provides a method for applications to get configuration
defined string values.
Shell programmers needing access to these parameters should use the
.Xr getconf 1
utility.
.Pp
The
.Fa name
argument specifies the system variable to be queried.
Symbolic constants for each name value are found in the include file
.Aq Pa unistd.h .
The
.Fa len
argument specifies the size of the buffer referenced by the
argument
.Fa buf .
If
.Fa len
is non-zero,
.Fa buf
is a non-null pointer, and
.Fa name
has a value, up to
.Fa len
\- 1 bytes of the value are copied into the buffer
.Fa buf .
The copied value is always null terminated.
.Pp
The available values are as follows:
.Pp
.Bl -tag -width 6n
.Pp
.It Li _CS_DARWIN_USER_DIR
Provides the path to a user's folder. The directory will be created if it
does not already exist.
.Pp
This directory is created with access permissions of 0755 and restricted by
the
.Xr umask 2
of the calling process and is not intended to be used for
sensitive or temporary file storage, as all users can see files created here.
If the user's umask allows it, files created here will be world readable,
which could lead to information disclosure.
.Pp
.It Li _CS_DARWIN_USER_TEMP_DIR
Provides the path to a user's temporary items directory. The directory will be
created it if does not already exist. This directory is created with access
permissions of 0700 and restricted by the
.Xr umask 2
of the calling process and is a good location for temporary files.
.Pp
By default, files in this location may be cleaned (removed) by the system if
they are not accessed in 3 days.
.Pp
.It Li _CS_DARWIN_USER_CACHE_DIR
Provides the path to the user's cache directory. The directory will be created
if it does not already exist. This directory is created with access permissions
of 0700 and restricted by the
.Xr umask 2
of the calling process and is a good location for user cache data as it will not
be automatically cleaned by the system.
.Pp
Files in this location will be removed during safe boot.
.Pp
.It Li _CS_PATH
Return a value for the
.Ev PATH
environment variable that finds all the standard utilities.
.El
.Sh RETURN VALUES
If the call to
.Fn confstr
is not successful, 0 is returned and
.Va errno
is set appropriately.
Otherwise, if the variable does not have a configuration defined value,
0 is returned and
.Va errno
is not modified.
Otherwise, the buffer size needed to hold the entire configuration-defined
value is returned.
If this size is greater than the argument
.Fa len ,
the string in
.Fa buf
was truncated.
.Sh ERRORS
The
.Fn confstr
function may fail and set
.Va errno
for any of the errors specified for the library functions
.Xr malloc 3
and
.Xr sysctl 3 .
.Pp
In addition, the following errors may be reported:
.Bl -tag -width Er
.It Bq Er EINVAL
The value of the
.Fa name
argument is invalid.
.It Bq Er ENOMEM
Insufficient storage space is available.
.It Bq Er EIO
I/O error communicating with
.Xr opendirectoryd 8 .
.El
.Sh LEGACY ERRORS
If the call to
.Fn confstr
is not successful, \-1 (rather than 0) is returned and
.Va errno
is set appropriately.
.Sh SEE ALSO
.Xr getconf 1 ,
.Xr pathconf 2 ,
.Xr sysconf 3 ,
.Xr sysctl 3
.Sh HISTORY
The
.Fn confstr
function first appeared in
.Bx 4.4 .