freebsd-dev/lib/libc/gen/ttyname.3
Xin LI 8dcb56dc78 Provide more POSIX-complaint ttyname_r(3) interface[1], which is slightly
different from what has been offered in libc_r (the one spotted in the
original PR which is found in libthr has already been removed by David's
commit, which is rev. 1.44 of lib/libthr/thread/thr_private.h):
	- Use POSIX standard prototype for ttyname_r, which is,
		int ttyname_r(int, char *, size_t);
	  Instead of:
	  	char *ttyname_r(int, char *, size_t);
	  This is to conform IEEE Std 1003.1, 2004 Edition [1].
	- Since we need to use standard errno for return code, include
	  errno.h in ttyname.c
	- Update ttyname(3) implementation according to reflect the API
	  change.
	- Document new ttyname_r(3) behavior
	- Since we already make use of a thread local storage for
	  ttyname(3), remove the BUGS section.
	- Remove conflicting ttyname_r related declarations found in libc_r.

Hopefully this change should not have changed the API/ABI, as the ttyname_r
symbol was never introduced before the last unistd.h change which happens a
couple of days before.

[1] http://www.opengroup.org/onlinepubs/009695399/functions/ttyname.html

Requested by:	Tom McLaughlin <tmclaugh sdf lonestar org>
Through PR:	threads/76938
Patched by:	Craig Rodrigues <rodrigc crodrigues org> (with minor changes)
Prompted by:	mezz@
2005-05-13 16:27:30 +00:00

149 lines
3.9 KiB
Groff

.\" Copyright (c) 1991, 1993
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.\" @(#)ttyname.3 8.1 (Berkeley) 6/4/93
.\" $FreeBSD$
.\"
.Dd May 14, 2005
.Dt TTYNAME 3
.Os
.Sh NAME
.Nm ttyname ,
.Nm ttyname_r ,
.Nm isatty ,
.Nm ttyslot
.Nd get name of associated terminal (tty) from file descriptor
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In unistd.h
.Ft char *
.Fn ttyname "int fd"
.Ft int
.Fn ttyname_r "int fd" "char *buf" "size_t len"
.Ft int
.Fn isatty "int fd"
.Ft int
.Fn ttyslot void
.Sh DESCRIPTION
These functions operate on the system file descriptors for terminal
type devices.
These descriptors are not related to the standard
.Tn I/O
.Dv FILE
typedef, but refer to the special device files found in
.Pa /dev
and named
.Pa /dev/tty Ns Ar xx
and for which an entry exists
in the initialization file
.Pa /etc/ttys .
(See
.Xr ttys 5 . )
.Pp
The
.Fn isatty
function
determines if the file descriptor
.Fa fd
refers to a valid
terminal type device.
.Pp
The
.Fn ttyname
function
gets the related device name of
a file descriptor for which
.Fn isatty
is true.
.Pp
.Fn ttyname
returns the name stored in a static buffer which will be overwritten
on subsequent calls.
.Fn ttyname_r
takes a buffer and length as arguments to avoid this problem.
.Pp
The
.Fn ttyslot
function
fetches the current process' control terminal number from the
.Xr ttys 5
file entry.
.Sh RETURN VALUES
The
.Fn ttyname
function
returns the null terminated name if the device is found and
.Fn isatty
is true; otherwise
a
.Dv NULL
pointer is returned.
The
.Fn ttyname_r
function returns 0 if successful. Otherwise an error number is returned.
.Pp
The
.Fn ttyslot
function
returns the unit number of the device file if found; otherwise
the value zero is returned.
.Sh ERRORS
.Fn ttyname_r
may return the following error codes:
.Bl -tag -width Er
.It Bq Er ENOTTY
.Fa fd
is not a valid file descriptor.
.It Bq Er ERANGE
.Fa bufsize
is smaller than the length of the string to be returned.
.Sh FILES
.Bl -tag -width /etc/ttys -compact
.It Pa /dev/\(**
.It Pa /etc/ttys
.El
.Sh SEE ALSO
.Xr ioctl 2 ,
.Xr ttys 5
.Sh HISTORY
A
.Fn isatty ,
.Fn ttyname ,
and
.Fn ttyslot
function
appeared in
.At v7 .
.Fn ttyname_r
appeared in
.Fx 6.0 .