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Revision 1.24, Sun Jun 3 21:42:46 2012 UTC (4 years, 8 months ago) by joerg
Switch device database to cdb(5). Rework ttyname(3) and ttyname_r(3) to depend on new devname_r(3) as heart. Add /dev/pts magic directly to devname(3). While it can lead to returning non-existing paths, the behavior is more consistent that way. Drop caching layer in devname(3), it doesn't buy anything for the common case of having access to the database. Teach devname(3) proper fallback behavior of scanning /dev. Create both old-style and new-style database for now in /etc/rc.d/sysdb.
.\" $NetBSD: ttyname.3,v 1.24 2012/06/03 21:42:46 joerg Exp $ .\" .\" Copyright (c) 1991, 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. .\" 3. 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. .\" .\" @(#)ttyname.3 8.1 (Berkeley) 6/4/93 .\" .Dd June 1, 2012 .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" .In stdlib.h .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 Em xx and for which an entry exists in the initialization file .Pa /etc/ttys (see .Xr ttys 5 ) , or for pseudo-terminal devices created in ptyfs and named .Pa /dev/pts/ Ns Em n . .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. The .Fn ttyname_r is the reentrant version of the above, and it places the results in .Fa buf . If there is not enough space to place the results (indicated by .Fa len ) , then it returns an error. .Pp The .Fn ttyslot function fetches the current process' control terminal number from the .Xr ttys 5 file entry. If the terminal is a pseudo-terminal, and there is no special entry in the .Xr ttys 5 file for it, the slot number returned is 1 + (last slot number) + minor(tty). This will return a consistent and unique number for each pseudo-terminal device without requiring one to enumerate all of them in .Xr ttys 5 . .Sh IMPLEMENTATION NOTES As an optimisation, these functions attempt to obtain information about all devices from the .Pa /var/run/dev.cdb database, if it exists. If the database exists but is out of date, then these functions may produce incorrect results. The database should be updated using the .Xr dev_mkdb 8 command. .Sh RETURN VALUES The .Fn ttyname function returns the NUL-terminated name if the device is found and .Fn isatty is true; otherwise a .Dv NULL pointer is returned and .Va errno is set to indicate the error. .Pp The .Fn ttyname_r functions returns 0 on success and an error code on failure. .Pp The .Fn isatty function returns 1 if .Fa fd is associated with a terminal device; otherwise it returns 0 and .Va errno is set to indicate the error. .Pp The .Fn ttyslot function returns the unit number of the device file if found; otherwise the value zero is returned. .Sh FILES .Bl -tag -width /etc/ttys -compact .It Pa /dev/\(** .It Pa /etc/ttys .El .Sh ERRORS The .Fn ttyname , .Fn ttyname_r , and .Fn isatty functions will fail if: .Bl -tag -width Er .It Bq Er EBADF The .Fa fd argument is not a valid file descriptor. .It Bq Er ENOTTY The .Fa fd argument does not refer to a terminal device. .El .Pp The .Fn ttyname_r function will also fail if: .Bl -tag -width Er .It Bq Er ENOENT The terminal device is not found. This can happen if the device node has been removed after it was opened. .It Bq Er ERANGE The buffer provided is not large enough to fit the result. .El .Sh SEE ALSO .Xr ioctl 2 , .Xr ttys 5 , .Xr dev_mkdb 8 .Sh STANDARDS The .Fn ttyname and .Fn isatty functions conform to .St -p1003.1-90 . .Sh HISTORY .Fn isatty , .Fn ttyname , and .Fn ttyslot functions appeared in .At v7 . .\" Use of the .Pa /var/run/dev.cdb file was added in netBSD 6.0. .Sh BUGS The .Fn ttyname function leaves its result in an internal static object and returns a pointer to that object. Subsequent calls to .Fn ttyname will modify the same object.