xref: /freebsd/lib/libc/gen/getpass.3 (revision 22cf89c938886d14f5796fc49f9f020c23ea8eaf)
1.\" Copyright (c) 1989, 1991, 1993
2.\"	The Regents of the University of California.  All rights reserved.
3.\"
4.\" Redistribution and use in source and binary forms, with or without
5.\" modification, are permitted provided that the following conditions
6.\" are met:
7.\" 1. Redistributions of source code must retain the above copyright
8.\"    notice, this list of conditions and the following disclaimer.
9.\" 2. Redistributions in binary form must reproduce the above copyright
10.\"    notice, this list of conditions and the following disclaimer in the
11.\"    documentation and/or other materials provided with the distribution.
12.\" 3. Neither the name of the University nor the names of its contributors
13.\"    may be used to endorse or promote products derived from this software
14.\"    without specific prior written permission.
15.\"
16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26.\" SUCH DAMAGE.
27.\"
28.\"     @(#)getpass.3	8.1 (Berkeley) 6/4/93
29.\"
30.Dd June 4, 1993
31.Dt GETPASS 3
32.Os
33.Sh NAME
34.Nm getpass
35.Nd get a password
36.Sh LIBRARY
37.Lb libc
38.Sh SYNOPSIS
39.In pwd.h
40.In unistd.h
41.Ft char *
42.Fn getpass "const char *prompt"
43.Sh DESCRIPTION
44The
45.Fn getpass
46function displays a prompt to, and reads in a password from,
47.Pa /dev/tty .
48If this file is not accessible,
49.Fn getpass
50displays the prompt on the standard error output and reads from the standard
51input.
52.Pp
53The password may be up to _PASSWORD_LEN (currently 128)
54characters in length.
55Any additional
56characters and the terminating newline character are discarded.
57.Pp
58The
59.Fn getpass
60function turns off character echoing while reading the password.
61.Sh RETURN VALUES
62The
63.Fn getpass
64function returns a pointer to the null terminated password.
65.Sh FILES
66.Bl -tag -width /dev/tty -compact
67.It Pa /dev/tty
68.El
69.Sh SEE ALSO
70.Xr crypt 3 ,
71.Xr readpassphrase 3
72.Sh HISTORY
73A
74.Fn getpass
75function appeared in
76.At v7 .
77.Sh BUGS
78The
79.Fn getpass
80function leaves its result in an internal static object and returns
81a pointer to that object.
82Subsequent calls to
83.Fn getpass
84will modify the same object.
85.Pp
86The calling process should zero the password as soon as possible to
87avoid leaving the cleartext password visible in the process's address
88space.
89.Pp
90Upon receipt of a SIGTSTP, the input buffer will be flushed, so any
91partially typed password must be retyped when the process
92continues.
93