xref: /freebsd/lib/libc/gen/getpass.3 (revision 1719886f6d08408b834d270c59ffcfd821c8f63a)
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.Dd June 4, 1993
29.Dt GETPASS 3
30.Os
31.Sh NAME
32.Nm getpass
33.Nd get a password
34.Sh LIBRARY
35.Lb libc
36.Sh SYNOPSIS
37.In pwd.h
38.In unistd.h
39.Ft char *
40.Fn getpass "const char *prompt"
41.Sh DESCRIPTION
42The
43.Fn getpass
44function displays a prompt to, and reads in a password from,
45.Pa /dev/tty .
46If this file is not accessible,
47.Fn getpass
48displays the prompt on the standard error output and reads from the standard
49input.
50.Pp
51The password may be up to _PASSWORD_LEN (currently 128)
52characters in length.
53Any additional
54characters and the terminating newline character are discarded.
55.Pp
56The
57.Fn getpass
58function turns off character echoing while reading the password.
59.Sh RETURN VALUES
60The
61.Fn getpass
62function returns a pointer to the null terminated password.
63.Sh FILES
64.Bl -tag -width /dev/tty -compact
65.It Pa /dev/tty
66.El
67.Sh SEE ALSO
68.Xr crypt 3 ,
69.Xr readpassphrase 3
70.Sh HISTORY
71A
72.Fn getpass
73function appeared in
74.At v7 .
75.Sh BUGS
76The
77.Fn getpass
78function leaves its result in an internal static object and returns
79a pointer to that object.
80Subsequent calls to
81.Fn getpass
82will modify the same object.
83.Pp
84The calling process should zero the password as soon as possible to
85avoid leaving the cleartext password visible in the process's address
86space.
87.Pp
88Upon receipt of a SIGTSTP, the input buffer will be flushed, so any
89partially typed password must be retyped when the process
90continues.
91