1 .\" $OpenBSD: readpassphrase.3,v 1.7 2001/12/15 15:37:51 millert Exp $
3 .\" Copyright (c) 2000 Todd C. Miller <Todd.Miller@courtesan.com>
4 .\" All rights reserved.
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28 .\" $FreeBSD: src/lib/libc/gen/readpassphrase.3,v 1.4.2.3 2003/03/15 15:11:05 trhodes Exp $
29 .\" $DragonFly: src/lib/libc/gen/readpassphrase.3,v 1.3 2006/02/17 19:35:06 swildner Exp $
36 .Nd get a passphrase from the user
40 .Fn readpassphrase "const char *prompt" "char *buf" "size_t bufsiz" "int flags"
44 function displays a prompt to, and reads in a passphrase from,
46 If this file is inaccessible
51 displays the prompt on the standard error output and reads from the standard
53 In this case it is generally not possible to turn off echo.
57 \- 1 characters (one is for the
59 are read into the provided buffer
62 characters and the terminating newline (or return) character are discarded.
67 takes the following optional
70 .Bl -tag -width ".Dv RPP_REQUIRE_TTY" -compact
72 turn off echo (default behavior)
75 .It Dv RPP_REQUIRE_TTY
76 fail if there is no tty
78 force input to lower case
80 force input to upper case
82 strip the high bit from input
85 The calling process should zero the passphrase as soon as possible to
86 avoid leaving the cleartext passphrase visible in the process's address
89 Upon successful completion,
91 returns a pointer to the null-terminated passphrase.
92 If an error is encountered, the terminal state is restored and
97 .Bl -tag -width ".Pa /dev/tty" -compact
101 The following code fragment will read a passphrase from
105 .Bd -literal -offset indent
110 if (readpassphrase("Response: ", passbuf, sizeof(passbuf),
111 RPP_REQUIRE_TTY) == NULL)
112 errx(1, "unable to read passphrase");
114 if (compare(transform(passbuf), epass) != 0)
115 errx(1, "bad passphrase");
119 memset(passbuf, 0, sizeof(passbuf));
126 function was interrupted by a signal.
132 The process is a member of a background process attempting to read
133 from its controlling terminal, the process is ignoring or blocking
136 signal or the process group is orphaned.
138 The process has already reached its limit for open file descriptors.
140 The system file table is full.
142 There is no controlling terminal and the
150 will catch the following signals:
162 When one of the above signals is intercepted, terminal echo will
163 be restored if it had previously been turned off.
164 If a signal handler was installed for the signal when
166 was called that handler is then executed.
167 If no handler was previously installed for the signal then the
168 default action is taken as per
172 .Dv SIGTSTP , SIGTTIN ,
175 signals (stop signal generated from keyboard or due to terminal I/O
176 from a background process) are treated specially.
177 When the process is resumed after it has been stopped,
179 will reprint the prompt and the user may then enter a passphrase.
187 extension and should not be used if portability is desired.
191 function first appeared in