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>
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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 1.4 2007/08/18 20:48:47 swildner Exp $
36 .Nd get a passphrase from the user
42 .Fn readpassphrase "const char *prompt" "char *buf" "size_t bufsiz" "int flags"
46 function displays a prompt to, and reads in a passphrase from,
48 If this file is inaccessible
53 displays the prompt on the standard error output and reads from the standard
55 In this case it is generally not possible to turn off echo.
59 \- 1 characters (one is for the
61 are read into the provided buffer
64 characters and the terminating newline (or return) character are discarded.
69 takes the following optional
72 .Bl -tag -width ".Dv RPP_REQUIRE_TTY" -compact
74 turn off echo (default behavior)
77 .It Dv RPP_REQUIRE_TTY
78 fail if there is no tty
80 force input to lower case
82 force input to upper case
84 strip the high bit from input
87 The calling process should zero the passphrase as soon as possible to
88 avoid leaving the cleartext passphrase visible in the process's address
91 Upon successful completion,
93 returns a pointer to the null-terminated passphrase.
94 If an error is encountered, the terminal state is restored and
99 .Bl -tag -width ".Pa /dev/tty" -compact
103 The following code fragment will read a passphrase from
107 .Bd -literal -offset indent
112 if (readpassphrase("Response: ", passbuf, sizeof(passbuf),
113 RPP_REQUIRE_TTY) == NULL)
114 errx(1, "unable to read passphrase");
116 if (compare(transform(passbuf), epass) != 0)
117 errx(1, "bad passphrase");
121 memset(passbuf, 0, sizeof(passbuf));
128 function was interrupted by a signal.
134 The process is a member of a background process attempting to read
135 from its controlling terminal, the process is ignoring or blocking
138 signal or the process group is orphaned.
140 The process has already reached its limit for open file descriptors.
142 The system file table is full.
144 There is no controlling terminal and the
152 will catch the following signals:
164 When one of the above signals is intercepted, terminal echo will
165 be restored if it had previously been turned off.
166 If a signal handler was installed for the signal when
168 was called that handler is then executed.
169 If no handler was previously installed for the signal then the
170 default action is taken as per
174 .Dv SIGTSTP , SIGTTIN ,
177 signals (stop signal generated from keyboard or due to terminal I/O
178 from a background process) are treated specially.
179 When the process is resumed after it has been stopped,
181 will reprint the prompt and the user may then enter a passphrase.
189 extension and should not be used if portability is desired.
193 function first appeared in