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/libcr/gen/Attic/readpassphrase.3,v 1.2 2003/06/17 04:26:42 dillon 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
101 function was interrupted by a signal.
107 The process is a member of a background process attempting to read
108 from its controlling terminal, the process is ignoring or blocking
111 signal or the process group is orphaned.
113 The process has already reached its limit for open file descriptors.
115 The system file table is full.
117 There is no controlling terminal and the
122 The following code fragment will read a passphrase from
126 .Bd -literal -offset indent
131 if (readpassphrase("Response: ", passbuf, sizeof(passbuf),
132 RPP_REQUIRE_TTY) == NULL)
133 errx(1, "unable to read passphrase");
135 if (compare(transform(passbuf), epass) != 0)
136 errx(1, "bad passphrase");
140 memset(passbuf, 0, sizeof(passbuf));
146 will catch the following signals:
158 When one of the above signals is intercepted, terminal echo will
159 be restored if it had previously been turned off.
160 If a signal handler was installed for the signal when
162 was called that handler is then executed.
163 If no handler was previously installed for the signal then the
164 default action is taken as per
168 .Dv SIGTSTP , SIGTTIN ,
171 signals (stop signal generated from keyboard or due to terminal I/O
172 from a background process) are treated specially.
173 When the process is resumed after it has been stopped,
175 will reprint the prompt and the user may then enter a passphrase.
177 .Bl -tag -width ".Pa /dev/tty" -compact
187 extension and should not be used if portability is desired.
191 function first appeared in