.\" $OpenBSD: readpassphrase.3,v 1.7 2001/12/15 15:37:51 millert Exp $ .\" .\" Copyright (c) 2000 Todd C. Miller <Todd.Miller@courtesan.com> .\" All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. The name of the author may not be used to endorse or promote products .\" derived from this software without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, .\" INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY .\" AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL .\" THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, .\" EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, .\" PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; .\" OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, .\" WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR .\" OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF .\" ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. .\" .\" $FreeBSD: src/lib/libc/gen/readpassphrase.3,v 1.7 2005/01/20 09:17:02 ru Exp $ .\" .Dd December 7, 2001 .Dt READPASSPHRASE 3 .Os .Sh NAME .Nm readpassphrase .Nd get a passphrase from the user .Sh SYNOPSIS .In readpassphrase.h .Ft "char *" .Fn readpassphrase "const char *prompt" "char *buf" "size_t bufsiz" "int flags" .Sh DESCRIPTION The .Fn readpassphrase function displays a prompt to, and reads in a passphrase from, .Pa /dev/tty . If this file is inaccessible and the .Dv RPP_REQUIRE_TTY flag is not set, .Fn readpassphrase displays the prompt on the standard error output and reads from the standard input. In this case it is generally not possible to turn off echo. .Pp Up to .Fa bufsiz \- 1 characters (one is for the .Dv NUL ) are read into the provided buffer .Fa buf . Any additional characters and the terminating newline (or return) character are discarded. .Pp The .Fn readpassphrase function takes the following optional .Fa flags : .Pp .Bl -tag -width ".Dv RPP_REQUIRE_TTY" -compact .It Dv RPP_ECHO_OFF turn off echo (default behavior) .It Dv RPP_ECHO_ON leave echo on .It Dv RPP_REQUIRE_TTY fail if there is no tty .It Dv RPP_FORCELOWER force input to lower case .It Dv RPP_FORCEUPPER force input to upper case .It Dv RPP_SEVENBIT strip the high bit from input .El .Pp The calling process should zero the passphrase as soon as possible to avoid leaving the cleartext passphrase visible in the process's address space. .Sh RETURN VALUES Upon successful completion, .Fn readpassphrase returns a pointer to the null-terminated passphrase. If an error is encountered, the terminal state is restored and a .Dv NULL pointer is returned. .Sh FILES .Bl -tag -width ".Pa /dev/tty" -compact .It Pa /dev/tty .El .Sh EXAMPLES The following code fragment will read a passphrase from .Pa /dev/tty into the buffer .Fa passbuf . .Bd -literal -offset indent char passbuf; \&... if (readpassphrase("Response: ", passbuf, sizeof(passbuf), RPP_REQUIRE_TTY) == NULL) errx(1, "unable to read passphrase"); if (compare(transform(passbuf), epass) != 0) errx(1, "bad passphrase"); \&... memset(passbuf, 0, sizeof(passbuf)); .Ed .Sh SIGNALS The .Fn readpassphrase function will catch the following signals: .Pp .Bl -tag -compact .It Dv SIGINT .It Dv SIGHUP .It Dv SIGQUIT .It Dv SIGTERM .It Dv SIGTSTP .It Dv SIGTTIN .It Dv SIGTTOU .El .Pp When one of the above signals is intercepted, terminal echo will be restored if it had previously been turned off. If a signal handler was installed for the signal when .Fn readpassphrase was called that handler is then executed. If no handler was previously installed for the signal then the default action is taken as per .Xr sigaction 2 . .Pp The .Dv SIGTSTP , SIGTTIN , and .Dv SIGTTOU signals (stop signal generated from keyboard or due to terminal I/O from a background process) are treated specially. When the process is resumed after it has been stopped, .Fn readpassphrase will reprint the prompt and the user may then enter a passphrase. .Sh ERRORS .Bl -tag -width Er .It Bq Er EINTR The .Fn readpassphrase function was interrupted by a signal. .It Bq Er EINVAL The .Fa bufsiz argument was zero. .It Bq Er EIO The process is a member of a background process attempting to read from its controlling terminal, the process is ignoring or blocking the .Dv SIGTTIN signal or the process group is orphaned. .It Bq Er EMFILE The process has already reached its limit for open file descriptors. .It Bq Er ENFILE The system file table is full. .It Bq Er ENOTTY There is no controlling terminal and the .Dv RPP_REQUIRE_TTY flag was specified. .El .Sh SEE ALSO .Xr sigaction 2 , .Xr getpass 3 .Sh STANDARDS The .Fn readpassphrase function is an extension and should not be used if portability is desired. .Sh HISTORY The .Fn readpassphrase function first appeared in .Ox 2.9 .