1.\" $OpenBSD: readpassphrase.3,v 1.7 2001/12/15 15:37:51 millert Exp $ 2.\" 3.\" Copyright (c) 2000 Todd C. Miller <Todd.Miller@courtesan.com> 4.\" All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. The name of the author may not be used to endorse or promote products 15.\" derived from this software without specific prior written permission. 16.\" 17.\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, 18.\" INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY 19.\" AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL 20.\" THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 21.\" EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 22.\" PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; 23.\" OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 24.\" WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR 25.\" OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF 26.\" ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27.\" 28.\" $FreeBSD$ 29.\" 30.Dd December 7, 2001 31.Dt READPASSPHRASE 3 32.Os 33.Sh NAME 34.Nm readpassphrase 35.Nd get a passphrase from the user 36.Sh SYNOPSIS 37.In readpassphrase.h 38.Ft "char *" 39.Fn readpassphrase "const char *prompt" "char *buf" "size_t bufsiz" "int flags" 40.Sh DESCRIPTION 41The 42.Fn readpassphrase 43function displays a prompt to, and reads in a passphrase from, 44.Pa /dev/tty . 45If this file is inaccessible 46and the 47.Dv RPP_REQUIRE_TTY 48flag is not set, 49.Fn readpassphrase 50displays the prompt on the standard error output and reads from the standard 51input. 52In this case it is generally not possible to turn off echo. 53.Pp 54Up to 55.Fa bufsiz 56\- 1 characters (one is for the 57.Dv NUL ) 58are read into the provided buffer 59.Fa buf . 60Any additional 61characters and the terminating newline (or return) character are discarded. 62.Pp 63The 64.Fn readpassphrase 65function 66takes the following optional 67.Fa flags : 68.Pp 69.Bl -tag -width ".Dv RPP_REQUIRE_TTY" -compact 70.It Dv RPP_ECHO_OFF 71turn off echo (default behavior) 72.It Dv RPP_ECHO_ON 73leave echo on 74.It Dv RPP_REQUIRE_TTY 75fail if there is no tty 76.It Dv RPP_FORCELOWER 77force input to lower case 78.It Dv RPP_FORCEUPPER 79force input to upper case 80.It Dv RPP_SEVENBIT 81strip the high bit from input 82.El 83.Pp 84The calling process should zero the passphrase as soon as possible to 85avoid leaving the cleartext passphrase visible in the process's address 86space. 87.Sh RETURN VALUES 88Upon successful completion, 89.Fn readpassphrase 90returns a pointer to the null-terminated passphrase. 91If an error is encountered, the terminal state is restored and 92a 93.Dv NULL 94pointer is returned. 95.Sh FILES 96.Bl -tag -width ".Pa /dev/tty" -compact 97.It Pa /dev/tty 98.El 99.Sh EXAMPLES 100The following code fragment will read a passphrase from 101.Pa /dev/tty 102into the buffer 103.Fa passbuf . 104.Bd -literal -offset indent 105char passbuf[1024]; 106 107\&... 108 109if (readpassphrase("Response: ", passbuf, sizeof(passbuf), 110 RPP_REQUIRE_TTY) == NULL) 111 errx(1, "unable to read passphrase"); 112 113if (compare(transform(passbuf), epass) != 0) 114 errx(1, "bad passphrase"); 115 116\&... 117 118memset(passbuf, 0, sizeof(passbuf)); 119.Ed 120.Sh SIGNALS 121The 122.Fn readpassphrase 123function 124will catch the following signals: 125.Pp 126.Bl -tag -compact 127.It Dv SIGINT 128.It Dv SIGHUP 129.It Dv SIGQUIT 130.It Dv SIGTERM 131.It Dv SIGTSTP 132.It Dv SIGTTIN 133.It Dv SIGTTOU 134.El 135.Pp 136When one of the above signals is intercepted, terminal echo will 137be restored if it had previously been turned off. 138If a signal handler was installed for the signal when 139.Fn readpassphrase 140was called that handler is then executed. 141If no handler was previously installed for the signal then the 142default action is taken as per 143.Xr sigaction 2 . 144.Pp 145The 146.Dv SIGTSTP , SIGTTIN , 147and 148.Dv SIGTTOU 149signals (stop signal generated from keyboard or due to terminal I/O 150from a background process) are treated specially. 151When the process is resumed after it has been stopped, 152.Fn readpassphrase 153will reprint the prompt and the user may then enter a passphrase. 154.Sh ERRORS 155.Bl -tag -width Er 156.It Bq Er EINTR 157The 158.Fn readpassphrase 159function was interrupted by a signal. 160.It Bq Er EINVAL 161The 162.Fa bufsiz 163argument was zero. 164.It Bq Er EIO 165The process is a member of a background process attempting to read 166from its controlling terminal, the process is ignoring or blocking 167the 168.Dv SIGTTIN 169signal or the process group is orphaned. 170.It Bq Er EMFILE 171The process has already reached its limit for open file descriptors. 172.It Bq Er ENFILE 173The system file table is full. 174.It Bq Er ENOTTY 175There is no controlling terminal and the 176.Dv RPP_REQUIRE_TTY 177flag was specified. 178.El 179.Sh SEE ALSO 180.Xr sigaction 2 , 181.Xr getpass 3 182.Sh STANDARDS 183The 184.Fn readpassphrase 185function is an 186extension and should not be used if portability is desired. 187.Sh HISTORY 188The 189.Fn readpassphrase 190function first appeared in 191.Ox 2.9 . 192