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 63.Fn readpassphrase 64takes the following optional 65.Fa flags : 66.Pp 67.Bl -tag -width ".Dv RPP_REQUIRE_TTY" -compact 68.It Dv RPP_ECHO_OFF 69turn off echo (default behavior) 70.It Dv RPP_ECHO_ON 71leave echo on 72.It Dv RPP_REQUIRE_TTY 73fail if there is no tty 74.It Dv RPP_FORCELOWER 75force input to lower case 76.It Dv RPP_FORCEUPPER 77force input to upper case 78.It Dv RPP_SEVENBIT 79strip the high bit from input 80.El 81.Pp 82The calling process should zero the passphrase as soon as possible to 83avoid leaving the cleartext passphrase visible in the process's address 84space. 85.Sh RETURN VALUES 86Upon successful completion, 87.Fn readpassphrase 88returns a pointer to the null-terminated passphrase. 89If an error is encountered, the terminal state is restored and 90a 91.Dv NULL 92pointer is returned. 93.Sh ERRORS 94.Bl -tag -width Er 95.It Bq Er EINTR 96The 97.Fn readpassphrase 98function was interrupted by a signal. 99.It Bq Er EINVAL 100The 101.Fa bufsiz 102argument was zero. 103.It Bq Er EIO 104The process is a member of a background process attempting to read 105from its controlling terminal, the process is ignoring or blocking 106the 107.Dv SIGTTIN 108signal or the process group is orphaned. 109.It Bq Er EMFILE 110The process has already reached its limit for open file descriptors. 111.It Bq Er ENFILE 112The system file table is full. 113.It Bq Er ENOTTY 114There is no controlling terminal and the 115.Dv RPP_REQUIRE_TTY 116flag was specified. 117.El 118.Sh EXAMPLES 119The following code fragment will read a passphrase from 120.Pa /dev/tty 121into the buffer 122.Fa passbuf . 123.Bd -literal -offset indent 124char passbuf[1024]; 125 126\&... 127 128if (readpassphrase("Response: ", passbuf, sizeof(passbuf), 129 RPP_REQUIRE_TTY) == NULL) 130 errx(1, "unable to read passphrase"); 131 132if (compare(transform(passbuf), epass) != 0) 133 errx(1, "bad passphrase"); 134 135\&... 136 137memset(passbuf, 0, sizeof(passbuf)); 138.Ed 139.Sh SIGNALS 140.Fn readpassphrase 141will catch the following signals: 142.Pp 143.Bl -tag -compact 144.It Dv SIGINT 145.It Dv SIGHUP 146.It Dv SIGQUIT 147.It Dv SIGTERM 148.It Dv SIGTSTP 149.It Dv SIGTTIN 150.It Dv SIGTTOU 151.El 152.Pp 153When one of the above signals is intercepted, terminal echo will 154be restored if it had previously been turned off. 155If a signal handler was installed for the signal when 156.Fn readpassphrase 157was called that handler is then executed. 158If no handler was previously installed for the signal then the 159default action is taken as per 160.Xr sigaction 2 . 161.Pp 162The 163.Dv SIGTSTP , SIGTTIN , 164and 165.Dv SIGTTOU 166signals (stop signal generated from keyboard or due to terminal I/O 167from a background proccess) are treated specially. 168When the process is resumed after it has been stopped, 169.Fn readpassphrase 170will reprint the prompt and the user may then enter a passphrase. 171.Sh FILES 172.Bl -tag -width ".Pa /dev/tty" -compact 173.It Pa /dev/tty 174.El 175.Sh SEE ALSO 176.Xr sigaction 2 , 177.Xr getpass 3 178.Sh STANDARDS 179The 180.Fn readpassphrase 181function is an 182extension and should not be used if portability is desired. 183.Sh HISTORY 184The 185.Fn readpassphrase 186function first appeared in 187.Ox 2.9 . 188