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: 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 1.2 2003/06/17 04:26:42 dillon Exp $ 30.\" 31.Dd December 7, 2001 32.Dt READPASSPHRASE 3 33.Os 34.Sh NAME 35.Nm readpassphrase 36.Nd get a passphrase from the user 37.Sh SYNOPSIS 38.In readpassphrase.h 39.Ft "char *" 40.Fn readpassphrase "const char *prompt" "char *buf" "size_t bufsiz" "int flags" 41.Sh DESCRIPTION 42The 43.Fn readpassphrase 44function displays a prompt to, and reads in a passphrase from, 45.Pa /dev/tty . 46If this file is inaccessible 47and the 48.Dv RPP_REQUIRE_TTY 49flag is not set, 50.Fn readpassphrase 51displays the prompt on the standard error output and reads from the standard 52input. 53In this case it is generally not possible to turn off echo. 54.Pp 55Up to 56.Fa bufsiz 57\- 1 characters (one is for the 58.Dv NUL ) 59are read into the provided buffer 60.Fa buf . 61Any additional 62characters and the terminating newline (or return) character are discarded. 63.Pp 64The 65.Fn readpassphrase 66function 67takes the following optional 68.Fa flags : 69.Pp 70.Bl -tag -width ".Dv RPP_REQUIRE_TTY" -compact 71.It Dv RPP_ECHO_OFF 72turn off echo (default behavior) 73.It Dv RPP_ECHO_ON 74leave echo on 75.It Dv RPP_REQUIRE_TTY 76fail if there is no tty 77.It Dv RPP_FORCELOWER 78force input to lower case 79.It Dv RPP_FORCEUPPER 80force input to upper case 81.It Dv RPP_SEVENBIT 82strip the high bit from input 83.El 84.Pp 85The calling process should zero the passphrase as soon as possible to 86avoid leaving the cleartext passphrase visible in the process's address 87space. 88.Sh RETURN VALUES 89Upon successful completion, 90.Fn readpassphrase 91returns a pointer to the null-terminated passphrase. 92If an error is encountered, the terminal state is restored and 93a 94.Dv NULL 95pointer is returned. 96.Sh ERRORS 97.Bl -tag -width Er 98.It Bq Er EINTR 99The 100.Fn readpassphrase 101function was interrupted by a signal. 102.It Bq Er EINVAL 103The 104.Fa bufsiz 105argument was zero. 106.It Bq Er EIO 107The process is a member of a background process attempting to read 108from its controlling terminal, the process is ignoring or blocking 109the 110.Dv SIGTTIN 111signal or the process group is orphaned. 112.It Bq Er EMFILE 113The process has already reached its limit for open file descriptors. 114.It Bq Er ENFILE 115The system file table is full. 116.It Bq Er ENOTTY 117There is no controlling terminal and the 118.Dv RPP_REQUIRE_TTY 119flag was specified. 120.El 121.Sh EXAMPLES 122The following code fragment will read a passphrase from 123.Pa /dev/tty 124into the buffer 125.Fa passbuf . 126.Bd -literal -offset indent 127char passbuf[1024]; 128 129\&... 130 131if (readpassphrase("Response: ", passbuf, sizeof(passbuf), 132 RPP_REQUIRE_TTY) == NULL) 133 errx(1, "unable to read passphrase"); 134 135if (compare(transform(passbuf), epass) != 0) 136 errx(1, "bad passphrase"); 137 138\&... 139 140memset(passbuf, 0, sizeof(passbuf)); 141.Ed 142.Sh SIGNALS 143The 144.Fn readpassphrase 145function 146will catch the following signals: 147.Pp 148.Bl -tag -compact 149.It Dv SIGINT 150.It Dv SIGHUP 151.It Dv SIGQUIT 152.It Dv SIGTERM 153.It Dv SIGTSTP 154.It Dv SIGTTIN 155.It Dv SIGTTOU 156.El 157.Pp 158When one of the above signals is intercepted, terminal echo will 159be restored if it had previously been turned off. 160If a signal handler was installed for the signal when 161.Fn readpassphrase 162was called that handler is then executed. 163If no handler was previously installed for the signal then the 164default action is taken as per 165.Xr sigaction 2 . 166.Pp 167The 168.Dv SIGTSTP , SIGTTIN , 169and 170.Dv SIGTTOU 171signals (stop signal generated from keyboard or due to terminal I/O 172from a background process) are treated specially. 173When the process is resumed after it has been stopped, 174.Fn readpassphrase 175will reprint the prompt and the user may then enter a passphrase. 176.Sh FILES 177.Bl -tag -width ".Pa /dev/tty" -compact 178.It Pa /dev/tty 179.El 180.Sh SEE ALSO 181.Xr sigaction 2 , 182.Xr getpass 3 183.Sh STANDARDS 184The 185.Fn readpassphrase 186function is an 187extension and should not be used if portability is desired. 188.Sh HISTORY 189The 190.Fn readpassphrase 191function first appeared in 192.Ox 2.9 . 193