Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages

  
 
  

home | help
READPASSPHRASE(3)	 BSD Library Functions Manual	     READPASSPHRASE(3)

NAME
     readpassphrase -- get a passphrase	from the user

SYNOPSIS
     #include <readpassphrase.h>

     char *
     readpassphrase(const char *prompt,	char *buf, size_t bufsiz, int flags);

DESCRIPTION
     The readpassphrase() function displays a prompt to, and reads in a
     passphrase	from, /dev/tty.	 If this file is inaccessible and the
     RPP_REQUIRE_TTY flag is not set, 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.

     Up	to bufsiz - 1 characters (one is for the NUL) are read into the	pro-
     vided buffer buf.	Any additional characters and the terminating newline
     (or return) character are discarded.

     The readpassphrase() function takes the following optional	flags:

     RPP_ECHO_OFF     turn off echo (default behavior)
     RPP_ECHO_ON      leave echo on
     RPP_REQUIRE_TTY  fail if there is no tty
     RPP_FORCELOWER   force input to lower case
     RPP_FORCEUPPER   force input to upper case
     RPP_SEVENBIT     strip the	high bit from input
     RPP_STDIN	      force read of passphrase from stdin

     The calling process should	zero the passphrase as soon as possible	to
     avoid leaving the cleartext passphrase visible in the process's address
     space.

RETURN VALUES
     Upon successful completion, readpassphrase() returns a pointer to the
     NUL-terminated passphrase.	 If an error is	encountered, the terminal
     state is restored and a NULL pointer is returned.

FILES
     /dev/tty

EXAMPLES
     The following code	fragment will read a passphrase	from /dev/tty into the
     buffer passbuf.

	   char	passbuf[1024];

	   ...

	   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));

ERRORS
     [EINTR]		The readpassphrase() function was interrupted by a
			signal.

     [EINVAL]		The bufsiz argument was	zero.

     [EIO]		The process is a member	of a background	process	at-
			tempting to read from its controlling terminal,	the
			process	is ignoring or blocking	the SIGTTIN signal, or
			the process group is orphaned.

     [EMFILE]		The process has	already	reached	its limit for open
			file descriptors.

     [ENFILE]		The system file	table is full.

     [ENOTTY]		There is no controlling	terminal and the
			RPP_REQUIRE_TTY	flag was specified.

SIGNALS
     The readpassphrase() function will	catch the following signals:

	   SIGALRM	   SIGHUP	   SIGINT
	   SIGPIPE	   SIGQUIT	   SIGTERM
	   SIGTSTP	   SIGTTIN	   SIGTTOU

     When one of the above signals is intercepted, terminal echo will be re-
     stored if it had previously been turned off.  If a	signal handler was in-
     stalled for the signal when 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 sigaction(2).

     The SIGTSTP, SIGTTIN and SIGTTOU signals (stop signals 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,
     readpassphrase() will reprint the prompt and the user may then enter a
     passphrase.

SEE ALSO
     sigaction(2), getpass(3)

STANDARDS
     The readpassphrase() function is an extension and should not be used if
     portability is desired.

HISTORY
     The readpassphrase() function first appeared in OpenBSD 2.9.

BSD				 May 31, 2007				   BSD

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUES | FILES | EXAMPLES | ERRORS | SIGNALS | SEE ALSO | STANDARDS | HISTORY

Want to link to this manual page? Use this URL:
<https://www.freebsd.org/cgi/man.cgi?query=readpassphrase&sektion=3&manpath=FreeBSD+8.4-RELEASE>

home | help