kc3-lang/libbsd/man/readpassphrase.3bsd

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  Date : 2022-08-03T02:21:16
  

  man: Lowercase man page title While using fully uppercase man page titles has been the usual convention for a very long time, it is rather ugly and something that some other projects are switching away from.

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• man/readpassphrase.3bsd

• .\"	$OpenBSD: readpassphrase.3,v 1.20 2014/03/06 23:03:18 millert Exp $
  .\"
  .\" Copyright (c) 2000, 2002 Todd C. Miller <Todd.Miller@courtesan.com>
  .\"
  .\" Permission to use, copy, modify, and distribute this software for any
  .\" purpose with or without fee is hereby granted, provided that the above
  .\" copyright notice and this permission notice appear in all copies.
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  .\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  .\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  .\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  .\"
  .\" Sponsored in part by the Defense Advanced Research Projects
  .\" Agency (DARPA) and Air Force Research Laboratory, Air Force
  .\" Materiel Command, USAF, under agreement number F39502-99-1-0512.
  .\"
  .Dd $Mdocdate: March 6 2014 $
  .Dt readpassphrase 3bsd
  .Os
  .Sh NAME
  .Nm readpassphrase
  .Nd get a passphrase from the user
  .Sh LIBRARY
  .ds str-Lb-libbsd Utility functions from BSD systems (libbsd, \-lbsd)
  .ds doc-str-Lb-libbsd \*[str-Lb-libbsd]
  .Lb libbsd
  .Sh SYNOPSIS
  .In readpassphrase.h
  (See
  .Xr libbsd 7
  for include usage.)
  .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 NUL) are read into the provided buffer
  .Fa buf .
  Any additional
  characters and the terminating newline (or return) character are discarded.
  .Pp
  The
  .Fa flags
  argument is the bitwise
  .Tn OR
  of zero or more of the following values:
  .Bd -literal -offset indent
  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		read passphrase from stdin; ignore prompt
  .Ed
  .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 NUL-terminated passphrase.
  If an error is encountered, the terminal state is restored and
  a null pointer is returned.
  .Sh FILES
  .Bl -tag -width /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[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");
  
  \&...
  
  explicit_bzero(passbuf, sizeof(passbuf));
  .Ed
  .Sh ERRORS
  .Bl -tag -width Er
  .It Bq Er EINTR
  The
  .Fn readpassphrase
  function was interrupted by a signal.
  .It Bq Er EINVAL
  The
  .Ar 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 SIGNALS
  .Fn readpassphrase
  will catch the following signals:
  .Bd -literal -offset indent
  SIGALRM		SIGHUP		SIGINT
  SIGPIPE		SIGQUIT		SIGTERM
  SIGTSTP		SIGTTIN		SIGTTOU
  .Ed
  .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 ,
  .Dv SIGTTIN ,
  and
  .Dv 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,
  .Fn readpassphrase
  will reprint the prompt and the user may then enter a passphrase.
  .Sh SEE ALSO
  .Xr sigaction 2 ,
  .Xr getpass 3
  .Sh STANDARDS
  The
  .Fn readpassphrase
  function is an
  .Ox
  extension and should not be used if portability is desired.
  .Sh HISTORY
  The
  .Fn readpassphrase
  function first appeared in
  .Ox 2.9 .
  

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