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readpassphrase (3)
  • >> readpassphrase (3) ( FreeBSD man: Библиотечные вызовы )

  • BSD mandoc
     

    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 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.

    The readpassphrase ();
    function takes the following optional Fa 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

    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 null-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 Fa 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));
    
     

    SIGNALS

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

    SIGINT
    SIGHUP
    SIGQUIT
    SIGTERM
    SIGTSTP
    SIGTTIN
    SIGTTOU

    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 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 signal 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.  

    ERRORS

    Bq Er EINTR
    The readpassphrase ();
    function was interrupted by a signal.
    Bq Er EINVAL
    The Fa bufsiz argument was zero.
    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 SIGTTIN signal or the process group is orphaned.
    Bq Er EMFILE
    The process has already reached its limit for open file descriptors.
    Bq Er ENFILE
    The system file table is full.
    Bq Er ENOTTY
    There is no controlling terminal and the RPP_REQUIRE_TTY flag was specified.

     

    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 Ox 2.9 .


     

    Index

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


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