Manpages - readpassphrase.3bsd

(See

for include usage.)

The

function displays a prompt to, and reads in a passphrase from,

If this file is inaccessible and the

flag is not set,

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

• 1 characters (one is for the NUL) are read into the provided buffer

Any additional characters and the terminating newline (or return) character are discarded.

The

argument is the bitwise

of zero or more of the following values:

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

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

Upon successful completion,

returns a pointer to the NUL-terminated passphrase. If an error is encountered, the terminal state is restored and a null pointer is returned.

The following code fragment will read a passphrase from

into the buffer

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));

The

function was interrupted by a signal.

The

argument was zero.

The process is a member of a background process attempting to read from its controlling terminal, the process is ignoring or blocking the

signal, or the process group is orphaned.

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

The system file table is full.

There is no controlling terminal and the

flag was specified.

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 restored if it had previously been turned off. If a signal handler was installed for the signal when

was called, that handler is then executed. If no handler was previously installed for the signal then the default action is taken as per

The

and

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,

will reprint the prompt and the user may then enter a passphrase.

The

function is an

extension and should not be used if portability is desired.

The

function first appeared in