MirBSD manpage: getpass(3)

GETPASS(3)                 BSD Programmer's Manual                  GETPASS(3)


     getpass - get a password


     #include <pwd.h>
     #include <unistd.h>

     char *
     getpass(const char *prompt);


     The getpass() function displays a prompt to, and reads in a password
     from, /dev/tty. If this file is not accessible, getpass() displays the
     prompt on the standard error output and reads from the standard input.

     The password may be up to _PASSWORD_LEN (currently 128, as defined in the
     <pwd.h> include file) characters in length. Any additional characters and
     the terminating newline character are discarded.

     getpass() turns off character echoing while reading the password.

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


     Upon successful completion, getpass() returns a pointer to a NUL-
     terminated string of at most _PASSWORD_LEN characters. If an error is en-
     countered, the terminal state is restored and a null pointer is returned.




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

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

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

     [ENFILE]      The system file table is full.


     crypt(3), readpassphrase(3)


     Historically, BSD versions of getpass() have accepted a password on the
     standard input if /dev/tty is unavailable. This contradicts X/Open Porta-
     bility Guide Issue 4, Version 2 ("XPG4.2") but the OpenBSD implementation
     is conformant in all other respects.


     A getpass() function appeared in Version 7 AT&T UNIX.


     The getpass() function leaves its result in an internal static object and
     returns a pointer to that object. Subsequent calls to getpass() will
     modify the same object.

MirBSD #10-current             December 7, 2001                              1

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