redhat man page for getpass

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

NAME
       getpass - get a password

SYNOPSIS
       #include <unistd.h>

       char *getpass( const char * prompt );

DESCRIPTION
       This function is obsolete. Do not use it.

       The  getpass()  function  opens /dev/tty (the controlling terminal of the process), outputs the string prompt, turns off echoing, reads one
       line (the "password"), restores the terminal state and closes /dev/tty again.

RETURN VALUE
       The function getpass returns a pointer to a static buffer containing the (first PASS_MAX bytes of) the password without the  trailing  new-
       line,  terminated  by  a  NUL.  This buffer may be overwritten by a following call.  On error, the terminal state is restored, errno is set
       appropriately, and NULL is returned.

ERRORS
       The function may fail if

       ENXIO  The process does not have a controlling terminal.

NOTES
       For libc4 and libc5, the prompt is not written to /dev/tty but to stderr.  Moreover, if /dev/tty cannot be opened,  the	password  is  read
       from  stdin.   The static buffer has length 128 so that only the first 127 bytes of the password are returned.  While reading the password,
       signal generation (SIGINT, SIGQUIT, SIGSTOP, SIGTSTOP) is disabled and the corresponding characters (usually control-C, control-, control-
       Z  and control-Y) are transmitted as part of the password.  Since libc 5.4.19 also line editing is disabled, so that also backspace and the
       like will be seen as part of the password.

       For glibc2, if /dev/tty cannot be opened, the prompt is written to stderr and the password is read from stdin.  There is no  limit  on  the
       length of the password.	Line editing is not disabled.

       According  to  the SUSv2, the value of PASS_MAX must be defined in <limits.h> in case it is smaller than 8, and can in any case be obtained
       using sysconf(_SC_PASS_MAX).  However, POSIX.2 withdraws the constants PASS_MAX and _SC_PASS_MAX, and the function getpass ().	Libc4  and
       libc5 have never supported PASS_MAX or _SC_PASS_MAX.  Glibc2 accepts _SC_PASS_MAX and returns BUFSIZ (e.g., 8192).

FILES
       /dev/tty

SEE ALSO
       crypt(3)

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

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

Linux Manpage							    2000-12-05								GETPASS(3)