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This function is obsolete.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 newline, terminated by a NUL. This
buffer may be overwritten by a following call. On error,
the terminal state is restored, errno is set appropri
ately, 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 pass
word are returned. While reading the password, signal
generation (SIGINT, SIGQUIT, SIGSTOP, SIGTSTOP) is dis
abled 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.,
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.
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