Volume 6A: Motif Programming Manual

/* check_passwd() −− handle the input of a password. */

void

check_passwd(text_w, client_data, call_data)

Widget text_w;

XtPointer client_data;

XtPointer call_data;

{

char *new;

int len;

XmTextVerifyCallbackStruct *cbs =

(XmTextVerifyCallbackStruct *) call_data;

if (cbs−>reason == XmCR_ACTIVATE) {

printf ("Password: %s0, passwd);

return;

}

if (cbs−>startPos < cbs−>currInsert) { /* backspace */

cbs−>endPos = strlen (passwd); /* delete from here to end */

passwd[cbs−>startPos] = 0; /* backspace−−terminate */

return;

}

if (cbs−>text−>length > 1) {

cbs−>doit = False; /* don't allow "paste" operations */

return; /* make the user *type* the password! */

}

new = XtMalloc (cbs−>endPos + 2); /* new char + NULL terminator */

if (passwd) {

strcpy (new, passwd);

XtFree (passwd);

} else

new[0] = NULL;

passwd = new;

strncat (passwd, cbs−>text−>ptr, cbs−>text−>length);

passwd[cbs−>endPos + cbs−>text−>length] = 0;

for (len = 0; len < cbs−>text−>length; len++)

cbs−>text−>ptr[len] = '*';

}

As you can see in the figure, the Text widget only displays asterisks, no matter what the user has typed.

Output of password.c

We use the check_passwd() function for both the XmNactivateCallback and the

XmNmodifyVerifyCallback callbacks. When the user presses RETURN, the routine prints what has been typed

to stdout. If the user is not backspacing through the text, we know we can add the new text to passwd, which ...