In the Linux world, masking isn’t usually done with asterisks, normally echoing is just turned off and the terminal displays blanks E.g. if you use su
or log into a virtual terminal etc.
There is a library function to handle getting passwords, it won’t mask the password with asterisks but will disable echoing of the password to terminal. I pulled this out of a linux book I have. I believe its part of the posix standard
#include <unistd.h> char *getpass(const char *prompt); /*Returns pointer to statically allocated input password string on success, or NULL on error*/
The getpass() function first disables echoing and all processing of
terminal special characters (such as the interrupt character, normally
Control-C).It then prints the string pointed to by prompt, and reads a line of
input, returning the null-terminated input string with the trailing
newline stripped, as its function result.
A google search for getpass() has a reference to the GNU implementation (should be in most linux distros) and some sample code for implementing your own if need be
http://www.gnu.org/s/hello/manual/libc/getpass.html
Their example for rolling your own:
#include <termios.h>
#include <stdio.h>
ssize_t
my_getpass (char **lineptr, size_t *n, FILE *stream)
{
struct termios old, new;
int nread;
/* Turn echoing off and fail if we can't. */
if (tcgetattr (fileno (stream), &old) != 0)
return -1;
new = old;
new.c_lflag &= ~ECHO;
if (tcsetattr (fileno (stream), TCSAFLUSH, &new) != 0)
return -1;
/* Read the password. */
nread = getline (lineptr, n, stream);
/* Restore terminal. */
(void) tcsetattr (fileno (stream), TCSAFLUSH, &old);
return nread;
}
If need be you could use this as the basis as modify it to display asterisks.