crypto: to show stars or not to show them

On Friday 2011-03-18 01:41, Lennart Poettering wrote:

>On Fri, 18.03.11 00:18, Jan Engelhardt (jengelh@medozas.de) wrote:
>
>> Meanwhile, I have two new suggestions.
>
>I have one too (or actually Kay came up with it), and I think you are
>going to like it:
>
>Start with showing input feedback as we currently do. If the user then
>presses TAB the stars disappear, and instead we show "(no echo)" or
>so. Then, the user can proceed with typing his password without
>asterisks.
>[...]

Incorporating Graham's suggestion to use BKSP instead:

The following changes since commit 65c9e46752:

  tainted: don't check if /usr is a mount point, only if it's not already mounted at startup (2011-03-24 22:32:21 +0100)

are available in the git repository at:
  git://dev.medozas.de/systemd master

Jan Engelhardt (1):
      ask-password: provide a way to activate a silent prompt

 src/ask-password-api.c |   11 +++++++----
 1 files changed, 7 insertions(+), 4 deletions(-)

src/ask-password-api.c

@@ -18,7 +18,7 @@
   You should have received a copy of the GNU General Public License
   along with systemd; If not, see <http://www.gnu.org/licenses/>.
 ***/
-
+#include <stdbool.h>
 #include <termios.h>
 #include <unistd.h>
 #include <sys/poll.h>
@@ -48,6 +48,7 @@ int ask_password_tty(
         int r, ttyfd = -1, notify = -1;
         struct pollfd pollfd[2];
         bool reset_tty = false;
+        bool silent_mode = false;
         enum {
                 POLL_TTY,
                 POLL_INOTIFY
@@ -156,7 +157,6 @@ int ask_password_tty(
                 if (c == '\n')
                         break;
                 else if (c == 21) {
-
                         while (p > 0) {
                                 p--;
 
@@ -165,7 +165,10 @@ int ask_password_tty(
                         }
 
                 } else if (c == '\b' || c == 127) {
-                        if (p > 0) {
+                        if (p == 0 && !silent_mode) {
+                                silent_mode = true;
+                                loop_write(ttyfd, "(no echo) ", 10, false);
+                        } else if (p > 0) {
                                 p--;
 
                                 if (ttyfd >= 0)
@@ -174,7 +177,7 @@ int ask_password_tty(
                 } else {
                         passphrase[p++] = c;
 
-                        if (ttyfd >= 0)
+                        if (!silent_mode && ttyfd >= 0)
                                 loop_write(ttyfd, "*", 1, false);
                 }
         }