[Toybox] [PATCH] Add fflush to lib/password; remove print from stty

[Rob Landley]

On 9/15/20 11:39 AM, Chris Sarra via Toybox wrote:
> toybox logins were displaying the "password:" prompt after
> the user entered a password. This patch fixes the issue so the
> password prompt shows *before* password is entered.
> ---
>  lib/password.c      | 1 +
>  toys/pending/stty.c | 2 +-
>  2 files changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/lib/password.c b/lib/password.c
> index 432905cc..2f5997ff 100644
> --- a/lib/password.c
> +++ b/lib/password.c
> @@ -63,6 +63,7 @@ int read_password(char *buf, int buflen, char *mesg)
>    xset_terminal(0, 1, 0, &oldtermio);
>  
>    xprintf("%s", mesg);
> +  fflush(NULL);

This is why xprintf() had the x. This is literally why, but actually flushing
before checking for error was too slow. (And then Elliott wanted to enable line
buffering for everything, which breaks tee...)

Sigh, ok I'm replacing it with dprintf() to avoid the borked stdio buffering
entirely, which raises the question should the prompt go to stdout or stderr?

  $ sudo /bin/bash
  [sudo] password for landley:
  $ sudo /bin/bash 2>/dev/null
  [sudo] password for landley:
  $ sudo /bin/bash >/dev/null
  [sudo] password for landley:

Answer: it goes to /dev/tty. Right, stop, BIG HAMMER time. ("There's never time
to do it right, there's always time to do it over" meets "it is better to light
a flamethrower than to curse the darkness", as usual for this project.)

>    for (i=0; i < buflen-1; i++) {
>      if ((ret = read(0, buf+i, 1)) < 0 || (!ret && !i)) {
> diff --git a/toys/pending/stty.c b/toys/pending/stty.c
> index 8c937696..fe8f5c8d 100644
> --- a/toys/pending/stty.c
> +++ b/toys/pending/stty.c
> @@ -271,7 +271,7 @@ static int set_special_character(struct termios *new, int *i, char *char_name)
>        else if (arg[0] == '^' && arg[2] == 0) ch = (toupper(arg[1])-'@');
>        else if (!arg[1]) ch = arg[0];
>        else error_exit("invalid arg: %s", arg);
> -      xprintf("setting %s to %s (%02x)\n", char_name, arg, ch);
> +      //xprintf("setting %s to %s (%02x)\n", char_name, arg, ch);

What's this one about? (It's pending, which usually means I'm not as familiar
with the guts of the command...)

Rob