Small Change to chpass.c

[Giorgos Keramidas]

On Wed, 10 Dec 2008 18:00:25 -0800, "Sheldon Givens" <sheldon at sigsegv.ca> wrote:
> Hi guys,
>
> When I was doing some user management today I noticed that chpass, and
> all the utilities that use chpass.c, only give one attempt to
> authenticate to make the change. After I messed this up once or twice
> (and after doing 4-5 minutes of editing only to have it lost when I
> typo'd the password) I wrote this little change in to chpass.c.

This seems useful, thanks for submitting the patch :)

> ---snip---
> --- /usr/src/usr.bin/chpass.c   2008-12-11 01:55:27.000000000 -0800
> +++ /usr/src/usr.bin/chpass.c   2008-12-11 01:57:09.000000000 -0800
> @@ -80,10 +80,11 @@
>  {
>         enum { NEWSH, LOADENTRY, EDITENTRY, NEWPW, NEWEXP } op;
>         struct passwd lpw, *old_pw, *pw;
> -       int ch, pfd, tfd;
> +       int ch, pfd, tfd, itr, auth;
>         const char *password;
>         char *arg = NULL;
>         uid_t uid;
> +       int max_retries = 3;
>  #ifdef YP
>         struct ypclnt *ypclnt;
>         const char *yp_domain = NULL, *yp_host = NULL;
> @@ -227,9 +228,16 @@
>         }
>
>         if (old_pw && !master_mode) {
> -               password = getpass("Password: ");
> -               if (strcmp(crypt(password, old_pw->pw_passwd),
> -                   old_pw->pw_passwd) != 0)
> +               auth = 0;
> +               for(itr=0;itr<max_retries;itr++) {
> +                       password = getpass("Password:");
> +                       if(strcmp(crypt(password, old_pw->pw_passwd),
> +                       old_pw->pw_passwd) == 0) {
> +                               auth=1;
> +                               break;
> +                       }
> +               }
> +               if (!auth)
>                         baduser();
>         } else {
>                 password = "";
> ---snip---

You can probably do away with `auth' and reset password to NULL when
strcmp() fails (note that we also use whitespace in for statements to
separate everything more clearly):

        if (old_pw && !master_mode) {
                for (itr = 0; itr < max_retries; itr++) {
                        password = getpass("Password:");
                        if (strcmp(crypt(password, old_pw->pw_passwd),
                            old_pw->pw_passwd) != 0)
                                break;
                        password = NULL;
                }
                if (password == NULL)
                        baduser();
        } else {
                password = "";