sulogin: use common password-checking routine.

This needed some extensions correct_passwd() function,
which got renamed ask_and_check_password() to better describe what it does.

function                                             old     new   delta
ask_and_check_password_extended                        -     215    +215
ask_and_check_password                                 -      12     +12
vlock_main                                           394     397      +3
sulogin_main                                         494     326    -168
correct_password                                     207       -    -207
------------------------------------------------------------------------------
(add/remove: 2/1 grow/shrink: 1/1 up/down: 230/-375)         Total: -145 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

6 files changed, 26 insertions, 47 deletions

diff --git a/include/libbb.h b/include/libbb.h
index 58271655d..e99bb928f 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -1301,7 +1301,8 @@ int sd_listen_fds(void);
 #define SETUP_ENV_TO_TMP    (1 << 2)
 #define SETUP_ENV_NO_CHDIR  (1 << 4)
 extern void setup_environment(const char *shell, int flags, const struct passwd *pw) FAST_FUNC;
-extern int correct_password(const struct passwd *pw) FAST_FUNC;
+extern int ask_and_check_password_extended(const struct passwd *pw, int timeout, const char *prompt) FAST_FUNC;
+extern int ask_and_check_password(const struct passwd *pw) FAST_FUNC;
 /* Returns a malloced string */
 #if !ENABLE_USE_BB_CRYPT
 #define pw_encrypt(clear, salt, cleanup) pw_encrypt(clear, salt)
diff --git a/libbb/correct_password.c b/libbb/correct_password.c
index 7cabd33d0..d02d0d6a0 100644
--- a/libbb/correct_password.c
+++ b/libbb/correct_password.c
@@ -31,12 +31,15 @@
 #include "libbb.h"
 
 /* Ask the user for a password.
+ * Return 1 without asking if PW has an empty password.
+ * Return -1 on EOF, error while reading input, or timeout.
  * Return 1 if the user gives the correct password for entry PW,
- * 0 if not.  Return 1 without asking if PW has an empty password.
+ * 0 if not.
  *
- * NULL pw means "just fake it for login with bad username" */
-
-int FAST_FUNC correct_password(const struct passwd *pw)
+ * NULL pw means "just fake it for login with bad username"
+ */
+int FAST_FUNC ask_and_check_password_extended(const struct passwd *pw,
+                int timeout, const char *prompt)
 {
         char *unencrypted, *encrypted;
         const char *correct;
@@ -65,9 +68,10 @@ int FAST_FUNC correct_password(const struct passwd *pw)
                 return 1;
 
  fake_it:
-        unencrypted = bb_ask_stdin("Password: ");
+        unencrypted = bb_ask(STDIN_FILENO, timeout, prompt);
         if (!unencrypted) {
-                return 0;
+                /* EOF (such as ^D) or error (such as ^C) */
+                return -1;
         }
         encrypted = pw_encrypt(unencrypted, correct, 1);
         r = (strcmp(encrypted, correct) == 0);
@@ -75,3 +79,8 @@ int FAST_FUNC correct_password(const struct passwd *pw)
         memset(unencrypted, 0, strlen(unencrypted));
         return r;
 }
+
+int FAST_FUNC ask_and_check_password(const struct passwd *pw)
+{
+        return ask_and_check_password_extended(pw, 0, "Password: ");
+}
diff --git a/loginutils/login.c b/loginutils/login.c
index 6ec8dc42e..a4b19ccfc 100644
--- a/loginutils/login.c
+++ b/loginutils/login.c
@@ -420,7 +420,7 @@ int login_main(int argc UNUSED_PARAM, char **argv)
                  * Note that reads (in no-echo mode) trash tty attributes.
                  * If we get interrupted by SIGALRM, we need to restore attrs.
                  */
-                if (correct_password(pw))
+                if (ask_and_check_password(pw) > 0)
                         break;
 #endif /* ENABLE_PAM */
  auth_failed:
diff --git a/loginutils/su.c b/loginutils/su.c
index 2ec05e125..c51f26f70 100644
--- a/loginutils/su.c
+++ b/loginutils/su.c
@@ -93,7 +93,7 @@ int su_main(int argc UNUSED_PARAM, char **argv)
 
         pw = xgetpwnam(opt_username);
 
-        if (cur_uid == 0 || correct_password(pw)) {
+        if (cur_uid == 0 || ask_and_check_password(pw) > 0) {
                 if (ENABLE_FEATURE_SU_SYSLOG)
                         syslog(LOG_NOTICE, "%c %s %s:%s",
                                 '+', tty, old_user, opt_username);
diff --git a/loginutils/sulogin.c b/loginutils/sulogin.c
index 65e638489..2a2909937 100644
--- a/loginutils/sulogin.c
+++ b/loginutils/sulogin.c
@@ -14,24 +14,12 @@
 #include "libbb.h"
 #include <syslog.h>
 
-//static void catchalarm(int UNUSED_PARAM junk)
-//{
-//      exit(EXIT_FAILURE);
-//}
-
-
 int sulogin_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int sulogin_main(int argc UNUSED_PARAM, char **argv)
 {
-        char *cp;
         int timeout = 0;
         struct passwd *pwd;
         const char *shell;
-#if ENABLE_FEATURE_SHADOWPASSWDS
-        /* Using _r function to avoid pulling in static buffers */
-        char buffer[256];
-        struct spwd spw;
-#endif
 
         logmode = LOGMODE_BOTH;
         openlog(applet_name, 0, LOG_AUTH);
@@ -62,43 +50,24 @@ int sulogin_main(int argc UNUSED_PARAM, char **argv)
                 goto auth_error;
         }
 
-#if ENABLE_FEATURE_SHADOWPASSWDS
-        {
-                /* getspnam_r may return 0 yet set result to NULL.
-                 * At least glibc 2.4 does this. Be extra paranoid here. */
-                struct spwd *result = NULL;
-                int r = getspnam_r(pwd->pw_name, &spw, buffer, sizeof(buffer), &result);
-                if (r || !result) {
-                        goto auth_error;
-                }
-                pwd->pw_passwd = result->sp_pwdp;
-        }
-#endif
-
         while (1) {
-                char *encrypted;
                 int r;
 
-                /* cp points to a static buffer */
-                cp = bb_ask(STDIN_FILENO, timeout,
-                                "Give root password for system maintenance\n"
-                                "(or type Control-D for normal startup):");
-                if (!cp) {
+                r = ask_and_check_password_extended(pwd, timeout,
+                        "Give root password for system maintenance\n"
+                        "(or type Control-D for normal startup):"
+                );
+                if (r < 0) {
                         /* ^D, ^C, timeout, or read error */
                         bb_info_msg("Normal startup");
                         return 0;
                 }
-                encrypted = pw_encrypt(cp, pwd->pw_passwd, 1);
-                r = strcmp(encrypted, pwd->pw_passwd);
-                free(encrypted);
-                if (r == 0) {
+                if (r > 0) {
                         break;
                 }
                 bb_do_delay(LOGIN_FAIL_DELAY);
                 bb_info_msg("Login incorrect");
         }
-        memset(cp, 0, strlen(cp));
-//      signal(SIGALRM, SIG_DFL);
 
         bb_info_msg("System Maintenance Mode");
 
diff --git a/loginutils/vlock.c b/loginutils/vlock.c
index 75af9390e..44b14e6bc 100644
--- a/loginutils/vlock.c
+++ b/loginutils/vlock.c
@@ -104,7 +104,7 @@ int vlock_main(int argc UNUSED_PARAM, char **argv)
                                 /* "s" if -a, else "": */ "s" + !option_mask32,
                                 pw->pw_name
                 );
-                if (correct_password(pw)) {
+                if (ask_and_check_password(pw) > 0) {
                         break;
                 }
                 bb_do_delay(LOGIN_FAIL_DELAY);