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 5827165..e99bb92 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 7cabd33..d02d0d6 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 6ec8dc4..a4b19cc 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 2ec05e1..c51f26f 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 65e6384..2a29099 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 75af939..44b14e6 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);