libbb: move nuke_str() from passwd into libbb

function                                             old     new   delta
nuke_str                                               -      15     +15
ask_and_check_password_extended                      215     206      -9
init_main                                            781     771     -10
nuke_str                                              27       -     -27
------------------------------------------------------------------------------
(add/remove: 1/1 grow/shrink: 0/2 up/down: 15/-46)            Total: -31 bytes

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

4 files changed, 15 insertions, 10 deletions

diff --git a/include/libbb.h b/include/libbb.h
index e99bb928f..64167bba3 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -1300,9 +1300,10 @@ int sd_listen_fds(void);
 #define SETUP_ENV_CLEARENV  (1 << 1)
 #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 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;
+void setup_environment(const char *shell, int flags, const struct passwd *pw) FAST_FUNC;
+void nuke_str(char *str) FAST_FUNC;
+int ask_and_check_password_extended(const struct passwd *pw, int timeout, const char *prompt) FAST_FUNC;
+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/init/init.c b/init/init.c
index 2dcdfd471..c63bba1ff 100644
--- a/init/init.c
+++ b/init/init.c
@@ -1128,7 +1128,7 @@ int init_main(int argc UNUSED_PARAM, char **argv)
         strncpy(argv[0], "init", strlen(argv[0]));
         /* Wipe argv[1]-argv[N] so they don't clutter the ps listing */
         while (*++argv)
-                memset(*argv, 0, strlen(*argv));
+                nuke_str(*argv);
 
         /* Set up signal handlers */
         if (!DEBUG_INIT) {
diff --git a/libbb/correct_password.c b/libbb/correct_password.c
index d39a5839c..5727c65fb 100644
--- a/libbb/correct_password.c
+++ b/libbb/correct_password.c
@@ -30,6 +30,15 @@
 
 #include "libbb.h"
 
+void FAST_FUNC nuke_str(char *str)
+{
+        if (str) {
+                while (*str)
+                        *str++ = 0;
+                /* or: memset(str, 0, strlen(str)); - not as small as above */
+        }
+}
+
 /* 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.
@@ -76,7 +85,7 @@ int FAST_FUNC ask_and_check_password_extended(const struct passwd *pw,
         encrypted = pw_encrypt(unencrypted, correct, 1);
         r = (strcmp(encrypted, correct) == 0);
         free(encrypted);
-        memset(unencrypted, 0, strlen(unencrypted));
+        nuke_str(unencrypted);
         return r;
 }
 
diff --git a/loginutils/passwd.c b/loginutils/passwd.c
index a7006f054..150908932 100644
--- a/loginutils/passwd.c
+++ b/loginutils/passwd.c
@@ -17,11 +17,6 @@
 #include <syslog.h>
 #include <sys/resource.h> /* setrlimit */
 
-static void nuke_str(char *str)
-{
-        if (str) memset(str, 0, strlen(str));
-}
-
 static char* new_password(const struct passwd *pw, uid_t myuid, const char *algo)
 {
         char salt[MAX_PW_SALT_LEN];