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>

1 files changed, 10 insertions, 1 deletions

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;
 }