bin/multiuser: Fix PVS 1809 and 1896

Replace memset() with explicit_bzero(), since compiler could delete
memset() funnction call.

Change-Id: I6d6ad991951f516cf94b6fdf1772715ef4a42822
Reviewed-on: https://review.haiku-os.org/c/880
Reviewed-by: waddlesplash <[email protected]>

src/bin/multiuser/Jamfile

@@ -6,14 +6,16 @@ UsePrivateHeaders kernel ;
 	# for <util/KMessage.h>
 UsePrivateHeaders libroot ;
 UsePrivateHeaders shared ;
+UseHeaders [ FDirName $(HAIKU_TOP) headers compatibility bsd ] : true ;
+SubDirC++Flags [ FDefines _BSD_SOURCE=1 ] ;
 
 StaticLibrary libmultiuser_utils.a : multiuser_utils.cpp ;
 
-BinCommand login : login.cpp : libmultiuser_utils.a ;
+BinCommand login : login.cpp : libmultiuser_utils.a libbsd.so ;
 
-BinCommand su : su.cpp : libmultiuser_utils.a ;
+BinCommand su : su.cpp : libmultiuser_utils.a libbsd.so ;
 
-BinCommand passwd : passwd.cpp : libmultiuser_utils.a ;
+BinCommand passwd : passwd.cpp : libmultiuser_utils.a libbsd.so ;
 
 BinCommand useradd : useradd.cpp ;
 

src/bin/multiuser/login.cpp

@@ -91,7 +91,7 @@ login(const char* user, struct passwd** _passwd)
 	struct spwd* spwd = getspnam(user);
 
 	bool ok = verify_password(passwd, spwd, password);
-	memset(password, 0, sizeof(password));
+	explicit_bzero(password, sizeof(password));
 
 	if (!ok)
 		return B_PERMISSION_DENIED;

src/bin/multiuser/multiuser_utils.cpp

@@ -140,7 +140,7 @@ authenticate_user(const char* prompt, passwd* passwd, spwd* spwd, int maxTries,
 
 		// check it
 		bool ok = verify_password(passwd, spwd, plainPassword);
-		memset(plainPassword, 0, sizeof(plainPassword));
+		explicit_bzero(plainPassword, sizeof(plainPassword));
 		if (ok)
 			return B_OK;
 

src/bin/multiuser/passwd.cpp

@@ -169,11 +169,11 @@ main(int argc, const char* const* argv)
 			exit(1);
 		}
 
-		memset(repeatedPassword, 0, sizeof(repeatedPassword));
+		explicit_bzero(repeatedPassword, sizeof(repeatedPassword));
 
 		// crypt it
 		encryptedPassword = crypt(password, NULL);
-		memset(password, 0, sizeof(password));
+		explicit_bzero(password, sizeof(password));
 	}
 
 	// prepare request for the registrar