Clear passwords on __gr_dup/__pw_dup errors.

The functions __gr_dup and __pw_dup do not explicitly zero the
memory which hold the passwords after free. The gr_free and pw_free
functions do this explicitly.

To guarantee same behaviour, it's possible to call these *_free
functions directly from __*_dup, because the memory is initialized
with zeros at the beginning. Calling free(NULL) has no negative
effect and can be considered safe these days.

lib/groupmem.c

@@ -55,15 +55,14 @@
 	gr->gr_name = strdup (grent->gr_name);
 	/*@=mustfreeonly@*/
 	if (NULL == gr->gr_name) {
-		free(gr);
+		gr_free(gr);
 		return NULL;
 	}
 	/*@-mustfreeonly@*/
 	gr->gr_passwd = strdup (grent->gr_passwd);
 	/*@=mustfreeonly@*/
 	if (NULL == gr->gr_passwd) {
-		free(gr->gr_name);
+		gr_free(gr);
-		free(gr);
 		return NULL;
 	}
 
@@ -73,21 +72,13 @@
 	gr->gr_mem = (char **) malloc ((i + 1) * sizeof (char *));
 	/*@=mustfreeonly@*/
 	if (NULL == gr->gr_mem) {
-		free(gr->gr_passwd);
+		gr_free(gr);
-		free(gr->gr_name);
-		free(gr);
 		return NULL;
 	}
 	for (i = 0; grent->gr_mem[i]; i++) {
 		gr->gr_mem[i] = strdup (grent->gr_mem[i]);
 		if (NULL == gr->gr_mem[i]) {
-			int j;
+			gr_free(gr);
-			for (j=0; j<i; j++)
-				free(gr->gr_mem[j]);
-			free(gr->gr_mem);
-			free(gr->gr_passwd);
-			free(gr->gr_name);
-			free(gr);
 			return NULL;
 		}
 	}

lib/pwmem.c

@@ -56,45 +56,35 @@
 	pw->pw_name = strdup (pwent->pw_name);
 	/*@=mustfreeonly@*/
 	if (NULL == pw->pw_name) {
-		free(pw);
+		pw_free(pw);
 		return NULL;
 	}
 	/*@-mustfreeonly@*/
 	pw->pw_passwd = strdup (pwent->pw_passwd);
 	/*@=mustfreeonly@*/
 	if (NULL == pw->pw_passwd) {
-		free(pw->pw_name);
+		pw_free(pw);
-		free(pw);
 		return NULL;
 	}
 	/*@-mustfreeonly@*/
 	pw->pw_gecos = strdup (pwent->pw_gecos);
 	/*@=mustfreeonly@*/
 	if (NULL == pw->pw_gecos) {
-		free(pw->pw_passwd);
+		pw_free(pw);
-		free(pw->pw_name);
-		free(pw);
 		return NULL;
 	}
 	/*@-mustfreeonly@*/
 	pw->pw_dir = strdup (pwent->pw_dir);
 	/*@=mustfreeonly@*/
 	if (NULL == pw->pw_dir) {
-		free(pw->pw_gecos);
+		pw_free(pw);
-		free(pw->pw_passwd);
-		free(pw->pw_name);
-		free(pw);
 		return NULL;
 	}
 	/*@-mustfreeonly@*/
 	pw->pw_shell = strdup (pwent->pw_shell);
 	/*@=mustfreeonly@*/
 	if (NULL == pw->pw_shell) {
-		free(pw->pw_dir);
+		pw_free(pw);
-		free(pw->pw_gecos);
-		free(pw->pw_passwd);
-		free(pw->pw_name);
-		free(pw);
 		return NULL;
 	}