Disable core dumps in case passwd(1) crashes

Avoids leaking the shadow db.

passwd.c

@@ -39,6 +39,8 @@ main(int argc, char *argv[])
 	if (argc != 1)
 		usage();
 
+	pw_init();
+
 	errno = 0;
 	pw = getpwnam(argv[0]);
 	if (errno)

passwd.h

@@ -2,4 +2,5 @@
 /* passwd.c */
 int pw_check(struct passwd *, const char *);
 int pw_copy(int, int, const struct passwd *);
+int pw_init(void);
 int pw_scan(char *, struct passwd *);

util/passwd.c

@@ -6,6 +6,8 @@
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
+#include <sys/resource.h>
+#include <sys/time.h>
 #include "../passwd.h"
 #include "../text.h"
 #include "../util.h"
@@ -107,6 +109,18 @@ pw_copy(int ffd, int tfd, const struct passwd *newpw)
 	return 0;
 }
 
+int
+pw_init(void)
+{
+	struct rlimit rlim;
+
+	rlim.rlim_cur = 0;
+	rlim.rlim_max = 0;
+	if (setrlimit(RLIMIT_CORE, &rlim) < 0)
+		eprintf("setrlimit:");
+	return 0;
+}
+
 int
 pw_scan(char *bp, struct passwd *pw)
 {