taskset: disallow "taskset -p 0"

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/util-linux/taskset.c b/util-linux/taskset.c
index afe2f04..d2ef9b9 100644
--- a/util-linux/taskset.c
+++ b/util-linux/taskset.c
@@ -218,7 +218,7 @@
 	ul *mask;
 	unsigned mask_size_in_bytes;
 	const char *current_new;
-	pid_t pid = xatoi_positive(pid_str);
+	pid_t pid = !pid_str ? 0 : xatou_range(pid_str, 1, INT_MAX); /* disallow "0": "taskset -p 0" should fail */
 
 	mask_size_in_bytes = SZOF_UL;
 	current_new = "current";
@@ -343,7 +343,7 @@
 		/* <aff> <cmd...> */
 		if (!*argv)
 			bb_show_usage();
-		process_pid_str("0", opts, aff);
+		process_pid_str(NULL, opts, aff);
 		BB_EXECVP_or_die(argv);
 	}