LXR busybox/coreutils/usleep.c

   1/* vi: set sw=4 ts=4: */
   2/*
   3 * usleep implementation for busybox
   4 *
   5 * Copyright (C) 2003  Manuel Novoa III  <mjn3@codepoet.org>
   6 *
   7 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
   8 */
   9//config:config USLEEP
  10//config:       bool "usleep (1.1 kb)"
  11//config:       default y
  12//config:       help
  13//config:       usleep is used to pause for a specified number of microseconds.
  14
  15//applet:IF_USLEEP(APPLET_NOFORK(usleep, usleep, BB_DIR_BIN, BB_SUID_DROP, usleep))
  16
  17//kbuild:lib-$(CONFIG_USLEEP) += usleep.o
  18
  19/* BB_AUDIT SUSv3 N/A -- Apparently a busybox extension. */
  20
  21//usage:#define usleep_trivial_usage
  22//usage:       "N"
  23//usage:#define usleep_full_usage "\n\n"
  24//usage:       "Pause for N microseconds"
  25//usage:
  26//usage:#define usleep_example_usage
  27//usage:       "$ usleep 1000000\n"
  28//usage:       "[pauses for 1 second]\n"
  29
  30#include "libbb.h"
  31
  32/* This is a NOFORK applet. Be very careful! */
  33
  34int usleep_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  35int usleep_main(int argc UNUSED_PARAM, char **argv)
  36{
  37        if (!argv[1]) {
  38                bb_show_usage();
  39        }
  40
  41        /* Safe wrt NOFORK? (noforks are not allowed to run for
  42         * a long time). Try "usleep 99999999" + ^C + "echo $?"
  43         * in hush with FEATURE_SH_NOFORK=y.
  44         * At least on uclibc, usleep() thanslates to nanosleep()
  45         * which returns early on any signal (even caught one),
  46         * and uclibc does not loop back on EINTR.
  47         */
  48        usleep(xatou(argv[1]));
  49
  50        return EXIT_SUCCESS;
  51}
  52