LXR busybox/util-linux/freeramdisk.c

   1/* vi: set sw=4 ts=4: */
   2/*
   3 * freeramdisk and fdflush implementations for busybox
   4 *
   5 * Copyright (C) 2000 and written by Emanuele Caratti <wiz@iol.it>
   6 * Adjusted a bit by Erik Andersen <andersen@codepoet.org>
   7 * Unified with fdflush by Tito Ragusa <farmatito@tiscali.it>
   8 *
   9 * Licensed under GPLv2, see file LICENSE in this source tree.
  10 */
  11//config:config FDFLUSH
  12//config:       bool "fdflush (1.3 kb)"
  13//config:       default y
  14//config:       help
  15//config:       fdflush is only needed when changing media on slightly-broken
  16//config:       removable media drives. It is used to make Linux believe that a
  17//config:       hardware disk-change switch has been actuated, which causes Linux to
  18//config:       forget anything it has cached from the previous media. If you have
  19//config:       such a slightly-broken drive, you will need to run fdflush every time
  20//config:       you change a disk. Most people have working hardware and can safely
  21//config:       leave this disabled.
  22//config:
  23//config:config FREERAMDISK
  24//config:       bool "freeramdisk (1.3 kb)"
  25//config:       default y
  26//config:       help
  27//config:       Linux allows you to create ramdisks. This utility allows you to
  28//config:       delete them and completely free all memory that was used for the
  29//config:       ramdisk. For example, if you boot Linux into a ramdisk and later
  30//config:       pivot_root, you may want to free the memory that is allocated to the
  31//config:       ramdisk. If you have no use for freeing memory from a ramdisk, leave
  32//config:       this disabled.
  33
  34//                     APPLET_ODDNAME:name         main         location     suid_type     help
  35//applet:IF_FDFLUSH(   APPLET_ODDNAME(fdflush,     freeramdisk, BB_DIR_BIN,  BB_SUID_DROP, fdflush    ))
  36//applet:IF_FREERAMDISK(APPLET_NOEXEC(freeramdisk, freeramdisk, BB_DIR_SBIN, BB_SUID_DROP, freeramdisk))
  37
  38//kbuild:lib-$(CONFIG_FDFLUSH) += freeramdisk.o
  39//kbuild:lib-$(CONFIG_FREERAMDISK) += freeramdisk.o
  40
  41//usage:#define freeramdisk_trivial_usage
  42//usage:       "DEVICE"
  43//usage:#define freeramdisk_full_usage "\n\n"
  44//usage:       "Free all memory used by the specified ramdisk"
  45//usage:
  46//usage:#define freeramdisk_example_usage
  47//usage:       "$ freeramdisk /dev/ram2\n"
  48//usage:
  49//usage:#define fdflush_trivial_usage
  50//usage:       "DEVICE"
  51//usage:#define fdflush_full_usage "\n\n"
  52//usage:       "Force floppy disk drive to detect disk change"
  53
  54#include <sys/mount.h>
  55#include "libbb.h"
  56
  57/* From <linux/fd.h> */
  58#define FDFLUSH  _IO(2,0x4b)
  59
  60int freeramdisk_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  61int freeramdisk_main(int argc UNUSED_PARAM, char **argv)
  62{
  63        int fd;
  64
  65        fd = xopen(single_argv(argv), O_RDWR);
  66
  67        // Act like freeramdisk, fdflush, or both depending on configuration.
  68        ioctl_or_perror_and_die(fd,
  69                ((ENABLE_FREERAMDISK && applet_name[1] == 'r') || !ENABLE_FDFLUSH)
  70                                ? BLKFLSBUF
  71                                : FDFLUSH,
  72                NULL, "%s", argv[1]
  73        );
  74
  75        if (ENABLE_FEATURE_CLEAN_UP) close(fd);
  76
  77        return EXIT_SUCCESS;
  78}
  79