LXR busybox/util-linux/blkdiscard.c

   1/*
   2 * Mini blkdiscard implementation for busybox
   3 *
   4 * Copyright (C) 2015 by Ari Sundholm <ari@tuxera.com> and Tuxera Inc.
   5 *
   6 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
   7 */
   8//config:config BLKDISCARD
   9//config:       bool "blkdiscard (4.3 kb)"
  10//config:       default y
  11//config:       select PLATFORM_LINUX
  12//config:       help
  13//config:       blkdiscard discards sectors on a given device.
  14
  15//applet:IF_BLKDISCARD(APPLET_NOEXEC(blkdiscard, blkdiscard, BB_DIR_USR_BIN, BB_SUID_DROP, blkdiscard))
  16
  17//kbuild:lib-$(CONFIG_BLKDISCARD) += blkdiscard.o
  18
  19//usage:#define blkdiscard_trivial_usage
  20//usage:       "[-o OFS] [-l LEN] [-s] DEVICE"
  21//usage:#define blkdiscard_full_usage "\n\n"
  22//usage:        "Discard sectors on DEVICE\n"
  23//usage:        "\n     -o OFS  Byte offset into device"
  24//usage:        "\n     -l LEN  Number of bytes to discard"
  25//usage:        "\n     -s      Perform a secure discard"
  26//usage:
  27//usage:#define blkdiscard_example_usage
  28//usage:        "$ blkdiscard -o 0 -l 1G /dev/sdb"
  29
  30#include "libbb.h"
  31#include <linux/fs.h>
  32
  33#ifndef BLKDISCARD
  34#define BLKDISCARD 0x1277
  35#endif
  36#ifndef BLKSECDISCARD
  37#define BLKSECDISCARD 0x127d
  38#endif
  39
  40int blkdiscard_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  41int blkdiscard_main(int argc UNUSED_PARAM, char **argv)
  42{
  43        unsigned opts;
  44        const char *offset_str = "0";
  45        const char *length_str;
  46        uint64_t offset; /* Leaving these two variables out does not  */
  47        uint64_t length; /* shrink code size and hampers readability. */
  48        uint64_t range[2];
  49        int fd;
  50
  51        enum {
  52                OPT_OFFSET = (1 << 0),
  53                OPT_LENGTH = (1 << 1),
  54                OPT_SECURE = (1 << 2),
  55        };
  56
  57        opts = getopt32(argv, "^" "o:l:s" "\0" "=1", &offset_str, &length_str);
  58        argv += optind;
  59
  60        fd = xopen(argv[0], O_RDWR|O_EXCL);
  61//Why bother, BLK[SEC]DISCARD will fail on non-blockdevs anyway?
  62//      xfstat(fd, &st);
  63//      if (!S_ISBLK(st.st_mode))
  64//              bb_error_msg_and_die("%s: not a block device", argv[0]);
  65
  66        offset = xatoull_sfx(offset_str, kMG_suffixes);
  67
  68        if (opts & OPT_LENGTH)
  69                length = xatoull_sfx(length_str, kMG_suffixes);
  70        else {
  71                xioctl(fd, BLKGETSIZE64, &length);
  72                length -= offset;
  73        }
  74
  75        range[0] = offset;
  76        range[1] = length;
  77        ioctl_or_perror_and_die(fd,
  78                        (opts & OPT_SECURE) ? BLKSECDISCARD : BLKDISCARD,
  79                        &range,
  80                        "%s: %s failed",
  81                        argv[0],
  82                        (opts & OPT_SECURE) ? "BLKSECDISCARD" : "BLKDISCARD"
  83        );
  84
  85        if (ENABLE_FEATURE_CLEAN_UP)
  86                close(fd);
  87
  88        return EXIT_SUCCESS;
  89}
  90