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:       help
  12//config:       blkdiscard discards sectors on a given device.
  13
  14//applet:IF_BLKDISCARD(APPLET_NOEXEC(blkdiscard, blkdiscard, BB_DIR_USR_BIN, BB_SUID_DROP, blkdiscard))
  15
  16//kbuild:lib-$(CONFIG_BLKDISCARD) += blkdiscard.o
  17
  18//usage:#define blkdiscard_trivial_usage
  19//usage:       "[-o OFS] [-l LEN] [-s] DEVICE"
  20//usage:#define blkdiscard_full_usage "\n\n"
  21//usage:       "Discard sectors on DEVICE\n"
  22//usage:     "\n        -o OFS  Byte offset into device"
  23//usage:     "\n        -l LEN  Number of bytes to discard"
  24//usage:     "\n        -s      Perform a secure discard"
  25///////:     "\n        -f      Disable check for mounted filesystem"
  26//////////////// -f: accepted but is a nop (we do no check anyway)
  27//usage:
  28//usage:#define blkdiscard_example_usage
  29//usage:        "$ blkdiscard -o 0 -l 1G /dev/sdb"
  30
  31#include "libbb.h"
  32#include <linux/fs.h>
  33
  34#ifndef BLKDISCARD
  35#define BLKDISCARD 0x1277
  36#endif
  37#ifndef BLKSECDISCARD
  38#define BLKSECDISCARD 0x127d
  39#endif
  40
  41int blkdiscard_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  42int blkdiscard_main(int argc UNUSED_PARAM, char **argv)
  43{
  44        unsigned opts;
  45        const char *offset_str = "0";
  46        const char *length_str;
  47        uint64_t offset; /* Leaving these two variables out does not  */
  48        uint64_t length; /* shrink code size and hampers readability. */
  49        uint64_t range[2];
  50        int fd;
  51
  52        enum {
  53                OPT_OFFSET = (1 << 0),
  54                OPT_LENGTH = (1 << 1),
  55                OPT_SECURE = (1 << 2),
  56                OPT_FORCE  = (1 << 3), //nop
  57        };
  58
  59        opts = getopt32(argv, "^" "o:l:sf" "\0" "=1", &offset_str, &length_str);
  60        argv += optind;
  61
  62        fd = xopen(argv[0], O_RDWR|O_EXCL);
  63//Why bother, BLK[SEC]DISCARD will fail on non-blockdevs anyway?
  64//      xfstat(fd, &st);
  65//      if (!S_ISBLK(st.st_mode))
  66//              bb_error_msg_and_die("%s: not a block device", argv[0]);
  67
  68        offset = xatoull_sfx(offset_str, kMG_suffixes);
  69
  70        if (opts & OPT_LENGTH)
  71                length = xatoull_sfx(length_str, kMG_suffixes);
  72        else {
  73                xioctl(fd, BLKGETSIZE64, &length);
  74                length -= offset;
  75        }
  76
  77        range[0] = offset;
  78        range[1] = length;
  79        ioctl_or_perror_and_die(fd,
  80                        (opts & OPT_SECURE) ? BLKSECDISCARD : BLKDISCARD,
  81                        &range,
  82                        "%s: %s failed",
  83                        argv[0],
  84                        (opts & OPT_SECURE) ? "BLKSECDISCARD" : "BLKDISCARD"
  85        );
  86
  87        if (ENABLE_FEATURE_CLEAN_UP)
  88                close(fd);
  89
  90        return EXIT_SUCCESS;
  91}
  92