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