util-linux/blockdev.c

   1 /*
   2  * blockdev implementation for busybox
   3  *
   4  * Copyright (C) 2010 Sergey Naumov <sknaumov@gmail.com>
   5  *
   6  * Licensed under GPLv2, see file LICENSE in this source tree.
   7  */
   8
   9 //applet:IF_BLOCKDEV(APPLET(blockdev, BB_DIR_SBIN, BB_SUID_DROP))
  10
  11 //kbuild:lib-$(CONFIG_BLOCKDEV) += blockdev.o
  12
  13 //config:config BLOCKDEV
  14 //config:       bool "blockdev"
  15 //config:       default y
  16 //config:       help
  17 //config:         Performs some ioctls with block devices.
  18
  19 //usage:#define blockdev_trivial_usage
  20 //usage:        "OPTION BLOCKDEV"
  21 //usage:#define blockdev_full_usage "\n\n"
  22 //usage:       "Options:"
  23 //usage:     "\n        --setro         Set ro"
  24 //usage:     "\n        --setrw         Set rw"
  25 //usage:     "\n        --getro         Get ro"
  26 //usage:     "\n        --getss         Get sector size"
  27 //usage:     "\n        --getbsz        Get block size"
  28 //usage:     "\n        --setbsz BYTES  Set block size"
  29 //usage:     "\n        --getsz         Get device size in 512-byte sectors"
  30 /*//usage:     "\n      --getsize       Get device size in sectors (deprecated)"*/
  31 //usage:     "\n        --getsize64     Get device size in bytes"
  32 //usage:     "\n        --flushbufs     Flush buffers"
  33 //usage:     "\n        --rereadpt      Reread partition table"
  34
  35
  36 #include "libbb.h"
  37 #include <linux/fs.h>
  38
  39 enum {
  40         ARG_NONE   = 0,
  41         ARG_INT    = 1,
  42         ARG_ULONG  = 2,
  43         /* Yes, BLKGETSIZE64 takes pointer to uint64_t, not ullong! */
  44         ARG_U64    = 3,
  45         ARG_MASK   = 3,
  46
  47         FL_USRARG   = 4, /* argument is provided by user */
  48         FL_NORESULT = 8,
  49         FL_SCALE512 = 16,
  50 };
  51
  52 struct bdc {
  53         uint32_t   ioc;                       /* ioctl code */
  54         const char name[sizeof("flushbufs")]; /* "--setfoo" wothout "--" */
  55         uint8_t    flags;
  56         int8_t     argval;                    /* default argument value */
  57 };
  58
  59 static const struct bdc bdcommands[] = {
  60         {
  61                 .ioc = BLKROSET,
  62                 .name = "setro",
  63                 .flags = ARG_INT + FL_NORESULT,
  64                 .argval = 1,
  65         },{
  66                 .ioc = BLKROSET,
  67                 .name = "setrw",
  68                 .flags = ARG_INT + FL_NORESULT,
  69                 .argval = 0,
  70         },{
  71                 .ioc = BLKROGET,
  72                 .name = "getro",
  73                 .flags = ARG_INT,
  74                 .argval = -1,
  75         },{
  76                 .ioc = BLKSSZGET,
  77                 .name = "getss",
  78                 .flags = ARG_INT,
  79                 .argval = -1,
  80         },{
  81                 .ioc = BLKBSZGET,
  82                 .name = "getbsz",
  83                 .flags = ARG_INT,
  84                 .argval = -1,
  85         },{
  86                 .ioc = BLKBSZSET,
  87                 .name = "setbsz",
  88                 .flags = ARG_INT + FL_NORESULT + FL_USRARG,
  89                 .argval = 0,
  90         },{
  91                 .ioc = BLKGETSIZE64,
  92                 .name = "getsz",
  93                 .flags = ARG_U64 + FL_SCALE512,
  94                 .argval = -1,
  95         },{
  96                 .ioc = BLKGETSIZE,
  97                 .name = "getsize",
  98                 .flags = ARG_ULONG,
  99                 .argval = -1,
 100         },{
 101                 .ioc = BLKGETSIZE64,
 102                 .name = "getsize64",
 103                 .flags = ARG_U64,
 104                 .argval = -1,
 105         },{
 106                 .ioc = BLKFLSBUF,
 107                 .name = "flushbufs",
 108                 .flags = ARG_NONE + FL_NORESULT,
 109                 .argval = 0,
 110         },{
 111                 .ioc = BLKRRPART,
 112                 .name = "rereadpt",
 113                 .flags = ARG_NONE + FL_NORESULT,
 114                 .argval = 0,
 115         }
 116 };
 117
 118 static const struct bdc *find_cmd(const char *s)
 119 {
 120         const struct bdc *bdcmd = bdcommands;
 121         if (s[0] == '-' && s[1] == '-') {
 122                 s += 2;
 123                 do {
 124                         if (strcmp(s, bdcmd->name) == 0)
 125                                 return bdcmd;
 126                         bdcmd++;
 127                 } while (bdcmd != bdcommands + ARRAY_SIZE(bdcommands));
 128         }
 129         bb_show_usage();
 130 }
 131
 132 int blockdev_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 133 int blockdev_main(int argc UNUSED_PARAM, char **argv)
 134 {
 135         const struct bdc *bdcmd;
 136         int fd;
 137         uint64_t u64;
 138         union {
 139                 int i;
 140                 unsigned long lu;
 141                 uint64_t u64;
 142         } ioctl_val_on_stack;
 143
 144         argv++;
 145         if (!argv[0] || !argv[1]) /* must have at least 2 args */
 146                 bb_show_usage();
 147
 148         bdcmd = find_cmd(*argv);
 149
 150         u64 = (int)bdcmd->argval;
 151         if (bdcmd->flags & FL_USRARG)
 152                 u64 = xatoi_positive(*++argv);
 153
 154         argv++;
 155         if (!argv[0] || argv[1])
 156                 bb_show_usage();
 157         fd = xopen(argv[0], O_RDONLY);
 158
 159         ioctl_val_on_stack.u64 = u64;
 160 #if BB_BIG_ENDIAN
 161         /* Store data properly wrt data size.
 162          * (1) It's no-op for little-endian.
 163          * (2) it's no-op for 0 and -1. Only --setro uses arg != 0 and != -1,
 164          * and it is ARG_INT. --setbsz USER_VAL is also ARG_INT.
 165          * Thus, we don't need to handle ARG_ULONG.
 166          */
 167         switch (bdcmd->flags & ARG_MASK) {
 168         case ARG_INT:
 169                 ioctl_val_on_stack.i = (int)u64;
 170                 break;
 171 # if 0 /* unused */
 172         case ARG_ULONG:
 173                 ioctl_val_on_stack.lu = (unsigned long)u64;
 174                 break;
 175 # endif
 176         }
 177 #endif
 178
 179         if (ioctl(fd, bdcmd->ioc, &ioctl_val_on_stack.u64) == -1)
 180                 bb_simple_perror_msg_and_die(*argv);
 181
 182         /* Fetch it into register(s) */
 183         u64 = ioctl_val_on_stack.u64;
 184
 185         if (bdcmd->flags & FL_SCALE512)
 186                 u64 >>= 9;
 187
 188         /* Zero- or one-extend the value if needed, then print */
 189         switch (bdcmd->flags & (ARG_MASK+FL_NORESULT)) {
 190         case ARG_INT:
 191                 /* Smaller code when we use long long
 192                  * (gcc tail-merges printf call)
 193                  */
 194                 printf("%lld\n", (long long)(int)u64);
 195                 break;
 196         case ARG_ULONG:
 197                 u64 = (unsigned long)u64;
 198                 /* FALLTHROUGH */
 199         case ARG_U64:
 200                 printf("%llu\n", (unsigned long long)u64);
 201                 break;
 202         }
 203
 204         if (ENABLE_FEATURE_CLEAN_UP)
 205                 close(fd);
 206         return EXIT_SUCCESS;
 207 }