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