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