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 //config:config BLOCKDEV
   9 //config:       bool "blockdev (2.3 kb)"
  10 //config:       default y
  11 //config:       help
  12 //config:       Performs some ioctls with block devices.
  13
  14 //applet:IF_BLOCKDEV(APPLET_NOEXEC(blockdev, blockdev, BB_DIR_SBIN, BB_SUID_DROP, blockdev))
  15
  16 //kbuild:lib-$(CONFIG_BLOCKDEV) += blockdev.o
  17
  18 //usage:#define blockdev_trivial_usage
  19 //usage:        "OPTION BLOCKDEV"
  20 //usage:#define blockdev_full_usage "\n\n"
  21 //usage:       "        --setro         Set ro"
  22 //usage:     "\n        --setrw         Set rw"
  23 //usage:     "\n        --getro         Get ro"
  24 //usage:     "\n        --getss         Get sector size"
  25 //usage:     "\n        --getbsz        Get block size"
  26 //usage:     "\n        --setbsz BYTES  Set block size"
  27 //usage:     "\n        --getsz         Get device size in 512-byte sectors"
  28 /*//usage:     "\n      --getsize       Get device size in sectors (deprecated)"*/
  29 //usage:     "\n        --getsize64     Get device size in bytes"
  30 //usage:     "\n        --flushbufs     Flush buffers"
  31 //usage:     "\n        --rereadpt      Reread partition table"
  32
  33
  34 #include "libbb.h"
  35 #include <linux/fs.h>
  36
  37 /* Takes less space is separate arrays than one array of struct */
  38 static const char bdcmd_names[] ALIGN1 =
  39         "setro"     "\0"
  40 #define CMD_SETRO 0
  41         "setrw"     "\0"
  42         "getro"     "\0"
  43         "getss"     "\0"
  44         "getbsz"    "\0"
  45         "setbsz"    "\0"
  46 #define CMD_SETBSZ 5
  47         "getsz"     "\0"
  48         "getsize"   "\0"
  49         "getsize64" "\0"
  50         "flushbufs" "\0"
  51         "rereadpt"  "\0"
  52 ;
  53 static const uint32_t bdcmd_ioctl[] = {
  54         BLKROSET,       //setro
  55         BLKROSET,       //setrw
  56         BLKROGET,       //getro
  57         BLKSSZGET,      //getss
  58         BLKBSZGET,      //getbsz
  59         BLKBSZSET,      //setbsz
  60         BLKGETSIZE64,   //getsz
  61         BLKGETSIZE,     //getsize
  62         BLKGETSIZE64,   //getsize64
  63         BLKFLSBUF,      //flushbufs
  64         BLKRRPART,      //rereadpt
  65 };
  66 enum {
  67         ARG_NONE   = 0,
  68         ARG_INT    = 1,
  69         ARG_ULONG  = 2,
  70         /* Yes, BLKGETSIZE64 takes pointer to uint64_t, not ullong! */
  71         ARG_U64    = 3,
  72         ARG_MASK   = 3,
  73
  74         FL_USRARG   = 4, /* argument is provided by user */
  75         FL_NORESULT = 8,
  76         FL_SCALE512 = 16,
  77 };
  78 static const uint8_t bdcmd_flags[] ALIGN1 = {
  79         ARG_INT + FL_NORESULT,             //setro
  80         ARG_INT + FL_NORESULT,             //setrw
  81         ARG_INT,                           //getro
  82         ARG_INT,                           //getss
  83         ARG_INT,                           //getbsz
  84         ARG_INT + FL_NORESULT + FL_USRARG, //setbsz
  85         ARG_U64 + FL_SCALE512,             //getsz
  86         ARG_ULONG,                         //getsize
  87         ARG_U64,                           //getsize64
  88         ARG_NONE + FL_NORESULT,            //flushbufs
  89         ARG_NONE + FL_NORESULT,            //rereadpt
  90 };
  91
  92 static unsigned find_cmd(const char *s)
  93 {
  94         if (s[0] == '-' && s[1] == '-') {
  95                 int n = index_in_strings(bdcmd_names, s + 2);
  96                 if (n >= 0)
  97                         return n;
  98         }
  99         bb_show_usage();
 100 }
 101
 102 int blockdev_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 103 int blockdev_main(int argc UNUSED_PARAM, char **argv)
 104 {
 105         unsigned bdcmd;
 106         unsigned flags;
 107         int fd;
 108         uint64_t u64;
 109         union {
 110                 int i;
 111                 unsigned long lu;
 112                 uint64_t u64;
 113         } ioctl_val_on_stack;
 114
 115         argv++;
 116         if (!argv[0] || !argv[1]) /* must have at least 2 args */
 117                 bb_show_usage();
 118
 119         bdcmd = find_cmd(*argv);
 120         /* setrw translates to BLKROSET(0), most other ioctls don't care... */
 121         /* ...setro will do BLKROSET(1) */
 122         u64 = (bdcmd == CMD_SETRO);
 123         if (bdcmd == CMD_SETBSZ) {
 124                 /* ...setbsz is BLKBSZSET(bytes) */
 125                 u64 = xatoi_positive(*++argv);
 126         }
 127
 128         argv++;
 129         if (!argv[0] || argv[1])
 130                 bb_show_usage();
 131         fd = xopen(argv[0], O_RDONLY);
 132
 133         ioctl_val_on_stack.u64 = u64;
 134         flags = bdcmd_flags[bdcmd];
 135 #if BB_BIG_ENDIAN
 136         /* Store data properly wrt data size.
 137          * (1) It's no-op for little-endian.
 138          * (2) it's no-op for 0 and -1. Only --setro uses arg != 0 and != -1,
 139          * and it is ARG_INT. --setbsz USER_VAL is also ARG_INT.
 140          * Thus, we don't need to handle ARG_ULONG.
 141          */
 142         switch (flags & ARG_MASK) {
 143         case ARG_INT:
 144                 ioctl_val_on_stack.i = (int)u64;
 145                 break;
 146 # if 0 /* unused */
 147         case ARG_ULONG:
 148                 ioctl_val_on_stack.lu = (unsigned long)u64;
 149                 break;
 150 # endif
 151         }
 152 #endif
 153
 154         if (ioctl(fd, bdcmd_ioctl[bdcmd], &ioctl_val_on_stack.u64) == -1)
 155                 bb_simple_perror_msg_and_die(*argv);
 156
 157         /* Fetch it into register(s) */
 158         u64 = ioctl_val_on_stack.u64;
 159
 160         if (flags & FL_SCALE512)
 161                 u64 >>= 9;
 162
 163         /* Zero- or one-extend the value if needed, then print */
 164         switch (flags & (ARG_MASK+FL_NORESULT)) {
 165         case ARG_INT:
 166                 /* Smaller code when we use long long
 167                  * (gcc tail-merges printf call)
 168                  */
 169                 printf("%lld\n", (long long)(int)u64);
 170                 break;
 171         case ARG_ULONG:
 172                 u64 = (unsigned long)u64;
 173                 /* FALLTHROUGH */
 174         case ARG_U64:
 175                 printf("%llu\n", (unsigned long long)u64);
 176                 break;
 177         }
 178
 179         if (ENABLE_FEATURE_CLEAN_UP)
 180                 close(fd);
 181         return EXIT_SUCCESS;
 182 }