ddnuke.c

   1 /*
   2  * released into the public domain
   3  * written by Mike Frysinger <vapier>
   4  */
   5
   6 #pragma GCC diagnostic warning "-Wall"
   7 #pragma GCC diagnostic warning "-Wextra"
   8
   9 #define _FILE_OFFSET_BITS 64
  10 #define _LARGEFILE_SOURCE
  11 #define _LARGEFILE64_SOURCE
  12 #define _GNU_SOURCE
  13
  14 #include <errno.h>
  15 #include <fcntl.h>
  16 #include <inttypes.h>
  17 #include <locale.h>
  18 #include <stdbool.h>
  19 #include <stdio.h>
  20 #include <stdlib.h>
  21 #include <string.h>
  22 #include <sysexits.h>
  23 #include <time.h>
  24 #include <unistd.h>
  25 #include <sys/ioctl.h>
  26 #include <sys/stat.h>
  27 #include <linux/fs.h>
  28
  29 #define errp(msg, args...) \
  30         do { \
  31                 printf("%s: " msg ": %m\n", program_invocation_short_name, ## args); \
  32                 exit(1); \
  33         } while (0)
  34
  35 static unsigned long long mbps(struct timespec *stime, struct timespec *etime, off_t len)
  36 {
  37         uint64_t dtime;
  38         clock_gettime(CLOCK_MONOTONIC, etime);
  39         dtime = ((etime->tv_sec - stime->tv_sec) * 1000 * 1000 * 1000) +
  40                 (etime->tv_nsec - stime->tv_nsec);
  41         *stime = *etime;
  42         return 1000 * len / dtime;
  43 }
  44
  45 static off_t get_blk_size(int fd)
  46 {
  47         uint64_t size;
  48         if (ioctl(fd, BLKGETSIZE64, &size))
  49                 errp("ioctl(BLKGETSIZE64) failed");
  50         return size;
  51 }
  52
  53 static off_t get_size(int fd)
  54 {
  55         struct stat st;
  56
  57         if (fstat(fd, &st))
  58                 errp("could not stat %i", fd);
  59
  60         if (S_ISREG(st.st_mode))
  61                 return st.st_size;
  62         else if (S_ISBLK(st.st_mode))
  63                 return get_blk_size(fd);
  64
  65         errno = EINVAL;
  66         errp("unknown type of file");
  67 }
  68
  69 static void nuke(int fd, off_t offset, off_t max_size, unsigned char pattern)
  70 {
  71         static char mem[1024 * 1024];
  72         memset(mem, pattern, sizeof(mem));
  73         if (pattern)
  74                 printf("Writing 0x%X to the output\n", pattern);
  75
  76         unsigned long long speed = 0;
  77         struct timespec stime, etime, itime;
  78         clock_gettime(CLOCK_MONOTONIC, &stime);
  79         itime = stime;
  80
  81         off_t pos = offset, last_pos = 0;
  82         ssize_t ret;
  83         int fsync_pos = 0;
  84         while (pos < max_size) {
  85                 /* This will round up to sizeof(mem) ... */
  86                 ret = write(fd, mem, sizeof(mem));
  87                 pos += ret;
  88                 if (ret != sizeof(mem)) {
  89                         printf("\nread() returned %zi (wanted %zu)\n%'llu MB/s over entire run\n",
  90                                 ret, sizeof(mem), mbps(&itime, &etime, pos));
  91                         return;
  92                 }
  93
  94                 printf("%'llu bytes %u%% (%'llu MB/s)%20s\r", (unsigned long long)pos,
  95                         (unsigned)((pos * 100) / max_size), speed, "");
  96
  97                 if ((++fsync_pos % 16) == 0) {
  98                         speed = mbps(&stime, &etime, pos - last_pos);
  99                         last_pos = pos;
 100                         fflush(stdout);
 101                         fsync(fd);
 102                 }
 103         }
 104
 105         printf("\n");
 106 }
 107
 108 static void usage(int status)
 109 {
 110         fprintf(
 111                 status ? stderr : stdout,
 112                 "Usage: ddnuke [options] <dev>\n"
 113                 "\n"
 114                 "Options:"
 115                 " -o <offset>   Position to start writing\n"
 116                 " -r            Write random garbage to the device\n"
 117         );
 118         exit(status);
 119 }
 120
 121 int main(int argc, char *argv[])
 122 {
 123         off_t offset = 0;
 124         const char *file;
 125         bool random = false;
 126         int o;
 127
 128         setlocale(LC_NUMERIC, "en_US");
 129
 130         while ((o = getopt(argc, argv, "ho:r")) != -1) {
 131                 switch (o) {
 132                 case 'o':
 133                         offset = atoll(optarg);
 134                         break;
 135                 case 'r':
 136                         random = true;
 137                         break;
 138                 case 'h': usage(EX_OK);
 139                 default:  usage(EX_USAGE);
 140                 }
 141         }
 142         if (argc != optind + 1)
 143                 usage(EX_USAGE);
 144         file = argv[optind];
 145
 146         int fd = open(file, O_WRONLY|O_CLOEXEC);
 147         if (fd == -1)
 148                 errp("open(%s) failed", file);
 149
 150         off_t max_size = get_size(fd);
 151
 152         if (lseek(fd, offset, SEEK_SET) != offset)
 153                 errp("lseek(%"PRIu64"u) failed", offset);
 154
 155         nuke(fd, offset, max_size, 0x00);
 156         if (random) {
 157                 nuke(fd, offset, max_size, 0xaa);
 158                 nuke(fd, offset, max_size, 0x55);
 159         }
 160
 161         return EX_OK;
 162 }