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 <stdio.h>
  19 #include <stdlib.h>
  20 #include <string.h>
  21 #include <time.h>
  22 #include <unistd.h>
  23 #include <sys/ioctl.h>
  24 #include <sys/stat.h>
  25 #include <linux/fs.h>
  26
  27 static const char zero[1024 * 1024];
  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 int main(int argc, char *argv[])
  70 {
  71         off_t offset = 0;
  72         const char *file;
  73
  74         setlocale(LC_NUMERIC, "en_US");
  75
  76         switch (argc) {
  77         case 3:
  78                 offset = atoll(argv[2]);
  79         case 2:
  80                 file = argv[1];
  81                 break;
  82         default:
  83                 puts("Usage: ddnuke <dev> [offset in bytes]");
  84                 return 1;
  85         }
  86
  87         int fd = open(file, O_WRONLY);
  88         if (fd == -1)
  89                 errp("open(%s) failed", file);
  90
  91         off_t max_size = get_size(fd);
  92
  93         if (lseek(fd, offset, SEEK_SET) != offset)
  94                 errp("lseek(%"PRIu64"u) failed", offset);
  95
  96         unsigned long long speed = 0;
  97         struct timespec stime, etime, itime;
  98         clock_gettime(CLOCK_MONOTONIC, &stime);
  99         itime = stime;
 100
 101         off_t pos = offset, last_pos = 0;
 102         ssize_t ret;
 103         int fsync_pos = 0;
 104         while (pos < max_size) {
 105                 ret = write(fd, zero, sizeof(zero));
 106                 pos += ret;
 107                 if (ret != sizeof(zero)) {
 108                         printf("\nread() returned %zi (wanted %zu)\n%'llu MB/s over entire run\n",
 109                                 ret, sizeof(zero), mbps(&itime, &etime, pos));
 110                         return 0;
 111                 }
 112
 113                 printf("%'llu bytes %u%% (%'llu MB/s)%20s\r", (unsigned long long)pos,
 114                         (unsigned)((pos * 100) / max_size), speed, "");
 115
 116                 if ((++fsync_pos % 16) == 0) {
 117                         speed = mbps(&stime, &etime, pos - last_pos);
 118                         last_pos = pos;
 119                         fflush(stdout);
 120                         fsync(fd);
 121                 }
 122         }
 123
 124         printf("\n");
 125         return 0;
 126 }