linux-tests/writebigsparse.c

   1 #define _LARGEFILE64_SOURCE
   2 #include<stdio.h>
   3 #include <sys/types.h>
   4 #include <sys/stat.h>
   5 #include <fcntl.h>
   6 #include <unistd.h>
   7 #include <stdlib.h>
   8
   9
  10 #define N_WRITES 16
  11 #define STRIDE   250000
  12
  13 #define BUFFER_N 1100
  14 unsigned  xxbuffer[BUFFER_N];
  15
  16
  17 void set_buffer(int n)
  18 {
  19         int i;
  20         for(i = 0; i < BUFFER_N; i++)
  21                 xxbuffer[i] = i + n;
  22 }
  23
  24 void write_big_sparse_file(int h)
  25 {
  26         int i;
  27         loff_t offset = 0;
  28         loff_t pos;
  29         int n = sizeof(xxbuffer);
  30         int wrote;
  31
  32         for(i = 0; i < N_WRITES; i++) {
  33                 printf("writing at %lld\n", offset);
  34                 set_buffer(i);
  35                 pos = lseek64(h, offset, SEEK_SET);
  36                 if(pos != offset) {
  37                         printf("mismatched seek pos %lld offset %lld\n",
  38                                 pos, offset);
  39                         perror("lseek64");
  40                         exit(1);
  41                 }
  42                 wrote = write(h, xxbuffer, n);
  43
  44                 if(wrote != n) {
  45                         printf("mismatched write wrote %d n %d\n", wrote, n);
  46                         exit(1);
  47                 }
  48
  49                 offset += (STRIDE * sizeof(xxbuffer));
  50         }
  51
  52         ftruncate(h, offset);
  53
  54 }
  55
  56
  57 int main(int argc, char *argv[])
  58 {
  59         int handle;
  60
  61         if(argc < 2) {
  62                 printf("Gimme a file name!\n");
  63                 exit(1);
  64         }
  65
  66         handle = open(argv[1], O_CREAT | O_RDWR | O_TRUNC, S_IREAD | S_IWRITE);
  67
  68         if(handle < 0) {
  69                 perror("opening file");
  70                 exit(1);
  71         }
  72
  73         write_big_sparse_file(handle);
  74
  75         printf("Job done\n");
  76         return 0;
  77 }