197191/test.c

   1 #include <stdio.h>
   2 #include <string.h>
   3 #include <fcntl.h>
   4 #include <unistd.h>
   5 #include <stdlib.h>
   6 #include <sys/mman.h>
   7 #include <sys/stat.h>
   8 #include <assert.h>
   9
  10 int main(int argc, char *argv[])
  11 {
  12         char *file;
  13         struct stat buf;
  14         int max, fd;
  15
  16         max = (argc < 2 ? sysconf(_SC_PAGE_SIZE) : atoi(argv[1]));
  17         printf("size of file = %i\n", max);
  18
  19         fd = open("ppImage.config", O_WRONLY | O_TRUNC, 644);
  20         assert(lseek(fd, max-1, SEEK_SET) != -1);
  21         write(fd, argv[0], 1);
  22         close(fd);
  23
  24         fd = open("ppImage.config", O_RDONLY);
  25         assert(fstat(fd, &buf) == 0);
  26         max = buf.st_size + 1;
  27         file = mmap(0, max, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
  28         printf("%i\n", file[0]);
  29         printf("%i\n", file[max - 1]);
  30         munmap(file, max);
  31         close(fd);
  32
  33         return 0;
  34 }