unixordos.c

   1 #include <stdio.h>
   2
   3 int is_dos_file(FILE *f) {
   4         int c, was_cr = 0;
   5         while((c = fgetc(f)) != EOF) {
   6                 if(c == 0xd) was_cr = 1;
   7                 else if(c == 0xa && was_cr) {
   8                         return 1;
   9                 } else was_cr = 0;
  10         }
  11         return 0;
  12 }
  13
  14 int main(int argc, char**argv) {
  15         if(argc < 2) {
  16                 dprintf(2, "need filename\n");
  17                 return 1;
  18         }
  19         FILE *f = fopen(argv[1], "r");
  20         if(!f) {
  21                 perror("fopen");
  22                 return 2;
  23         }
  24         if(is_dos_file(f))
  25                 dprintf(1, "DOS\n");
  26         else
  27                 dprintf(1, "UNIX\n");
  28         fclose(f);
  29         return 0;
  30 }