#include <stdio.h>

#define BUFSIZE 4096
#define FILEMAX 128

int main(int argc, char* argv[])
{
  char buf1[BUFSIZE];
  char buf2[BUFSIZE];
  FILE* f[FILEMAX];
  int s1, i, j, nbfiles;

  nbfiles = argc - 1;
  if (nbfiles <= 0)
    {
      fprintf(stderr, "usage:  and  maskfiles... > outputfile\n");
      exit(2);
    }
  if (nbfiles > FILEMAX)
    {
      fprintf(stderr, "too many files on the command line\n");
      exit(1);
    }
  for (j=0; j<nbfiles; j++)
    {
      f[j] = fopen(argv[j+1], "rb");
      if (!f[j])
        {
          perror("and");
          exit(1);
        }
    }

  while ((s1=fread(buf1, 1, BUFSIZE, f[0])) > 0)
    {
      for (j=1; j<nbfiles; j++)
        {
          s1 = fread(buf2, 1, s1, f[j]);
          for (i=0; i<s1; i++)
            buf1[i] &= buf2[i];
        }
      fwrite(buf1, 1, s1, stdout);
    }
}