Quick dirty tool to reverse a file - for a CTF

reverse.c

#include <stdio.h>
#include <stdlib.h>

int main(int argc, char** argv)
{
  char* buf = malloc(0x10000000);
  int size = 0;
  int v;

  while((v = getchar()) != EOF) {
    char c = v;
    char rc = 0;
    rc |= (c & 1) << 7;
    rc |= (c & 2) << 5;
    rc |= (c & 4) << 3;
    rc |= (c & 8) << 1;
    rc |= (c & 16) >> 1;
    rc |= (c & 32) >> 3;
    rc |= (c & 64) >> 5;
    rc |= (c & 128) >> 7;
    buf[size++] = rc;
  }

  for(int i = 0; i < size; ++i)
    putchar(buf[size-1-i]);

  free(buf);
  return 0;
}