Dropbox ext4 hack

dropbox_ext4.c

/*
 * dropbox_ext4.c
 *
 * Compile like this:
 *   gcc -shared -fPIC -ldl -o libdropbox_ext4.so dropbox_ext4.c
 *
 * Run Dropbox like this:
 *   LD_PRELOAD=./libdropbox_ext4.so ~/.dropbox-dist/dropboxd
 */
 
#define _GNU_SOURCE
 
#include <stdlib.h>
#include <sys/vfs.h>
#include <linux/magic.h>
#include <dlfcn.h>
 
int (*orig_statfs)(const char *path, struct statfs64 *buf) = NULL;
 
int statfs64(const char *path, struct statfs64 *buf) {
  if (orig_statfs == NULL) {
    orig_statfs = dlsym(RTLD_NEXT, "statfs64");
  }
  int retval = orig_statfs(path, buf);
  if (retval == 0) {
    buf->f_type = EXT4_SUPER_MAGIC;
  }
  return retval;
}