Wrap ioctls

fakeioctl.c

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <termios.h>
/*#include <sys/ioctl.h>*/
#include <assert.h>
#include <dlfcn.h>
#include <unistd.h>

/* Avoid load the sys/ioctl.h header since it will conflict with our ioctl() definition */
#define TIOCMGET 0x5415


typedef int (*type_ioctl)(int __fd, unsigned long int __request, int *x);

int ioctl (int __fd, unsigned long int __request, int *x) {

  static type_ioctl original_ioctl = NULL;

  if(original_ioctl == NULL) {
    void* libc = dlopen("libc.so.6", RTLD_LAZY);
    original_ioctl = (type_ioctl)dlsym(libc, "ioctl");
    dlclose(libc);
  }

  if(__request == TIOCMGET) {
    *x = 448;
    return 0;
  }

  return original_ioctl(__fd, __request, x);

}

Makefile

all: fakeioctl.so

CFLAGS=-D_GNU_SOURCE -g -Wall

fakeioctl.so: fakeioctl.c
        gcc $(CFLAGS) -fPIC -shared -ldl -o fakeioctl.so fakeioctl.c

.PHONY: all clean