#include <xen/lib.h>

#include <xen/guest_access.h>

#include <xen/err.h>

/*

 * The function copies a string from the guest and adds a NUL to

 * make sure the string is correctly terminated.

 */

char *safe_copy_string_from_guest(XEN_GUEST_HANDLE(char) u_buf,

                                  size_t size, size_t max_size)

{

    char *tmp;

    if ( size > max_size )

        return ERR_PTR(-ENOBUFS);

    /* Add an extra +1 to append \0 */

    tmp = xmalloc_array(char, size + 1);

    if ( !tmp )

        return ERR_PTR(-ENOMEM);

    if ( copy_from_guest(tmp, u_buf, size) )

    {

        xfree(tmp);

        return ERR_PTR(-EFAULT);

    }

    tmp[size] = '\0';

    return tmp;

}