#include "assert.h"
#include "mmuContext.h"
#include "paging.h"
#include "thread.h"
#include "uaccess.h"

static int bindtoUserContext()
{
    struct thread *currentThread;
    struct mmu_context *ctx;

    currentThread = getCurrentThread();
    assert(NULL != currentThread->process);

    /* Switch to the user's address space */
    ctx = processGetMMUContext(currentThread->process);
    return threadChangeCurrentContext(ctx);
}

static int unbindUserContext()
{
    return threadChangeCurrentContext(NULL);
}

static int memcpyUserMemNoCheck(vaddr_t dest, vaddr_t src, size_t size)
{

    int ret;

    ret = bindtoUserContext();
    if (ret != 0)
        return ret;

    memcpy((void *)dest, (void *)src, size);

    ret = unbindUserContext();
    if (ret != 0)
        return ret;

    return size;
}

int memcpyFromUser(vaddr_t to, uaddr_t from, size_t size)
{

    if ((uint)from < PAGING_BASE_USER_ADDRESS)
        return -EPERM;
    if ((uint)from > PAGING_TOP_USER_ADDRESS - size)
        return -EPERM;

    return memcpyUserMemNoCheck(to, from, size);
}