/* Copyright (C) 2005  David Decotigny
 
    This program is free software; you can redistribute it and/or
    modify it under the terms of the GNU General Public License
    as published by the Free Software Foundation; either version 2
    of the License, or (at your option) any later version.
    
    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.
    
    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
    USA. 
 */
 
 #include <hwcore/paging.h>
 #include <sos/thread.h>
 #include <sos/assert.h>
 #include <sos/kmalloc.h>
 
 #include "uaccess.h"
 
 
 /**
  * Helper function to force the MMU to switch to the address space of
  * the process
  */
 static sos_ret_t bindto_user_mm_context()
 {
   struct sos_thread * current_thread;
   struct sos_mm_context * process_mm_ctxt;
 
   current_thread = sos_thread_get_current();
   SOS_ASSERT_FATAL(NULL != current_thread->process);
 
   /* Switch to the user's address space */
   process_mm_ctxt
     = sos_process_get_mm_context(current_thread->process);
   return sos_thread_change_current_mm_context(process_mm_ctxt);
 }
 
 
 /**
  * Helper macro to restore the MMU configuration prior to
  * bindto_user_mm_context()
  */
 #define unbindto_user_mm_context() \
    sos_thread_change_current_mm_context(NULL)
 
 
 static sos_ret_t nocheck_user_memcpy(sos_vaddr_t dest,
                                      sos_vaddr_t src,
                                      sos_size_t size,
                                      sos_bool_t transfer_from_user)
 {
   sos_ret_t retval;
 
   retval = bindto_user_mm_context();
   if (SOS_OK != retval)
     return retval;
 
   memcpy((void*) dest, (void*) src, size);
 
   retval = unbindto_user_mm_context();
   if (SOS_OK != retval)
     return retval;
 
   return size;
 }
 
 
 sos_ret_t sos_memcpy_from_user(sos_vaddr_t kernel_to,
                                sos_uaddr_t user_from,
                                sos_size_t size)
 {
   /* Make sure user is trying to access user space */
   if (user_from < SOS_PAGING_BASE_USER_ADDRESS)
     return -SOS_EPERM;
 
   if (user_from > SOS_PAGING_TOP_USER_ADDRESS - size)
     return -SOS_EPERM;
 
   return nocheck_user_memcpy(kernel_to, user_from, size, TRUE);
 }
 
 
 sos_ret_t sos_memcpy_to_user(sos_uaddr_t user_to,
                              sos_vaddr_t kernel_from,
                              sos_size_t size)
 {
   /* Make sure user is trying to access user space */
   if (user_to < SOS_PAGING_BASE_USER_ADDRESS)
     return -SOS_EPERM;
 
   if (user_to > SOS_PAGING_TOP_USER_ADDRESS - size)
     return -SOS_EPERM;
 
   return nocheck_user_memcpy(user_to, kernel_from, size, FALSE);
 }
 
 
 sos_ret_t sos_strnlen_from_user(sos_uaddr_t user_str, sos_size_t max_len)
 {
   sos_ret_t retval, len;
 
   /* Make sure user is trying to access user space */
   if (user_str < SOS_PAGING_BASE_USER_ADDRESS)
     return -SOS_EPERM;
 
   /* Don't allow invalid max_len */
   if ( (max_len < 1) || (max_len > SOS_PAGING_USER_SPACE_SIZE) )
     return -SOS_EINVAL;
 
   retval = bindto_user_mm_context();
   if (SOS_OK != retval)
     return retval;
 
   len = strnlen((const char*)user_str, max_len);
 
   retval = unbindto_user_mm_context();
   if (SOS_OK != retval)
     return retval;
 
   return len;
 }
 
 
 static sos_ret_t nocheck_user_strzcpy(char *dst, const char *src,
                                       sos_size_t len)
 {
   sos_ret_t retval;
 
   retval = bindto_user_mm_context();
   if (SOS_OK != retval)
     return retval;
 
   strzcpy(dst, src, len);
 
   retval = unbindto_user_mm_context();
   if (SOS_OK != retval)
     return retval;
 
   return SOS_OK;
 }
 
 
 sos_ret_t sos_strzcpy_from_user(char *kernel_to, sos_uaddr_t user_from,
                                 sos_size_t max_len)
 {
   /* Make sure user is trying to access user space */
   if ((sos_uaddr_t)user_from < SOS_PAGING_BASE_USER_ADDRESS)
     return -SOS_EPERM;
 
   /* Don't allow invalid max_len */
   if ( (max_len < 1) || (max_len > SOS_PAGING_USER_SPACE_SIZE) )
     return -SOS_EINVAL;
 
   return nocheck_user_strzcpy(kernel_to, (const char*)user_from, max_len);
 }
 
 
 sos_ret_t sos_strzcpy_to_user(sos_uaddr_t user_to, const char *kernel_from,
                               sos_size_t max_len)
 {
   /* Make sure user is trying to access user space */
   if ((sos_uaddr_t)user_to < SOS_PAGING_BASE_USER_ADDRESS)
     return -SOS_EPERM;
 
   /* Don't allow invalid max_len */
   if ( (max_len < 1) || (max_len > SOS_PAGING_USER_SPACE_SIZE) )
     return -SOS_EINVAL;
 
   return nocheck_user_strzcpy((char*)user_to, kernel_from, max_len);
 }
 
 
 sos_ret_t sos_strndup_from_user(char ** kernel_to, sos_uaddr_t from_user,
                                 sos_size_t max_len,
                                 sos_ui32_t kmalloc_flags)
 {
   sos_ret_t retval = sos_strnlen_from_user(from_user, max_len);
   if (retval < 0)
     return retval;
 
   *kernel_to = (char*)sos_kmalloc(retval + 1, kmalloc_flags);
   if (NULL == *kernel_to)
     return -SOS_ENOMEM;
 
   retval = sos_strzcpy_from_user(*kernel_to, from_user, retval + 1);
   if (SOS_OK != retval)
     {
       sos_kfree((sos_vaddr_t)*kernel_to);
       *kernel_to = NULL;
     }
 
   return retval;
 }