/* 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. 
 */
 #ifndef _SOS_PROCESS_H_
 #define _SOS_PROCESS_H_
 
 /**
  * @file process.h
  *
  * SOS Definition of a process and associated management API. A
  * process is basically the collection of all the resources requested
  * by a user program. The threads are one of these resources, the
  * mm_context is one other example of such resources.  In SOS, a
  * "process" is mainly a resource manager, a container. It does not
  * provide much advanced functionality apart from a reference counter.
  *
  * Only the user threads belong to a process. The kernel
  * threads don't because the resources they hold are held by the whole
  * kernel, thus by ALL the threads (kernel AND user): the notion of
  * "process" doesn't have any meaning for them because they don't own
  * any proper resource (apart from their stack).
  */
 
 #include <sos/errno.h>
 
 
 /**
  * The definition of an SOS process is opaque. @see process.c
  */
 struct sos_process;
 
 #include <sos/thread.h>
 
 
 /**
  * Default size of a user stack (8 MB)
  */
 #define SOS_DEFAULT_USER_STACK_SIZE (8 << 20)
 
 
 /**
  * Initialization of the process subsystem
  */
 sos_ret_t sos_process_subsystem_setup();
 
 
 /**
  * Initialize a new (empty) process and return a reference to it. This
  * means that:
  *  - A new mm_context has been initialized
  *  - No threads belong to this process yet
  *  - Nothing is mapped in user space
  *  - No other resource is used
  *
  * @return NULL on error (not enough memory)
  */
 struct sos_process *sos_process_create_empty(const char *name);
 
 
 /**
  * Signal we're using another reference to a process.
  */
 sos_ret_t sos_process_ref(struct sos_process *proc);
 
 
 /**
  * Release the reference to a process. If nobody holds a reference to
  * it and if the process does not have any thread anymore, the process
  * is destroyed.
  *
  * @return -SOS_EBUSY when the process is still referenced afterwards
  */
 sos_ret_t sos_process_unref(struct sos_process *proc);
 
 
 /**
  * Return the number of threads currently registered in the process
  */
 sos_count_t sos_process_get_nb_threads(const struct sos_process *proc);
 
 
 /**
  * Retrieve the address of the MMU configuration description
  *
  * @return NULL on error
  */
 struct sos_mm_context *
 sos_process_get_mm_context(const struct sos_process *proc);
 
 
 /* ***************************************************
  * Restricted functions
  */
 
 
 /**
  * Change the name of the process
  */
 sos_ret_t sos_process_set_name(struct sos_process * proc,
                                const char * new_name);
 
 
 /**
  * Attach the given thread to the process
  *
  * @note This function is called internally by thread.c . The thread
  * is assumed to be in the "CREATED" state, ie one cannot attach a
  * thread to some other process once it has been created.
  */
 sos_ret_t sos_process_register_thread(struct sos_process *in_proc,
                                       struct sos_thread *thr);
 
 
 /**
  * Remove the given thread from the given process threads' list. When
  * the process becomes empty (ie does not contain any thread anymore
  * and is not referenced by anybody), all its resources are released.
  *
  * @note This function is called internally by thread.c . The thread
  * is assumed to be in the "ZOMBIE" state.
  */
 sos_ret_t sos_process_unregister_thread(struct sos_thread *thr);
 
 #endif /* _SOS_PROCESS_H_ */