/*
 * Copyright (c) 2013
 *	The President and Fellows of Harvard College.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE UNIVERSITY OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#ifndef _PROC_H_
#define _PROC_H_

/*
 * Definition of a process.
 *
 * Note: curproc is defined by <current.h>.
 */

#include <spinlock.h>
#include <thread.h> /* required for struct threadarray */
#include <limits.h> // using to restrict array size of procs
#include <synch.h>
#include <list.h>

struct addrspace;
struct vnode;
#ifdef UW
struct semaphore;
#endif // UW

/*
 * Process structure.
 */
struct proc
{
	char * p_name;			/* Name of this process */
	int pid; // pretty self-explanatory
	struct proc * parent; // again, pretty damn obvious
	struct list * kids; // list of kid processes (by pid)
	int exitcode; // exitcode if exited, -1 if running
	struct cv * waiting; // parents can wait on this CV
	struct lock * waitlock; // waitlock for the CV
	struct spinlock p_lock;		/* Lock for this structure */
	struct threadarray p_threads;	/* Threads in this process */

	/* VM */
	struct addrspace * p_addrspace;	/* virtual address space */

	/* VFS */
	struct vnode * p_cwd;		/* current working directory */

#ifdef UW
  /* a vnode to refer to the console device */
  /* this is a quick-and-dirty way to get console writes working */
  /* you will probably need to change this when implementing file-related
     system calls, since each process will need to keep track of all files
     it has opened, not just the console. */
  struct vnode * console;                /* a vnode for the console device */
#endif

	/* add more material here as needed */
};

// struct that contains all the processes in the system
struct procs
{
  struct proc  * pids[PID_MAX + 1]; // total # of valid PIDs
  int lastpid; // last pid issued
};

/* This is the process structure for the kernel and for kernel-only threads. */
extern struct proc * kproc;

// The process array
extern struct procs * processes;

// The lock for the above array
extern struct lock * proclock;

/* Semaphore used to signal when there are no more processes */
#ifdef UW
extern struct semaphore * no_proc_sem;
#endif // UW

/* Call once during system startup to allocate data structures. */
void proc_bootstrap(void);

/* Create a fresh process for use by runprogram(). */
struct proc *proc_create_runprogram(const char * name);// get and return a pid for the process

/* Destroy a process. */
void proc_destroy(struct proc * proc);

/* Attach a thread to a process. Must not already have a process. */
int proc_addthread(struct proc * proc, struct thread * t);

/* Detach a thread from its process. */
void proc_remthread(struct thread * t);

/* Fetch the address space of the current process. */
struct addrspace *curproc_getas(void);

/* Change the address space of the current process, and return the old one. */
struct addrspace *curproc_setas(struct addrspace *);

// get and return a pid for the process
int assignpid(struct proc * proc);

// returns the child process if it is a child, otherwise null
struct proc * getChild(struct proc * p, int pid);

// adds child pid to parent's list
void add_child(struct proc * parent, int pid);

#endif /* _PROC_H_ */