//-------------------------------------------------------
//
// mbox_t MboxCreate();
//
// Allocate an available mailbox structure for use.
//
// Returns the mailbox handle on success
// Returns MBOX_FAIL on error.
//
//-------------------------------------------------------
mbox_t MboxCreate() {
mbox_t imbox;
uint32 intrval;
// grabbing a Mbox should be an atomic operation
intrval = DisableIntrs();
for(imbox = 0; imbox < MBOX_NUM_MBOXES; imbox++) {
if(mboxes[imbox].inuse == false) {
mboxes[imbox].inuse = true;
break;
}
}
RestoreIntrs(intrval);
if(imbox == MAX_SEMS) return MBOX_FAIL;
if ((mboxes[imbox].s_mbox_emptyslots = SemCreate(MBOX_MAX_BUFFERS_PER_MBOX - 1)) == SYNC_FAIL) {
printf("Bad sem_create in MboxOpen");
exitsim();
}
if ((mboxes[imbox].s_mbox_fillslots = SemCreate(0)) == SYNC_FAIL) {
printf("Bad sem_create in MboxOpen");
exitsim();
}
if((mboxes[imbox].l_mbox = LockCreate()) == SYNC_FAIL) {
printf("Bad lock_create in MboxModInit");
exitsim();
}
return imbox;
}
//---------------------------------------------------------------------------
// CondHandleWait
//
// This function makes the calling process block on the condition variable
// till either ConditionHandleSignal or ConditionHandleBroadcast is
// received. The process calling CondHandleWait must have acquired the
// lock associated with the condition variable (the lock that was passed
// to CondCreate. This implies the lock handle needs to be stored
// somewhere. hint! hint!) for this function to
// succeed. If the calling process has not acquired the lock, it does not
// block on the condition variable, but a value of 1 is returned
// indicating that the call was not successful. Return value of 0 implies
// that the call was successful.
//
// This function should be written in such a way that the calling process
// should release the lock associated with this condition variable before
// going to sleep, so that the process that intends to signal this
// process could acquire the lock for that purpose. After waking up, the
// blocked process should acquire (i.e. wait on) the lock associated with
// the condition variable. In other words, this process does not
// "actually" wake up until the process calling CondHandleSignal or
// CondHandleBroadcast releases the lock explicitly.
//---------------------------------------------------------------------------
int CondWait(Cond *c) {
Link *l;
int intrval;
if (!c) return SYNC_FAIL;
// Conds are atomic
intrval = DisableIntrs ();
dbprintf ('I', "CondWait: Old interrupt value was 0x%x.\n", intrval);
// Check to see if the current process owns the lock
if (c->lock->pid != GetCurrentPid()) {
dbprintf('s', "CondWait: Proc %d does not own cond %d\n", GetCurrentPid(), (int)(c-conds));
RestoreIntrs(intrval);
return SYNC_FAIL;
}
dbprintf ('s', "CondWait: Proc %d waiting on cond %d. Putting to sleep.\n", GetCurrentPid(), (int)(c-conds));
if ((l = AQueueAllocLink ((void *)currentPCB)) == NULL) {
printf("FATAL ERROR: could not allocate link for cond queue in CondWait!\n");
exitsim();
}
if (AQueueInsertLast (&c->waiting, l) != QUEUE_SUCCESS) {
printf("FATAL ERROR: could not insert new link into cond waiting queue in CondWait!\n");
exitsim();
}
// Release the lock before going to sleep
LockRelease(c->lock);
RestoreIntrs(intrval); // Don't want interrupts disabled while we sleep
ProcessSleep();
// Immediately acquire the lock upon waking
LockAcquire(c->lock);
return SYNC_SUCCESS;
}
//----------------------------------------------------------------------
//
// SemWait
//
// Wait on a semaphore. As described in Section 6.4 of _OSC_,
// we decrement the counter and suspend the process if the
// semaphore's value is less than 0. To ensure atomicity,
// interrupts are disabled for the entire operation, but must be
// turned on before going to sleep.
//
//----------------------------------------------------------------------
int SemWait (Sem *sem) {
Link *l;
int intrval;
if (!sem) return SYNC_FAIL;
intrval = DisableIntrs ();
dbprintf ('I', "SemWait: Old interrupt value was 0x%x.\n", intrval);
dbprintf ('s', "SemWait: Proc %d waiting on sem %d, count=%d.\n", GetCurrentPid(), (int)(sem-sems), sem->count);
if (sem->count <= 0) {
dbprintf('s', "SemWait: putting process %d to sleep\n", GetCurrentPid());
if ((l = AQueueAllocLink ((void *)currentPCB)) == NULL) {
printf("FATAL ERROR: could not allocate link for semaphore queue in SemWait!\n");
exitsim();
}
if (AQueueInsertLast (&sem->waiting, l) != QUEUE_SUCCESS) {
printf("FATAL ERROR: could not insert new link into semaphore waiting queue in SemWait!\n");
exitsim();
}
ProcessSleep();
// Don't decrement couter here because that's handled in SemSignal for us
} else {
sem->count--; // Decrement internal counter
dbprintf('s', "SemWait: Proc %d granted permission to continue by sem %d\n", GetCurrentPid(), (int)(sem-sems));
}
RestoreIntrs (intrval);
return SYNC_SUCCESS;
}
//----------------------------------------------------------------------
//
// ProcessFreeResources
//
// Free the resources associated with a process. This assumes the
// process isn't currently on any queue.
//
//----------------------------------------------------------------------
void ProcessFreeResources (PCB *pcb) {
int i = 0;
int usrsp = MEM_ADDRESS_TO_PAGE(pcb->currentSavedFrame[PROCESS_STACK_USER_STACKPOINTER]);
// Allocate a new link for this pcb on the freepcbs queue
if ((pcb->l = AQueueAllocLink(pcb)) == NULL) {
printf("FATAL ERROR: could not get Queue Link in ProcessFreeResources!\n");
exitsim();
}
// Set the pcb's status to available
pcb->flags = PROCESS_STATUS_FREE;
// Insert the link into the freepcbs queue
if (AQueueInsertLast(&freepcbs, pcb->l) != QUEUE_SUCCESS) {
printf("FATAL ERROR: could not insert PCB link into freepcbs queue in ProcessFreeResources!\n");
exitsim();
}
//------------------------------------------------------------
// STUDENT: Free any memory resources on process death here.
//------------------------------------------------------------
for(i = 0; i < 5; i++) {
MemoryFreePte(pcb->pagetable[i]);
}
for(i = usrsp; i <= MEM_ADDRESS_TO_PAGE(MEM_MAX_VIRTUAL_ADDRESS); i++) {
MemoryFreePte(pcb->pagetable[i]);
}
MemoryFreePage (pcb->sysStackArea / MEM_PAGESIZE);
ProcessSetStatus (pcb, PROCESS_STATUS_FREE);
dbprintf ('p', "ProcessFreeResources: function complete\n");
}
//----------------------------------------------------------------------
//
// ProcessSchedule
//
// Schedule the next process to run. If there are no processes to
// run, exit. This means that there should be an idle loop process
// if you want to allow the system to "run" when there's no real
// work to be done.
//
// NOTE: the scheduler should only be called from a trap or interrupt
// handler. This way, interrupts are disabled. Also, it must be
// called consistently, and because it might be called from an interrupt
// handler (the timer interrupt), it must ALWAYS be called from a trap
// or interrupt handler.
//
// Note that this procedure doesn't actually START the next process.
// It only changes the currentPCB and other variables so the next
// return from interrupt will restore a different context from that
// which was saved.
//
//----------------------------------------------------------------------
void ProcessSchedule () {
PCB *pcb=NULL;
int i=0;
Link *l=NULL;
uint32 intrvals = 0;
intrvals = DisableIntrs();
// The OS exits if there's no runnable process. This is a feature, not a
// bug. An easy solution to allowing no runnable "user" processes is to
// have an "idle" process that's simply an infinite loop.
if (AQueueEmpty(&runQueue)) {
if (!AQueueEmpty(&waitQueue)) {
printf("FATAL ERROR: no runnable processes, but there are sleeping processes waiting!\n");
l = AQueueFirst(&waitQueue);
while (l != NULL) {
pcb = AQueueObject(l);
printf("Sleeping process %d: ", i++); printf("PID = %d\n", (int)(pcb - pcbs));
l = AQueueNext(l);
}
exitsim();
}
printf ("No runnable processes - exiting!\n");
exitsim (); // NEVER RETURNS
}
// Move the front of the queue to the end if currentPCB is not on sleep queue.
// The running process was the one in front.
if (currentPCB->flags & PROCESS_STATUS_RUNNABLE) {
AQueueMoveAfter(&runQueue, AQueueLast(&runQueue), AQueueFirst(&runQueue));
}
// Now, run the one at the head of the queue.
pcb = (PCB *)AQueueObject(AQueueFirst(&runQueue));
currentPCB = pcb;
dbprintf ('p',"About to switch to PCB 0x%x,flags=0x%x @ 0x%x\n",
(int)pcb, pcb->flags, (int)(pcb->sysStackPtr[PROCESS_STACK_IAR]));
// Clean up zombie processes here. This is done at interrupt time
// because it can't be done while the process might still be running
while (!AQueueEmpty(&zombieQueue)) {
pcb = (PCB *)AQueueObject(AQueueFirst(&zombieQueue));
dbprintf ('p', "Freeing zombie PCB 0x%x.\n", (int)pcb);
if (AQueueRemove(&(pcb->l)) != QUEUE_SUCCESS) {
printf("FATAL ERROR: could not remove zombie process from zombieQueue in ProcessSchedule!\n");
exitsim();
}
ProcessFreeResources(pcb);
}
RestoreIntrs(intrvals);
}
//---------------------------------------------------------------------------
// CondHandleSignal
//
// This call wakes up exactly one process waiting on the condition
// variable, if at least one is waiting. If there are no processes
// waiting on the condition variable, it does nothing. In either case,
// the calling process must have acquired the lock associated with
// condition variable for this call to succeed, in which case it returns
// 0. If the calling process does not own the lock, it returns 1,
// indicating that the call was not successful. This function should be
// written in such a way that the calling process should retain the
// acquired lock even after the call completion (in other words, it
// should not release the lock it has already acquired before the call).
//
// Note that the process woken up by this call tries to acquire the lock
// associated with the condition variable as soon as it wakes up. Thus,
// for such a process to run, the process invoking CondHandleSignal
// must explicitly release the lock after the call is complete.
//---------------------------------------------------------------------------
int CondSignal(Cond *c) {
Link *l;
int intrs;
PCB *pcb;
if (!c) return SYNC_FAIL;
intrs = DisableIntrs ();
dbprintf ('s', "CondSignal: Proc %d signalling cond %d.\n", GetCurrentPid(), (int)(c-conds));
if (c->lock->pid != GetCurrentPid()) {
dbprintf('s', "CondSignal: Proc %d does not own cond %d.\n", GetCurrentPid(), (int)(c-conds));
return SYNC_FAIL;
}
if (!AQueueEmpty(&c->waiting)) { // there is a process to wake up
l = AQueueFirst(&c->waiting);
pcb = (PCB *)AQueueObject(l);
if (AQueueRemove(&l) != QUEUE_SUCCESS) {
printf("FATAL ERROR: could not remove link from cond queue in CondSignal!\n");
exitsim();
}
dbprintf ('s', "CondSignal: Waking up PID %d, it still needs to acquire lock.\n", GetPidFromAddress(pcb));
ProcessWakeup (pcb);
} else {
dbprintf('s', "CondSignal: Proc %d signalled, but no processes were waiting.\n", GetCurrentPid());
}
RestoreIntrs (intrs);
return SYNC_SUCCESS;
}
//---------------------------------------------------------------------------
// LockHandleRelease
//
// This procedure releases the unique lock described by the handle. It
// first checks whether the lock is a valid lock. If not, it returns SYNC_FAIL.
// If the lock is a valid lock, it should check whether the calling
// process actually holds the lock. If not it returns SYNC_FAIL. Otherwise it
// releases the lock, and returns SYNC_SUCCESS.
//---------------------------------------------------------------------------
int LockRelease(Lock *k) {
Link *l;
int intrs;
PCB *pcb;
if (!k) return SYNC_FAIL;
intrs = DisableIntrs ();
dbprintf ('s', "LockRelease: Proc %d releasing lock %d.\n", GetCurrentPid(), (int)(k-locks));
if (k->pid != GetCurrentPid()) {
dbprintf('s', "LockRelease: Proc %d does not own lock %d.\n", GetCurrentPid(), (int)(k-locks));
return SYNC_FAIL;
}
k->pid = -1;
if (!AQueueEmpty(&k->waiting)) { // there is a process to wake up
l = AQueueFirst(&k->waiting);
pcb = (PCB *)AQueueObject(l);
if (AQueueRemove(&l) != QUEUE_SUCCESS) {
printf("FATAL ERROR: could not remove link from lock queue in LockRelease!\n");
exitsim();
}
dbprintf ('s', "LockRelease: Waking up PID %d, assigning lock.\n", (int)(GetPidFromAddress(pcb)));
k->pid = GetPidFromAddress(pcb);
ProcessWakeup (pcb);
}
RestoreIntrs (intrs);
return SYNC_SUCCESS;
}
//----------------------------------------------------------------------
//
// SemSignal
//
// Signal on a semaphore. Again, details are in Section 6.4 of
// _OSC_.
//
//----------------------------------------------------------------------
int SemSignal (Sem *sem) {
Link *l;
int intrs;
PCB *pcb;
if (!sem) return SYNC_FAIL;
intrs = DisableIntrs ();
dbprintf ('s', "SemSignal: Process %d Signalling on sem %d, count=%d.\n", GetCurrentPid(), (int)(sem-sems), sem->count);
// Increment internal counter before checking value
sem->count++;
if (sem->count > 0) { // check if there is a process to wake up
if (!AQueueEmpty(&sem->waiting)) { // there is a process to wake up
l = AQueueFirst(&sem->waiting);
pcb = (PCB *)AQueueObject(l);
if (AQueueRemove(&l) != QUEUE_SUCCESS) {
printf("FATAL ERROR: could not remove link from semaphore queue in SemSignal!\n");
exitsim();
}
dbprintf ('s', "SemSignal: Waking up PID %d.\n", (int)(GetPidFromAddress(pcb)));
ProcessWakeup (pcb);
// Decrement counter on behalf of woken up PCB
sem->count--;
}
}
RestoreIntrs (intrs);
return SYNC_SUCCESS;
}
void MboxModuleInit() {
int i;
int j;
for(i = 0; i < MBOX_NUM_MBOXES; i++) {
for(j = 0; j < PROCESS_MAX_PROCS; j++) {
mboxes[i].opened_pids[j] = false;
}
for(j = 0; j < MBOX_MAX_BUFFERS_PER_MBOX; j++) {
mboxes[i].cbobi[j] = -1; // invalid
}
mboxes[i].opened_pids_count = 0;
mboxes[i].head_cbobi = 0;
mboxes[i].tail_cbobi = 0;
mboxes[i].inuse = false;
mboxes[i].mbox_id = i;
}
for(i = 0; i < MBOX_NUM_BUFFERS; i++) {
mbox_buffers[i].inuse = false;
}
// if ((s_buff_emptyslots = SemCreate(MBOX_NUM_BUFFERS - 1)) == SYNC_FAIL) {
// printf("Bad sem_create in MboxModInit");
// exitsim();
// }
if((l_buff = LockCreate()) == SYNC_FAIL) {
printf("Bad lock_create in MboxModInit");
exitsim();
}
}
//-------------------------------------------------------
//
// void MboxOpen(mbox_t);
//
// Open the mailbox for use by the current process. Note
// that it is assumed that the internal lock/mutex handle
// of the mailbox and the inuse flag will not be changed
// during execution. This allows us to get the a valid
// lock handle without a need for synchronization.
//
// Returns MBOX_FAIL on failure.
// Returns MBOX_SUCCESS on success.
//
//-------------------------------------------------------
int MboxOpen(mbox_t handle) {
unsigned int curr_pid = GetCurrentPid();
// Check if handle is a valid number
if(handle < 0 || handle >= MBOX_NUM_MBOXES){
return MBOX_FAIL;
}
// Check if the mbox is reserved (activated)
if(system_mbox[handle].num_of_pid_inuse < 0){
return MBOX_FAIL;
}
// Acquire the lock
if(LockHandleAcquire(system_mbox[handle].mbox_buffer_lock) != SYNC_SUCCESS){
printf("FATAL ERROR: Acquire lock for the mbox %d!\n", handle);
exitsim();
}
// Update the number of pid used
if(system_mbox[handle].mbox_pid_list[curr_pid] == 1){
printf("The mbox %d has already been opened\n", handle);
}
else if(system_mbox[handle].mbox_pid_list[curr_pid] == 0){
system_mbox[handle].num_of_pid_inuse += 1;
system_mbox[handle].mbox_pid_list[curr_pid] = 1;
}
else{
printf("FATAL ERROR: Unkown Pid %d for mbox %d!\n", curr_pid, handle);
// Release the lock
if(LockHandleRelease(system_mbox[handle].mbox_buffer_lock) != SYNC_SUCCESS){
printf("FATAL ERROR: Release lock for the mbox %d!\n", handle);
exitsim();
}
return MBOX_FAIL;
}
// Release the lock
if(LockHandleRelease(system_mbox[handle].mbox_buffer_lock) != SYNC_SUCCESS){
printf("FATAL ERROR: Release lock for the mbox %d!\n", handle);
exitsim();
}
return MBOX_SUCCESS;
}
static void TrapProcessCreateHandler(uint32 *trapArgs, int sysmode)
{
char allargs[SIZE_ARG_BUFF];
char name[100];
int i=0, j=0, k=0;
uint32 args[MAX_ARGS];
char *destination;
// The first argument is the name of the executable file
i=0;
for(i=0;i<100; i++)
allargs[i] = 0;
i=0;
if(!sysmode)
{
//Get the arguments into the sytem space
MemoryCopyUserToSystem (currentPCB, trapArgs, args, sizeof (args));
do {
MemoryCopyUserToSystem (currentPCB,((char*)args[0])+i,name+i,1);
i++;
} while ((i < sizeof (name)) && (name[i-1] != '\0'));
} else {
bcopy (trapArgs, args, sizeof (args));
dstrncpy ((char *)args[0], name, sizeof (name));
}
name[sizeof(name)-1] = '\0'; // null terminate the name
i=0;
if(!sysmode)
{
//Copy the rest of the arguments to the system space
for(j=0; (j<11)&&(args[j]!=0); j++)
{
k=0;
do
{
MemoryCopyUserToSystem (currentPCB,((char*)args[j])+k,allargs+i,1);
i++; k++;
} while ((i<sizeof(allargs)) && (allargs[i-1]!='\0'));
}
}
else
{
destination = &allargs[0];
for(j=0; (j<11)&&(args[j]!=0); j++)
{
k = dstrlen((char *)args[j]); //length of the argument
if(&destination[k]-allargs>100)
{
printf("Fatal: Cumulative length of all arguments > 100\n");
exitsim();
}
dstrcpy(destination, (char *)args[j]);
destination[k] = '\0';
}
}
allargs[sizeof(allargs)-1] = '\0'; // null terminate the name
ProcessFork(0, (uint32)allargs, name, 1);
}
//-------------------------------------------------------
//
// void MboxOpen(mbox_t);
//
// Open the mailbox for use by the current process. Note
// that it is assumed that the internal lock/mutex handle
// of the mailbox and the inuse flag will not be changed
// during execution. This allows us to get the a valid
// lock handle without a need for synchronization.
//
// Returns MBOX_FAIL on failure.
// Returns MBOX_SUCCESS on success.
//
//-------------------------------------------------------
int MboxOpen(mbox_t handle) {
Link *l;
if(!&mboxs[handle]) return MBOX_FAIL;
if ((l = AQueueAllocLink ((void *)GetCurrentPid())) == NULL) {
printf("FATAL ERROR: could not allocate link for pid queue in Mbox Open!\n");
exitsim();
}
if (AQueueInsertLast (&mboxs[handle].pids, l) != QUEUE_SUCCESS) {
printf("FATAL ERROR: could not insert new link into pid queue in Mbox Open!\n");
exitsim();
}
return MBOX_SUCCESS;
}
int CondInit(Cond *c) {
if (!c) return SYNC_FAIL;
if (AQueueInit (&c->waiting) != QUEUE_SUCCESS) {
printf("FATAL ERROR: could not initialize lock waiting queue in CondInit!\n");
exitsim();
}
return SYNC_SUCCESS;
}
//----------------------------------------------------------------------
//
// ProcessDestroy
//
// Destroy a process by setting its status to zombie and putting it
// on the zombie queue. The next time the scheduler is called, this
// process will be marked as free. We can't necessarily do it now
// because we might be the currently running process.
//
// NOTE: This must only be called from an interrupt or trap. However,
// it need not be followed immediately by a ProcessSchedule() because
// the process can continue running.
//
//----------------------------------------------------------------------
void ProcessDestroy (PCB *pcb) {
dbprintf('p', "Entering ProcessDestroy for 0x%x.\n", (int)pcb);
ProcessSetStatus (pcb, PROCESS_STATUS_ZOMBIE);
if (AQueueRemove(&(pcb->l)) != QUEUE_SUCCESS) {
printf("FATAL ERROR: could not remove link from queue in ProcessDestroy!\n");
exitsim();
}
if ((pcb->l = AQueueAllocLink(pcb)) == NULL) {
printf("FATAL ERROR: could not get link for zombie PCB in ProcessDestroy!\n");
exitsim();
}
if (AQueueInsertFirst(&zombieQueue, pcb->l) != QUEUE_SUCCESS) {
printf("FATAL ERROR: could not insert link into runQueue in ProcessWakeup!\n");
exitsim();
}
dbprintf('p', "Leaving ProcessDestroy for 0x%x.\n", (int)pcb);
}
//----------------------------------------------------------------------
//
// ProcessFreeResources
//
// Free the resources associated with a process. This assumes the
// process isn't currently on any queue.
//
//----------------------------------------------------------------------
void ProcessFreeResources (PCB *pcb) {
int i = 0;
uint32 page;
// Allocate a new link for this pcb on the freepcbs queue
if ((pcb->l = AQueueAllocLink(pcb)) == NULL) {
printf("FATAL ERROR: could not get Queue Link in ProcessFreeResources!\n");
exitsim();
}
// Set the pcb's status to available
pcb->flags = PROCESS_STATUS_FREE;
// Insert the link into the freepcbs queue
if (AQueueInsertLast(&freepcbs, pcb->l) != QUEUE_SUCCESS) {
printf("FATAL ERROR: could not insert PCB link into freepcbs queue in ProcessFreeResources!\n");
exitsim();
}
//------------------------------------------------------------
// STUDENT: Free any memory resources on process death here.
//------------------------------------------------------------
/////////////////////////////////////////////////////////////
// TODO CHANGE FOR 2 LEVEL Free Resource
// JSM - free all physical pages corresponding to valid page table entries in process
// AS WEL AS FREEING SYSTEM STACK PAGE ASSOCIATED WITH PROCESS
for (i = 0; i < MEM_L1_PAGE_TABLE_SIZE; i++)
{
if(pcb->pagetable[i] & MEM_PTE_VALID) // For every page currently valid in page table
{
pcb->pagetable[i] &= ~(MEM_PTE_VALID); // Invalidate page table entry
page = (pcb->pagetable[i]) / MEM_PAGE_SIZE;
dbprintf ('p', "Preparing to free physical page #%d\n", page);
MemoryFreePage(page); // Free page in freemap
}
}
dbprintf ('p', "Preparing to free physical page #%d (System Stack)\n", (pcb->sysStackArea / MEM_PAGE_SIZE) );
MemoryFreePage(pcb->sysStackArea / MEM_PAGE_SIZE); // Free page in freemap
/////////////////////////////////////////////////////////////
dbprintf ('p', "Free Resources DONE!\n\n");
//while(1);
ProcessSetStatus (pcb, PROCESS_STATUS_FREE);
}
//---------------------------------------------------------------------
//
// SemInit
//
// Initialize a semaphore to a particular value. This just means
// initting the process queue and setting the counter.
//
//----------------------------------------------------------------------
int SemInit (Sem *sem, int count) {
if (!sem) return SYNC_FAIL;
if (AQueueInit (&sem->waiting) != QUEUE_SUCCESS) {
printf("FATAL ERROR: could not initialize semaphore waiting queue in SemInit!\n");
exitsim();
}
sem->count = count;
return SYNC_SUCCESS;
}
int LockInit(Lock *l) {
if (!l) return SYNC_FAIL;
if (AQueueInit (&l->waiting) != QUEUE_SUCCESS) {
printf("FATAL ERROR: could not initialize lock waiting queue in LockInit!\n");
exitsim();
}
l->pid = -1;
return SYNC_SUCCESS;
}
//----------------------------------------------------------------------
//
// ProcessWakeup
//
// Wake up a process from its slumber. This only involves putting
// it on the run queue; it's not guaranteed to be the next one to
// run.
//
// NOTE: This must only be called from an interrupt or trap. It
// need not be followed immediately by ProcessSchedule() because
// the currently running process is unaffected.
//
//----------------------------------------------------------------------
void ProcessWakeup (PCB *wakeup) {
dbprintf ('p',"Waking up PID %d.\n", (int)(wakeup - pcbs));
// Make sure it's not yet a runnable process.
ASSERT (wakeup->flags & PROCESS_STATUS_WAITING, "Trying to wake up a non-sleeping process!\n");
ProcessSetStatus (wakeup, PROCESS_STATUS_RUNNABLE);
if (AQueueRemove(&(wakeup->l)) != QUEUE_SUCCESS) {
printf("FATAL ERROR: could not remove wakeup PCB from waitQueue in ProcessWakeup!\n");
exitsim();
}
if ((wakeup->l = AQueueAllocLink(wakeup)) == NULL) {
printf("FATAL ERROR: could not get link for wakeup PCB in ProcessWakeup!\n");
exitsim();
}
if (AQueueInsertLast(&runQueue, wakeup->l) != QUEUE_SUCCESS) {
printf("FATAL ERROR: could not insert link into runQueue in ProcessWakeup!\n");
exitsim();
}
}
//----------------------------------------------------------------------
//
// ProcessModuleInit
//
// Initialize the process module. This involves initializing all
// of the process control blocks to appropriate values (ie, free
// and available). We also need to initialize all of the queues.
//
//----------------------------------------------------------------------
void ProcessModuleInit () {
int i,j;
dbprintf ('p', "Entering ProcessModuleInit\n");
AQueueInit (&freepcbs);
AQueueInit (&runQueue);
AQueueInit (&waitQueue);
AQueueInit (&zombieQueue);
// For each PCB slot in the global pcbs array:
for (i = 0; i < PROCESS_MAX_PROCS; i++) {
dbprintf ('p', "Initializing PCB %d @ 0x%x.\n", i, (int)&(pcbs[i]));
// First, set the internal PCB link pointer to a newly allocated link
if ((pcbs[i].l = AQueueAllocLink(&pcbs[i])) == NULL) {
printf("FATAL ERROR: could not allocate link in ProcessModuleInit!\n");
exitsim();
}
// Next, set the pcb to be available
pcbs[i].flags = PROCESS_STATUS_FREE;
//-------------------------------------------------------
// STUDENT: Initialize the PCB's page table here.
//-------------------------------------------------------
////////////////////////////////////
// TODO3 CHANGE FOR 2 LEVEL DONE
// JSM, Set all entries of every page table to 0 (Invalid) since no pages have been allocated for any process
// and no level 2 page tables have been allocated for any processes
for (j = 0; j < MEM_L1_PAGE_TABLE_SIZE; j++)
{
pcbs[i].pagetable[j] = 0x00000000;
}
///////////////////////////////////
// Finally, insert the link into the queue
if (AQueueInsertFirst(&freepcbs, pcbs[i].l) != QUEUE_SUCCESS) {
printf("FATAL ERROR: could not insert PCB link into queue in ProcessModuleInit!\n");
exitsim();
}
}
// There are no processes running at this point, so currentPCB=NULL
currentPCB = NULL;
dbprintf ('p', "Leaving ProcessModuleInit\n");
}
//----------------------------------------------------------------------
//
// ProcessSuspend
//
// Place a process in suspended animation until it's
// awakened by ProcessAwaken.
//
// NOTE: This must only be called from an interrupt or trap. It
// should be immediately followed by ProcessSchedule().
//
//----------------------------------------------------------------------
void ProcessSuspend (PCB *suspend) {
// Make sure it's already a runnable process.
dbprintf ('p', "Suspending PCB 0x%x (%s).\n", (int)suspend, suspend->name);
ASSERT (suspend->flags & PROCESS_STATUS_RUNNABLE, "Trying to suspend a non-running process!\n");
ProcessSetStatus (suspend, PROCESS_STATUS_WAITING);
ClkResetProcess();
if (AQueueRemove(&(suspend->l)) != QUEUE_SUCCESS) {
printf("FATAL ERROR: could not remove process from run Queue in ProcessSuspend!\n");
exitsim();
}
if ((suspend->l = AQueueAllocLink(suspend)) == NULL) {
printf("FATAL ERROR: could not get Queue Link in ProcessSuspend!\n");
exitsim();
}
if (AQueueInsertLast(&waitQueue, suspend->l) != QUEUE_SUCCESS) {
printf("FATAL ERROR: could not insert suspend PCB into waitQueue!\n");
exitsim();
}
}
//-------------------------------------------------------
//
// mbox_t MboxCreate();
//
// Allocate an available mailbox structure for use.
//
// Returns the mailbox handle on success
// Returns MBOX_FAIL on error.
//
//-------------------------------------------------------
mbox_t MboxCreate() {
mbox_t mbox;
uint32 intrval;
//grabbing a mailbox should be an atomic operation
intrval = DisableIntrs();
for(mbox=0; mbox<MBOX_NUM_MBOXES; mbox++){
if(mboxs[mbox].inuse == 0){
mboxs[mbox].inuse = 1;
break;
}
}
RestoreIntrs(intrval);
if((mboxs[mbox].l = LockCreate()) == SYNC_FAIL){
printf("FATAL ERROR: Could not create lock for mbox\n");
exitsim();
}
if((mboxs[mbox].s_msg_full = SemCreate(0)) == SYNC_FAIL) {
printf("Bad sem create in mbox create\n ");
exitsim();
}
if((mboxs[mbox].s_msg_empty = SemCreate(MBOX_MAX_BUFFERS_PER_MBOX)) == SYNC_FAIL) {
printf("Bad sem create in mbox create\n ");
exitsim();
}
if(mbox == MBOX_NUM_MBOXES) return MBOX_FAIL;
if(AQueueInit(&mboxs[mbox].messages) != QUEUE_SUCCESS){
printf("FATAL ERROR: Could not initialize mbox messsage queue\n");
exitsim();
}
if(AQueueInit(&mboxs[mbox].pids) != QUEUE_SUCCESS){
printf("FATAL ERROR: Could not initialize mbox pid queue\n");
exitsim();
}
return mbox;
}
int AQueueModuleInit() {
int i;
if (AQueueInit(&freeLinks) != QUEUE_SUCCESS) {
printf("FATAL ERROR: could not initialize freeLinks queue in AQueueModuleInit!\n");
exitsim();
}
dbprintf ('q', "Initializing %d links.\n", QUEUE_MAX_LINKS);
for (i = 0; i < QUEUE_MAX_LINKS; i++) {
// Initialize link structure
linkpool[i].next = NULL;
linkpool[i].prev = NULL;
linkpool[i].object = NULL;
// Add link to freeLinks queue
if (AQueueInsertLast(&freeLinks, &(linkpool[i])) != QUEUE_SUCCESS) {
printf("FATAL ERROR: could not insert link into freeLinks in AQueueModuleInit!\n"); // Adds structure to global queue of free links
exitsim();
}
}
return QUEUE_SUCCESS;
}
//---------------------------------------------------------------------------
// LockHandleAcquire
//
// This routine acquires a lock given its handle. The handle must be a
// valid handle for this routine to succeed. In that case this routine
// returns SYNC_FAIL. Otherwise the routine returns SYNC_SUCCESS.
//
// Your implementation should be such that if a process that already owns
// the lock calls LockHandleAcquire for that lock, it should not block.
//---------------------------------------------------------------------------
int LockAcquire(Lock *k) {
Link *l;
int intrval;
if (!k) return SYNC_FAIL;
// Locks are atomic
intrval = DisableIntrs ();
dbprintf ('I', "LockAcquire: Old interrupt value was 0x%x.\n", intrval);
// Check to see if the current process owns the lock
if (k->pid == GetCurrentPid()) {
dbprintf('s', "LockAcquire: Proc %d already owns lock %d\n", GetCurrentPid(), (int)(k-locks));
RestoreIntrs(intrval);
return SYNC_SUCCESS;
}
dbprintf ('s', "LockAcquire: Proc %d asking for lock %d.\n", GetCurrentPid(), (int)(k-locks));
if (k->pid >= 0) { // Lock is already in use by another process
dbprintf('s', "LockAcquire: putting process %d to sleep\n", GetCurrentPid());
if ((l = AQueueAllocLink ((void *)currentPCB)) == NULL) {
printf("FATAL ERROR: could not allocate link for lock queue in LockAcquire!\n");
exitsim();
}
if (AQueueInsertLast (&k->waiting, l) != QUEUE_SUCCESS) {
printf("FATAL ERROR: could not insert new link into lock waiting queue in LockAcquire!\n");
exitsim();
}
ProcessSleep();
} else {
dbprintf('s', "LockAcquire: lock is available, assigning to proc %d\n", GetCurrentPid());
k->pid = GetCurrentPid();
}
RestoreIntrs(intrval);
return SYNC_SUCCESS;
}
//----------------------------------------------------------------------
//
// ProcessSchedule
//
// Schedule the next process to run. If there are no processes to
// run, exit. This means that there should be an idle loop process
// if you want to allow the system to "run" when there's no real
// work to be done.
//
// NOTE: the scheduler should only be called from a trap or interrupt
// handler. This way, interrupts are disabled. Also, it must be
// called consistently, and because it might be called from an interrupt
// handler (the timer interrupt), it must ALWAYS be called from a trap
// or interrupt handler.
//
// Note that this procedure doesn't actually START the next process.
// It only changes the currentPCB and other variables so the next
// return from interrupt will restore a different context from that
// which was saved.
//
//----------------------------------------------------------------------
void
ProcessSchedule ()
{
PCB *pcb;
int i;
dbprintf ('p', "Now entering ProcessSchedule (cur=0x%x, %d ready)\n",
currentPCB, QueueLength (&runQueue));
// The OS exits if there's no runnable process. This is a feature, not a
// bug. An easy solution to allowing no runnable "user" processes is to
// have an "idle" process that's simply an infinite loop.
if (QueueEmpty (&runQueue)) {
printf ("No runnable processes - exiting!\n");
exitsim (); // NEVER RETURNS
}
// Move the front of the queue to the end, if it is the running process.
pcb = (PCB *)((QueueFirst (&runQueue))->object);
if (pcb == currentPCB)
{
QueueRemove (&pcb->l);
QueueInsertLast (&runQueue, &pcb->l);
}
// Now, run the one at the head of the queue.
pcb = (PCB *)((QueueFirst (&runQueue))->object);
currentPCB = pcb;
dbprintf ('p',"About to switch to PCB 0x%x,flags=0x%x @ 0x%x\n",
pcb, pcb->flags,
pcb->sysStackPtr[PROCESS_STACK_IAR]);
// Clean up zombie processes here. This is done at interrupt time
// because it can't be done while the process might still be running
while (!QueueEmpty (&zombieQueue)) {
pcb = (PCB *)(QueueFirst (&zombieQueue)->object);
dbprintf ('p', "Freeing zombie PCB 0x%x.\n", pcb);
QueueRemove (&pcb->l);
ProcessFreeResources (pcb);
}
// Set the timer so this process gets at most a fixed quantum of time.
TimerSet (processQuantum);
dbprintf ('p', "Leaving ProcessSchedule (cur=0x%x)\n", currentPCB);
}
//-------------------------------------------------------
//
// int MboxRecv(mbox_t handle, int maxlength, void* message);
//
// Receive a message from the specified mailbox. The call
// blocks when there is no message in the buffer. Maxlength
// should indicate the maximum number of bytes that can be
// copied from the buffer into the address of "message".
// An error occurs if the message is larger than maxlength.
// Note that the calling process must have opened the mailbox
// via MboxOpen.
//
// Returns MBOX_FAIL on failure.
// Returns number of bytes written into message on success.
//
//-------------------------------------------------------
int MboxRecv(mbox_t handle, int maxlength, void* message) {
int ibuff;
int cpid = GetCurrentPid();
int i;
mbox* xbox = &mboxes[handle];
char* cmessage = (char*) message;
if(xbox->opened_pids[cpid] == false) {
return MBOX_FAIL;
}
// printf("***%d Waiting on mbox filled slot\n", cpid);
SemHandleWait(xbox->s_mbox_fillslots);
// printf("******%d Done waiting on mbox filled slot\n", cpid);
// printf("=%d is waiting on mbox lock\n", cpid);
while(LockHandleAcquire(xbox->l_mbox) != SYNC_SUCCESS);
// printf("==%d has acquired mbox lock\n", cpid);
ibuff = xbox->cbobi[xbox->head_cbobi];
if(ibuff < 0) {
printf("Invalid message buffer index from cbobi.head: %d\n", xbox->head_cbobi);
exitsim();
}
if(mbox_buffers[ibuff].inuse == false) {
LockHandleRelease(xbox->l_mbox);
return MBOX_FAIL;
}
if(mbox_buffers[ibuff].length > maxlength) {
LockHandleRelease(xbox->l_mbox);
return MBOX_FAIL;
}
for(i = 0; i < mbox_buffers[ibuff].length; i++) {
cmessage[i] = mbox_buffers[ibuff].msg[i];
}
xbox->cbobi[xbox->head_cbobi] = -1; // invalidate the cbobi
mbox_buffers[ibuff].inuse = false;
xbox->head_cbobi = (xbox->head_cbobi + 1) % MBOX_MAX_BUFFERS_PER_MBOX;
// SemHandleSignal(s_buff_emptyslots);
SemHandleSignal(xbox->s_mbox_emptyslots);
LockHandleRelease(xbox->l_mbox);
// printf("===%d has released mbox lock\n", cpid);
return mbox_buffers[ibuff].length;
}
//--------------------------------------------------------------------------------
//
// int MboxCloseAllByPid(int pid);
//
// Scans through all mailboxes and removes this pid from their "open procs" list.
// If this was the only open process, then it makes the mailbox available. Call
// this function in ProcessFreeResources in process.c.
//
// Returns MBOX_FAIL on failure.
// Returns MBOX_SUCCESS on success.
//
//--------------------------------------------------------------------------------
int MboxCloseAllByPid(int pid) {
int ct;
int clear_ct;
int mbox_pid_status;
// Check if the pid is valid
if(pid < 0 || pid >= PROCESS_MAX_PROCS){
return MBOX_FAIL;
}
// Go througth all the mboxes
for(ct = 0; ct < MBOX_NUM_MBOXES; ct++){
// Acquire the lock of the mbox
if(LockHandleAcquire(system_mbox[ct].mbox_buffer_lock) != SYNC_SUCCESS){
printf("FATAL ERROR: Acquire lock for the mbox %d!\n", ct);
exitsim();
}
// Check if the pid is in the mbox's "open procs" list.
// If so, remove the pid and make the mailbox available if no other proc opens the mbox
// Else, do nothing
mbox_pid_status = system_mbox[ct].mbox_pid_list[pid];
if(mbox_pid_status == 0){
// Do nothing
}
else if(mbox_pid_status == 1){
// Update the number of pid used
system_mbox[ct].num_of_pid_inuse -= 1;
system_mbox[ct].mbox_pid_list[pid] = 0;
}
else{
printf("FATAL ERROR: Unkown Pid %d for mbox %d\n", pid, ct);
// Release the lock
if(LockHandleRelease(system_mbox[ct].mbox_buffer_lock) != SYNC_SUCCESS){
printf("FATAL ERROR: Release lock for the mbox %d!\n", ct);
exitsim();
}
return MBOX_FAIL;
}
// Return the mbox to the pool of available mboxes for the system
// Reset this mbox, clear rest of messages in this mbox (clear the linkings in the system)
if(system_mbox[ct].num_of_pid_inuse == 0){
system_mbox[ct].num_of_pid_inuse = -1;
for(clear_ct = 0; clear_ct < system_mbox[ct].mbox_buffer_slot_used; clear_ct++){
// Make the system buffer slot available again
system_mbox_message.system_buffer_index_array[system_mbox[ct].mbox_buffer_tail] = 0;
system_mbox_message.system_buffer_slot_used -= 1;
system_mbox[ct].mbox_buffer_tail = (system_mbox[ct].mbox_buffer_tail + 1) % MBOX_MAX_BUFFERS_PER_MBOX;
}
}
// Release the lock of the mbox
if(LockHandleRelease(system_mbox[ct].mbox_buffer_lock) != SYNC_SUCCESS){
printf("FATAL ERROR: Release lock for the mbox %d!\n", ct);
exitsim();
}
}
return MBOX_SUCCESS;
}
//-------------------------------------------------------
//
// int MboxRecv(mbox_t handle, int maxlength, void* message);
//
// Receive a message from the specified mailbox. The call
// blocks when there is no message in the buffer. Maxlength
// should indicate the maximum number of bytes that can be
// copied from the buffer into the address of "message".
// An error occurs if the message is larger than maxlength.
// Note that the calling process must have opened the mailbox
// via MboxOpen.
//
// Returns MBOX_FAIL on failure.
// Returns number of bytes written into message on success.
//
//-------------------------------------------------------
int MboxRecv(mbox_t handle, int maxlength, void* message) {
int ct;
unsigned int curr_pid = GetCurrentPid();
int system_buffer_index = system_mbox[handle].mbox_buffer_index_array[system_mbox[handle].mbox_buffer_tail];
// Check if the length of the message can fit into the buffer slot
if(maxlength < 0 || maxlength > MBOX_MAX_MESSAGE_LENGTH){
return MBOX_FAIL;
}
// Check if handle is a valid number
if(handle < 0 || handle >= MBOX_NUM_MBOXES){
return MBOX_FAIL;
}
// Check if the mbox is reserved (activated). If not, return FAIL
if(system_mbox[handle].num_of_pid_inuse < 0){
return MBOX_FAIL;
}
// Check if the mbox is opened. If the mbox is not opened, return FAIL
if(system_mbox[handle].mbox_pid_list[curr_pid] == 0){
printf("Mbox Send Error: The mbox %d hasn't been opened yet\n", handle);
return MBOX_FAIL;
}
// Acquire the lock of the mbox
if(LockHandleAcquire(system_mbox[handle].mbox_buffer_lock) != SYNC_SUCCESS){
printf("FATAL ERROR: Acquire lock for the mbox %d!\n", handle);
exitsim();
}
// Else, check if the mbox is empty. If so, wait
while(system_mbox[handle].mbox_buffer_slot_used == 0){
if(CondHandleWait(system_mbox[handle].mbox_buffer_fill) != SYNC_SUCCESS){
printf("FATAL ERROR: Wait on CV empty for mbox %d!\n", handle);
exitsim();
}
}
// Acquire the lock of the mbox message buffer
if(LockHandleAcquire(system_mbox_message.system_buffer_lock) != SYNC_SUCCESS){
printf("FATAL ERROR: Acquire lock for the mbox %d!\n", handle);
exitsim();
}
// Receive the message from the mbox
for(ct = 0; ct < maxlength; ct++){
*((char *) message + ct) = system_mbox_message.system_message_buffer[system_buffer_index][ct];
}
// Make the system buffer slot available again
system_mbox_message.system_buffer_index_array[system_mbox[handle].mbox_buffer_tail] = 0;
system_mbox_message.system_buffer_slot_used -= 1;
// Update mbox used and mbox buffer tail info
system_mbox[handle].mbox_buffer_slot_used -= 1;
system_mbox[handle].mbox_buffer_tail = (system_mbox[handle].mbox_buffer_tail + 1) % MBOX_MAX_BUFFERS_PER_MBOX;
// Signal system buffer empty CV
if(CondHandleSignal(system_mbox_message.system_buffer_empty) != SYNC_SUCCESS){
printf("FATAL ERROR: Signal on CV empty for system buffer!\n");
exitsim();
}
// Release the lock of the mbox message buffer
if(LockHandleRelease(system_mbox_message.system_buffer_lock) != SYNC_SUCCESS){
printf("FATAL ERROR: Release lock for the system buffer!\n");
exitsim();
}
// Signal mbox empty CV
if(CondHandleSignal(system_mbox[handle].mbox_buffer_empty) != SYNC_SUCCESS){
printf("FATAL ERROR: Signal on CV empty for mbox %d!\n", handle);
exitsim();
}
// Release the lock of the mbox
if(LockHandleRelease(system_mbox[handle].mbox_buffer_lock) != SYNC_SUCCESS){
printf("FATAL ERROR: Release lock for the mbox %d!\n", handle);
exitsim();
}
return MBOX_SUCCESS;
}
//-------------------------------------------------------
//
// int MboxSend(mbox_t handle,int length, void* message);
//
// Send a message (pointed to by "message") of length
// "length" bytes to the specified mailbox. Messages of
// length 0 are allowed. The call
// blocks when there is not enough space in the mailbox.
// Messages cannot be longer than MBOX_MAX_MESSAGE_LENGTH.
// Note that the calling process must have opened the
// mailbox via MboxOpen.
//
// Returns MBOX_FAIL on failure.
// Returns MBOX_SUCCESS on success.
//
//-------------------------------------------------------
int MboxSend(mbox_t handle, int length, void* message) {
int ct;
int system_buffer_index;
unsigned int curr_pid = GetCurrentPid();
// Check if the length of the message can fit into the buffer slot
if(length < 0 || length > MBOX_MAX_MESSAGE_LENGTH){
return MBOX_FAIL;
}
// Check if handle is a valid number
if(handle < 0 || handle >= MBOX_NUM_MBOXES){
return MBOX_FAIL;
}
// Check if the mbox is reserved (activated)
if(system_mbox[handle].num_of_pid_inuse < 0){
return MBOX_FAIL;
}
// Check if the mbox is opened
if(system_mbox[handle].mbox_pid_list[curr_pid] == 0){
printf("Mbox Send Error: The mbox %d hasn't been opened yet\n", handle);
return MBOX_FAIL;
}
// Acquire the lock of the mbox
if(LockHandleAcquire(system_mbox[handle].mbox_buffer_lock) != SYNC_SUCCESS){
printf("FATAL ERROR: Acquire lock for the mbox %d!\n", handle);
exitsim();
}
// Else, check if the mbox is full. If so, wait
while(system_mbox[handle].mbox_buffer_slot_used == MBOX_MAX_BUFFERS_PER_MBOX){
if(CondHandleWait(system_mbox[handle].mbox_buffer_empty) != SYNC_SUCCESS){
printf("FATAL ERROR: Wait on CV empty for mbox %d!\n", handle);
exitsim();
}
}
// Acquire the lock of the mbox message buffer
if(LockHandleAcquire(system_mbox_message.system_buffer_lock) != SYNC_SUCCESS){
printf("FATAL ERROR: Acquire lock for the system buffer!\n");
exitsim();
}
// Check if the system buffer is full. If so, wait
while(system_mbox_message.system_buffer_slot_used == MBOX_NUM_BUFFERS){
// First Release the lock of the mbox
if(LockHandleRelease(system_mbox[handle].mbox_buffer_lock) != SYNC_SUCCESS){
printf("FATAL ERROR: Release lock for the mbox %d!\n", handle);
exitsim();
}
// Wait on the system CV
if(CondHandleWait(system_mbox_message.system_buffer_empty) != SYNC_SUCCESS){
printf("FATAL ERROR: Wait on CV empty for system buffer!\n");
exitsim();
}
// Re-Acquire the lock of the mbox
if(LockHandleAcquire(system_mbox[handle].mbox_buffer_lock) != SYNC_SUCCESS){
printf("FATAL ERROR: Acquire lock for the mbox %d!\n", handle);
exitsim();
}
}
// Find out an available slot in the system message buffer for the message
for(system_buffer_index = 0; system_buffer_index < MBOX_NUM_BUFFERS; system_buffer_index++){
if(system_mbox_message.system_buffer_index_array[system_buffer_index] == 0){
system_mbox_message.system_buffer_index_array[system_buffer_index] = 1; // Reserved the slot
break;
}
}
// Double check if the index is valid
if(system_buffer_index == MBOX_NUM_BUFFERS){
printf("FATAL ERROR: System buffer sync error\n");
exitsim();
}
// Put the message into the system message slot
for(ct = 0; ct < length; ct++){
system_mbox_message.system_message_buffer[system_buffer_index][ct] = *((char *) message + ct);
}
// Set the mbox linking
system_mbox[handle].mbox_buffer_index_array[system_mbox[handle].mbox_buffer_head] = system_buffer_index;
// Update head and used info
system_mbox_message.system_buffer_slot_used += 1;
system_mbox[handle].mbox_buffer_slot_used += 1;
system_mbox[handle].mbox_buffer_head = (system_mbox[handle].mbox_buffer_head + 1) % MBOX_MAX_BUFFERS_PER_MBOX;
// Release the lock of the mbox message buffer
if(LockHandleRelease(system_mbox_message.system_buffer_lock) != SYNC_SUCCESS){
printf("FATAL ERROR: Release lock for the system buffer %d!\n", handle);
exitsim();
}
// Signal mbox fill CV
if(CondHandleSignal(system_mbox[handle].mbox_buffer_fill) != SYNC_SUCCESS){
printf("FATAL ERROR: Signal on CV fill for mbox %d!\n", handle);
exitsim();
}
// Release the lock of the mbox
if(LockHandleRelease(system_mbox[handle].mbox_buffer_lock) != SYNC_SUCCESS){
printf("FATAL ERROR: Release lock for the mbox %d!\n", handle);
exitsim();
}
return MBOX_SUCCESS;
}
//-------------------------------------------------------
//
// int MboxClose(mbox_t);
//
// Close the mailbox for use to the current process.
// If the number of processes using the given mailbox
// is zero, then disable the mailbox structure and
// return it to the set of available mboxes.
//
// Returns MBOX_FAIL on failure.
// Returns MBOX_SUCCESS on success.
//
//-------------------------------------------------------
int MboxClose(mbox_t handle) {
int clear_ct;
unsigned int curr_pid = GetCurrentPid();
int mbox_pid_status = system_mbox[handle].mbox_pid_list[curr_pid];
// Check if handle is a valid number
if(handle < 0 || handle >= MBOX_NUM_MBOXES){
return MBOX_FAIL;
}
// Check if the mbox is reserved (activated)
if(system_mbox[handle].num_of_pid_inuse < 0){
return MBOX_FAIL;
}
// Acquire the lock
if(LockHandleAcquire(system_mbox[handle].mbox_buffer_lock) != SYNC_SUCCESS){
printf("FATAL ERROR: Acquire lock for the mbox %d!\n", handle);
exitsim();
}
if(mbox_pid_status == 0){
printf("The mbox %d has already been closed for process %d\n", handle, curr_pid);
}
else if(mbox_pid_status == 1){
// Update the number of pid used
system_mbox[handle].num_of_pid_inuse -= 1;
system_mbox[handle].mbox_pid_list[curr_pid] = 0;
}
else{
printf("FATAL ERROR: Unkown Pid %d for mbox %d\n", curr_pid, handle);
// Release the lock
if(LockHandleRelease(system_mbox[handle].mbox_buffer_lock) != SYNC_SUCCESS){
printf("FATAL ERROR: Release lock for the mbox %d!\n", handle);
exitsim();
}
return MBOX_FAIL;
}
// Return the mbox to the pool of available mboxes for the system
// Reset this mbox, clear rest of messages in this mbox (clear the linkings in the system)
if(system_mbox[handle].num_of_pid_inuse == 0){
system_mbox[handle].num_of_pid_inuse = -1;
for(clear_ct = 0; clear_ct < system_mbox[handle].mbox_buffer_slot_used; clear_ct++){
// Make the system buffer slot available again
system_mbox_message.system_buffer_index_array[system_mbox[handle].mbox_buffer_tail] = 0;
system_mbox_message.system_buffer_slot_used -= 1;
system_mbox[handle].mbox_buffer_tail = (system_mbox[handle].mbox_buffer_tail + 1) % MBOX_MAX_BUFFERS_PER_MBOX;
}
}
// Release the lock
if(LockHandleRelease(system_mbox[handle].mbox_buffer_lock) != SYNC_SUCCESS){
printf("FATAL ERROR: Release lock for the mbox %d!\n", handle);
exitsim();
}
return MBOX_SUCCESS;
}
//--------------------------------------------------------------------
//
// int process_create(char *exec_name, ...);
//
// Here we support reading command-line arguments. Maximum MAX_ARGS
// command-line arguments are allowed. Also the total length of the
// arguments including the terminating '\0' should be less than or
// equal to SIZE_ARG_BUFF.
//
//--------------------------------------------------------------------
static void TrapProcessCreateHandler(uint32 *trapArgs, int sysmode) {
char allargs[SIZE_ARG_BUFF]; // Stores full string of arguments (unparsed)
char name[PROCESS_MAX_NAME_LENGTH]; // Local copy of name of executable (100 chars or less)
char *username=NULL; // Pointer to user-space address of exec_name string
int i=0, j=0; // Loop index variables
char *args[MAX_ARGS]; // All parsed arguments (char *'s)
int allargs_position = 0; // Index into current "position" in allargs
char *userarg = NULL; // Current pointer to user argument string
int numargs = 0; // Number of arguments passed on command line
dbprintf('p', "TrapProcessCreateHandler: function started\n");
// Initialize allargs string to all NULL's for safety
for(i=0;i<SIZE_ARG_BUFF; i++) {
allargs[i] = '\0';
}
// First deal with user-space addresses
if(!sysmode) {
dbprintf('p', "TrapProcessCreateHandler: creating user process\n");
// Get the known arguments into the kernel space.
// Argument 0: user-space pointer to name of executable
MemoryCopyUserToSystem (currentPCB, (char *)(trapArgs+0), (char *)&username, sizeof(char *));
// Copy the user-space string at user-address "username" into kernel space
for(i=0; i<PROCESS_MAX_NAME_LENGTH; i++) {
MemoryCopyUserToSystem(currentPCB, (char *)(username+i), (char *)&(name[i]), sizeof(char));
// Check for end of user-space string
if (name[i] == '\0') break;
}
dbprintf('p', "TrapProcessCreateHandler: just parsed executable name (%s) from trapArgs\n", name);
if (i == PROCESS_MAX_NAME_LENGTH) {
printf("TrapProcessCreateHandler: length of executable filename longer than allowed!\n");
exitsim();
}
// Copy the program name into "allargs", since it has to be the first argument (i.e. argv[0])
allargs_position = 0;
dstrcpy(&(allargs[allargs_position]), name);
allargs_position += dstrlen(name) + 1; // The "+1" is so we're pointing just beyond the NULL
// Rest of arguments: a series of char *'s until we hit NULL or MAX_ARGS
for(i=0; i<MAX_ARGS; i++) {
// First, must copy the char * itself into kernel space in order to read its value
MemoryCopyUserToSystem(currentPCB, (char *)(trapArgs+1+i), (char *)&userarg, sizeof(char *));
// If this is a NULL in the set of char *'s, this is the end of the list
if (userarg == NULL) break;
// Store a pointer to the kernel-space location where we're copying the string
args[i] = &(allargs[allargs_position]);
// Copy the string into the allargs, starting where we left off last time through this loop
for (j=0; j<SIZE_ARG_BUFF; j++) {
MemoryCopyUserToSystem(currentPCB, (char *)(userarg+j), (char *)&(allargs[allargs_position]), sizeof(char));
// Move current character in allargs to next spot
allargs_position++;
// Check that total length of arguments is still ok
if (allargs_position == SIZE_ARG_BUFF) {
printf("TrapProcessCreateHandler: strlen(all arguments) > maximum length allowed!\n");
exitsim();
}
// Check for end of user-space string
if (allargs[allargs_position-1] == '\0') break;
}
}
if (i == MAX_ARGS) {
printf("TrapProcessCreateHandler: too many arguments on command line (did you forget to pass a NULL?)\n");
exitsim();
}
numargs = i+1;
// Arguments are now setup
} else {
// Addresses are already in kernel space, so just copy into our local variables
// for simplicity
// Argument 0: (char *) name of program
dstrncpy(name, (char *)(trapArgs[0]), PROCESS_MAX_NAME_LENGTH);
// Copy the program name into "allargs", since it has to be the first argument (i.e. argv[0])
allargs_position = 0;
dstrcpy(&(allargs[allargs_position]), name);
allargs_position += dstrlen(name) + 1; // The "+1" is so that we are now pointing just beyond the "null" in the name
allargs_position = 0;
for (i=0; i<MAX_ARGS; i++) {
userarg = (char *)(trapArgs[i+1]);
if (userarg == NULL) break; // found last argument
// Store the address of where we're copying the string
args[i] = &(allargs[allargs_position]);
// Copy string into allargs
for(j=0; j<SIZE_ARG_BUFF; j++) {
allargs[allargs_position] = userarg[j];
allargs_position++;
if (allargs_position == SIZE_ARG_BUFF) {
printf("TrapProcessCreateHandler: strlen(all arguments) > maximum length allowed!\n");
exitsim();
}
// Check for end of user-space string
if (allargs[allargs_position-1] == '\0') break;
}
}
if (i == MAX_ARGS) {
printf("TrapProcessCreateHandler: too many arguments on command line (did you forget to pass a NULL?)\n");
exitsim();
}
numargs = i+1;
}
ProcessFork(0, (uint32)allargs, name, 1);
}