int DfsFreeBlock(int blocknum) {
int fbvnum;
int bitnum;
int i;
if((blocknum<0)||(blocknum>sb.filesys_blocknum)){
printf("Invalid blocknum = %d\n",blocknum);
return DFS_FAIL;
}
fbvnum = (blocknum)/32;
bitnum = (blocknum)%32;
// printf("In DfsFreeBlock\n");
if (sb.valid == 0){
printf("File system not open!\n");
return DFS_FAIL;
}
LockHandleAcquire(lock_fbv);
fbv[fbvnum] = (fbv[fbvnum] & invert(1<<bitnum))|(1 << bitnum);
LockHandleRelease(lock_fbv);
// for(i=0;i<10;i++){
// printf("fbv[%d] : 0x%x\n",i,fbv[i]);
// }
return DFS_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) {
// if(mbox_list[handle].msg_count >= MBOX_MAX_BUFFERS_PER_MBOX) {
SemHandleWait(mbox_list[handle].empty);
// }
LockHandleAcquire(mbox_list[handle].lock);
bcopy(message,mbox_list[handle].msgs[mbox_list[handle].head].message,length);
mbox_list[handle].msgs[mbox_list[handle].head].length = length;
mbox_list[handle].head = (mbox_list[handle].head + 1) % MBOX_MAX_BUFFERS_PER_MBOX;
mbox_list[handle].msg_count++;
// printf("MBOX INFO: handle: %d\n head: %d\n tail: %d\n in_use: %d\n msg_count: %d\n ",mbox_list[handle].handle,
// mbox_list[handle].head,mbox_list[handle].tail,mbox_list[handle].in_use,mbox_list[handle].msg_count);
// printf("user_list: ");
// for(i = 0; i < MBOX_NUM_BUFFERS; i++) {
// printf("%d",mbox_list[handle].users[i]);
// }
// printf("\n\n msg info: \n");
// for(i = 0; i < MBOX_MAX_MESSAGE_LENGTH; i++) {
// printf("ID: %d, msg: %s, length: %d\n",mbox_list[handle].msgs[i].id,
// mbox_list[handle].msgs[i].message,
// mbox_list[handle].msgs[i].length);
// }
SemHandleSignal(mbox_list[handle].full);
LockHandleRelease(mbox_list[handle].lock);
return MBOX_SUCCESS;
return MBOX_FAIL;
}
//-----------------------------------------------------------------
// DfsInodeOpen: search the list of all inuse inodes for the
// specified filename. If the filename exists, return the handle
// of the inode. If it does not, allocate a new inode for this
// filename and return its handle. Return DFS_FAIL on failure.
// Remember to use locks whenever you allocate a new inode.
//-----------------------------------------------------------------
uint32 DfsInodeOpen(char *filename) {
uint32 i;
if(!sb.valid) {
printf("DfsInodeOpen: invalid file system\n");
return DFS_FAIL;
}
i = DfsInodeFilenameExists(filename);
if(i != DFS_FAIL) {
printf("[DEBUG] Opened inode:%d\n", i);
return i;
}
while(LockHandleAcquire(dfs_inode_lock) != SYNC_SUCCESS);
for(i = 0; i < sb.total_inodes; i++) {
if(inodes[i].valid) {
continue;
}
inodes[i].valid = 1;
inodes[i].filesize = 0;
dstrncpy(inodes[i].filename, filename, DFS_FILENAME_LENGTH);
break;
}
LockHandleRelease(dfs_inode_lock);
printf("[DEBUG] Opened inode:%d\n", i);
return i;
}
int DfsAllocateBlock() {
// Check that file system has been validly loaded into memory
// Find the first free block using the free block vector (FBV), mark it in use
// Return handle to block
int fbvnum;
int bitnum;
int block;
uint32 v;
int i;
// printf("In DfsAllocateBlock\n");
if(sb.valid ==0){
printf("Filesystem not open!\n");
return DFS_FAIL;
}
LockHandleAcquire(lock_fbv);
block = sb.filesys_datastart;
fbvnum = block/32;
while(fbv[fbvnum] == 0){
fbvnum+=1;
if(fbvnum>=(DFS_FBV_MAX_NUM)){
fbvnum = block/32;
}
}
v = fbv[fbvnum];
for (bitnum = 0;(v & (1 << bitnum)) == 0; bitnum++);
fbv[fbvnum] &= invert(1 << bitnum);
v = (fbvnum * 32) + bitnum;
LockHandleRelease(lock_fbv);
// for(i=0;i<10;i++){
// printf("fbv[%d]: 0x%x\n",i,fbv[i]);
// }
return (int)v;
}
uint32 DfsAllocateBlock() {
int i;
uint32 bitnum;
uint32 vector;
// Check that file system has been validly loaded into memory
if(!sb.valid) {
printf("DfsAllocateBlock: Filesystem is not validly loaded into memory\n");
return DFS_FAIL;
}
while(LockHandleAcquire(dfs_fbv_lock) != SYNC_SUCCESS);
// Find the first free block using the free block vector (FBV), mark it in use
for(i = 0; i < sb.fbv_num_words; i++) {
if(fbv[i] != 0) {
break;
}
}
if(i == sb.fbv_num_words) {
printf("DfsAllocateBlock: Could not allocate block\n");
return DFS_FAIL;
}
vector = fbv[i];
for(bitnum = 0; (vector & (1 << bitnum)) == 0; bitnum++) {}
fbv[i] &= invert(1 << bitnum);
vector = (i * 32) + bitnum;
dbprintf('d', "DfsAllocateBlock: Allocated block %d\n", vector);
LockHandleRelease(dfs_fbv_lock);
// Return handle to block
return vector;
}
//-------------------------------------------------------
//
// 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;
}
//-------------------------------------------------------
//
// 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 ibuff;
int i;
int cpid = GetCurrentPid();
char* cmessage = (char*) message;
mbox* xbox = &mboxes[handle];
if(xbox->opened_pids[cpid] == false) {
return MBOX_FAIL;
}
if(length > MBOX_MAX_MESSAGE_LENGTH) {
return MBOX_FAIL;
}
// printf("***%d Waiting on mbox empty slot\n", cpid);
SemHandleWait(xbox->s_mbox_emptyslots);
// printf("******%d Done waiting on mbox empty slot\n", cpid);
while(true) {
// SemHandleWait(s_buff_emptyslots);
while(LockHandleAcquire(l_buff) != SYNC_SUCCESS);
for(ibuff = 0; ibuff < MBOX_NUM_BUFFERS; ibuff++) {
if(mbox_buffers[ibuff].inuse == false) {
break;
}
}
if(ibuff != MBOX_NUM_BUFFERS) {
// buffers are not full
mbox_buffers[ibuff].inuse = true;
LockHandleRelease(l_buff);
break;
}
LockHandleRelease(l_buff);
}
// printf("=%d is waiting on mbox lock\n", cpid);
while(LockHandleAcquire(xbox->l_mbox) != SYNC_SUCCESS);
// printf("==%d has acquired mbox lock\n", cpid);
xbox->cbobi[xbox->tail_cbobi] = ibuff;
xbox->tail_cbobi = (xbox->tail_cbobi + 1) % MBOX_MAX_BUFFERS_PER_MBOX;
for(i = 0; i < length; i++) {
mbox_buffers[ibuff].msg[i] = cmessage[i];
}
mbox_buffers[ibuff].length = length;
mbox_buffers[ibuff].inuse = true;
SemHandleSignal(xbox->s_mbox_fillslots);
LockHandleRelease(xbox->l_mbox);
// printf("===%d has released mbox lock\n", cpid);
return MBOX_SUCCESS;
}
int DfsInodeDelete(int handle) {
int i;
dfs_block indirect_table;
uint32 *table;
// printf("In DfsInodeDelete\n");
if (sb.valid == 0){
printf("File system not open!\n");
return DFS_FAIL;
}
if((handle<0)||(handle>DFS_INODE_MAX_NUM)){
printf("Invalid inode handle = %d\n",handle);
return DFS_FAIL;
}
if(inodes[handle].inuse == 0){
printf("Inode not allocated!\n");
return DFS_FAIL;
}
LockHandleAcquire(lock_inode);
//Free direct table then check if there is indirect address
for(i=0;i<10;i++){
if(inodes[handle].direct[i]!=0){
if(DfsFreeBlock((int)inodes[handle].direct[i])==DFS_FAIL){
printf("Cannot free blocks in direct table!\n");
return DFS_FAIL;
}
inodes[handle].direct[i]=0;
}
}
//Free the indirect table
if(inodes[handle].indirect != 0){
table =(uint32 *)(&indirect_table);
DfsReadBlock(inodes[handle].indirect,&indirect_table);
for(i=0;i<(sb.filesys_blocksize)/sizeof(uint32);i++){
if(table[i]!=0){
if (DfsFreeBlock((int)table[i])== DFS_FAIL){
printf("Cannot free blocks in indirect table\n");
return DFS_FAIL;
}
}
}
if(DfsFreeBlock((int)inodes[handle].indirect)==DFS_FAIL){
printf("Cannot free blocks in indirect table\n");
}
inodes[handle].indirect=0;
}
FreeEntry(handle);
inodes[handle].filesize = 0;
// for(i=0;i< FILENAME_LENGTH;i++){
// inodes[handle].filename[i]='\0';
// }
inodes[handle].permission = 0;
inodes[handle].type = 0;
inodes[handle].ownerid = 0;
inodes[handle].inuse = 0;
LockHandleRelease(lock_inode);
return DFS_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 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;
}
//-----------------------------------------------------------------
// DfsFreeBlock deallocates a DFS block.
//-----------------------------------------------------------------
int DfsFreeBlock(uint32 blocknum) {
if(!sb.valid) {
printf("DfsFreeBlock: Filesystem is not validly loaded into memory\n");
return DFS_FAIL;
}
while(LockHandleAcquire(dfs_fbv_lock) != SYNC_SUCCESS);
SetFreeVector(blocknum, 1);
LockHandleRelease(dfs_fbv_lock);
dbprintf('d', "DfsFreeBlock: Freed block %d\n", blocknum);
return DFS_SUCCESS;
}
//-----------------------------------------------------------------
// DfsInodeDelete de-allocates any data blocks used by this inode,
// including the indirect addressing block if necessary, then mark
// the inode as no longer in use. Use locks when modifying the
// "inuse" flag in an inode.Return DFS_FAIL on failure, and
// DFS_SUCCESS on success.
//-----------------------------------------------------------------
int DfsInodeDelete(uint32 handle) {
int i;
dfs_block dfsb;
int* inints = (int*) dfsb.data;
if(!sb.valid) {
printf("DfsInodeDelete: invalid file system\n");
return DFS_FAIL;
}
if(!inodes[handle].valid) {
printf("DfsInodeDelete: invalid inode\n");
return DFS_FAIL;
}
while(LockHandleAcquire(dfs_fbv_lock) != SYNC_SUCCESS);
if(DFS_IS_BLOCK_ENTRY_VALID(inodes[handle].indir_block_entry)) {
DfsReadBlock(DFS_GET_BLOCK_NUM(inodes[handle].indir_block_entry), &dfsb);
for(i = 0; i < (sb.blocksize / sizeof(int)); i++) {
if(DFS_IS_BLOCK_ENTRY_VALID(inints[i])) {
SetFreeVector(DFS_GET_BLOCK_NUM(inints[i]), 1);
}
}
// clear out the indirect block entry table
bzero(dfsb.data, sb.blocksize);
DfsWriteBlock(DFS_GET_BLOCK_NUM(inodes[handle].indir_block_entry), &dfsb);
SetFreeVector(DFS_GET_BLOCK_NUM(inodes[handle].indir_block_entry), 1);
inodes[handle].indir_block_entry = DFS_SET_BLOCK_ENTRY(0, 0);
}
for(i = 0; i < 10; i++) {
if(DFS_IS_BLOCK_ENTRY_VALID(inodes[handle].direct_block_entries[i])) {
SetFreeVector(DFS_GET_BLOCK_NUM(inodes[handle].direct_block_entries[i]), 1);
inodes[handle].direct_block_entries[i] = DFS_SET_BLOCK_ENTRY(0, 0);
}
}
LockHandleRelease(dfs_fbv_lock);
while(LockHandleAcquire(dfs_inode_lock) != SYNC_SUCCESS);
inodes[handle].valid = 0;
LockHandleRelease(dfs_inode_lock);
return DFS_SUCCESS;
}
int DfsInodeOpen(char *filename,int handle,int type,int ownerid,unsigned char permission) {
int i,j;
int handler;
// printf("In DfsInodeOpen\n");
if(sb.valid == 0){
printf("File system not open!\n");
return DFS_FAIL;
}
if((handler = DfsInodeFilenameExists(filename,handle))!= DFS_FAIL){
printf("Open existing file!\n");
return handler;
}
else{
for(i=0;i<sb.inodenum;i++){
if(inodes[i].inuse == 0){
LockHandleAcquire(lock_inode);
inodes[i].inuse = 1;
inodes[i].filesize = 0;
for(j=0;j<sb.dirnum;j++){
if(dir[j].inuse == 0){
inodes[i].dir = &dir[j];
break;
}
}
inodes[i].permission = permission;
inodes[i].type = type;
inodes[i].ownerid = ownerid;
handler=i;
LockHandleRelease(lock_inode);
if(InsertEntry(filename,handle,handler)== DFS_FAIL){
printf ("Error: Cannot insert inode %d into dir of inode %d\n",handler,handle);
return DFS_FAIL;
}
return handler;
}
}
}
printf("No free inodes!\n");
return DFS_FAIL;
}
//-------------------------------------------------------
//
// 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 size;
// if(mbox_list[handle].msg_count == 0) {
SemHandleWait(mbox_list[handle].full);
// }
LockHandleAcquire(mbox_list[handle].lock);
if (mbox_list[handle].msgs[mbox_list[handle].tail].length <= maxlength) {
size = mbox_list[handle].msgs[mbox_list[handle].tail].length;
}
else {
return MBOX_FAIL;
}
bcopy(mbox_list[handle].msgs[mbox_list[handle].tail].message,message, size);
mbox_list[handle].tail = (mbox_list[handle].tail + 1) % MBOX_MAX_BUFFERS_PER_MBOX;
mbox_list[handle].msg_count--;
SemHandleSignal(mbox_list[handle].empty);
LockHandleRelease(mbox_list[handle].lock);
return size;
}
//-------------------------------------------------------
//
// 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 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 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 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 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 intrs;
int wasEmpty = 0;
Link * mbuffer_link;
if(MailBox[handle].inuse == 0)
{
printf("Currently passed mailbox handle : %d by calling process : %d is unallocated\n", handle, GetCurrentPid());
return MBOX_FAIL;
}
if(MailBox[handle].procs_link[GetCurrentPid()] == false)
{
printf("Mailbox : %d not already opened by calling proces :%d\n", handle, GetCurrentPid());
return MBOX_FAIL;
}
intrs = DisableIntrs();
LockHandleAcquire(MailBox[handle].lock);
while(AQueueLength(&MailBox[handle].buffers) == MBOX_MAX_BUFFERS_PER_MBOX || used_buffers == MBOX_NUM_BUFFERS)
{
CondHandleWait(MailBox[handle].moreSpace);
}
//printf("Buffer size of queue before inserting messager by : %d is : %d\n", GetCurrentPid(), AQueueLength(&MailBox[handle].buffers));
if(AQueueLength(&MailBox[handle].buffers) == 0)
wasEmpty = 1;
if(AQueueLength(&MailBox[handle].buffers) != MBOX_MAX_BUFFERS_PER_MBOX)
{
if(length > MBOX_MAX_MESSAGE_LENGTH)
{
printf("Messge passed by user process : %d larger than accepted message length (Messge length sent - %d)", GetCurrentPid(), length);
return MBOX_FAIL;
}
bcopy(message, Messg_Buffers[used_buffers++].message, 8);
Messg_Buffers[used_buffers - 1].size = length;
//printf("Original Message : %s Copied : %s in : %d\n", (char *)message, (char *)(Messg_Buffers[used_buffers - 1].message), handle);
if((mbuffer_link = AQueueAllocLink(&Messg_Buffers[used_buffers - 1])) == QUEUE_FAIL)
{
printf("FATAL Error : Link object could not be created for message buffer : %d in process : %d",used_buffers - 1, GetCurrentPid());
exitsim();
}
if(AQueueInsertLast(&MailBox[handle].buffers, mbuffer_link) != QUEUE_SUCCESS)
{
printf("FATAL Error : Link object could not be created for message buffer : %d in process : %d",used_buffers - 1, GetCurrentPid());
exitsim();
}
}
//printf("Message inserted by process : %d using buffer : %d with current count : %d\n", GetCurrentPid(), buffer_no, AQueueLength(&MailBox[handle].buffers));
//if(wasEmpty)
CondHandleSignal(MailBox[handle].moreData);
LockHandleRelease(MailBox[handle].lock);
RestoreIntrs(intrs);
return MBOX_SUCCESS;
}
//----------------------------------------------------------------------
//
// doInterrupt
//
// Handle an interrupt or trap.
//
//----------------------------------------------------------------------
void
dointerrupt (unsigned int cause, unsigned int iar, unsigned int isr,
uint32 *trapArgs)
{
int result;
int i;
uint32 args[4];
int intrs;
uint32 handle;
int ihandle;
dbprintf ('t',"Interrupt cause=0x%x iar=0x%x isr=0x%x args=0x%08x.\n",
cause, iar, isr, (int)trapArgs);
// If the TRAP_INSTR bit is set, this was from a trap instruction.
// If the bit isn't set, this was a system interrupt.
if (cause & TRAP_TRAP_INSTR) {
cause &= ~TRAP_TRAP_INSTR;
switch (cause) {
case TRAP_CONTEXT_SWITCH:
dbprintf ('t', "Got a context switch trap!\n");
ProcessSchedule ();
ClkResetProcess();
break;
case TRAP_EXIT:
case TRAP_USER_EXIT:
dbprintf ('t', "Got an exit trap!\n");
ProcessDestroy (currentPCB);
ProcessSchedule ();
ClkResetProcess();
break;
case TRAP_PROCESS_FORK:
dbprintf ('t', "Got a fork trap!\n");
break;
case TRAP_PROCESS_SLEEP:
dbprintf ('t', "Got a process sleep trap!\n");
ProcessSuspend (currentPCB);
ProcessSchedule ();
ClkResetProcess();
break;
case TRAP_PRINTF:
// Call the trap printf handler and pass the arguments and a flag
// indicating whether the trap was called from system mode.
dbprintf ('t', "Got a printf trap!\n");
TrapPrintfHandler (trapArgs, isr & DLX_STATUS_SYSMODE);
break;
case TRAP_OPEN:
// Get the arguments to the trap handler. If this is a user mode trap,
// copy them from user space.
if (isr & DLX_STATUS_SYSMODE) {
args[0] = trapArgs[0];
args[1] = trapArgs[1];
} else {
char filename[32];
// trapArgs points to the trap arguments in user space. There are
// two of them, so copy them to to system space. The first argument
// is a string, so it has to be copied to system space and the
// argument replaced with a pointer to the string in system space.
MemoryCopyUserToSystem (currentPCB, (char *)trapArgs, (char *)args, sizeof(args[0])*2);
MemoryCopyUserToSystem (currentPCB, (char *)(args[0]), (char *)filename, 31);
// Null-terminate the string in case it's longer than 31 characters.
filename[31] = '\0';
// Set the argument to be the filename
args[0] = (uint32)filename;
}
// Allow Open() calls to be interruptible!
intrs = EnableIntrs ();
ProcessSetResult (currentPCB, args[1] + 0x10000);
printf ("Got an open with parameters ('%s',0x%x)\n", (char *)(args[0]), args[1]);
RestoreIntrs (intrs);
break;
case TRAP_CLOSE:
// Allow Close() calls to be interruptible!
intrs = EnableIntrs ();
ProcessSetResult (currentPCB, -1);
RestoreIntrs (intrs);
break;
case TRAP_READ:
// Allow Read() calls to be interruptible!
intrs = EnableIntrs ();
ProcessSetResult (currentPCB, -1);
RestoreIntrs (intrs);
break;
case TRAP_WRITE:
// Allow Write() calls to be interruptible!
intrs = EnableIntrs ();
ProcessSetResult (currentPCB, -1);
RestoreIntrs (intrs);
break;
case TRAP_DELETE:
intrs = EnableIntrs ();
ProcessSetResult (currentPCB, -1);
RestoreIntrs (intrs);
break;
case TRAP_SEEK:
intrs = EnableIntrs ();
ProcessSetResult (currentPCB, -1);
RestoreIntrs (intrs);
break;
case TRAP_PROCESS_GETPID:
ProcessSetResult(currentPCB, GetCurrentPid());
break;
case TRAP_PROCESS_CREATE:
TrapProcessCreateHandler(trapArgs, isr & DLX_STATUS_SYSMODE);
break;
case TRAP_SEM_CREATE:
ihandle = GetIntFromTrapArg(trapArgs, isr & DLX_STATUS_SYSMODE);
ihandle = SemCreate(ihandle);
ProcessSetResult(currentPCB, ihandle); //Return handle
break;
case TRAP_SEM_WAIT:
ihandle = GetIntFromTrapArg(trapArgs, isr & DLX_STATUS_SYSMODE);
handle = SemHandleWait(ihandle);
ProcessSetResult(currentPCB, handle); //Return 1 or 0
break;
case TRAP_SEM_SIGNAL:
ihandle = GetIntFromTrapArg(trapArgs, isr & DLX_STATUS_SYSMODE);
handle = SemHandleSignal(ihandle);
ProcessSetResult(currentPCB, handle); //Return 1 or 0
break;
case TRAP_MALLOC:
ihandle = GetIntFromTrapArg(trapArgs, isr & DLX_STATUS_SYSMODE);
ihandle = (int)malloc(currentPCB, ihandle);
ProcessSetResult(currentPCB, ihandle); //Return handle
break;
case TRAP_MFREE:
ihandle = GetIntFromTrapArg(trapArgs, isr & DLX_STATUS_SYSMODE);
ihandle = mfree(currentPCB, (void*)ihandle);
ProcessSetResult(currentPCB, ihandle); //Return handle
break;
case TRAP_LOCK_CREATE:
ihandle = LockCreate();
ProcessSetResult(currentPCB, ihandle); //Return handle
break;
case TRAP_LOCK_ACQUIRE:
ihandle = GetIntFromTrapArg(trapArgs, isr & DLX_STATUS_SYSMODE);
handle = LockHandleAcquire(ihandle);
ProcessSetResult(currentPCB, handle); //Return 1 or 0
break;
case TRAP_LOCK_RELEASE:
ihandle = GetIntFromTrapArg(trapArgs, isr & DLX_STATUS_SYSMODE);
handle = LockHandleRelease(ihandle);
ProcessSetResult(currentPCB, handle); //Return 1 or 0
break;
case TRAP_COND_CREATE:
ihandle = GetIntFromTrapArg(trapArgs, isr & DLX_STATUS_SYSMODE);
ihandle = CondCreate(ihandle);
ProcessSetResult(currentPCB, ihandle); //Return handle
break;
case TRAP_COND_WAIT:
ihandle = GetIntFromTrapArg(trapArgs, isr & DLX_STATUS_SYSMODE);
ihandle = CondHandleWait(ihandle);
ProcessSetResult(currentPCB, ihandle); //Return 1 or 0
break;
case TRAP_COND_SIGNAL:
ihandle = GetIntFromTrapArg(trapArgs, isr & DLX_STATUS_SYSMODE);
ihandle = CondHandleSignal(ihandle);
ProcessSetResult(currentPCB, ihandle); //Return 1 or 0
break;
case TRAP_COND_BROADCAST:
ihandle = GetIntFromTrapArg(trapArgs, isr & DLX_STATUS_SYSMODE);
ihandle = CondHandleBroadcast(ihandle);
ProcessSetResult(currentPCB, ihandle); //Return 1 or 0
break;
default:
printf ("Got an unrecognized trap (0x%x) - exiting!\n",
cause);
exitsim ();
break;
}
} else {
switch (cause) {
case TRAP_TIMER:
dbprintf ('t', "Got a timer interrupt!\n");
// ClkInterrupt returns 1 when 1 "process quantum" has passed, meaning
// that it's time to call ProcessSchedule again.
if (ClkInterrupt()) {
ProcessSchedule ();
}
break;
case TRAP_KBD:
do {
i = *((uint32 *)DLX_KBD_NCHARSIN);
result = *((uint32 *)DLX_KBD_GETCHAR);
printf ("Got a keyboard interrupt (char=0x%x(%c), nleft=%d)!\n",
result, result, i);
} while (i > 1);
break;
case TRAP_ACCESS:
printf ("Exiting after illegal access at iar=0x%x, isr=0x%x\n", iar, isr);
exitsim ();
break;
case TRAP_ADDRESS:
printf ("Exiting after illegal address at iar=0x%x, isr=0x%x\n",
iar, isr);
exitsim ();
break;
case TRAP_ILLEGALINST:
printf ("Exiting after illegal instruction at iar=0x%x, isr=0x%x\n",
iar, isr);
exitsim ();
break;
case TRAP_PAGEFAULT:
MemoryPageFaultHandler(currentPCB);
break;
default:
printf ("Got an unrecognized system interrupt (0x%x) - exiting!\n",
cause);
exitsim ();
break;
}
}
dbprintf ('t',"About to return from dointerrupt.\n");
// Note that this return may schedule a new process!
intrreturn ();
}
//-------------------------------------------------------
//
// 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 intrs;
int wasFull = 0, buffersSaturated = 0;
mbox_message * user_mesg;
Link *l;
if(MailBox[handle].inuse == false)
{
printf("Currently passed mailbox handle : %d by calling process : %d is unallocated\n", handle, GetCurrentPid());
return MBOX_FAIL;
}
if(MailBox[handle].procs_link[GetCurrentPid()] == false)
{
printf("Mailbox : %d not already opened by calling proces :%d\n", handle, GetCurrentPid());
return MBOX_FAIL;
}
intrs = DisableIntrs();
LockHandleAcquire(MailBox[handle].lock);
while(AQueueLength(&MailBox[handle].buffers) == 0)
{
//printf("Waiting for mailbox to have more messages\n");
CondHandleWait(MailBox[handle].moreData);
}
//printf("Received mailbox lock by calling process : %d with mailbox buffer count : %d\n", GetCurrentPid(), AQueueLength(&MailBox[handle].buffers));
if(AQueueLength(&MailBox[handle].buffers) == MBOX_MAX_BUFFERS_PER_MBOX)
wasFull = 1;
if(AQueueLength(&MailBox[handle].buffers) < MBOX_MAX_BUFFERS_PER_MBOX && used_buffers == MBOX_NUM_BUFFERS)
buffersSaturated = 1;
//printf("Obtained message in receiver : %d from buffer index : %d\n", user_mesg->size, (user_mesg - Messg_Buffers));
if((user_mesg = (mbox_message *)AQueueObject(MailBox[handle].buffers.first)) == NULL)
{
printf("Undefined/unallocated Link pointer obtained from mailbox queue with handle :%d in process : %d\n", handle, GetCurrentPid());
//printf("MailBox buffer size : %d\n", AQueueLength(&MailBox[handle].buffers));
return MBOX_FAIL;
}
if(maxlength < user_mesg->size)
{
printf("Message : %s requested by user process : %d larger than acceptable message length : %d (Messge length received : %d)\n", user_mesg->message, GetCurrentPid(), maxlength, user_mesg->size);
return MBOX_FAIL;
}
bcopy(user_mesg->message, message, user_mesg->size);
l = MailBox[handle].buffers.first;
MailBox[handle].buffers.first = AQueueNext(MailBox[handle].buffers.first);
if(AQueueRemove(&l) == QUEUE_FAIL)
{
printf("FATAL Error : Message object Link for buffer : %d received by process : %d could not be removed from queue of mailbox handle : %d",used_buffers, GetCurrentPid(), handle);
exitsim();
}
used_buffers--;
//if(wasFull || buffersSaturated)
CondHandleSignal(MailBox[handle].moreSpace);
LockHandleRelease(MailBox[handle].lock);
RestoreIntrs(intrs);
return user_mesg;
}
//-------------------------------------------------------
//
// 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 i;
int qlen;
Link *l;
int exists = 0;
//check if mailbox is real
if(!&mboxs[handle]) return MBOX_FAIL;
//check if pid opened this mailbox
if(!AQueueEmpty(&mboxs[handle].pids ) ){
qlen = AQueueLength(&mboxs[handle].pids);
l = AQueueFirst(&mboxs[handle].pids);
for(i=0; i < qlen; i++){
if((int)AQueueObject(l) == GetCurrentPid()){
exists = 1;
break;
}
l = AQueueNext(l);
}
//actuall checks if pid exists
if(exists == 0){
return MBOX_FAIL;
}
//check if message longer than max length
if(length > MBOX_MAX_MESSAGE_LENGTH) {
return MBOX_FAIL;
}
//check for space in mailbox
if((SemHandleWait(mboxs[handle].s_msg_empty)) == SYNC_FAIL ){
printf("bad sem handle wait in mbox send\n");
exitsim();
}
//lock
if(LockHandleAcquire(mboxs[handle].l) != SYNC_SUCCESS){
printf("FATAL ERROR: could not get lock in Mbox send!\n");
exitsim();
}
for(i=0; i<MBOX_NUM_BUFFERS; i++){
if(mbox_messages[i].inuse == 0){
mbox_messages[i].inuse = 1;
break;
}
}
//creating mbox_message structure
dstrncpy(mbox_messages[i].message, (char *) message, length);
mbox_messages[i].length = length;
if ((l = AQueueAllocLink(&mbox_messages[i])) == NULL) {
printf("FATAL ERROR: could not allocate link for pid queue in Mbox Open!\n");
exitsim();
}
//add message to end of queue
AQueueInsertLast(&mboxs[handle].messages, l);
//unlock
if(LockHandleRelease(mboxs[handle].l) != SYNC_SUCCESS){
printf("FATAL ERROR: could not release lock in Mbox send!\n");
exitsim();
}
if(SemHandleSignal(mboxs[handle].s_msg_full) == SYNC_FAIL){
printf("bad sem handle signal in mbox send\n");
exitsim();
}
}else{
return MBOX_FAIL;
}
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 i;
int qlen;
Link *l;
int exists = 0;
mbox_message *m;
//check if mailbox is real
if(!&mboxs[handle]) return MBOX_FAIL;
//check if pid opened this mailbox
if(!AQueueEmpty(&mboxs[handle].pids ) ){
qlen = AQueueLength(&mboxs[handle].pids);
l = AQueueFirst(&mboxs[handle].pids);
for(i=0; i < qlen; i++){
if((int)AQueueObject(l) == GetCurrentPid()){
exists = 1;
break;
}
l = AQueueNext(l);
}
//actualy checks if pid exists
if(exists == 0){
return MBOX_FAIL;
}
//wait until queue has something in it
if(SemHandleWait(mboxs[handle].s_msg_full) == SYNC_FAIL){
printf("bad sem handle wait in mbox recv\n");
exitsim();
}
//lock
if(LockHandleAcquire(mboxs[handle].l) != SYNC_SUCCESS){
printf("FATAL ERROR: could not get lock in Mbox send!\n");
exitsim();
}
l = AQueueFirst(&mboxs[handle].messages);
m = (mbox_message *) l->object;
//check if message longer than max length
if(m->length > maxlength) {
return MBOX_FAIL;
}
//copy message to local variable
dstrncpy(message,(void*) m->message, m->length);
//reset structure for use elsewhere
m->inuse =0;
//delete link
AQueueRemove(&l);
//unlock
if(LockHandleRelease(mboxs[handle].l) != SYNC_SUCCESS){
printf("FATAL ERROR: could not release lock in Mbox send!\n");
exitsim();
}
if(SemHandleSignal(mboxs[handle].s_msg_empty) == SYNC_FAIL){
printf("bad sem handle signal in mbox recv\n");
exitsim();
}
}else{
return MBOX_FAIL;
}
return MBOX_SUCCESS;
}
