opensimfs

SIMFS_ERROR simfsOpenFile(SIMFS_NAME_TYPE fileName, SIMFS_FILE_HANDLE_TYPE *fileHandle)
{
    // TODO: implement

    unsigned long hashedIndex = hash(fileName);

    SIMFS_DIR_ENT *conflictResolver = simfsContext->directory[hashedIndex];

    if (conflictResolver == NULL)
        return SIMFS_NOT_FOUND_ERROR;

    while (conflictResolver != NULL){

        if (conflictResolver->uniqueFileIdentifier == simfsVolume->block[conflictResolver->nodeReference].content.fileDescriptor.identifier) {
            break;
        }
        conflictResolver = conflictResolver->next;
    }

    if(conflictResolver->globalOpenFileTableIndex != SIMFS_INVALID_INDEX){
        simfsContext->globalOpenFileTable[conflictResolver->globalOpenFileTableIndex].referenceCount++;
    } else {

        bool isEmptySlot = false;
        SIMFS_OPEN_FILE_GLOBAL_TABLE_TYPE *emptySlot = NULL;
        for (int i = 0; i < SIMFS_MAX_NUMBER_OF_OPEN_FILES && !isEmptySlot; ++i) {
            if (simfsContext->globalOpenFileTable[i].fileDescriptor == SIMFS_INVALID_OPEN_FILE_TABLE_INDEX){
                memcpy(simfsContext->globalOpenFileTable[i].fileDescriptor,
                        &(simfsVolume->block[conflictResolver->nodeReference].content.fileDescriptor), sizeof(SIMFS_FILE_DESCRIPTOR_TYPE));
                simfsContext->globalOpenFileTable[i].referenceCount = 1;
                conflictResolver->globalOpenFileTableIndex = i;
                isEmptySlot = true;
                break;
            }
        }

        if (!isEmptySlot)
            return SIMFS_ALLOC_ERROR;
    }

    pid_t pid = simfs_debug_get_context()->pid;

    bool isProcessInProcessControlBlock = false;
    SIMFS_PROCESS_CONTROL_BLOCK_TYPE *currentProcess = simfsContext->processControlBlocks;

    while (!isProcessInProcessControlBlock){
        if (currentProcess->pid == pid)//if found
            isProcessInProcessControlBlock = true;
        if (currentProcess->next != NULL)//if there's more to go
            currentProcess = currentProcess->next;
        else
            break;
    }

    if (!isProcessInProcessControlBlock){
        //create one
        SIMFS_PROCESS_CONTROL_BLOCK_TYPE *newProcessBlock = malloc(sizeof(SIMFS_PROCESS_CONTROL_BLOCK_TYPE));
        if (newProcessBlock == NULL)
            return SIMFS_ALLOC_ERROR;
        newProcessBlock->currentWorkingDirectory = simfsVolume->superblock.attr.rootNodeIndex;
        newProcessBlock->numberOfOpenFiles = 1;
        newProcessBlock->pid = pid;
        newProcessBlock->next = NULL;
        currentProcess->next = newProcessBlock;
        currentProcess = currentProcess->next;
    }

    SIMFS_PER_PROCESS_OPEN_FILE_TYPE currentJElement;
    for (int j = 0; j < SIMFS_MAX_NUMBER_OF_OPEN_FILES_PER_PROCESS; ++j) {
         currentJElement = currentProcess->openFileTable[j];
        if (currentJElement.globalOpenFileTableIndex!= SIMFS_INVALID_OPEN_FILE_TABLE_INDEX &&
        currentJElement.globalOpenFileTableIndex == conflictResolver->globalOpenFileTableIndex){
            *fileHandle = j;
            return SIMFS_DUPLICATE_ERROR;
        }
    }

    bool isFreeSlotFound = false;
    for (int j = 0; j < SIMFS_MAX_NUMBER_OF_OPEN_FILES_PER_PROCESS && !isFreeSlotFound; ++j) {
        currentJElement = currentProcess->openFileTable[j];
        if (currentJElement.globalOpenFileTableIndex == SIMFS_INVALID_OPEN_FILE_TABLE_INDEX){
            currentJElement.globalOpenFileTableIndex = conflictResolver->globalOpenFileTableIndex;
            currentJElement.accessRights = simfs_debug_get_context()->umask;
            fileHandle = j;
            isFreeSlotFound = true;
        }
    }

    if (!isFreeSlotFound)
        return SIMFS_ALLOC_ERROR;


    return SIMFS_NO_ERROR;
}