Operating System question

/** *CommandNode.c *Author: Bill Andreopoulos *The function bodies for a linked list of commands *CS149 assignment 3 usage only **/ /** Example of linked list initialization in code: //First command node (head of list) headCommand = (CommandNode*)malloc(sizeof(CommandNode)); CreateCommandNode(headCommand, command, index, NULL); ..... //Later command nodes nextCommand1 = (CommandNode*)malloc(sizeof(CommandNode)); CreateCommandNode(nextCommand1, command, index, NULL); InsertCommandAfter(headCommand, nextCommand1); **/ //create a new command node. usually nextCmd can be NULL and function InsertCommandAfter can be called to insert after head node. void CreateCommandNode(CommandNode* thisNode, char cmd[20][20], int ind, CommandNode* nextCmd) { //this is useful if you store a string (char *): strcpy(thisNode->command, cmd); for (int i = 0; i < 20; i++) for (int j = 0; j < 20; j++) thisNode->command[i][j] = cmd[i][j]; thisNode->index = ind; thisNode->nextCommandPtr = nextCmd; return; } //insert node newNode after thisNode void InsertCommandAfter(CommandNode* thisNode, CommandNode* newNode) { CommandNode* tmpNext = NULL; tmpNext = thisNode->nextCommandPtr; thisNode->nextCommandPtr = newNode; newNode->nextCommandPtr = tmpNext; return; } //get next command node in linked list CommandNode* GetNextCommand(CommandNode* thisNode) { return thisNode->nextCommandPtr; } //find a command based on the pid CommandNode* FindCommand(CommandNode* cmd, int pid) { CommandNode* tmpNext = cmd; while (tmpNext != null) { if (tmpNext->PID == pid) { return tmpNext; } tmpNext = tmpNext->nextCommandPtr; } return NULL; }