pkoech / designdoc2 Goto Github PK

Add a function that will parse the arguments and put it in an array to process.c.

void parse_arguments(char *input) 
{
  char args [1024];
  char *tokens = strtok_r(input, " ");
  while(tokens != null){
  	args[i] = tokens;
	}
    }
 

process_execute() will create a user program with "filename" as the arguments. We will call the function we created parse_arguments(filename) to parse the user input and pushed them to the stack. We will also perform a check to see if the arguments are valid.

In setup_stack() we call parse_arguments(char *input) where we will call strtok_r() with a space as the delimiter. We store each of these tokens in an array and increase our argc at the same time. When we push these tokens onto the stack we start with the last one to the first one, pushing each pointer onto the stack. This way, we will get each element of argv[] to be in the right order. To avoid overflowing the stack page we limited the size of the total arguments to be less than one page size (4 KB).

When a user program is started, we create a thread to handle the each user program started therefore, we will also modify process_wait() such that when a child process is created, the parent process will wait for this process to finish loading properly, then proceed to continue with its execution.

• We chose to use strtok_r instead of strtok because its thread safe i.e it is reentrant.
• we will be pushing the parsed user arguments into the stack to esp. Pushing the user arguments to esp will ensure that the arguments are ran.