kern/user/progKL.c

#include <common.h>

/**
** User function main #4:  exit, fork, exec, sleep, write
**
** Loops, spawning N copies of userX and sleeping between spawns.
**
** Invoked as:  main4  x  n
**	 where x is the ID character
**		   n is the iteration count (defaults to 5)
*/

USERMAIN(main)
{
	int count = 5; // default iteration count
	char ch = '4'; // default character to print
	int nap = 30; // nap time
	char msg2[] = "*4*"; // "error" message to print
	char buf[32];

	// process the command-line arguments
	switch (argc) {
	case 3:
		count = str2int(argv[2], 10);
		// FALL THROUGH
	case 2:
		ch = argv[1][0];
		break;
	default:
		sprint(buf, "main4: argc %d, args: ", argc);
		cwrites(buf);
		for (int i = 0; i <= argc; ++i) {
			sprint(buf, " %s", argv[argc] ? argv[argc] : "(null)");
			cwrites(buf);
		}
		cwrites("\n");
	}

	// announce our presence
	write(CHAN_SIO, &ch, 1);

	// argument vector for the processes we will spawn
	char *arglist[] = { "userX", "X", buf, NULL };

	for (int i = 0; i < count; ++i) {
		write(CHAN_SIO, &ch, 1);

		// second argument to X is 100 plus the iteration number
		sprint(buf, "%d", 100 + i);
		int whom = spawn(ProgX, arglist);
		if (whom < 0) {
			swrites(msg2);
		} else {
			write(CHAN_SIO, &ch, 1);
		}

		sleep(SEC_TO_MS(nap));
	}

	exit(0);

	return (42); // shut the compiler up!
}