kern/user/progMN.c

#include <common.h>

/**
** User function main #5:  exit, fork, exec, write
**
** Iterates spawning copies of userW (and possibly userZ), reporting
** their PIDs as it goes.
**
** Invoked as:  main5  x  n  b
**	 where x is the ID character
**		   n is the iteration count
**		   b is the w&z boolean
*/

USERMAIN(main)
{
	int count = 5; // default iteration count
	char ch = '5'; // default character to print
	int alsoZ = 0; // also do userZ?
	char msgw[] = "*5w*";
	char msgz[] = "*5z*";
	char buf[128];

	// process the command-line arguments
	switch (argc) {
	case 4:
		alsoZ = argv[3][0] == 't';
		// FALL THROUGH
	case 3:
		count = str2int(argv[2], 10);
		// FALL THROUGH
	case 2:
		ch = argv[1][0];
		break;
	default:
		sprint(buf, "main5: 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");
	}

	// update the extra message strings
	msgw[1] = msgz[1] = ch;

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

	// set up the argument vector(s)

	// W:  15 iterations, 5-second sleep
	char *argsw[] = { "userW", "W", "15", "5", NULL };

	// Z:  15 iterations
	char *argsz[] = { "userZ", "Z", "15", NULL };

	for (int i = 0; i < count; ++i) {
		write(CHAN_SIO, &ch, 1);
		int whom = spawn(ProgW, argsw);
		if (whom < 1) {
			swrites(msgw);
		}
		if (alsoZ) {
			whom = spawn(ProgZ, argsz);
			if (whom < 1) {
				swrites(msgz);
			}
		}
	}

	exit(0);

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