kern/user/progJ.c

#include <common.h>

/**
** User function J:   exit, fork, exec, write
**
** Reports, tries to spawn lots of children, then exits
**
** Invoked as:  userJ  x  [ n ]
**	 where x is the ID character
**		   n is the number of children to spawn (defaults to 2 * N_PROCS)
*/

USERMAIN(main)
{
	int count = 2 * N_PROCS; // number of children to spawn
	char ch = 'j'; // default character to print
	char buf[128];

	// 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, "userJ: 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);

	// set up the command-line arguments
	char *argsy[] = { "userY", "Y", "10", NULL };

	for (int i = 0; i < count; ++i) {
		int whom = spawn(ProgY, argsy);
		if (whom < 0) {
			write(CHAN_SIO, "!j!", 3);
		} else {
			write(CHAN_SIO, &ch, 1);
		}
	}

	exit(0);

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