kern/user/progQ.c

#include <common.h>

/**
** User function Q:   exit, write, bogus
**
** Reports itself, then tries to execute a bogus system call
**
** Invoked as:  userQ  x
**	 where x is the ID character
*/

USERMAIN(main)
{
	char ch = 'q'; // default character to print
	char buf[128];

	// process the command-line arguments
	switch (argc) {
	case 2:
		ch = argv[1][0];
		break;
	default:
		sprint(buf, "userQ: 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);

	// try something weird
	bogus();

	// should not have come back here!
	sprint(buf, "!!!!! %c returned from bogus syscall!?!?!\n", ch);
	cwrites(buf);

	exit(1);

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