/*
 * bauble: a tiny room-based messaging system
 *
 * lock: person/system/tty locking.
 */
#include <fcntl.h>
#if OS2|MSDOS
#define S_IREAD	0444
#define S_IWRITE 0222
#endif
#include "news.h"

extern char *basename();

/*
 * mklock() constructs a lockname
 */
static char *
mklock(thing)
char *thing;
{
    static char lockname[128];

    makepath(lockname, SPOOL, "@%s.lck", thing);
#if GEMDOS|MSDOS|OS2
    {   register char *s;

	for (s=lockname+strlen(SPOOL); *s; s++)
	    if (*s == ':')
		*s = '!';
    }
#endif
    return lockname;
} /* mklock */


/*
 * lock() puts a lock on someone
 */
lock(thing)
char *thing;
{
    register char *lock = mklock(thing);
    register fd;

    if ((fd=open(lock, O_RDWR|O_EXCL|O_CREAT, S_IREAD|S_IWRITE)) >= 0) {
	close(fd);
	return 1;
    }
    return 0;
}


/*
 * unlock() lifts the lock on someone
 */
unlock(thing)
char *thing;
{
    unlink(mklock(thing));
}