Subversion Repositories planix.SVN

#include <u.h>
#include <libc.h>

static struct
{
        int     fd;
        int     consfd;
        char    *name;
        Dir     *d;
        Dir     *consd;
        Lock;
} sl =
{
        -1, -1,
};

static void
_syslogopen(void)
{
        char buf[1024];

        if(sl.fd >= 0)
                close(sl.fd);
        snprint(buf, sizeof(buf), "/sys/log/%s", sl.name);
        sl.fd = open(buf, OWRITE|OCEXEC);
}

static int
eqdirdev(Dir *a, Dir *b)
{
        return a != nil && b != nil &&
                a->dev == b->dev && a->type == b->type &&
                a->qid.path == b->qid.path;
}

/*
 * Print
 *  sysname: time: mesg
 * on /sys/log/logname.
 * If cons or log file can't be opened, print on the system console, too.
 */
void
syslog(int cons, char *logname, char *fmt, ...)
{
        char buf[1024];
        char *ctim, *p;
        va_list arg;
        int n;
        Dir *d;
        char err[ERRMAX];

        err[0] = '\0';
        errstr(err, sizeof err);
        lock(&sl);

        /*
         *  paranoia makes us stat to make sure a fork+close
         *  hasn't broken our fd's
         */
        d = dirfstat(sl.fd);
        if(sl.fd < 0 || sl.name == nil || strcmp(sl.name, logname) != 0 ||
           !eqdirdev(d, sl.d)){
                free(sl.name);
                sl.name = strdup(logname);
                if(sl.name == nil)
                        cons = 1;
                else{
                        free(sl.d);
                        sl.d = nil;
                        _syslogopen();
                        if(sl.fd < 0)
                                cons = 1;
                        else
                                sl.d = dirfstat(sl.fd);
                }
        }
        free(d);
        if(cons){
                d = dirfstat(sl.consfd);
                if(sl.consfd < 0 || !eqdirdev(d, sl.consd)){
                        free(sl.consd);
                        sl.consd = nil;
                        sl.consfd = open("#c/cons", OWRITE|OCEXEC);
                        if(sl.consfd >= 0)
                                sl.consd = dirfstat(sl.consfd);
                }
                free(d);
        }

        if(fmt == nil){
                unlock(&sl);
                return;
        }

        ctim = ctime(time(0));
        p = buf + snprint(buf, sizeof(buf)-1, "%s ", sysname());
        strncpy(p, ctim+4, 15);
        p += 15;
        *p++ = ' ';
        errstr(err, sizeof err);
        va_start(arg, fmt);
        p = vseprint(p, buf+sizeof(buf)-1, fmt, arg);
        va_end(arg);
        *p++ = '\n';
        n = p - buf;

        if(sl.fd >= 0){
                seek(sl.fd, 0, 2);
                write(sl.fd, buf, n);
        }

        if(cons && sl.consfd >=0)
                write(sl.consfd, buf, n);

        unlock(&sl);
}