utils.c

经典的ppp程序

    if (len > 32)
	printer(arg, "%.32B ...", p);
    else
	printer(arg, "%.*B", len, p);
}

/*
 * init_pr_log, end_pr_log - initialize and finish use of pr_log.
 */

static char line[256];		/* line to be logged accumulated here */
static char *linep;		/* current pointer within line */
static int llevel;		/* level for logging */

void
init_pr_log(prefix, level)
     char *prefix;
     int level;
{
	linep = line;
	if (prefix != NULL) {
		strlcpy(line, prefix, sizeof(line));
		linep = line + strlen(line);
	}
	llevel = level;
}

void
end_pr_log()
{
	if (linep != line) {
		*linep = 0;
		log_write(llevel, line);
	}
}

/*
 * pr_log - printer routine for outputting to syslog
 */
void
pr_log __V((void *arg, char *fmt, ...))
{
	int l, n;
	va_list pvar;
	char *p, *eol;
	char buf[256];

#if defined(__STDC__)
	va_start(pvar, fmt);
#else
	void *arg;
	char *fmt;
	va_start(pvar);
	arg = va_arg(pvar, void *);
	fmt = va_arg(pvar, char *);
#endif

	n = vslprintf(buf, sizeof(buf), fmt, pvar);
	va_end(pvar);

	p = buf;
	eol = strchr(buf, '\n');
	if (linep != line) {
		l = (eol == NULL)? n: eol - buf;
		if (linep + l < line + sizeof(line)) {
			if (l > 0) {
				memcpy(linep, buf, l);
				linep += l;
			}
			if (eol == NULL)
				return;
			p = eol + 1;
			eol = strchr(p, '\n');
		}
		*linep = 0;
		log_write(llevel, line);
		linep = line;
	}

	while (eol != NULL) {
		*eol = 0;
		log_write(llevel, p);
		p = eol + 1;
		eol = strchr(p, '\n');
	}

	/* assumes sizeof(buf) <= sizeof(line) */
	l = buf + n - p;
	if (l > 0) {
		memcpy(line, p, n);
		linep = line + l;
	}
}

/*
 * print_string - print a readable representation of a string using
 * printer.
 */
void
print_string(p, len, printer, arg)
    char *p;
    int len;
    void (*printer) __P((void *, char *, ...));
    void *arg;
{
    int c;

    printer(arg, "\"");
    for (; len > 0; --len) {
	c = *p++;
	if (' ' <= c && c <= '~') {
	    if (c == '\\' || c == '"')
		printer(arg, "\\");
	    printer(arg, "%c", c);
	} else {
	    switch (c) {
	    case '\n':
		printer(arg, "\\n");
		break;
	    case '\r':
		printer(arg, "\\r");
		break;
	    case '\t':
		printer(arg, "\\t");
		break;
	    default:
		printer(arg, "\\%.3o", c);
	    }
	}
    }
    printer(arg, "\"");
}

/*
 * logit - does the hard work for fatal et al.
 */
static void
logit(level, fmt, args)
    int level;
    char *fmt;
    va_list args;
{
    int n;
    char buf[1024];

    n = vslprintf(buf, sizeof(buf), fmt, args);
    log_write(level, buf);
}

static void
log_write(level, buf)
    int level;
    char *buf;
{
    syslog(level, "%s", buf);
    if (log_to_fd >= 0 && (level != LOG_DEBUG || debug)) {
	int n = strlen(buf);

	if (n > 0 && buf[n-1] == '\n')
	    --n;
	if (write(log_to_fd, buf, n) != n
	    || write(log_to_fd, "\n", 1) != 1)
	    log_to_fd = -1;
    }
}

/*
 * fatal - log an error message and die horribly.
 */
void
fatal __V((char *fmt, ...))
{
    va_list pvar;

#if defined(__STDC__)
    va_start(pvar, fmt);
#else
    char *fmt;
    va_start(pvar);
    fmt = va_arg(pvar, char *);
#endif

    logit(LOG_ERR, fmt, pvar);
    va_end(pvar);

    die(1);			/* as promised */
}

/*
 * error - log an error message.
 */
void
error __V((char *fmt, ...))
{
    va_list pvar;

#if defined(__STDC__)
    va_start(pvar, fmt);
#else
    char *fmt;
    va_start(pvar);
    fmt = va_arg(pvar, char *);
#endif

    logit(LOG_ERR, fmt, pvar);
    va_end(pvar);
}

/*
 * warn - log a warning message.
 */
void
warn __V((char *fmt, ...))
{
    va_list pvar;

#if defined(__STDC__)
    va_start(pvar, fmt);
#else
    char *fmt;
    va_start(pvar);
    fmt = va_arg(pvar, char *);
#endif

    logit(LOG_WARNING, fmt, pvar);
    va_end(pvar);
}

/*
 * notice - log a notice-level message.
 */
void
notice __V((char *fmt, ...))
{
    va_list pvar;

#if defined(__STDC__)
    va_start(pvar, fmt);
#else
    char *fmt;
    va_start(pvar);
    fmt = va_arg(pvar, char *);
#endif

    logit(LOG_NOTICE, fmt, pvar);
    va_end(pvar);
}

/*
 * info - log an informational message.
 */
void
info __V((char *fmt, ...))
{
    va_list pvar;

#if defined(__STDC__)
    va_start(pvar, fmt);
#else
    char *fmt;
    va_start(pvar);
    fmt = va_arg(pvar, char *);
#endif

    logit(LOG_INFO, fmt, pvar);
    va_end(pvar);
}

/*
 * dbglog - log a debug message.
 */
void
dbglog __V((char *fmt, ...))
{
    va_list pvar;

#if defined(__STDC__)
    va_start(pvar, fmt);
#else
    char *fmt;
    va_start(pvar);
    fmt = va_arg(pvar, char *);
#endif

    logit(LOG_DEBUG, fmt, pvar);
    va_end(pvar);
}

/* Procedures for locking the serial device using a lock file. */
#ifndef LOCK_DIR
#ifdef _linux_
#define LOCK_DIR	"/var/lock"
#else
#ifdef SVR4
#define LOCK_DIR	"/var/spool/locks"
#else
#define LOCK_DIR	"/var/spool/lock"
#endif
#endif
#endif /* LOCK_DIR */

static char lock_file[MAXPATHLEN];

/*
 * lock - create a lock file for the named device
 */
int
lock(dev)
    char *dev;
{
#ifdef LOCKLIB
    int result;

    result = mklock (dev, (void *) 0);
    if (result == 0) {
	strlcpy(lock_file, sizeof(lock_file), dev);
	return 0;
    }

    if (result > 0)
        notice("Device %s is locked by pid %d", dev, result);
    else
	error("Can't create lock file %s", lock_file);
    return -1;

#else /* LOCKLIB */

    char lock_buffer[12];
    int fd, pid, n;

#ifdef SVR4
    struct stat sbuf;

    if (stat(dev, &sbuf) < 0) {
	error("Can't get device number for %s: %m", dev);
	return -1;
    }
    if ((sbuf.st_mode & S_IFMT) != S_IFCHR) {
	error("Can't lock %s: not a character device", dev);
	return -1;
    }
    slprintf(lock_file, sizeof(lock_file), "%s/LK.%03d.%03d.%03d",
	     LOCK_DIR, major(sbuf.st_dev),
	     major(sbuf.st_rdev), minor(sbuf.st_rdev));
#else
    char *p;

    if ((p = strrchr(dev, '/')) != NULL)
	dev = p + 1;
    slprintf(lock_file, sizeof(lock_file), "%s/LCK..%s", LOCK_DIR, dev);
#endif

    while ((fd = open(lock_file, O_EXCL | O_CREAT | O_RDWR, 0644)) < 0) {
	if (errno != EEXIST) {
	    error("Can't create lock file %s: %m", lock_file);
	    break;
	}

	/* Read the lock file to find out who has the device locked. */
	fd = open(lock_file, O_RDONLY, 0);
	if (fd < 0) {
	    if (errno == ENOENT) /* This is just a timing problem. */
		continue;
	    error("Can't open existing lock file %s: %m", lock_file);
	    break;
	}
#ifndef LOCK_BINARY
	n = read(fd, lock_buffer, 11);
#else
	n = read(fd, &pid, sizeof(pid));
#endif /* LOCK_BINARY */
	close(fd);
	fd = -1;
	if (n <= 0) {
	    error("Can't read pid from lock file %s", lock_file);
	    break;
	}

	/* See if the process still exists. */
#ifndef LOCK_BINARY
	lock_buffer[n] = 0;
	pid = atoi(lock_buffer);
#endif /* LOCK_BINARY */
	if (pid == getpid())
	    return 1;		/* somebody else locked it for us */
	if (pid == 0
	    || (kill(pid, 0) == -1 && errno == ESRCH)) {
	    if (unlink (lock_file) == 0) {
		notice("Removed stale lock on %s (pid %d)", dev, pid);
		continue;
	    }
	    warn("Couldn't remove stale lock on %s", dev);
	} else
	    notice("Device %s is locked by pid %d", dev, pid);
	break;
    }

    if (fd < 0) {
	lock_file[0] = 0;
	return -1;
    }

    pid = getpid();
#ifndef LOCK_BINARY
    slprintf(lock_buffer, sizeof(lock_buffer), "%10d\n", pid);
    write (fd, lock_buffer, 11);
#else
    write(fd, &pid, sizeof (pid));
#endif
    close(fd);
    return 0;

#endif
}

/*
 * relock - called to update our lockfile when we are about to detach,
 * thus changing our pid (we fork, the child carries on, and the parent dies).
 * Note that this is called by the parent, with pid equal to the pid
 * of the child.  This avoids a potential race which would exist if
 * we had the child rewrite the lockfile (the parent might die first,
 * and another process could think the lock was stale if it checked
 * between when the parent died and the child rewrote the lockfile).
 */
int
relock(pid)
    int pid;
{
#ifdef LOCKLIB
    /* XXX is there a way to do this? */
    return -1;
#else /* LOCKLIB */

    int fd;
    char lock_buffer[12];

    if (lock_file[0] == 0)
	return -1;
    fd = open(lock_file, O_WRONLY, 0);
    if (fd < 0) {
	error("Couldn't reopen lock file %s: %m", lock_file);
	lock_file[0] = 0;
	return -1;
    }

#ifndef LOCK_BINARY
    slprintf(lock_buffer, sizeof(lock_buffer), "%10d\n", pid);
    write (fd, lock_buffer, 11);
#else
    write(fd, &pid, sizeof(pid));
#endif /* LOCK_BINARY */
    close(fd);
    return 0;

#endif /* LOCKLIB */
}

/*
 * unlock - remove our lockfile
 */
void
unlock()
{
    if (lock_file[0]) {
#ifdef LOCKLIB
	(void) rmlock(lock_file, (void *) 0);
#else
	unlink(lock_file);
#endif
	lock_file[0] = 0;
    }
}