static sexp sexp_get_file_descriptor_status_stub (sexp ctx, sexp self, sexp_sint_t n, sexp arg0) {
sexp res;
if (! (sexp_portp(arg0) || sexp_filenop(arg0) || sexp_fixnump(arg0)))
return sexp_xtype_exception(ctx, self, "not a port or file descriptor",arg0);
res = sexp_make_integer(ctx, fcntl((sexp_portp(arg0) ? sexp_port_fileno(arg0) : sexp_filenop(arg0) ? sexp_fileno_fd(arg0) : sexp_unbox_fixnum(arg0)), F_GETFL));
return res;
}
static sexp sexp_is_a_tty_p_stub (sexp ctx, sexp self, sexp_sint_t n, sexp arg0) {
sexp res;
if (! (sexp_portp(arg0) || sexp_filenop(arg0) || sexp_fixnump(arg0)))
return sexp_xtype_exception(ctx, self, "not a port or file descriptor",arg0);
res = sexp_make_boolean(isatty((sexp_portp(arg0) ? sexp_port_fileno(arg0) : sexp_filenop(arg0) ? sexp_fileno_fd(arg0) : sexp_unbox_fixnum(arg0))));
return res;
}
static sexp sexp_file_truncate_stub (sexp ctx, sexp self, sexp_sint_t n, sexp arg0, sexp arg1) {
sexp res;
if (! (sexp_portp(arg0) || sexp_filenop(arg0) || sexp_fixnump(arg0)))
return sexp_xtype_exception(ctx, self, "not a port or file descriptor",arg0);
if (! sexp_exact_integerp(arg1))
return sexp_type_exception(ctx, self, SEXP_FIXNUM, arg1);
res = sexp_make_integer(ctx, ftruncate((sexp_portp(arg0) ? sexp_port_fileno(arg0) : sexp_filenop(arg0) ? sexp_fileno_fd(arg0) : sexp_unbox_fixnum(arg0)), sexp_uint_value(arg1)));
return res;
}
static sexp sexp_set_file_descriptor_flags_x_stub (sexp ctx, sexp self, sexp_sint_t n, sexp arg0, sexp arg2) {
int err;
sexp res;
if (! (sexp_portp(arg0) || sexp_filenop(arg0) || sexp_fixnump(arg0)))
return sexp_xtype_exception(ctx, self, "not a port or file descriptor",arg0);
if (! sexp_exact_integerp(arg2))
return sexp_type_exception(ctx, self, SEXP_FIXNUM, arg2);
err = fcntl((sexp_portp(arg0) ? sexp_port_fileno(arg0) : sexp_filenop(arg0) ? sexp_fileno_fd(arg0) : sexp_unbox_fixnum(arg0)), F_SETFD, sexp_sint_value(arg2));
if (err) {
res = SEXP_FALSE;
} else {
res = SEXP_TRUE;
}
return res;
}
static void sexp_make_unblocking (sexp ctx, sexp port) {
if (!(sexp_portp(port) && sexp_port_fileno(port) >= 0))
return;
if (sexp_port_flags(port) == SEXP_PORT_UNKNOWN_FLAGS)
sexp_port_flags(port) = fcntl(sexp_port_fileno(port), F_GETFL);
if (!(sexp_port_flags(port) & O_NONBLOCK))
if (fcntl(sexp_port_fileno(port), F_SETFL, sexp_port_flags(port) | O_NONBLOCK) == 0)
sexp_port_flags(port) |= O_NONBLOCK;
}
static sexp sexp_load_standard_repl_env (sexp ctx, sexp env, sexp k) {
sexp_gc_var3(e, p, res);
sexp_gc_preserve3(ctx, e, p, res);
e = sexp_load_standard_env(ctx, env, k);
if (sexp_exceptionp(e)) return e;
sexp_load_standard_ports(ctx, e, stdin, stdout, stderr, 0);
#if SEXP_USE_GREEN_THREADS
p = sexp_param_ref(ctx, e, sexp_global(ctx, SEXP_G_CUR_IN_SYMBOL));
if (sexp_portp(p)) sexp_maybe_block_port(ctx, p, 1);
#endif
res = sexp_make_env(ctx);
sexp_env_parent(res) = e;
sexp_set_parameter(ctx, res, sexp_global(ctx, SEXP_G_INTERACTION_ENV_SYMBOL), res);
sexp_gc_release3(ctx);
return res;
}
sexp sexp_seek (sexp ctx, sexp self, sexp x, off_t offset, int whence) {
off_t res;
if (! (sexp_portp(x) || sexp_filenop(x)))
return sexp_type_exception(ctx, self, SEXP_IPORT, x);
if (sexp_filenop(x))
return sexp_make_integer(ctx, lseek(sexp_fileno_fd(x), offset, whence));
if (sexp_filenop(sexp_port_fd(x))) {
res = lseek(sexp_fileno_fd(sexp_port_fd(x)), offset, whence);
if (res >= 0 && !(whence == SEEK_CUR && offset == 0))
sexp_port_offset(x) = 0;
return sexp_make_integer(ctx, res);
}
if (sexp_stream_portp(x))
return sexp_make_integer(ctx, fseek(sexp_port_stream(x), offset, whence));
return sexp_xtype_exception(ctx, self, "not a seekable port", x);
}
/* block the current thread on the specified port */
static sexp sexp_blocker (sexp ctx, sexp self, sexp_sint_t n, sexp portorfd) {
int fd;
/* register the fd */
if (sexp_portp(portorfd))
fd = sexp_port_fileno(portorfd);
else if (sexp_filenop(portorfd))
fd = sexp_fileno_fd(portorfd);
else if (sexp_fixnump(portorfd))
fd = sexp_unbox_fixnum(portorfd);
else
return sexp_type_exception(ctx, self, SEXP_IPORT, portorfd);
if (fd >= 0)
sexp_insert_pollfd(ctx, fd, sexp_oportp(portorfd) ? POLLOUT : POLLIN);
/* pause the current thread */
sexp_context_waitp(ctx) = 1;
sexp_context_event(ctx) = portorfd;
sexp_insert_timed(ctx, ctx, SEXP_FALSE);
return SEXP_VOID;
}
sexp sexp_scheduler (sexp ctx, sexp self, sexp_sint_t n, sexp root_thread) {
int i, k;
struct timeval tval;
struct pollfd *pfds;
useconds_t usecs = 0;
sexp res, ls1, ls2, evt, runner, paused, front, pollfds;
sexp_gc_var1(tmp);
sexp_gc_preserve1(ctx, tmp);
front = sexp_global(ctx, SEXP_G_THREADS_FRONT);
paused = sexp_global(ctx, SEXP_G_THREADS_PAUSED);
/* check signals */
if (sexp_global(ctx, SEXP_G_THREADS_SIGNALS) != SEXP_ZERO) {
runner = sexp_global(ctx, SEXP_G_THREADS_SIGNAL_RUNNER);
if (! sexp_contextp(runner)) { /* ensure the runner exists */
if (sexp_envp(runner)) {
tmp = sexp_env_cell(runner, (tmp=sexp_intern(ctx, "signal-runner", -1)), 0);
if (sexp_pairp(tmp) && sexp_procedurep(sexp_cdr(tmp))) {
runner = sexp_make_thread(ctx, self, 2, sexp_cdr(tmp), SEXP_FALSE);
sexp_global(ctx, SEXP_G_THREADS_SIGNAL_RUNNER) = runner;
sexp_thread_start(ctx, self, 1, runner);
if (!sexp_pairp(front))
front = sexp_global(ctx, SEXP_G_THREADS_FRONT);
}
}
} else if (sexp_context_waitp(runner)) { /* wake it if it's sleeping */
sexp_context_waitp(runner) = 0;
sexp_thread_start(ctx, self, 1, runner);
}
}
/* check blocked fds */
pollfds = sexp_global(ctx, SEXP_G_THREADS_POLL_FDS);
if (sexp_pollfdsp(ctx, pollfds) && sexp_pollfds_num_fds(pollfds) > 0) {
pfds = sexp_pollfds_fds(pollfds);
k = poll(sexp_pollfds_fds(pollfds), sexp_pollfds_num_fds(pollfds), 0);
for (i=sexp_pollfds_num_fds(pollfds)-1; i>=0 && k>0; --i) {
if (pfds[i].revents > 0) { /* free all threads blocked on this fd */
k--;
/* maybe unblock the current thread */
evt = sexp_context_event(ctx);
if ((sexp_portp(evt) && (sexp_port_fileno(evt) == pfds[i].fd))
|| (sexp_fixnump(evt) && (sexp_unbox_fixnum(evt) == pfds[i].fd))) {
sexp_context_waitp(ctx) = 0;
sexp_context_timeoutp(ctx) = 0;
sexp_context_event(ctx) = SEXP_FALSE;
}
/* maybe unblock paused threads */
for (ls1=SEXP_NULL, ls2=paused; sexp_pairp(ls2); ) {
/* TODO: distinguish input and output on the same fd? */
evt = sexp_context_event(sexp_car(ls2));
if ((sexp_portp(evt) && sexp_port_fileno(evt) == pfds[i].fd)
|| (sexp_fixnump(evt) && sexp_unbox_fixnum(evt) == pfds[i].fd)) {
sexp_context_waitp(sexp_car(ls2)) = 0;
sexp_context_timeoutp(sexp_car(ls2)) = 0;
sexp_context_event(sexp_car(ls2)) = SEXP_FALSE;
if (ls1==SEXP_NULL)
sexp_global(ctx, SEXP_G_THREADS_PAUSED) = paused = sexp_cdr(ls2);
else
sexp_cdr(ls1) = sexp_cdr(ls2);
tmp = sexp_cdr(ls2);
sexp_cdr(ls2) = SEXP_NULL;
if (sexp_car(ls2) != ctx) {
if (! sexp_pairp(sexp_global(ctx, SEXP_G_THREADS_BACK))) {
sexp_global(ctx, SEXP_G_THREADS_FRONT) = front = ls2;
} else {
sexp_cdr(sexp_global(ctx, SEXP_G_THREADS_BACK)) = ls2;
}
sexp_global(ctx, SEXP_G_THREADS_BACK) = ls2;
}
ls2 = tmp;
} else {
ls1 = ls2;
ls2 = sexp_cdr(ls2);
}
}
if (i < (sexp_pollfds_num_fds(pollfds) - 1)) {
pfds[i] = pfds[sexp_pollfds_num_fds(pollfds) - 1];
}
sexp_pollfds_num_fds(pollfds) -= 1;
}
}
}
/* if we've terminated, check threads joining us */
if (sexp_context_refuel(ctx) <= 0) {
for (ls1=SEXP_NULL, ls2=paused; sexp_pairp(ls2); ) {
if (sexp_context_event(sexp_car(ls2)) == ctx) {
sexp_context_waitp(sexp_car(ls2)) = 0;
sexp_context_timeoutp(sexp_car(ls2)) = 0;
if (ls1==SEXP_NULL)
sexp_global(ctx, SEXP_G_THREADS_PAUSED) = paused = sexp_cdr(ls2);
else
sexp_cdr(ls1) = sexp_cdr(ls2);
tmp = sexp_cdr(ls2);
sexp_cdr(ls2) = SEXP_NULL;
if (! sexp_pairp(sexp_global(ctx, SEXP_G_THREADS_BACK))) {
sexp_global(ctx, SEXP_G_THREADS_FRONT) = front = ls2;
} else {
sexp_cdr(sexp_global(ctx, SEXP_G_THREADS_BACK)) = ls2;
}
sexp_global(ctx, SEXP_G_THREADS_BACK) = ls2;
ls2 = tmp;
} else {
ls1 = ls2;
ls2 = sexp_cdr(ls2);
}
}
}
/* check timeouts */
if (sexp_pairp(paused)) {
if (gettimeofday(&tval, NULL) == 0) {
ls1 = SEXP_NULL;
ls2 = paused;
while (sexp_pairp(ls2) && sexp_context_before(sexp_car(ls2), tval)) {
sexp_context_timeoutp(sexp_car(ls2)) = 1;
sexp_context_waitp(sexp_car(ls2)) = 0;
ls1 = ls2;
ls2 = sexp_cdr(ls2);
}
if (sexp_pairp(ls1)) {
sexp_cdr(ls1) = SEXP_NULL;
if (! sexp_pairp(sexp_global(ctx, SEXP_G_THREADS_BACK))) {
sexp_global(ctx, SEXP_G_THREADS_FRONT) = front = paused;
} else {
sexp_cdr(sexp_global(ctx, SEXP_G_THREADS_BACK)) = paused;
}
sexp_global(ctx, SEXP_G_THREADS_BACK) = ls1;
sexp_global(ctx, SEXP_G_THREADS_PAUSED) = paused = ls2;
}
}
}
/* dequeue next thread */
if (sexp_pairp(front)) {
res = sexp_car(front);
if ((sexp_context_refuel(ctx) <= 0) || sexp_context_waitp(ctx)) {
/* orig ctx is either terminated or paused */
sexp_global(ctx, SEXP_G_THREADS_FRONT) = sexp_cdr(front);
if (! sexp_pairp(sexp_cdr(front)))
sexp_global(ctx, SEXP_G_THREADS_BACK) = SEXP_NULL;
if (sexp_context_refuel(ctx) > 0 && sexp_not(sexp_memq(ctx, ctx, paused)))
sexp_insert_timed(ctx, ctx, SEXP_FALSE);
paused = sexp_global(ctx, SEXP_G_THREADS_PAUSED);
} else {
/* swap with front of queue */
sexp_car(sexp_global(ctx, SEXP_G_THREADS_FRONT)) = ctx;
/* rotate front of queue to back */
sexp_cdr(sexp_global(ctx, SEXP_G_THREADS_BACK))
= sexp_global(ctx, SEXP_G_THREADS_FRONT);
sexp_global(ctx, SEXP_G_THREADS_FRONT)
= sexp_cdr(sexp_global(ctx, SEXP_G_THREADS_FRONT));
sexp_global(ctx, SEXP_G_THREADS_BACK)
= sexp_cdr(sexp_global(ctx, SEXP_G_THREADS_BACK));
sexp_cdr(sexp_global(ctx, SEXP_G_THREADS_BACK)) = SEXP_NULL;
}
} else {
/* no threads to dequeue */
res = ctx;
/* prefer a thread we can wait on instead of spinning */
if (sexp_context_refuel(ctx) <= 0) {
for (ls1=paused; sexp_pairp(ls1); ls1=sexp_cdr(ls1)) {
evt = sexp_context_event(sexp_car(ls1));
if (sexp_fixnump(evt) || sexp_portp(evt)) {
res = sexp_car(ls1);
break;
}
}
}
}
if (sexp_context_waitp(res)) {
/* the only thread available was waiting */
if (sexp_pairp(paused)
&& sexp_context_before(sexp_car(paused), sexp_context_timeval(res))) {
tmp = res;
res = sexp_car(paused);
paused = sexp_global(ctx, SEXP_G_THREADS_PAUSED) = sexp_cdr(paused);
if (sexp_not(sexp_memq(ctx, tmp, paused)))
sexp_insert_timed(ctx, tmp, tmp);
} else {
sexp_delete_list(ctx, SEXP_G_THREADS_PAUSED, res);
}
paused = sexp_global(ctx, SEXP_G_THREADS_PAUSED);
usecs = 0;
if ((sexp_context_timeval(res).tv_sec == 0)
&& (sexp_context_timeval(res).tv_usec == 0)) {
/* no timeout, wait for default 10ms */
usecs = 10*1000;
} else {
/* wait until the next timeout */
gettimeofday(&tval, NULL);
if (tval.tv_sec <= sexp_context_timeval(res).tv_sec) {
usecs = (sexp_context_timeval(res).tv_sec - tval.tv_sec) * 1000000;
if (tval.tv_usec < sexp_context_timeval(res).tv_usec || usecs > 0)
usecs += sexp_context_timeval(res).tv_usec - tval.tv_usec;
}
}
/* take a nap to avoid busy looping */
usleep(usecs);
sexp_context_waitp(res) = 0;
sexp_context_timeoutp(res) = 1;
}
sexp_gc_release1(ctx);
return res;
}
sexp sexp_fileno (sexp ctx, sexp self, sexp_sint_t n, sexp port) {
if (! sexp_portp(port))
return sexp_type_exception(ctx, self, SEXP_IPORT, port);
return sexp_make_fixnum(fileno(sexp_port_stream(port)));
}
sexp sexp_scheduler (sexp ctx, sexp self, sexp_sint_t n, sexp root_thread) {
int i, k;
struct timeval tval;
struct pollfd *pfds;
useconds_t usecs = 0;
sexp res, ls1, ls2, runner, paused, front, pollfds;
sexp_gc_var1(tmp);
sexp_gc_preserve1(ctx, tmp);
front = sexp_global(ctx, SEXP_G_THREADS_FRONT);
paused = sexp_global(ctx, SEXP_G_THREADS_PAUSED);
/* check signals */
if (sexp_global(ctx, SEXP_G_THREADS_SIGNALS) != SEXP_ZERO) {
runner = sexp_global(ctx, SEXP_G_THREADS_SIGNAL_RUNNER);
if (! sexp_contextp(runner)) { /* ensure the runner exists */
if (sexp_envp(runner)) {
tmp = sexp_env_cell(runner, (tmp=sexp_intern(ctx, "signal-runner", -1)), 0);
if (sexp_pairp(tmp) && sexp_procedurep(sexp_cdr(tmp))) {
runner = sexp_make_thread(ctx, self, 2, sexp_cdr(tmp), SEXP_FALSE);
sexp_global(ctx, SEXP_G_THREADS_SIGNAL_RUNNER) = runner;
sexp_thread_start(ctx, self, 1, runner);
}
}
} else if (sexp_context_waitp(runner)) { /* wake it if it's sleeping */
sexp_context_waitp(runner) = 0;
sexp_thread_start(ctx, self, 1, runner);
}
}
/* check blocked fds */
pollfds = sexp_global(ctx, SEXP_G_THREADS_POLL_FDS);
if (sexp_pollfdsp(ctx, pollfds) && sexp_pollfds_num_fds(pollfds) > 0) {
pfds = sexp_pollfds_fds(pollfds);
k = poll(sexp_pollfds_fds(pollfds), sexp_pollfds_num_fds(pollfds), 0);
unblock_io_threads:
for (i=sexp_pollfds_num_fds(pollfds)-1; i>=0 && k>0; --i) {
if (pfds[i].revents > 0) { /* free all threads blocked on this fd */
k--;
pfds[i].events = 0; /* FIXME: delete from queue completely */
for (ls1=SEXP_NULL, ls2=paused; sexp_pairp(ls2); ) {
/* FIXME distinguish input and output on the same fd */
if (sexp_portp(sexp_context_event(sexp_car(ls2)))
&& sexp_port_fileno(sexp_context_event(sexp_car(ls2))) == pfds[i].fd) {
sexp_context_waitp(sexp_car(ls2)) = 0;
sexp_context_timeoutp(sexp_car(ls2)) = 0;
if (ls1==SEXP_NULL)
sexp_global(ctx, SEXP_G_THREADS_PAUSED) = paused = sexp_cdr(ls2);
else
sexp_cdr(ls1) = sexp_cdr(ls2);
tmp = sexp_cdr(ls2);
sexp_cdr(ls2) = SEXP_NULL;
if (! sexp_pairp(sexp_global(ctx, SEXP_G_THREADS_BACK))) {
sexp_global(ctx, SEXP_G_THREADS_FRONT) = front = ls2;
} else {
sexp_cdr(sexp_global(ctx, SEXP_G_THREADS_BACK)) = ls2;
}
sexp_global(ctx, SEXP_G_THREADS_BACK) = ls2;
ls2 = tmp;
} else {
ls1 = ls2;
ls2 = sexp_cdr(ls2);
}
}
}
}
}
/* if we've terminated, check threads joining us */
if (sexp_context_refuel(ctx) <= 0) {
for (ls1=SEXP_NULL, ls2=paused; sexp_pairp(ls2); ) {
if (sexp_context_event(sexp_car(ls2)) == ctx) {
sexp_context_waitp(sexp_car(ls2)) = 0;
sexp_context_timeoutp(sexp_car(ls2)) = 0;
if (ls1==SEXP_NULL)
sexp_global(ctx, SEXP_G_THREADS_PAUSED) = paused = sexp_cdr(ls2);
else
sexp_cdr(ls1) = sexp_cdr(ls2);
tmp = sexp_cdr(ls2);
sexp_cdr(ls2) = SEXP_NULL;
if (! sexp_pairp(sexp_global(ctx, SEXP_G_THREADS_BACK))) {
sexp_global(ctx, SEXP_G_THREADS_FRONT) = front = ls2;
} else {
sexp_cdr(sexp_global(ctx, SEXP_G_THREADS_BACK)) = ls2;
}
sexp_global(ctx, SEXP_G_THREADS_BACK) = ls2;
ls2 = tmp;
} else {
ls1 = ls2;
ls2 = sexp_cdr(ls2);
}
}
}
/* check timeouts */
if (sexp_pairp(paused)) {
if (gettimeofday(&tval, NULL) == 0) {
ls1 = SEXP_NULL;
ls2 = paused;
while (sexp_pairp(ls2) && sexp_context_before(sexp_car(ls2), tval)) {
sexp_context_timeoutp(sexp_car(ls2)) = 1;
sexp_context_waitp(ctx) = 0;
ls1 = ls2;
ls2 = sexp_cdr(ls2);
}
if (sexp_pairp(ls1)) {
sexp_cdr(ls1) = SEXP_NULL;
if (! sexp_pairp(sexp_global(ctx, SEXP_G_THREADS_BACK))) {
sexp_global(ctx, SEXP_G_THREADS_FRONT) = front = paused;
} else {
sexp_cdr(sexp_global(ctx, SEXP_G_THREADS_BACK)) = paused;
}
sexp_global(ctx, SEXP_G_THREADS_BACK) = ls1;
sexp_global(ctx, SEXP_G_THREADS_PAUSED) = paused = ls2;
}
}
}
/* dequeue next thread */
if (sexp_pairp(front)) {
res = sexp_car(front);
if ((sexp_context_refuel(ctx) <= 0) || sexp_context_waitp(ctx)) {
/* either terminated or paused */
sexp_global(ctx, SEXP_G_THREADS_FRONT) = sexp_cdr(front);
if (! sexp_pairp(sexp_cdr(front)))
sexp_global(ctx, SEXP_G_THREADS_BACK) = SEXP_NULL;
} else {
/* swap with front of queue */
sexp_car(sexp_global(ctx, SEXP_G_THREADS_FRONT)) = ctx;
/* rotate front of queue to back */
sexp_cdr(sexp_global(ctx, SEXP_G_THREADS_BACK))
= sexp_global(ctx, SEXP_G_THREADS_FRONT);
sexp_global(ctx, SEXP_G_THREADS_FRONT)
= sexp_cdr(sexp_global(ctx, SEXP_G_THREADS_FRONT));
sexp_global(ctx, SEXP_G_THREADS_BACK)
= sexp_cdr(sexp_global(ctx, SEXP_G_THREADS_BACK));
sexp_cdr(sexp_global(ctx, SEXP_G_THREADS_BACK)) = SEXP_NULL;
}
} else {
res = ctx;
}
if (sexp_context_waitp(res)) {
/* the only thread available was waiting */
if (sexp_pairp(paused)
&& sexp_context_before(sexp_car(paused), sexp_context_timeval(res))) {
tmp = res;
res = sexp_car(paused);
sexp_global(ctx, SEXP_G_THREADS_PAUSED) = sexp_cdr(paused);
if (sexp_not(sexp_memq(ctx, tmp, paused)))
sexp_insert_timed(ctx, tmp, tmp);
}
usecs = 0;
if ((sexp_context_timeval(res).tv_sec == 0)
&& (sexp_context_timeval(res).tv_usec == 0)) {
/* no timeout, wait for default 10ms */
usecs = 10*1000;
} else {
/* wait until the next timeout */
gettimeofday(&tval, NULL);
if (tval.tv_sec <= sexp_context_timeval(res).tv_sec) {
usecs = (sexp_context_timeval(res).tv_sec - tval.tv_sec) * 1000000;
if (tval.tv_usec < sexp_context_timeval(res).tv_usec || usecs > 0)
usecs += sexp_context_timeval(res).tv_usec - tval.tv_usec;
}
}
/* either wait on an fd, or just sleep */
pollfds = sexp_global(res, SEXP_G_THREADS_POLL_FDS);
if (sexp_portp(sexp_context_event(res)) && sexp_pollfdsp(ctx, pollfds)) {
if ((k = poll(sexp_pollfds_fds(pollfds), sexp_pollfds_num_fds(pollfds), usecs/1000)) > 0) {
pfds = sexp_pollfds_fds(pollfds);
goto unblock_io_threads;
}
} else {
usleep(usecs);
sexp_context_waitp(res) = 0;
sexp_context_timeoutp(res) = 1;
}
}
sexp_gc_release1(ctx);
return res;
}
sexp sexp_tell (sexp ctx, sexp self, sexp x) {
if (sexp_portp(x) && sexp_stream_portp(x))
return sexp_make_integer(ctx, ftell(sexp_port_stream(x)));
return sexp_seek(ctx, self, x, 0, SEEK_CUR);
}