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-rw-r--r--libguile/poll.c229
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diff --git a/libguile/poll.c b/libguile/poll.c
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+++ b/libguile/poll.c
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+/* Copyright 2010,2013,2018
+ Free Software Foundation, Inc.
+
+ This file is part of Guile.
+
+ Guile is free software: you can redistribute it and/or modify it
+ under the terms of the GNU Lesser General Public License as published
+ by the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
+
+ Guile is distributed in the hope that it will be useful, but WITHOUT
+ ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
+ License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with Guile. If not, see
+ <https://www.gnu.org/licenses/>. */
+
+
+
+
+#define _GNU_SOURCE
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include <errno.h>
+#include <poll.h>
+
+#include "async.h"
+#include "bytevectors.h"
+#include "error.h"
+#include "extensions.h"
+#include "gsubr.h"
+#include "modules.h"
+#include "numbers.h"
+#include "ports-internal.h"
+#include "syscalls.h"
+#include "vectors.h"
+#include "version.h"
+
+#include "poll.h"
+
+
+
+
+/* {Poll}
+ */
+
+/* Poll a set of file descriptors, waiting until one or more of them is
+ ready to perform input or output.
+
+ This is a low-level interface. See the `(ice-9 poll)' module for a more
+ usable wrapper.
+
+ `pollfds' is expected to be a bytevector, laid out in contiguous blocks of 64
+ bits. Each block has the format of one `struct pollfd': a 32-bit int file
+ descriptor, a 16-bit int events mask, and a 16-bit int revents mask.
+
+ The number of pollfd structures in `pollfds' is specified in
+ `nfds'. `pollfds' must be at least long enough to support that number of
+ structures. It may be longer, in which case the trailing entries are left
+ untouched.
+
+ The pollfds bytevector is modified directly, setting the returned events in
+ the final two bytes (the revents member).
+
+ Since Scheme ports can buffer input or output in userspace, a Scheme
+ poll interface needs to take that into account as well. The `ports'
+ argument, a vector big enough for `nfds' elements, is given for this
+ purpose. If a pollfd entry has a corresponding open port, that port
+ is scanned for available input or output before dropping into the
+ poll. If any port has buffered I/O available, the poll syscall is
+ still issued, but with a timeout of 0 milliseconds, and a full port
+ scan occurs after the poll returns.
+
+ If timeout is given and is non-negative, the poll will return after that
+ number of milliseconds if no fd became active.
+ */
+static SCM
+scm_primitive_poll (SCM pollfds, SCM nfds, SCM ports, SCM timeout)
+#define FUNC_NAME "primitive-poll"
+{
+ int rv = 0;
+ nfds_t i;
+ nfds_t c_nfds;
+ int c_timeout;
+ int have_buffered_io = 0;
+ struct pollfd *fds;
+
+ SCM_VALIDATE_BYTEVECTOR (SCM_ARG1, pollfds);
+ c_nfds = scm_to_uint32 (nfds);
+ c_timeout = scm_to_int (timeout);
+
+ if (SCM_UNLIKELY (SCM_BYTEVECTOR_LENGTH (pollfds)
+ < c_nfds * sizeof(struct pollfd)))
+ SCM_OUT_OF_RANGE (SCM_ARG2, nfds);
+
+ SCM_VALIDATE_VECTOR (SCM_ARG3, ports);
+ if (SCM_UNLIKELY (SCM_SIMPLE_VECTOR_LENGTH (ports) < c_nfds))
+ SCM_OUT_OF_RANGE (SCM_ARG3, ports);
+
+ fds = (struct pollfd*)SCM_BYTEVECTOR_CONTENTS (pollfds);
+
+ for (i = 0; i < c_nfds; i++)
+ {
+ SCM port = SCM_SIMPLE_VECTOR_REF (ports, i);
+ short int revents = 0;
+
+ if (SCM_PORTP (port))
+ {
+ if (SCM_CLOSEDP (port))
+ revents |= POLLERR;
+ else
+ {
+ scm_t_port *pt = SCM_PORT (port);
+ size_t tmp;
+
+ if (scm_port_buffer_can_take (pt->read_buf, &tmp) > 0)
+ /* Buffered input waiting to be read. */
+ revents |= POLLIN;
+ if (SCM_OUTPUT_PORT_P (port)
+ && scm_port_buffer_can_put (pt->write_buf, &tmp) > 1)
+ /* Buffered output possible. The "> 1" is because
+ writing the last byte would flush the port. */
+ revents |= POLLOUT;
+ }
+ }
+
+ if (revents & fds[i].events)
+ {
+ have_buffered_io = 1;
+ c_timeout = 0;
+ break;
+ }
+ }
+
+ SCM_SYSCALL (rv = poll (fds, c_nfds, c_timeout));
+
+ if (rv == -1)
+ SCM_SYSERROR;
+
+ if (have_buffered_io)
+ for (i = 0; i < c_nfds; i++)
+ {
+ SCM port = SCM_SIMPLE_VECTOR_REF (ports, i);
+ short int revents = 0;
+
+ if (SCM_PORTP (port))
+ {
+ if (SCM_CLOSEDP (port))
+ revents |= POLLERR;
+ else
+ {
+ scm_t_port *pt = SCM_PORT (port);
+ size_t tmp;
+
+ if (scm_port_buffer_can_take (pt->read_buf, &tmp) > 0)
+ /* Buffered input waiting to be read. */
+ revents |= POLLIN;
+ if (SCM_OUTPUT_PORT_P (port)
+ && scm_port_buffer_can_put (pt->write_buf, &tmp) > 1)
+ /* Buffered output possible. The "> 1" is because
+ writing the last byte would flush the port. */
+ revents |= POLLOUT;
+ }
+ }
+
+ /* Mask in the events we are interested, and test if any are
+ interesting. */
+ if ((revents &= fds[i].events))
+ {
+ /* Could be the underlying fd is also ready for reading. */
+ if (!fds[i].revents)
+ rv++;
+
+ /* In any case, add these events to whatever the syscall
+ set. */
+ fds[i].revents |= revents;
+ }
+ }
+
+ return scm_from_int (rv);
+}
+#undef FUNC_NAME
+
+
+
+
+static void
+scm_init_poll (void)
+{
+ scm_c_define_gsubr ("primitive-poll", 4, 0, 0, scm_primitive_poll);
+ scm_c_define ("%sizeof-struct-pollfd", scm_from_size_t (sizeof (struct pollfd)));
+
+#ifdef POLLIN
+ scm_c_define ("POLLIN", scm_from_int (POLLIN));
+#endif
+#ifdef POLLPRI
+ scm_c_define ("POLLPRI", scm_from_int (POLLPRI));
+#endif
+#ifdef POLLOUT
+ scm_c_define ("POLLOUT", scm_from_int (POLLOUT));
+#endif
+#ifdef POLLRDHUP
+ scm_c_define ("POLLRDHUP", scm_from_int (POLLRDHUP));
+#endif
+#ifdef POLLERR
+ scm_c_define ("POLLERR", scm_from_int (POLLERR));
+#endif
+#ifdef POLLHUP
+ scm_c_define ("POLLHUP", scm_from_int (POLLHUP));
+#endif
+#ifdef POLLNVAL
+ scm_c_define ("POLLNVAL", scm_from_int (POLLNVAL));
+#endif
+
+}
+
+void
+scm_register_poll (void)
+{
+ scm_c_register_extension ("libguile-" SCM_EFFECTIVE_VERSION,
+ "scm_init_poll",
+ (scm_t_extension_init_func) scm_init_poll,
+ NULL);
+}