/* Copyright (C) 2010, 2013 Free Software Foundation, Inc. * * This library 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. * * This library 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 this library; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA * 02110-1301 USA */ #define _GNU_SOURCE #ifdef HAVE_CONFIG_H # include #endif #include #include "libguile/_scm.h" #include "libguile/bytevectors.h" #include "libguile/error.h" #include "libguile/numbers.h" #include "libguile/ports-internal.h" #include "libguile/validate.h" #include "libguile/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); } /* Local Variables: c-file-style: "gnu" End: */