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elinks/src/main/select.c

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/* File descriptors managment and switching */
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <errno.h>
#include <signal.h>
#include <string.h> /* FreeBSD FD_ZERO() macro calls bzero() */
#ifdef __GNU__ /* For GNU Hurd bug workaround in set_handlers() */
#include <sys/stat.h> /* OS/2 needs this after sys/types.h */
#endif
#include <sys/types.h>
#ifdef HAVE_SYS_WAIT_H
#include <sys/wait.h>
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
/* This must be here, thanks to BSD. */
#ifdef HAVE_INTTYPES_H
#include <inttypes.h> /* OMG */
#endif
#if defined(HAVE_POLL_H) && defined(HAVE_POLL) && !defined(INTERIX) && !defined(__HOS_AIX__)
#define USE_POLL
#include <poll.h>
#endif
#if defined(HAVE_LIBEV) && !defined(OPENVMS) && !defined(DOS)
#ifdef HAVE_LIBEV_EVENT_H
#include <libev/event.h>
#elif defined(HAVE_EVENT_H)
#include <event.h>
#endif
#define USE_LIBEVENT
#endif
#if (defined(HAVE_EVENT_H) || defined(HAVE_EV_EVENT_H) || defined(HAVE_LIBEV_EVENT_H)) && defined(HAVE_LIBEVENT) && !defined(OPENVMS) && !defined(DOS)
#if defined(HAVE_EVENT_H)
#include <event.h>
#elif defined(HAVE_EV_EVENT_H)
#include <ev-event.h>
#endif
#define USE_LIBEVENT
#endif
#ifdef HAVE_SYS_SELECT_H
#include <sys/select.h>
#endif
#define EINTRLOOPX(ret_, call_, x_) \
do { \
(ret_) = (call_); \
} while ((ret_) == (x_) && errno == EINTR)
#define EINTRLOOP(ret_, call_) EINTRLOOPX(ret_, call_, -1)
#include "elinks.h"
#include "intl/gettext/libintl.h"
#include "main/main.h"
#include "main/select.h"
#include "main/timer.h"
#include "osdep/signals.h"
#include "terminal/terminal.h"
#include "util/error.h"
#include "util/memory.h"
#include "util/time.h"
#ifndef FD_SETSIZE
#define FD_SETSIZE 1024
#endif
/*
#define DEBUG_CALLS
*/
static int n_threads = 0;
struct thread {
select_handler_T read_func;
select_handler_T write_func;
select_handler_T error_func;
void *data;
#ifdef USE_LIBEVENT
struct event *read_event;
struct event *write_event;
#endif
};
#ifdef CONFIG_OS_WIN32
/* CreatePipe produces big numbers for handles */
#undef FD_SETSIZE
#define FD_SETSIZE 4096
#endif
static struct thread *threads = NULL;
static fd_set w_read;
static fd_set w_write;
static fd_set w_error;
static fd_set x_read;
static fd_set x_write;
static fd_set x_error;
static int w_max;
int
get_file_handles_count(void)
{
int i = 0, j;
for (j = 0; j < FD_SETSIZE; j++)
if (threads[j].read_func
|| threads[j].write_func
|| threads[j].error_func)
i++;
return i;
}
struct bottom_half {
LIST_HEAD(struct bottom_half);
select_handler_T fn;
void *data;
};
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static INIT_LIST_OF(struct bottom_half, bottom_halves);
int
register_bottom_half_do(select_handler_T fn, void *data)
{
struct bottom_half *bh;
foreach (bh, bottom_halves)
if (bh->fn == fn && bh->data == data)
return 0;
bh = mem_alloc(sizeof(*bh));
if (!bh) return -1;
bh->fn = fn;
bh->data = data;
add_to_list(bottom_halves, bh);
return 0;
}
void
check_bottom_halves(void)
{
while (!list_empty(bottom_halves)) {
struct bottom_half *bh = bottom_halves.prev;
select_handler_T fn = bh->fn;
void *data = bh->data;
del_from_list(bh);
mem_free(bh);
fn(data);
}
}
static void
restrict_fds(void)
{
#if defined(RLIMIT_OFILE) && !defined(RLIMIT_NOFILE)
#define RLIMIT_NOFILE RLIMIT_OFILE
#endif
#if defined(HAVE_GETRLIMIT) && defined(HAVE_SETRLIMIT) && defined(RLIMIT_NOFILE)
struct rlimit limit;
int rs;
EINTRLOOP(rs, getrlimit(RLIMIT_NOFILE, &limit));
if (rs)
goto skip_limit;
if (limit.rlim_cur > FD_SETSIZE) {
limit.rlim_cur = FD_SETSIZE;
EINTRLOOP(rs, setrlimit(RLIMIT_NOFILE, &limit));
}
skip_limit:;
#endif
}
#ifdef USE_LIBEVENT
int event_enabled = 0;
#ifndef HAVE_EVENT_GET_STRUCT_EVENT_SIZE
#define sizeof_struct_event sizeof(struct event)
#else
#define sizeof_struct_event (event_get_struct_event_size())
#endif
static inline
struct event *timer_event(struct timer *tm)
{
return (struct event *)((unsigned char *)tm - sizeof_struct_event);
}
#ifdef HAVE_EVENT_BASE_SET
struct event_base *event_base;
#endif
static void
event_callback(int h, short ev, void *data)
{
#ifndef EV_PERSIST
if (event_add((struct event *)data, NULL) == -1)
elinks_internal("ERROR: event_add failed: %s", strerror(errno));
#endif
if (!(ev & EV_READ) == !(ev & EV_WRITE))
elinks_internal("event_callback: invalid flags %d on handle %d", (int)ev, h);
if (ev & EV_READ) {
#if defined(HAVE_LIBEV)
/* Old versions of libev badly interact with fork and fire
* events spuriously. */
if (ev_version_major() < 4 && !can_read(h)) return;
#endif
threads[h].read_func(threads[h].data);
} else if (ev & EV_WRITE) {
#if defined(HAVE_LIBEV)
/* Old versions of libev badly interact with fork and fire
* events spuriously. */
if (ev_version_major() < 4 && !can_write(h)) return;
#endif
threads[h].write_func(threads[h].data);
}
check_bottom_halves();
}
static void
set_event_for_action(int h, void (*func)(void *), struct event **evptr, short evtype)
{
if (func) {
if (!*evptr) {
#ifdef EV_PERSIST
evtype |= EV_PERSIST;
#endif
*evptr = mem_alloc(sizeof_struct_event);
event_set(*evptr, h, evtype, event_callback, *evptr);
#ifdef HAVE_EVENT_BASE_SET
if (event_base_set(event_base, *evptr) == -1)
elinks_internal("ERROR: event_base_set failed: %s, handle %d", strerror(errno), h);
#endif
}
if (event_add(*evptr, NULL) == -1)
elinks_internal("ERROR: event_add failed: %s, handle %d", strerror(errno), h);
} else {
if (*evptr) {
if (event_del(*evptr) == -1)
elinks_internal("ERROR: event_del failed: %s, handle %d", strerror(errno), h);
}
}
}
static void
set_events_for_handle(int h)
{
set_event_for_action(h, threads[h].read_func, &threads[h].read_event, EV_READ);
set_event_for_action(h, threads[h].write_func, &threads[h].write_event, EV_WRITE);
}
static void
enable_libevent(void)
{
int i;
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if (get_cmd_opt_bool("no-libevent"))
return;
#if !defined(NO_FORK_ON_EXIT) && defined(HAVE_KQUEUE) && !defined(HAVE_EVENT_REINIT)
/* kqueue doesn't work after fork */
if (!F)
return;
#endif
#if defined(HAVE_EVENT_CONFIG_SET_FLAG)
{
struct event_config *cfg;
cfg = event_config_new();
if (!cfg)
return;
if (event_config_set_flag(cfg, EVENT_BASE_FLAG_NOLOCK) == -1) {
event_config_free(cfg);
return;
}
event_base = event_base_new_with_config(cfg);
event_config_free(cfg);
if (!event_base)
return;
}
#elif defined(HAVE_EVENT_BASE_NEW)
event_base = event_base_new();
if (!event_base)
return;
#elif defined(HAVE_EVENT_BASE_SET)
event_base = event_init();
if (!event_base)
return;
#else
event_init();
#endif
event_enabled = 1;
for (i = 0; i < w_max; i++)
set_events_for_handle(i);
/*
foreach(tm, timers)
set_event_for_timer(tm);
*/
set_events_for_timer();
}
static void
terminate_libevent(void)
{
int i;
if (event_enabled) {
for (i = 0; i < n_threads; i++) {
set_event_for_action(i, NULL, &threads[i].read_event, EV_READ);
if (threads[i].read_event)
mem_free(threads[i].read_event);
set_event_for_action(i, NULL, &threads[i].write_event, EV_WRITE);
if (threads[i].write_event)
mem_free(threads[i].write_event);
}
#ifdef HAVE_EVENT_BASE_FREE
event_base_free(event_base);
#endif
event_enabled = 0;
}
}
static void
do_event_loop(int flags)
{
int e;
#ifdef HAVE_EVENT_BASE_SET
e = event_base_loop(event_base, flags);
#else
e = event_loop(flags);
#endif
if (e == -1)
elinks_internal("ERROR: event_base_loop failed: %s", strerror(errno));
}
#endif
select_handler_T
get_handler(int fd, enum select_handler_type tp)
{
#ifndef CONFIG_OS_WIN32
assertm(fd >= 0 && fd < FD_SETSIZE,
"get_handler: handle %d >= FD_SETSIZE %d",
fd, FD_SETSIZE);
if_assert_failed return NULL;
#endif
switch (tp) {
case SELECT_HANDLER_READ: return threads[fd].read_func;
case SELECT_HANDLER_WRITE: return threads[fd].write_func;
case SELECT_HANDLER_ERROR: return threads[fd].error_func;
case SELECT_HANDLER_DATA: return threads[fd].data;
}
INTERNAL("get_handler: bad type %d", tp);
return NULL;
}
void
set_handlers(int fd, select_handler_T read_func, select_handler_T write_func,
select_handler_T error_func, void *data)
{
#ifndef CONFIG_OS_WIN32
assertm(fd >= 0 && fd < FD_SETSIZE,
"set_handlers: handle %d >= FD_SETSIZE %d",
fd, FD_SETSIZE);
if_assert_failed return;
#endif
#ifdef __GNU__
/* GNU Hurd pflocal bug <http://savannah.gnu.org/bugs/?22861>:
* If ELinks does a select() where the initial exceptfds set
* includes a pipe that is not listed in the other fd_sets,
* then select() always reports an exception there. That
* makes Elinks think the pipe has failed and close it.
* To work around this bug, do not monitor exceptions for
* pipes on the Hurd. */
if (error_func) {
struct stat st;
if (fstat(fd, &st) == 0 && S_ISFIFO(st.st_mode))
error_func = NULL;
}
#endif /* __GNU__ */
#if defined(USE_POLL) && defined(USE_LIBEVENT)
if (!event_enabled)
#endif
if (fd >= (int)FD_SETSIZE) {
elinks_internal("too big handle %d", fd);
return;
}
if (fd >= n_threads) {
threads = mem_realloc(threads, (fd + 1) * sizeof(struct thread));
memset(threads + n_threads, 0, (fd + 1 - n_threads) * sizeof(struct thread));
n_threads = fd + 1;
}
threads[fd].read_func = read_func;
threads[fd].write_func = write_func;
threads[fd].error_func = error_func;
threads[fd].data = data;
if (read_func || write_func || error_func) {
if (fd >= w_max) w_max = fd + 1;
} else if (fd == w_max - 1) {
int i;
for (i = fd - 1; i >= 0; i--)
if (FD_ISSET(i, &w_read)
|| FD_ISSET(i, &w_write)
|| FD_ISSET(i, &w_error))
break;
w_max = i + 1;
}
#ifdef USE_LIBEVENT
if (event_enabled) {
set_events_for_handle(fd);
return;
}
#endif
if (read_func) {
FD_SET(fd, &w_read);
} else {
FD_CLR(fd, &w_read);
FD_CLR(fd, &x_read);
}
if (write_func) {
FD_SET(fd, &w_write);
} else {
FD_CLR(fd, &w_write);
FD_CLR(fd, &x_write);
}
if (error_func) {
FD_SET(fd, &w_error);
} else {
FD_CLR(fd, &w_error);
FD_CLR(fd, &x_error);
}
}
void
select_loop(void (*init)(void))
{
timeval_T last_time;
int select_errors = 0;
clear_signal_mask_and_handlers();
FD_ZERO(&w_read);
FD_ZERO(&w_write);
FD_ZERO(&w_error);
w_max = 0;
timeval_now(&last_time);
#ifdef SIGPIPE
signal(SIGPIPE, SIG_IGN);
#endif
init();
check_bottom_halves();
#ifdef USE_LIBEVENT
enable_libevent();
#if defined(USE_POLL)
if (!event_enabled) {
restrict_fds();
}
#endif
if (event_enabled) {
while (!program.terminate) {
check_signals();
if (1 /*(!F)*/) {
do_event_loop(EVLOOP_NONBLOCK);
check_signals();
redraw_all_terminals();
}
if (program.terminate) break;
do_event_loop(EVLOOP_ONCE);
}
} else
#endif
while (!program.terminate) {
struct timeval *timeout = NULL;
int n, i, has_timer;
timeval_T t;
check_signals();
check_timers(&last_time);
redraw_all_terminals();
memcpy(&x_read, &w_read, sizeof(fd_set));
memcpy(&x_write, &w_write, sizeof(fd_set));
memcpy(&x_error, &w_error, sizeof(fd_set));
if (program.terminate) break;
has_timer = get_next_timer_time(&t);
if (!w_max && !has_timer) break;
critical_section = 1;
if (check_signals()) {
critical_section = 0;
continue;
}
#if 0
{
int i;
printf("\nR:");
for (i = 0; i < 256; i++)
if (FD_ISSET(i, &x_read)) printf("%d,", i);
printf("\nW:");
for (i = 0; i < 256; i++)
if (FD_ISSET(i, &x_write)) printf("%d,", i);
printf("\nE:");
for (i = 0; i < 256; i++)
if (FD_ISSET(i, &x_error)) printf("%d,", i);
fflush(stdout);
}
#endif
if (has_timer) {
/* Be sure timeout is not negative. */
timeval_limit_to_zero_or_one(&t);
timeout = (struct timeval *) &t;
}
n = select(w_max, &x_read, &x_write, &x_error, timeout);
if (n < 0) {
/* The following calls (especially gettext)
* might change errno. */
const int errno_from_select = errno;
critical_section = 0;
uninstall_alarm();
if (errno_from_select != EINTR) {
ERROR(gettext("The call to %s failed: %d (%s)"),
"select()", errno_from_select, (unsigned char *) strerror(errno_from_select));
if (++select_errors > 10) /* Infinite loop prevention. */
INTERNAL(gettext("%d select() failures."),
select_errors);
}
continue;
}
select_errors = 0;
critical_section = 0;
uninstall_alarm();
check_signals();
/*printf("sel: %d\n", n);*/
check_timers(&last_time);
i = -1;
while (n > 0 && ++i < w_max) {
int k = 0;
#if 0
printf("C %d : %d,%d,%d\n", i, FD_ISSET(i, &w_read),
FD_ISSET(i, &w_write), FD_ISSET(i, &w_error));
printf("A %d : %d,%d,%d\n", i, FD_ISSET(i, &x_read),
FD_ISSET(i, &x_write), FD_ISSET(i, &x_error));
#endif
if (FD_ISSET(i, &x_read)) {
if (threads[i].read_func) {
threads[i].read_func(threads[i].data);
check_bottom_halves();
}
k = 1;
}
if (FD_ISSET(i, &x_write)) {
if (threads[i].write_func) {
threads[i].write_func(threads[i].data);
check_bottom_halves();
}
k = 1;
}
if (FD_ISSET(i, &x_error)) {
if (threads[i].error_func) {
threads[i].error_func(threads[i].data);
check_bottom_halves();
}
k = 1;
}
n -= k;
}
}
}
static int
can_read_or_write(int fd, int write)
{
#if defined(USE_POLL)
struct pollfd p;
int rs;
p.fd = fd;
p.events = !write ? POLLIN : POLLOUT;
EINTRLOOP(rs, poll(&p, 1, 0));
if (rs < 0) elinks_internal("ERROR: poll for %s (%d) failed: %s", !write ? "read" : "write", fd, strerror(errno));
if (!rs) return 0;
if (p.revents & POLLNVAL) elinks_internal("ERROR: poll for %s (%d) failed: %s", !write ? "read" : "write", fd, strerror(errno));
return 1;
#else
struct timeval tv = {0, 0};
fd_set fds;
fd_set *rfds = NULL;
fd_set *wfds = NULL;
FD_ZERO(&fds);
FD_SET(fd, &fds);
if (write)
wfds = &fds;
else
rfds = &fds;
return select(fd + 1, rfds, wfds, NULL, &tv);
#endif
}
int
can_read(int fd)
{
return can_read_or_write(fd, 0);
}
int
can_write(int fd)
{
return can_read_or_write(fd, 1);
}
void
terminate_select(void)
{
#ifdef USE_LIBEVENT
terminate_libevent();
#endif
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mem_free_if(threads);
}