/*
- * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
+ * Copyright (C) 2011 David Goulet <david.goulet@polymtl.ca>
*
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License as published by the Free
- * Software Foundation; only version 2 of the License.
+ * SPDX-License-Identifier: GPL-2.0-only
*
- * This program 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 General Public License for
- * more details.
- *
- * You should have received a copy of the GNU General Public License along with
- * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
- * Place - Suite 330, Boston, MA 02111-1307, USA.
*/
+#define _LGPL_SOURCE
+#include <assert.h>
#include <fcntl.h>
#include <limits.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
-#include <config.h>
+#include <stdbool.h>
#include <common/error.h>
#include <common/defaults.h>
+#include <common/macros.h>
+#include <common/utils.h>
#include "poll.h"
-unsigned int poll_max_size;
+/*
+ * Maximum number of fd we can monitor.
+ *
+ * For epoll(7), /proc/sys/fs/epoll/max_user_watches (since Linux 2.6.28) will
+ * be used for the maximum size of the poll set. If this interface is not
+ * available, according to the manpage, the max_user_watches value is 1/25 (4%)
+ * of the available low memory divided by the registration cost in bytes which
+ * is 90 bytes on a 32-bit kernel and 160 bytes on a 64-bit kernel.
+ *
+ */
+static unsigned int poll_max_size;
+
+/*
+ * Resize the epoll events structure of the new size.
+ *
+ * Return 0 on success or else -1 with the current events pointer untouched.
+ */
+static int resize_poll_event(struct lttng_poll_event *events,
+ uint32_t new_size)
+{
+ struct epoll_event *ptr;
+
+ assert(events);
+
+ ptr = realloc(events->events, new_size * sizeof(*ptr));
+ if (ptr == NULL) {
+ PERROR("realloc epoll add");
+ goto error;
+ }
+ if (new_size > events->alloc_size) {
+ /* Zero newly allocated memory */
+ memset(ptr + events->alloc_size, 0,
+ (new_size - events->alloc_size) * sizeof(*ptr));
+ }
+ events->events = ptr;
+ events->alloc_size = new_size;
+
+ return 0;
+
+error:
+ return -1;
+}
/*
* Create epoll set and allocate returned events structure.
*/
+LTTNG_HIDDEN
int compat_epoll_create(struct lttng_poll_event *events, int size, int flags)
{
int ret;
goto error;
}
+ if (!poll_max_size) {
+ if (lttng_poll_set_max_size()) {
+ goto error;
+ }
+ }
+
/* Don't bust the limit here */
if (size > poll_max_size) {
size = poll_max_size;
}
- ret = epoll_create1(flags);
+ ret = compat_glibc_epoll_create(size, flags);
if (ret < 0) {
/* At this point, every error is fatal */
- perror("epoll_create1");
+ PERROR("epoll_create1");
goto error;
}
/* This *must* be freed by using lttng_poll_free() */
events->events = zmalloc(size * sizeof(struct epoll_event));
if (events->events == NULL) {
- perror("zmalloc epoll set");
+ PERROR("zmalloc epoll set");
goto error_close;
}
- events->events_size = size;
+ events->alloc_size = events->init_size = size;
events->nb_fd = 0;
return 0;
error_close:
- close(events->epfd);
+ ret = close(events->epfd);
+ if (ret) {
+ PERROR("close");
+ }
error:
return -1;
}
/*
* Add a fd to the epoll set with requesting events.
*/
+LTTNG_HIDDEN
int compat_epoll_add(struct lttng_poll_event *events, int fd, uint32_t req_events)
{
- int ret, new_size;
- struct epoll_event ev, *ptr;
+ int ret;
+ struct epoll_event ev;
if (events == NULL || events->events == NULL || fd < 0) {
ERR("Bad compat epoll add arguments");
goto error;
}
+ /*
+ * Zero struct epoll_event to ensure all representations of its
+ * union are zeroed.
+ */
+ memset(&ev, 0, sizeof(ev));
ev.events = req_events;
ev.data.fd = fd;
goto end;
case ENOSPC:
case EPERM:
- /* Print perror and goto end not failing. Show must go on. */
- perror("epoll_ctl ADD");
+ /* Print PERROR and goto end not failing. Show must go on. */
+ PERROR("epoll_ctl ADD");
goto end;
default:
- perror("epoll_ctl ADD fatal");
+ PERROR("epoll_ctl ADD fatal");
goto error;
}
}
events->nb_fd++;
- if (events->nb_fd >= events->events_size) {
- new_size = 2 * events->events_size;
- ptr = realloc(events->events, new_size * sizeof(struct epoll_event));
- if (ptr == NULL) {
- perror("realloc epoll add");
- goto error;
- }
- events->events = ptr;
- events->events_size = new_size;
- }
-
end:
return 0;
/*
* Remove a fd from the epoll set.
*/
+LTTNG_HIDDEN
int compat_epoll_del(struct lttng_poll_event *events, int fd)
{
int ret;
- if (events == NULL || fd < 0) {
+ if (events == NULL || fd < 0 || events->nb_fd == 0) {
goto error;
}
switch (errno) {
case ENOENT:
case EPERM:
- /* Print perror and goto end not failing. Show must go on. */
- perror("epoll_ctl DEL");
+ /* Print PERROR and goto end not failing. Show must go on. */
+ PERROR("epoll_ctl DEL");
goto end;
default:
- perror("epoll_ctl DEL fatal");
+ PERROR("epoll_ctl DEL fatal");
goto error;
}
- perror("epoll_ctl del");
- goto error;
}
events->nb_fd--;
return -1;
}
+/*
+ * Set an fd's events.
+ */
+LTTNG_HIDDEN
+int compat_epoll_mod(struct lttng_poll_event *events, int fd, uint32_t req_events)
+{
+ int ret;
+ struct epoll_event ev;
+
+ if (events == NULL || fd < 0 || events->nb_fd == 0) {
+ goto error;
+ }
+
+ /*
+ * Zero struct epoll_event to ensure all representations of its
+ * union are zeroed.
+ */
+ memset(&ev, 0, sizeof(ev));
+ ev.events = req_events;
+ ev.data.fd = fd;
+
+ ret = epoll_ctl(events->epfd, EPOLL_CTL_MOD, fd, &ev);
+ if (ret < 0) {
+ switch (errno) {
+ case ENOENT:
+ case EPERM:
+ /* Print PERROR and goto end not failing. Show must go on. */
+ PERROR("epoll_ctl MOD");
+ goto end;
+ default:
+ PERROR("epoll_ctl MOD fatal");
+ goto error;
+ }
+ }
+
+end:
+ return 0;
+
+error:
+ return -1;
+}
+
/*
* Wait on epoll set. This is a blocking call of timeout value.
*/
-int compat_epoll_wait(struct lttng_poll_event *events, int timeout)
+LTTNG_HIDDEN
+int compat_epoll_wait(struct lttng_poll_event *events, int timeout,
+ bool interruptible)
{
int ret;
+ uint32_t new_size;
- if (events == NULL || events->events == NULL ||
- events->events_size < events->nb_fd) {
+ if (events == NULL || events->events == NULL) {
ERR("Wrong arguments in compat_epoll_wait");
goto error;
}
+ if (events->nb_fd == 0) {
+ errno = EINVAL;
+ return -1;
+ }
+
+ /*
+ * Resize if needed before waiting. We could either expand the array or
+ * shrink it down. It's important to note that after this step, we are
+ * ensured that the events argument of the epoll_wait call will be large
+ * enough to hold every possible returned events.
+ */
+ new_size = 1U << utils_get_count_order_u32(events->nb_fd);
+ if (new_size != events->alloc_size && new_size >= events->init_size) {
+ ret = resize_poll_event(events, new_size);
+ if (ret < 0) {
+ /* ENOMEM problem at this point. */
+ goto error;
+ }
+ }
+
do {
ret = epoll_wait(events->epfd, events->events, events->nb_fd, timeout);
- } while (ret == -1 && errno == EINTR);
+ } while (!interruptible && ret == -1 && errno == EINTR);
if (ret < 0) {
- /* At this point, every error is fatal */
- perror("epoll_wait");
+ if (errno != EINTR) {
+ PERROR("epoll_wait");
+ }
goto error;
}
+ /*
+ * Since the returned events are set sequentially in the "events" structure
+ * we only need to return the epoll_wait value and iterate over it.
+ */
return ret;
error:
/*
* Setup poll set maximum size.
*/
-void compat_epoll_set_max_size(void)
+LTTNG_HIDDEN
+int compat_epoll_set_max_size(void)
{
- int ret, fd;
+ int ret, fd, retval = 0;
+ ssize_t size_ret;
char buf[64];
- poll_max_size = DEFAULT_POLL_SIZE;
-
fd = open(COMPAT_EPOLL_PROC_PATH, O_RDONLY);
if (fd < 0) {
- return;
+ /*
+ * Failing on opening [1] is not an error per see. [1] was
+ * introduced in Linux 2.6.28 but epoll is available since
+ * 2.5.44. Hence, goto end and set a default value without
+ * setting an error return value.
+ *
+ * [1] /proc/sys/fs/epoll/max_user_watches
+ */
+ retval = 0;
+ goto end;
}
- ret = read(fd, buf, sizeof(buf));
- if (ret < 0) {
- perror("read set max size");
- goto error;
+ size_ret = lttng_read(fd, buf, sizeof(buf));
+ /*
+ * Allow reading a file smaller than buf, but keep space for
+ * final \0.
+ */
+ if (size_ret < 0 || size_ret >= sizeof(buf)) {
+ PERROR("read set max size");
+ retval = -1;
+ goto end_read;
}
-
+ buf[size_ret] = '\0';
poll_max_size = atoi(buf);
- if (poll_max_size <= 0) {
- /* Extra precaution */
+end_read:
+ ret = close(fd);
+ if (ret) {
+ PERROR("close");
+ }
+end:
+ if (!poll_max_size) {
poll_max_size = DEFAULT_POLL_SIZE;
}
-
DBG("epoll set max size is %d", poll_max_size);
-
-error:
- close(fd);
+ return retval;
}
projects / lttng-tools.git / blobdiff