--- /dev/null
+/*
+ * Copyright (C) 2011 David Goulet <david.goulet@polymtl.ca>
+ * Copyright (C) 2019 Yannick Lamarre <ylamarre@efficios.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0-only
+ *
+ */
+
+#define _LGPL_SOURCE
+#include <assert.h>
+#include <stdlib.h>
+#include <stdbool.h>
+
+#include <common/defaults.h>
+#include <common/error.h>
+#include <common/macros.h>
+#include <common/utils.h>
+
+#include "poll.h"
+
+#if HAVE_EPOLL
+
+#include <fcntl.h>
+#include <limits.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+/*
+ * 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;
+
+ if (events == NULL || size <= 0) {
+ 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 = compat_glibc_epoll_create(size, flags);
+ if (ret < 0) {
+ /* At this point, every error is fatal */
+ PERROR("epoll_create1");
+ goto error;
+ }
+
+ events->epfd = ret;
+
+ /* 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");
+ goto error_close;
+ }
+
+ events->alloc_size = events->init_size = size;
+ events->nb_fd = 0;
+
+ return 0;
+
+error_close:
+ 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;
+ 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;
+
+ ret = epoll_ctl(events->epfd, EPOLL_CTL_ADD, fd, &ev);
+ if (ret < 0) {
+ switch (errno) {
+ case EEXIST:
+ /* If exist, it's OK. */
+ goto end;
+ case ENOSPC:
+ case EPERM:
+ /* Print PERROR and goto end not failing. Show must go on. */
+ PERROR("epoll_ctl ADD");
+ goto end;
+ default:
+ PERROR("epoll_ctl ADD fatal");
+ goto error;
+ }
+ }
+
+ events->nb_fd++;
+
+end:
+ return 0;
+
+error:
+ return -1;
+}
+
+/*
+ * 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 || events->nb_fd == 0) {
+ goto error;
+ }
+
+ ret = epoll_ctl(events->epfd, EPOLL_CTL_DEL, fd, NULL);
+ if (ret < 0) {
+ switch (errno) {
+ case ENOENT:
+ case EPERM:
+ /* Print PERROR and goto end not failing. Show must go on. */
+ PERROR("epoll_ctl DEL");
+ goto end;
+ default:
+ PERROR("epoll_ctl DEL fatal");
+ goto error;
+ }
+ }
+
+ events->nb_fd--;
+
+end:
+ return 0;
+
+error:
+ 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.
+ */
+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) {
+ 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 (!interruptible && ret == -1 && errno == EINTR);
+ if (ret < 0) {
+ 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:
+ return -1;
+}
+
+/*
+ * Setup poll set maximum size.
+ */
+LTTNG_HIDDEN
+int compat_epoll_set_max_size(void)
+{
+ int ret, fd, retval = 0;
+ ssize_t size_ret;
+ char buf[64];
+
+ fd = open(COMPAT_EPOLL_PROC_PATH, O_RDONLY);
+ if (fd < 0) {
+ /*
+ * 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;
+ }
+
+ 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);
+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);
+ return retval;
+}
+
+#else /* HAVE_EPOLL */
+
+#include <sys/resource.h>
+#include <sys/time.h>
+
+/*
+ * Maximum number of fd we can monitor.
+ *
+ * For poll(2), the max fds must not exceed RLIMIT_NOFILE given by
+ * getrlimit(2).
+ */
+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 compat_poll_event_array *array,
+ uint32_t new_size)
+{
+ struct pollfd *ptr;
+
+ assert(array);
+
+ /* Refuse to resize the array more than the max size. */
+ if (new_size > poll_max_size) {
+ goto error;
+ }
+
+ ptr = realloc(array->events, new_size * sizeof(*ptr));
+ if (ptr == NULL) {
+ PERROR("realloc epoll add");
+ goto error;
+ }
+ if (new_size > array->alloc_size) {
+ /* Zero newly allocated memory */
+ memset(ptr + array->alloc_size, 0,
+ (new_size - array->alloc_size) * sizeof(*ptr));
+ }
+ array->events = ptr;
+ array->alloc_size = new_size;
+
+ return 0;
+
+error:
+ return -1;
+}
+
+/*
+ * Update events with the current events object.
+ */
+static int update_current_events(struct lttng_poll_event *events)
+{
+ int ret;
+ struct compat_poll_event_array *current, *wait;
+
+ assert(events);
+
+ current = &events->current;
+ wait = &events->wait;
+
+ wait->nb_fd = current->nb_fd;
+ if (current->alloc_size != wait->alloc_size) {
+ ret = resize_poll_event(wait, current->alloc_size);
+ if (ret < 0) {
+ goto error;
+ }
+ }
+ memcpy(wait->events, current->events,
+ current->nb_fd * sizeof(*current->events));
+
+ /* Update is done. */
+ events->need_update = 0;
+
+ return 0;
+
+error:
+ return -1;
+}
+
+/*
+ * Create pollfd data structure.
+ */
+LTTNG_HIDDEN
+int compat_poll_create(struct lttng_poll_event *events, int size)
+{
+ struct compat_poll_event_array *current, *wait;
+
+ if (events == NULL || size <= 0) {
+ ERR("Wrong arguments for poll create");
+ 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;
+ }
+
+ /* Reset everything before begining the allocation. */
+ memset(events, 0, sizeof(struct lttng_poll_event));
+
+ current = &events->current;
+ wait = &events->wait;
+
+ /* This *must* be freed by using lttng_poll_free() */
+ wait->events = zmalloc(size * sizeof(struct pollfd));
+ if (wait->events == NULL) {
+ PERROR("zmalloc struct pollfd");
+ goto error;
+ }
+
+ wait->alloc_size = wait->init_size = size;
+
+ current->events = zmalloc(size * sizeof(struct pollfd));
+ if (current->events == NULL) {
+ PERROR("zmalloc struct current pollfd");
+ goto error;
+ }
+
+ current->alloc_size = current->init_size = size;
+
+ return 0;
+
+error:
+ return -1;
+}
+
+/*
+ * Add fd to pollfd data structure with requested events.
+ */
+LTTNG_HIDDEN
+int compat_poll_add(struct lttng_poll_event *events, int fd,
+ uint32_t req_events)
+{
+ int new_size, ret, i;
+ struct compat_poll_event_array *current;
+
+ if (events == NULL || events->current.events == NULL || fd < 0) {
+ ERR("Bad compat poll add arguments");
+ goto error;
+ }
+
+ current = &events->current;
+
+ /* Check if fd we are trying to add is already there. */
+ for (i = 0; i < current->nb_fd; i++) {
+ if (current->events[i].fd == fd) {
+ errno = EEXIST;
+ goto error;
+ }
+ }
+
+ /* Resize array if needed. */
+ new_size = 1U << utils_get_count_order_u32(current->nb_fd + 1);
+ if (new_size != current->alloc_size && new_size >= current->init_size) {
+ ret = resize_poll_event(current, new_size);
+ if (ret < 0) {
+ goto error;
+ }
+ }
+
+ current->events[current->nb_fd].fd = fd;
+ current->events[current->nb_fd].events = req_events;
+ current->nb_fd++;
+ events->need_update = 1;
+
+ DBG("fd %d of %d added to pollfd", fd, current->nb_fd);
+
+ return 0;
+
+error:
+ return -1;
+}
+
+/*
+ * Modify an fd's events..
+ */
+LTTNG_HIDDEN
+int compat_poll_mod(struct lttng_poll_event *events, int fd,
+ uint32_t req_events)
+{
+ int i;
+ struct compat_poll_event_array *current;
+
+ if (events == NULL || events->current.nb_fd == 0 ||
+ events->current.events == NULL || fd < 0) {
+ ERR("Bad compat poll mod arguments");
+ goto error;
+ }
+
+ current = &events->current;
+
+ for (i = 0; i < current->nb_fd; i++) {
+ if (current->events[i].fd == fd) {
+ current->events[i].events = req_events;
+ events->need_update = 1;
+ break;
+ }
+ }
+
+ /*
+ * The epoll flavor doesn't flag modifying a non-included FD as an
+ * error.
+ */
+
+ return 0;
+
+error:
+ return -1;
+}
+
+/*
+ * Remove a fd from the pollfd structure.
+ */
+LTTNG_HIDDEN
+int compat_poll_del(struct lttng_poll_event *events, int fd)
+{
+ int i, count = 0, ret;
+ uint32_t new_size;
+ struct compat_poll_event_array *current;
+
+ if (events == NULL || events->current.nb_fd == 0 ||
+ events->current.events == NULL || fd < 0) {
+ goto error;
+ }
+
+ /* Ease our life a bit. */
+ current = &events->current;
+
+ for (i = 0; i < current->nb_fd; i++) {
+ /* Don't put back the fd we want to delete */
+ if (current->events[i].fd != fd) {
+ current->events[count].fd = current->events[i].fd;
+ current->events[count].events = current->events[i].events;
+ count++;
+ }
+ }
+
+ /* The fd was not in our set, return no error as with epoll. */
+ if (current->nb_fd == count) {
+ goto end;
+ }
+
+ /* No fd duplicate should be ever added into array. */
+ assert(current->nb_fd - 1 == count);
+ current->nb_fd = count;
+
+ /* Resize array if needed. */
+ new_size = 1U << utils_get_count_order_u32(current->nb_fd);
+ if (new_size != current->alloc_size && new_size >= current->init_size
+ && current->nb_fd != 0) {
+ ret = resize_poll_event(current, new_size);
+ if (ret < 0) {
+ goto error;
+ }
+ }
+
+ events->need_update = 1;
+
+end:
+ return 0;
+
+error:
+ return -1;
+}
+
+/*
+ * Wait on poll() with timeout. Blocking call.
+ */
+LTTNG_HIDDEN
+int compat_poll_wait(struct lttng_poll_event *events, int timeout,
+ bool interruptible)
+{
+ int ret, active_fd_count;
+ int idle_pfd_index = 0;
+ size_t i;
+
+ if (events == NULL || events->current.events == NULL) {
+ ERR("poll wait arguments error");
+ goto error;
+ }
+
+ if (events->current.nb_fd == 0) {
+ /* Return an invalid error to be consistent with epoll. */
+ errno = EINVAL;
+ events->wait.nb_fd = 0;
+ goto error;
+ }
+
+ if (events->need_update) {
+ ret = update_current_events(events);
+ if (ret < 0) {
+ errno = ENOMEM;
+ goto error;
+ }
+ }
+
+ do {
+ ret = poll(events->wait.events, events->wait.nb_fd, timeout);
+ } while (!interruptible && ret == -1 && errno == EINTR);
+ if (ret < 0) {
+ if (errno != EINTR) {
+ PERROR("poll wait");
+ }
+ goto error;
+ }
+
+ active_fd_count = ret;
+
+ /*
+ * Swap all active pollfd structs to the beginning of the
+ * array to emulate compat-epoll behaviour. This algorithm takes
+ * advantage of poll's returned value and the burst nature of active
+ * events on the file descriptors. The while loop guarantees that
+ * idle_pfd will always point to an idle fd.
+ */
+ if (active_fd_count == events->wait.nb_fd) {
+ goto end;
+ }
+ while (idle_pfd_index < active_fd_count &&
+ events->wait.events[idle_pfd_index].revents != 0) {
+ idle_pfd_index++;
+ }
+
+ for (i = idle_pfd_index + 1; idle_pfd_index < active_fd_count;
+ i++) {
+ struct pollfd swap_pfd;
+ struct pollfd *idle_pfd = &events->wait.events[idle_pfd_index];
+ struct pollfd *current_pfd = &events->wait.events[i];
+
+ if (idle_pfd->revents != 0) {
+ swap_pfd = *current_pfd;
+ *current_pfd = *idle_pfd;
+ *idle_pfd = swap_pfd;
+ idle_pfd_index++;
+ }
+ }
+
+end:
+ return ret;
+
+error:
+ return -1;
+}
+
+/*
+ * Setup poll set maximum size.
+ */
+LTTNG_HIDDEN
+int compat_poll_set_max_size(void)
+{
+ int ret, retval = 0;
+ struct rlimit lim;
+
+ ret = getrlimit(RLIMIT_NOFILE, &lim);
+ if (ret < 0) {
+ PERROR("getrlimit poll RLIMIT_NOFILE");
+ retval = -1;
+ goto end;
+ }
+
+ poll_max_size = lim.rlim_cur;
+end:
+ if (poll_max_size == 0) {
+ poll_max_size = DEFAULT_POLL_SIZE;
+ }
+ DBG("poll set max size set to %u", poll_max_size);
+ return retval;
+}
+
+#endif /* !HAVE_EPOLL */
projects / lttng-tools.git / blobdiff