Add poll/epoll compat layer for session daemon

[lttng-tools.git] / ltt-sessiond / compat / compat-poll.c

diff --git a/ltt-sessiond/compat/compat-poll.c b/ltt-sessiond/compat/compat-poll.c
new file mode 100644 (file)
index 0000000..cc4bb0f
--- /dev/null
+++ b/ltt-sessiond/compat/compat-poll.c
@@ -0,0 +1,195 @@
+/*
+ * 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.
+ *
+ * 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.
+ */
+
+#include <stdlib.h>
+#include <sys/resource.h>
+#include <sys/time.h>
+
+#include <lttngerr.h>
+
+#include "poll.h"
+
+unsigned int poll_max_size;
+
+/*
+ * Create pollfd data structure.
+ */
+int compat_poll_create(struct lttng_poll_event *events, int size)
+{
+       if (events == NULL || size <= 0) {
+               ERR("Wrong arguments for poll create");
+               goto error;
+       }
+
+       /* Don't bust the limit here */
+       if (size > poll_max_size) {
+               size = poll_max_size;
+       }
+
+       /* This *must* be freed by using lttng_poll_free() */
+       events->events = zmalloc(size * sizeof(struct pollfd));
+       if (events->events == NULL) {
+               perror("malloc struct pollfd");
+               goto error;
+       }
+
+       events->events_size = size;
+       events->nb_fd = 0;
+
+       return 0;
+
+error:
+       return -1;
+}
+
+/*
+ * Add fd to pollfd data structure with requested events.
+ */
+int compat_poll_add(struct lttng_poll_event *events, int fd,
+               uint32_t req_events)
+{
+       int new_size;
+       struct pollfd *ptr;
+
+       if (events == NULL || events->events == NULL || fd < 0) {
+               ERR("Bad compat poll add arguments");
+               goto error;
+       }
+
+       /* Reallocate pollfd structure by a factor of 2 if needed. */
+       if (events->nb_fd >= events->events_size) {
+               new_size = 2 * events->events_size;
+               ptr = realloc(events->events, new_size * sizeof(struct pollfd));
+               if (ptr == NULL) {
+                       perror("realloc poll add");
+                       goto error;
+               }
+               events->events = ptr;
+               events->events_size = new_size;
+       }
+
+       events->events[events->nb_fd].fd = fd;
+       events->events[events->nb_fd].events = req_events;
+       events->nb_fd++;
+
+       DBG("fd %d of %d added to pollfd", fd, events->nb_fd);
+
+       return 0;
+
+error:
+       return -1;
+}
+
+/*
+ * Remove a fd from the pollfd structure.
+ */
+int compat_poll_del(struct lttng_poll_event *events, int fd)
+{
+       int new_size, i, count = 0;
+       struct pollfd *old = NULL, *new = NULL;
+
+       if (events == NULL || events->events == NULL || fd < 0) {
+               ERR("Wrong arguments for poll del");
+               goto error;
+       }
+
+       old = events->events;
+       new_size = events->events_size - 1;
+
+       /* Safety check on size */
+       if (new_size > poll_max_size) {
+               new_size = poll_max_size;
+       }
+
+       new = zmalloc(new_size * sizeof(struct pollfd));
+       if (new == NULL) {
+               perror("malloc poll del");
+               goto error;
+       }
+
+       for (i = 0; i < events->events_size; i++) {
+               /* Don't put back the fd we want to delete */
+               if (old[i].fd != fd) {
+                       new[count].fd = old[i].fd;
+                       new[count].events = old[i].events;
+                       count++;
+               }
+       }
+
+       events->events_size = new_size;
+       events->events = new;
+       events->nb_fd--;
+
+       free(old);
+
+       return 0;
+
+error:
+       return -1;
+}
+
+/*
+ * Wait on poll() with timeout. Blocking call.
+ */
+int compat_poll_wait(struct lttng_poll_event *events, int timeout)
+{
+       int ret;
+
+       if (events == NULL || events->events == NULL ||
+                       events->events_size < events->nb_fd) {
+               ERR("poll wait arguments error");
+               goto error;
+       }
+
+       ret = poll(events->events, events->nb_fd, timeout);
+       if (ret < 0) {
+               /* At this point, every error is fatal */
+               perror("poll wait");
+               goto error;
+       }
+
+       return ret;
+
+error:
+       return -1;
+}
+
+/*
+ * Setup poll set maximum size.
+ */
+void compat_poll_set_max_size(void)
+{
+       int ret;
+       struct rlimit lim;
+
+       /* Default value */
+       poll_max_size = LTTNG_POLL_DEFAULT_SIZE;
+
+       ret = getrlimit(RLIMIT_NOFILE, &lim);
+       if (ret < 0) {
+               perror("getrlimit poll RLIMIT_NOFILE");
+               return;
+       }
+
+       poll_max_size = lim.rlim_cur;
+       if (poll_max_size <= 0) {
+               /* Extra precaution */
+               poll_max_size = LTTNG_POLL_DEFAULT_SIZE;
+       }
+
+       DBG("poll set max size set to %u", poll_max_size);
+}