Fix: bad type of return variable

[lttng-tools.git] / src / common / compat / compat-epoll.c

diff --git a/src/common/compat/compat-epoll.c b/src/common/compat/compat-epoll.c
index e58497232a130c002940cd1ffeb5b879129d47b7..25c9955045b3bb09435beea959d891c67f1c77a4 100644 (file)
--- a/src/common/compat/compat-epoll.c
+++ b/src/common/compat/compat-epoll.c
@@ -16,6 +16,7 @@
  */
 
 #define _GNU_SOURCE
+#include <assert.h>
 #include <fcntl.h>
 #include <limits.h>
 #include <stdlib.h>
@@ -26,11 +27,39 @@
 
 #include <common/error.h>
 #include <common/defaults.h>
+#include <common/macros.h>
+#include <common/utils.h>
 
 #include "poll.h"
 
 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;
+       }
+       events->events = ptr;
+       events->alloc_size = new_size;
+
+       return 0;
+
+error:
+       return -1;
+}
+
 /*
  * Create epoll set and allocate returned events structure.
  */
@@ -43,7 +72,7 @@ int compat_epoll_create(struct lttng_poll_event *events, int size, int flags)
        }
 
        /* Don't bust the limit here */
-       if (size > poll_max_size) {
+       if (size > poll_max_size && poll_max_size != 0) {
                size = poll_max_size;
        }
 
@@ -63,7 +92,7 @@ int compat_epoll_create(struct lttng_poll_event *events, int size, int flags)
                goto error_close;
        }
 
-       events->events_size = size;
+       events->alloc_size = events->init_size = size;
        events->nb_fd = 0;
 
        return 0;
@@ -82,8 +111,8 @@ error:
  */
 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");
@@ -112,17 +141,6 @@ int compat_epoll_add(struct lttng_poll_event *events, int fd, uint32_t req_event
 
        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;
 
@@ -153,8 +171,6 @@ int compat_epoll_del(struct lttng_poll_event *events, int fd)
                        PERROR("epoll_ctl DEL fatal");
                        goto error;
                }
-               PERROR("epoll_ctl del");
-               goto error;
        }
 
        events->nb_fd--;
@@ -172,13 +188,43 @@ error:
 int compat_epoll_wait(struct lttng_poll_event *events, int timeout)
 {
        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;
        }
 
+       /*
+        * 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.
+        */
+       if (events->nb_fd > events->alloc_size) {
+               /* Expand if the nb_fd is higher than the actual size. */
+               new_size = max_t(uint32_t,
+                               1U << utils_get_count_order_u32(events->nb_fd),
+                               events->alloc_size << 1UL);
+       } else if ((events->nb_fd << 1UL) <= events->alloc_size &&
+                       events->nb_fd >= events->init_size) {
+               /* Shrink if nb_fd multiplied by two is <= than the actual size. */
+               new_size = max_t(uint32_t,
+                               utils_get_count_order_u32(events->nb_fd) >> 1U,
+                               events->alloc_size >> 1U);
+       } else {
+               /* Indicate that we don't want to resize. */
+               new_size = 0;
+       }
+
+       if (new_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);
@@ -188,6 +234,10 @@ int compat_epoll_wait(struct lttng_poll_event *events, int timeout)
                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:
@@ -200,6 +250,7 @@ error:
 void compat_epoll_set_max_size(void)
 {
        int ret, fd;
+       ssize_t size_ret;
        char buf[64];
 
        poll_max_size = DEFAULT_POLL_SIZE;
@@ -209,14 +260,19 @@ void compat_epoll_set_max_size(void)
                return;
        }
 
-       ret = read(fd, buf, sizeof(buf));
-       if (ret < 0) {
+       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");
                goto error;
        }
+       buf[size_ret] = '\0';
 
        poll_max_size = atoi(buf);
-       if (poll_max_size <= 0) {
+       if (poll_max_size == 0) {
                /* Extra precaution */
                poll_max_size = DEFAULT_POLL_SIZE;
        }