Merge pull request #1456 from pguyot/w01/fix-esp-idf-54-warning

Fix dubious logic revealed by esp idf 5.4 warning

These changes are made under both the "Apache 2.0" and the "GNU Lesser General
Public License 2.1 or later" license terms (dual license).

SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later

Author: bettio

src/platforms/esp32/components/avm_sys/sys.c

@@ -677,12 +677,12 @@ static void *select_thread_loop(void *arg)
 {
     GlobalContext *glb = arg;
     struct ESP32PlatformData *platform = glb->platform_data;
-    struct pollfd *fds = malloc(0);
+    struct pollfd *fds = NULL;
     while (!platform->select_thread_exit) {
         int select_events_poll_count = platform->select_events_poll_count;
         int poll_count = 1;
         int fd_index;
-        if (select_events_poll_count < 0) {
+        if (fds == NULL || select_events_poll_count < 0) {
             // Means it is dirty and should be rebuilt.
             struct ListHead *select_events = synclist_wrlock(&glb->select_events);
             size_t select_events_new_count;
@@ -692,7 +692,11 @@ static void *select_thread_loop(void *arg)
                 select_events_new_count = select_events_poll_count;
             }
 
-            fds = realloc(fds, sizeof(struct pollfd) * (poll_count + select_events_new_count));
+            if (fds) {
+                fds = realloc(fds, sizeof(struct pollfd) * (poll_count + select_events_new_count));
+            } else {
+                fds = malloc(sizeof(struct pollfd) * (poll_count + select_events_new_count));
+            }
 
             fds[0].fd = platform->signal_fd;
             fds[0].events = POLLIN;