fixup! posix_select: initial import of select() function

sys/posix/include/sys/select.h

@@ -29,14 +29,19 @@
 #define SYS_SELECT_H
 
 #include <string.h>
-#ifdef MODULE_NEWLIB    /* prevent cyclic dependency with newlib's `sys/types.h` */
+/* prevent cyclic dependency with newlib's `sys/types.h` */
+#if defined(MODULE_NEWLIB) && !defined(CPU_ESP32) && !defined(CPU_ESP8266)
 #include <sys/_timeval.h>
 #else
 #include <sys/time.h>
 #endif
 
 #include "bitfield.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /**
  * @addtogroup  config_posix
  * @{
@@ -55,6 +60,8 @@
 
 #define POSIX_SELECT_THREAD_FLAG    (1U << 3)
 
+/* ESP's newlib has this already defined in `sys/types.h` */
+#if !defined(CPU_ESP32) && !defined(CPU_ESP8266)
 /**
  * @brief   Maximum number of file descriptors in an `fd_set` structure.
  *
@@ -116,6 +123,7 @@ static inline void FD_ZERO(fd_set *fdsetp)
 {
     memset(fdsetp->fds, 0, sizeof(fdsetp->fds));
 }
+#endif /* !defined(CPU_ESP32) && !defined(CPU_ESP8266) */
 
 /**
  * @brief   Examines the given file descriptor sets if they are ready for their
@@ -148,4 +156,9 @@ static inline void FD_ZERO(fd_set *fdsetp)
 int select(int nfds, fd_set *restrict readfds, fd_set *restrict writefds,
            fd_set *restrict errorfds, struct timeval *restrict timeout);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* SYS_SELECT_H */
+/** @} */

sys/posix/select/posix_select.c

@@ -48,11 +48,12 @@ static inline void posix_socket_select(int fd)
 int select(int nfds, fd_set *restrict readfds, fd_set *restrict writefds,
            fd_set *restrict errorfds, struct timeval *restrict timeout)
 {
-    fd_set ret_readfds = { .fds = { 0U } };
+    fd_set ret_readfds;
     xtimer_t timeout_timer;
     int fds_set = 0;
     bool wait = true;
 
+    FD_ZERO(&ret_readfds);
     /* TODO ignored for now since there is no point for them with sockets */
     if (timeout != NULL) {
         uint64_t t = ((uint64_t)(timeout->tv_sec * US_PER_SEC) +