[posix-app] allow pseudo reset (#4184)

src/posix/platform/radio_spinel.cpp

@@ -51,6 +51,7 @@
 #include <common/code_utils.hpp>
 #include <common/encoding.hpp>
 #include <common/logging.hpp>
+#include <common/new.hpp>
 #include <openthread/platform/alarm-milli.h>
 #include <openthread/platform/diag.h>
 #include <openthread/platform/radio.h>
@@ -308,6 +309,8 @@ exit:
 void RadioSpinel::Deinit(void)
 {
     mHdlcInterface.Deinit();
+    // This allows implementing pseudo reset.
+    new (this) RadioSpinel();
 }
 
 void RadioSpinel::HandleSpinelFrame(HdlcInterface::RxFrameBuffer &aFrameBuffer)

src/posix/platform/uart.c

@@ -67,6 +67,9 @@ otError otPlatUartEnable(void)
     struct sockaddr_un sockname;
     int                ret;
 
+    // This allows implementing pseudo reset.
+    otEXPECT(sUartSocket == -1);
+
     sUartSocket = SocketWithCloseExec(AF_UNIX, SOCK_STREAM, 0);
 
     if (sUartSocket == -1)
@@ -109,6 +112,8 @@ otError otPlatUartEnable(void)
     {
         DieNowWithMessage("listen", OT_EXIT_ERROR_ERRNO);
     }
+
+exit:
 #endif // OPENTHREAD_ENABLE_POSIX_APP_DAEMON
 
     sEnabled = true;
@@ -135,6 +140,7 @@ otError otPlatUartDisable(void)
 
     if (sUartLock != -1)
     {
+        (void)flock(sUartLock, LOCK_UN);
         close(sUartLock);
         sUartLock = -1;
     }