lib/curl/Global: defer the ReadInfo() call

Fixes a crash that can occur due to recursion from InvalidateSockets()
to ReadInfo() to CurlRequest callbacks.

NEWS

@@ -1,4 +1,6 @@
 ver 0.20.1 (not yet released)
+* input
+  - curl: fix crash bug
 * mixer
   - alsa: normalize displayed volume according to human perception
 * fix crash with volume_normalization enabled

src/lib/curl/Global.cxx

@@ -96,7 +96,7 @@ private:
 };
 
 CurlGlobal::CurlGlobal(EventLoop &_loop)
-	:TimeoutMonitor(_loop)
+	:TimeoutMonitor(_loop), DeferredMonitor(_loop)
 {
 	multi.SetOption(CURLMOPT_SOCKETFUNCTION, CurlSocket::SocketFunction);
 	multi.SetOption(CURLMOPT_SOCKETDATA, this);
@@ -262,5 +262,11 @@ CurlGlobal::SocketAction(curl_socket_t fd, int ev_bitmask)
 			    "curl_multi_socket_action() failed: %s",
 			    curl_multi_strerror(mcode));
 
+	DeferredMonitor::Schedule();
+}
+
+void
+CurlGlobal::RunDeferred()
+{
 	ReadInfo();
 }

src/lib/curl/Global.hxx

@@ -32,6 +32,7 @@
 
 #include "Multi.hxx"
 #include "event/TimeoutMonitor.hxx"
+#include "event/DeferredMonitor.hxx"
 
 class CurlSocket;
 class CurlRequest;
@@ -39,7 +40,7 @@ class CurlRequest;
 /**
  * Manager for the global CURLM object.
  */
-class CurlGlobal final : private TimeoutMonitor {
+class CurlGlobal final : TimeoutMonitor, DeferredMonitor {
 	CurlMulti multi;
 
 public:
@@ -81,6 +82,9 @@ private:
 
 	/* virtual methods from class TimeoutMonitor */
 	void OnTimeout() override;
+
+	/* virtual methods from class DeferredMonitor */
+	void RunDeferred() override;
 };
 
 #endif