output/Interface: allow Pause() to throw exception

Coverity discovered that the Pulse plugin could throw exceptions from
Pause(), but that method was marked "noexcept" because its caller was
not designed to catch exceptions.  So instead of avoiding exceptions
(by catching and logging them in each and every implementation), let's
allow them, and do the catch/log game in the MPD core.

src/output/Interface.hxx

@@ -140,8 +140,11 @@ public:
 	 *
 	 * @return false on error (output will be closed by caller),
 	 * true for continue to pause
+	 *
+	 * Instead of returning false, the method may throw an
+	 * exception, which will be logged.
 	 */
-	virtual bool Pause() noexcept {
+	virtual bool Pause() {
 		/* fail because this method is not implemented */
 		return false;
 	}

src/output/plugins/JackOutputPlugin.cxx

@@ -135,7 +135,7 @@ struct JackOutput final : AudioOutput {
 
 	size_t Play(const void *chunk, size_t size) override;
 
-	bool Pause() noexcept override;
+	bool Pause() override;
 };
 
 static constexpr Domain jack_output_domain("jack_output");
@@ -661,7 +661,7 @@ JackOutput::Play(const void *chunk, size_t size)
 }
 
 inline bool
-JackOutput::Pause() noexcept
+JackOutput::Pause()
 {
 	if (shutdown)
 		return false;

src/output/plugins/PulseOutputPlugin.cxx

@@ -103,7 +103,7 @@ public:
 	std::chrono::steady_clock::duration Delay() const noexcept override;
 	size_t Play(const void *chunk, size_t size) override;
 	void Cancel() noexcept override;
-	bool Pause() noexcept override;
+	bool Pause() override;
 
 private:
 	/**
@@ -826,7 +826,7 @@ PulseOutput::Cancel() noexcept
 }
 
 bool
-PulseOutput::Pause() noexcept
+PulseOutput::Pause()
 {
 	assert(mainloop != nullptr);
 	assert(stream != nullptr);

src/output/plugins/ShoutOutputPlugin.cxx

@@ -65,7 +65,7 @@ struct ShoutOutput final : AudioOutput {
 	void SendTag(const Tag &tag) override;
 	size_t Play(const void *chunk, size_t size) override;
 	void Cancel() noexcept override;
-	bool Pause() noexcept override;
+	bool Pause() override;
 
 private:
 	void WritePage();
@@ -378,16 +378,12 @@ ShoutOutput::Play(const void *chunk, size_t size)
 }
 
 bool
-ShoutOutput::Pause() noexcept
+ShoutOutput::Pause()
 {
 	static char silence[1020];
 
-	try {
-		encoder->Write(silence, sizeof(silence));
-		WritePage();
-	} catch (const std::runtime_error &) {
-		return false;
-	}
+	encoder->Write(silence, sizeof(silence));
+	WritePage();
 
 	return true;
 }

src/output/plugins/httpd/HttpdInternal.hxx

@@ -252,7 +252,7 @@ public:
 	void CancelAllClients();
 
 	void Cancel() noexcept override;
-	bool Pause() noexcept override;
+	bool Pause() override;
 
 private:
 	virtual void RunDeferred() override;

src/output/plugins/httpd/HttpdOutputPlugin.cxx

@@ -371,7 +371,7 @@ HttpdOutput::Play(const void *chunk, size_t size)
 }
 
 bool
-HttpdOutput::Pause() noexcept
+HttpdOutput::Pause()
 {
 	pause = true;
 

src/output/plugins/sles/SlesOutputPlugin.cxx

@@ -102,7 +102,7 @@ private:
 
 	void Drain() override;
 	void Cancel() noexcept override;
-	bool Pause() noexcept override;
+	bool Pause() override;
 
 private:
 	void PlayedCallback();
@@ -368,7 +368,7 @@ SlesOutput::Cancel() noexcept
 }
 
 bool
-SlesOutput::Pause() noexcept
+SlesOutput::Pause()
 {
 	cancel = false;
 
@@ -378,10 +378,8 @@ SlesOutput::Pause() noexcept
 	pause = true;
 
 	SLresult result = play.SetPlayState(SL_PLAYSTATE_PAUSED);
-	if (result != SL_RESULT_SUCCESS) {
-		FormatError(sles_domain, "Play.SetPlayState(PAUSED) failed");
-		return false;
-	}
+	if (result != SL_RESULT_SUCCESS)
+		throw std::runtime_error("Play.SetPlayState(PAUSED) failed");
 
 	return true;
 }