From 543c5034afbec1ee3c46db2cb2d54966c55c7321 Mon Sep 17 00:00:00 2001
From: Max Kellermann <max@musicpd.org>
Date: Sat, 5 Nov 2016 15:13:14 +0100
Subject: [PATCH] output/fifo: migrate from class Error to C++ exceptions

---
 src/output/plugins/FifoOutputPlugin.cxx | 127 +++++++++---------------
 1 file changed, 48 insertions(+), 79 deletions(-)

diff --git a/src/output/plugins/FifoOutputPlugin.cxx b/src/output/plugins/FifoOutputPlugin.cxx
index b698de0c9..ba5775fe0 100644
--- a/src/output/plugins/FifoOutputPlugin.cxx
+++ b/src/output/plugins/FifoOutputPlugin.cxx
@@ -19,15 +19,14 @@
 
 #include "config.h"
 #include "FifoOutputPlugin.hxx"
-#include "config/ConfigError.hxx"
 #include "../OutputAPI.hxx"
 #include "../Wrapper.hxx"
 #include "../Timer.hxx"
 #include "fs/AllocatedPath.hxx"
 #include "fs/FileSystem.hxx"
 #include "fs/FileInfo.hxx"
-#include "util/Error.hxx"
 #include "util/Domain.hxx"
+#include "util/RuntimeError.hxx"
 #include "Log.hxx"
 #include "open.h"
 
@@ -40,35 +39,28 @@ class FifoOutput {
 
 	AudioOutput base;
 
-	AllocatedPath path;
+	const AllocatedPath path;
 	std::string path_utf8;
 
-	int input;
-	int output;
-	bool created;
+	int input = -1;
+	int output = -1;
+	bool created = false;
 	Timer *timer;
 
 public:
-	FifoOutput()
-		:base(fifo_output_plugin),
-		 path(AllocatedPath::Null()), input(-1), output(-1),
-		 created(false) {}
+	FifoOutput(const ConfigBlock &block);
 
 	~FifoOutput() {
 		CloseFifo();
 	}
 
-	bool Initialize(const ConfigBlock &block, Error &error) {
-		return base.Configure(block, error);
-	}
-
 	static FifoOutput *Create(const ConfigBlock &block, Error &error);
 
-	bool Create(Error &error);
-	bool Check(Error &error);
+	void Create();
+	void Check();
 	void Delete();
 
-	bool OpenFifo(Error &error);
+	void OpenFifo();
 	void CloseFifo();
 
 	bool Open(AudioFormat &audio_format, Error &error);
@@ -81,6 +73,18 @@ public:
 
 static constexpr Domain fifo_output_domain("fifo_output");
 
+FifoOutput::FifoOutput(const ConfigBlock &block)
+	:base(fifo_output_plugin, block),
+	 path(block.GetPath("path"))
+{
+	if (path.IsNull())
+		throw std::runtime_error("No \"path\" parameter specified");
+
+	path_utf8 = path.ToUTF8();
+
+	OpenFifo();
+}
+
 inline void
 FifoOutput::Delete()
 {
@@ -115,93 +119,59 @@ FifoOutput::CloseFifo()
 		Delete();
 }
 
-inline bool
-FifoOutput::Create(Error &error)
+inline void
+FifoOutput::Create()
 {
-	if (!MakeFifo(path, 0666)) {
-		error.FormatErrno("Couldn't create FIFO \"%s\"",
+	if (!MakeFifo(path, 0666))
+		throw FormatErrno("Couldn't create FIFO \"%s\"",
 				  path_utf8.c_str());
-		return false;
-	}
 
 	created = true;
-	return true;
 }
 
-inline bool
-FifoOutput::Check(Error &error)
+inline void
+FifoOutput::Check()
 {
 	struct stat st;
 	if (!StatFile(path, st)) {
 		if (errno == ENOENT) {
 			/* Path doesn't exist */
-			return Create(error);
+			Create();
+			return;
 		}
 
-		error.FormatErrno("Failed to stat FIFO \"%s\"",
+		throw FormatErrno("Failed to stat FIFO \"%s\"",
 				  path_utf8.c_str());
-		return false;
 	}
 
-	if (!S_ISFIFO(st.st_mode)) {
-		error.Format(fifo_output_domain,
-			     "\"%s\" already exists, but is not a FIFO",
-			     path_utf8.c_str());
-		return false;
-	}
-
-	return true;
+	if (!S_ISFIFO(st.st_mode))
+		throw FormatRuntimeError("\"%s\" already exists, but is not a FIFO",
+					 path_utf8.c_str());
 }
 
-inline bool
-FifoOutput::OpenFifo(Error &error)
-{
-	if (!Check(error))
-		return false;
+inline void
+FifoOutput::OpenFifo()
+try {
+	Check();
 
 	input = OpenFile(path, O_RDONLY|O_NONBLOCK|O_BINARY, 0);
-	if (input < 0) {
-		error.FormatErrno("Could not open FIFO \"%s\" for reading",
+	if (input < 0)
+		throw FormatErrno("Could not open FIFO \"%s\" for reading",
 				  path_utf8.c_str());
-		CloseFifo();
-		return false;
-	}
 
 	output = OpenFile(path, O_WRONLY|O_NONBLOCK|O_BINARY, 0);
-	if (output < 0) {
-		error.FormatErrno("Could not open FIFO \"%s\" for writing",
+	if (output < 0)
+		throw FormatErrno("Could not open FIFO \"%s\" for writing",
 				  path_utf8.c_str());
-		CloseFifo();
-		return false;
-	}
-
-	return true;
+} catch (...) {
+	CloseFifo();
+	throw;
 }
 
 inline FifoOutput *
-FifoOutput::Create(const ConfigBlock &block, Error &error)
+FifoOutput::Create(const ConfigBlock &block, Error &)
 {
-	FifoOutput *fd = new FifoOutput();
-
-	fd->path = block.GetPath("path");
-	if (fd->path.IsNull()) {
-		delete fd;
-		throw std::runtime_error("No \"path\" parameter specified");
-	}
-
-	fd->path_utf8 = fd->path.ToUTF8();
-
-	if (!fd->Initialize(block, error)) {
-		delete fd;
-		return nullptr;
-	}
-
-	if (!fd->OpenFifo(error)) {
-		delete fd;
-		return nullptr;
-	}
-
-	return fd;
+	return new FifoOutput(block);
 }
 
 bool
@@ -244,7 +214,7 @@ FifoOutput::Delay() const
 }
 
 inline size_t
-FifoOutput::Play(const void *chunk, size_t size, Error &error)
+FifoOutput::Play(const void *chunk, size_t size, Error &)
 {
 	if (!timer->IsStarted())
 		timer->Start();
@@ -265,9 +235,8 @@ FifoOutput::Play(const void *chunk, size_t size, Error &error)
 				continue;
 			}
 
-			error.FormatErrno("Failed to write to FIFO %s",
+			throw FormatErrno("Failed to write to FIFO %s",
 					  path_utf8.c_str());
-			return 0;
 		}
 	}
 }