input/nfs: use the asynchronous libnfs API

More robust and cancellable.

src/lib/nfs/FileReader.cxx

@@ -0,0 +1,244 @@
+/*
+ * Copyright (C) 2003-2014 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "config.h"
+#include "FileReader.hxx"
+#include "Glue.hxx"
+#include "Connection.hxx"
+#include "Domain.hxx"
+#include "event/Call.hxx"
+#include "IOThread.hxx"
+#include "util/StringUtil.hxx"
+#include "util/Error.hxx"
+
+#include <utility>
+
+#include <assert.h>
+#include <string.h>
+#include <fcntl.h>
+
+NfsFileReader::NfsFileReader()
+	:DeferredMonitor(io_thread_get()), state(State::INITIAL)
+{
+}
+
+NfsFileReader::~NfsFileReader()
+{
+	assert(state == State::INITIAL);
+}
+
+void
+NfsFileReader::Close()
+{
+	if (state == State::INITIAL)
+		return;
+
+	if (state == State::DEFER) {
+		state = State::INITIAL;
+		DeferredMonitor::Cancel();
+		return;
+	}
+
+	connection->RemoveLease(*this);
+
+	if (state > State::MOUNT && state != State::IDLE)
+		connection->Cancel(*this);
+
+	if (state > State::OPEN)
+		connection->Close(fh);
+
+	state = State::INITIAL;
+}
+
+void
+NfsFileReader::DeferClose()
+{
+	BlockingCall(io_thread_get(), [this](){ Close(); });
+}
+
+bool
+NfsFileReader::Open(const char *uri, Error &error)
+{
+	assert(state == State::INITIAL);
+
+	if (!StringStartsWith(uri, "nfs://")) {
+		error.Set(nfs_domain, "Malformed nfs:// URI");
+		return false;
+	}
+
+	uri += 6;
+
+	const char *slash = strchr(uri, '/');
+	if (slash == nullptr) {
+		error.Set(nfs_domain, "Malformed nfs:// URI");
+		return false;
+	}
+
+	server = std::string(uri, slash);
+
+	uri = slash;
+	slash = strrchr(uri + 1, '/');
+	if (slash == nullptr || slash[1] == 0) {
+		error.Set(nfs_domain, "Malformed nfs:// URI");
+		return false;
+	}
+
+	export_name = std::string(uri, slash);
+	path = slash;
+
+	state = State::DEFER;
+	DeferredMonitor::Schedule();
+	return true;
+}
+
+bool
+NfsFileReader::Read(uint64_t offset, size_t size, Error &error)
+{
+	assert(state == State::IDLE);
+
+	if (!connection->Read(fh, offset, size, *this, error))
+		return false;
+
+	state = State::READ;
+	return true;
+}
+
+void
+NfsFileReader::CancelRead()
+{
+	if (state == State::READ) {
+		connection->Cancel(*this);
+		state = State::IDLE;
+	}
+}
+
+void
+NfsFileReader::OnNfsConnectionReady()
+{
+	assert(state == State::MOUNT);
+
+	Error error;
+	if (!connection->Open(path, O_RDONLY, *this, error)) {
+		OnNfsFileError(std::move(error));
+		return;
+	}
+
+	state = State::OPEN;
+}
+
+void
+NfsFileReader::OnNfsConnectionFailed(const Error &error)
+{
+	assert(state == State::MOUNT);
+
+	Error copy;
+	copy.Set(error);
+	OnNfsFileError(std::move(copy));
+}
+
+void
+NfsFileReader::OnNfsConnectionDisconnected(const Error &error)
+{
+	assert(state > State::MOUNT);
+
+	state = State::INITIAL;
+
+	Error copy;
+	copy.Set(error);
+	OnNfsFileError(std::move(copy));
+}
+
+inline void
+NfsFileReader::OpenCallback(nfsfh *_fh)
+{
+	assert(state == State::OPEN);
+	assert(connection != nullptr);
+	assert(_fh != nullptr);
+
+	fh = _fh;
+
+	Error error;
+	if (!connection->Stat(fh, *this, error)) {
+		OnNfsFileError(std::move(error));
+		return;
+	}
+
+	state = State::STAT;
+}
+
+inline void
+NfsFileReader::StatCallback(const struct stat *st)
+{
+	assert(state == State::STAT);
+	assert(connection != nullptr);
+	assert(fh != nullptr);
+	assert(st != nullptr);
+
+	if (!S_ISREG(st->st_mode)) {
+		OnNfsFileError(Error(nfs_domain, "Not a regular file"));
+		return;
+	}
+
+	state = State::IDLE;
+
+	OnNfsFileOpen(st->st_size);
+}
+
+void
+NfsFileReader::OnNfsCallback(unsigned status, void *data)
+{
+	switch (state) {
+	case State::INITIAL:
+	case State::DEFER:
+	case State::MOUNT:
+	case State::IDLE:
+		assert(false);
+		gcc_unreachable();
+
+	case State::OPEN:
+		OpenCallback((struct nfsfh *)data);
+		break;
+
+	case State::STAT:
+		StatCallback((const struct stat *)data);
+		break;
+
+	case State::READ:
+		state = State::IDLE;
+		OnNfsFileRead(data, status);
+		break;
+	}
+}
+
+void
+NfsFileReader::OnNfsError(Error &&error)
+{
+	OnNfsFileError(std::move(error));
+}
+
+void
+NfsFileReader::RunDeferred()
+{
+	assert(state == State::DEFER);
+
+	state = State::MOUNT;
+
+	connection = &nfs_get_connection(server.c_str(), export_name.c_str());
+	connection->AddLease(*this);
+}