input/ffmpeg: add AVIOContext wrapper class

src/lib/ffmpeg/IOContext.hxx

@@ -0,0 +1,93 @@
+/*
+ * Copyright 2003-2019 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.
+ */
+
+#ifndef MPD_FFMPEG_IO_CONTEXT_HXX
+#define MPD_FFMPEG_IO_CONTEXT_HXX
+
+#include "util/Compiler.h"
+#include "Error.hxx"
+
+extern "C" {
+#include <libavformat/avio.h>
+}
+
+#include <utility>
+
+namespace Ffmpeg {
+
+class IOContext {
+	AVIOContext *io_context = nullptr;
+
+public:
+	IOContext() = default;
+
+	IOContext(const char *url, int flags) {
+		int err = avio_open(&io_context, url, flags);
+		if (err < 0)
+			throw MakeFfmpegError(err);
+	}
+
+	~IOContext() noexcept {
+		if (io_context != nullptr)
+			avio_close(io_context);
+	}
+
+	IOContext(IOContext &&src) noexcept
+		:io_context(std::exchange(src.io_context, nullptr)) {}
+
+	IOContext &operator=(IOContext &&src) noexcept {
+		using std::swap;
+		swap(io_context, src.io_context);
+		return *this;
+	}
+
+	AVIOContext &operator*() noexcept {
+		return *io_context;
+	}
+
+	AVIOContext *operator->() noexcept {
+		return io_context;
+	}
+
+	gcc_pure
+	auto GetSize() const noexcept {
+		return avio_size(io_context);
+	}
+
+	size_t Read(void *buffer, size_t size) {
+		int result = avio_read(io_context,
+				       (unsigned char *)buffer, size);
+		if (result < 0)
+			throw MakeFfmpegError(result, "avio_read() failed");
+
+		return result;
+	}
+
+	uint64_t Seek(uint64_t offset) {
+		int64_t result = avio_seek(io_context, offset, SEEK_SET);
+		if (result < 0)
+			throw MakeFfmpegError(result, "avio_seek() failed");
+
+		return result;
+	}
+};
+
+} // namespace Ffmpeg
+
+#endif