fs/OutputStream: new infrastructure for writing to files

1 files changed, 143 insertions, 0 deletions

diff --git a/src/fs/output/BufferedOutputStream.cxx b/src/fs/output/BufferedOutputStream.cxx
new file mode 100644
index 000000000..088a3e279
--- /dev/null
+++ b/src/fs/output/BufferedOutputStream.cxx
@@ -0,0 +1,143 @@
+/*
+ * 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 "BufferedOutputStream.hxx"
+#include "OutputStream.hxx"
+
+#include <stdarg.h>
+#include <string.h>
+#include <stdio.h>
+
+bool
+BufferedOutputStream::AppendToBuffer(const void *data, size_t size)
+{
+	auto r = buffer.Write();
+	if (r.size < size)
+		return false;
+
+	memcpy(r.data, data, size);
+	buffer.Append(size);
+	return true;
+}
+
+bool
+BufferedOutputStream::Write(const void *data, size_t size)
+{
+	if (gcc_unlikely(last_error.IsDefined()))
+		return false;
+
+	if (AppendToBuffer(data, size))
+		return true;
+
+	if (!Flush())
+		return false;
+
+	if (AppendToBuffer(data, size))
+		return true;
+
+	return os.Write(data, size, last_error);
+}
+
+bool
+BufferedOutputStream::Write(const char *p)
+{
+	return Write(p, strlen(p));
+}
+
+bool
+BufferedOutputStream::Format(const char *fmt, ...)
+{
+	if (gcc_unlikely(last_error.IsDefined()))
+		return false;
+
+	auto r = buffer.Write();
+	if (r.IsEmpty()) {
+		if (!Flush())
+			return false;
+
+		r = buffer.Write();
+	}
+
+	/* format into the buffer */
+	va_list ap;
+	va_start(ap, fmt);
+	size_t size = vsnprintf(r.data, r.size, fmt, ap);
+	va_end(ap);
+
+	if (gcc_unlikely(size >= r.size)) {
+		/* buffer was not large enough; flush it and try
+		   again */
+
+		if (!Flush())
+			return false;
+
+		r = buffer.Write();
+
+		if (gcc_unlikely(size >= r.size)) {
+			/* still not enough space: grow the buffer and
+			   try again */
+			r.size = size + 1;
+			r.data = buffer.Write(r.size);
+		}
+
+		/* format into the new buffer */
+		va_start(ap, fmt);
+		size = vsnprintf(r.data, r.size, fmt, ap);
+		va_end(ap);
+
+		/* this time, it must fit */
+		assert(size < r.size);
+	}
+
+	buffer.Append(size);
+	return true;
+}
+
+bool
+BufferedOutputStream::Flush()
+{
+	if (!Check())
+		return false;
+
+	auto r = buffer.Read();
+	if (r.IsEmpty())
+		return true;
+
+	bool success = os.Write(r.data, r.size, last_error);
+	if (gcc_likely(success))
+		buffer.Consume(r.size);
+	return success;
+}
+
+bool
+BufferedOutputStream::Flush(Error &error)
+{
+	if (!Check(error))
+		return false;
+
+	auto r = buffer.Read();
+	if (r.IsEmpty())
+		return true;
+
+	bool success = os.Write(r.data, r.size, error);
+	if (gcc_likely(success))
+		buffer.Consume(r.size);
+	return success;
+}