From b630afdeda4a5e1b38ec93e98fd4a9e2fe86d510 Mon Sep 17 00:00:00 2001
From: Max Kellermann <max@musicpd.org>
Date: Sun, 4 Sep 2016 12:05:37 +0200
Subject: [PATCH] fs/io/BufferedOutputStream: add wchar_t overloads

---
 src/fs/io/BufferedOutputStream.cxx | 51 ++++++++++++++++++++++++++++++
 src/fs/io/BufferedOutputStream.hxx | 18 +++++++++++
 2 files changed, 69 insertions(+)

diff --git a/src/fs/io/BufferedOutputStream.cxx b/src/fs/io/BufferedOutputStream.cxx
index 396fa91c7..7f7b7a4a5 100644
--- a/src/fs/io/BufferedOutputStream.cxx
+++ b/src/fs/io/BufferedOutputStream.cxx
@@ -25,6 +25,11 @@
 #include <string.h>
 #include <stdio.h>
 
+#ifdef _UNICODE
+#include "system/Error.hxx"
+#include <windows.h>
+#endif
+
 bool
 BufferedOutputStream::AppendToBuffer(const void *data, size_t size) noexcept
 {
@@ -103,6 +108,52 @@ BufferedOutputStream::Format(const char *fmt, ...)
 	buffer.Append(size);
 }
 
+#ifdef _UNICODE
+
+void
+BufferedOutputStream::Write(const wchar_t *p)
+{
+	WriteWideToUTF8(p, wcslen(p));
+}
+
+void
+BufferedOutputStream::WriteWideToUTF8(const wchar_t *src, size_t src_length)
+{
+	if (src_length == 0)
+		return;
+
+	auto r = buffer.Write();
+	if (r.IsEmpty()) {
+		Flush();
+		r = buffer.Write();
+	}
+
+	int length = WideCharToMultiByte(CP_UTF8, 0, src, src_length,
+					 r.data, r.size, nullptr, nullptr);
+	if (length <= 0) {
+		const auto error = GetLastError();
+		if (error != ERROR_INSUFFICIENT_BUFFER)
+			throw MakeLastError(error, "UTF-8 conversion failed");
+
+		/* how much buffer do we need? */
+		length = WideCharToMultiByte(CP_UTF8, 0, src, src_length,
+					     nullptr, 0, nullptr, nullptr);
+		if (length <= 0)
+			throw MakeLastError(error, "UTF-8 conversion failed");
+
+		/* grow the buffer and try again */
+		length = WideCharToMultiByte(CP_UTF8, 0, src, src_length,
+					     buffer.Write(length), length,
+					     nullptr, nullptr);
+		if (length <= 0)
+			throw MakeLastError(error, "UTF-8 conversion failed");
+	}
+
+	buffer.Append(length);
+}
+
+#endif
+
 void
 BufferedOutputStream::Flush()
 {
diff --git a/src/fs/io/BufferedOutputStream.hxx b/src/fs/io/BufferedOutputStream.hxx
index 1a0ae021d..3d42bedf7 100644
--- a/src/fs/io/BufferedOutputStream.hxx
+++ b/src/fs/io/BufferedOutputStream.hxx
@@ -26,11 +26,17 @@
 
 #include <stddef.h>
 
+#ifdef _UNICODE
+#include <wchar.h>
+#endif
+
 class OutputStream;
 
 /**
  * An #OutputStream wrapper that buffers its output to reduce the
  * number of OutputStream::Write() calls.
+ *
+ * All wchar_t based strings are converted to UTF-8.
  */
 class BufferedOutputStream {
 	OutputStream &os;
@@ -52,6 +58,14 @@ public:
 	gcc_printf(2,3)
 	void Format(const char *fmt, ...);
 
+#ifdef _UNICODE
+	void Write(const wchar_t &ch) {
+		WriteWideToUTF8(&ch, 1);
+	}
+
+	void Write(const wchar_t *p);
+#endif
+
 	/**
 	 * Write buffer contents to the #OutputStream.
 	 */
@@ -59,6 +73,10 @@ public:
 
 private:
 	bool AppendToBuffer(const void *data, size_t size) noexcept;
+
+#ifdef _UNICODE
+	void WriteWideToUTF8(const wchar_t *p, size_t length);
+#endif
 };
 
 #endif