Little helper class for writing the disk device/partition data into a buffer for userland.

git-svn-id: file:///srv/svn/repos/haiku/trunk/current@3879 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/kernel/core/disk_device_manager/UserDataWriter.cpp

@@ -0,0 +1,83 @@
+// UserDataWriter.cpp
+
+#include <ddm_userland_interface.h>
+
+#include "UserDataWriter.h"
+
+// constructor
+UserDataWriter::UserDataWriter()
+	: fBuffer(NULL),
+	  fBufferSize(0),
+	  fAllocatedSize(0)
+{
+}
+
+// constructor
+UserDataWriter::UserDataWriter(user_disk_device_data *buffer,
+							   size_t bufferSize)
+	: fBuffer(buffer),
+	  fBufferSize(bufferSize),
+	  fAllocatedSize(0)
+{
+}
+
+// destructor
+UserDataWriter::~UserDataWriter()
+{
+}
+
+// AllocateData
+void *
+UserDataWriter::AllocateData(size_t size, size_t align = 1)
+{
+	if (size == 0)
+		return NULL;
+	if (align > 1)
+		fAllocatedSize = (fAllocatedSize + align - 1) / align * align;
+	void *result = NULL;
+	if (fAllocatedSize + size <= fBufferSize)
+		result = (uint8*)fBuffer + fAllocatedSize;
+	fAllocatedSize += size;
+	return result;
+}
+
+// AllocatePartitionData
+user_partition_data *
+UserDataWriter::AllocatePartitionData(size_t childCount)
+{
+	return (user_partition_data*)AllocateData(
+		sizeof(user_partition_data)
+		+ sizeof(user_partition_data*) * ((int32)childCount - 1),
+		sizeof(int));
+}
+
+// AllocateDeviceData
+user_disk_device_data *
+UserDataWriter::AllocateDeviceData(size_t childCount)
+{
+	return (user_disk_device_data*)AllocateData(
+		sizeof(user_disk_device_data)
+		+ sizeof(user_partition_data*) * ((int32)childCount - 1),
+		sizeof(int));
+}
+
+// PlaceString
+char *
+UserDataWriter::PlaceString(const char *str)
+{
+	if (!str)
+		return NULL;
+	size_t len = strlen(str) + 1;
+	char *data = (char*)AllocateData(len);
+	if (data)
+		memcpy(data, str, len);
+	return data;
+}
+
+// AllocatedSize
+size_t
+UserDataWriter::AllocatedSize() const
+{
+	return fAllocatedSize;
+}
+

src/kernel/core/disk_device_manager/UserDataWriter.h

@@ -0,0 +1,39 @@
+// KDiskDeviceUserDataWriter.h
+
+#ifndef _K_DISK_DEVICE_USER_DATA_WRITER_H
+#define _K_DISK_DEVICE_USER_DATA_WRITER_H
+
+#include <SupportDefs.h>
+
+struct user_disk_device_data;
+struct user_partition_data;
+
+namespace BPrivate {
+namespace DiskDevice {
+
+class UserDataWriter {
+public:
+	UserDataWriter();
+	UserDataWriter(user_disk_device_data *buffer, size_t bufferSize);
+	~UserDataWriter();
+
+	void *AllocateData(size_t size, size_t align = 1);
+	user_partition_data *AllocatePartitionData(size_t childCount);
+	user_disk_device_data *AllocateDeviceData(size_t childCount);
+
+	char *PlaceString(const char *str);
+
+	size_t AllocatedSize() const;
+
+private:
+	user_disk_device_data	*fBuffer;
+	size_t					fBufferSize;
+	size_t					fAllocatedSize;
+};
+
+} // namespace DiskDevice
+} // namespace BPrivate
+
+using BPrivate::DiskDevice::UserDataWriter;
+
+#endif	// _K_DISK_DEVICE_USER_DATA_WRITER_H