Windows implementation of file, using CreateFile, WriteFile, ReadFile etc.

src/file_win.cpp

@@ -0,0 +1,185 @@
+#include <windows.h>
+#include "libtorrent/file.hpp"
+
+
+#define DWORD_MAX 0xffffffffu
+
+namespace libtorrent {
+
+	struct file::impl : boost::noncopyable
+	{
+		enum open_flags { read_flag=1,
+		                  write_flag=2 };
+		enum seek_mode  { seek_begin=FILE_BEGIN,
+			              seek_from_here=FILE_CURRENT,
+						  seek_end=FILE_END };
+
+		impl()
+		{
+			m_file_handle=INVALID_HANDLE_VALUE;
+		}
+
+		void open(const char *file_name, open_flags flags)
+		{
+			assert(file_name);
+			assert(flags&(read_flag|write_flag));
+
+			DWORD access_mask=0;
+			if (flags&read_flag)
+				access_mask|=GENERIC_READ;
+			if (flags&write_flag)
+				access_mask|=GENERIC_WRITE;
+
+			assert(access_mask&(GENERIC_READ|GENERIC_WRITE));
+
+			HANDLE new_handle=CreateFile(file_name,access_mask,FILE_SHARE_READ,NULL,
+				OPEN_ALWAYS,FILE_ATTRIBUTE_NORMAL,NULL);
+
+			if (new_handle==INVALID_HANDLE_VALUE)
+			{
+				throw file_error("could not open file");
+			}
+			// will only close old file if the open succeeded
+			close();
+			m_file_handle=new_handle;
+
+		}
+
+		void close()
+		{
+			if (m_file_handle!=INVALID_HANDLE_VALUE)
+			{
+				CloseHandle(m_file_handle);
+				m_file_handle=INVALID_HANDLE_VALUE;
+			}
+		}
+
+		~impl()
+		{
+			close();
+		}
+
+		size_type write(const char* buffer, size_type num_bytes)
+		{
+			assert(buffer);
+			assert(num_bytes>0);
+			assert((DWORD)num_bytes==num_bytes);
+				throw file_error("file::impl::write: num_bytes is negative");
+			if (num_bytes>=DWORD_MAX)
+				throw file_error("file::impl::write: num_bytes does not fit DWORD");
+			DWORD bytes_written=0;
+			if (num_bytes!=0)
+			{
+				if (FALSE == WriteFile(m_file_handle,buffer,(DWORD)num_bytes,&bytes_written,NULL))
+					throw file_error("file::impl::write: couldn't write to file");
+			}
+			return bytes_written;
+		}
+		
+		size_type read(char* buffer, size_type num_bytes)
+		{
+			assert(buffer);
+			assert(num_bytes>0);
+			assert((DWORD)num_bytes==num_bytes);
+
+			DWORD bytes_read=0;
+			if (num_bytes!=0)
+			{
+				if (FALSE == ReadFile(m_file_handle,buffer,(DWORD)num_bytes,&bytes_read,NULL))
+					throw file_error("file::impl::read: couldn't write to file");
+			}
+			return bytes_read;
+		}
+
+		void seek(size_type pos, seek_mode from_where)
+		{
+			assert(pos>=0);
+			LARGE_INTEGER offs;
+			offs.QuadPart=pos;
+				// FILE_CURRENT
+				// FILE_END
+			if (FALSE == SetFilePointerEx(m_file_handle,offs,&offs,from_where))
+				throw file_error("file::impl::seek: error");
+		}
+		
+		size_type tell()
+		{
+			LARGE_INTEGER offs;
+			offs.QuadPart=0;
+
+			// is there any other way to get offset?
+			if (FALSE == SetFilePointerEx(m_file_handle,offs,&offs,FILE_CURRENT))
+				throw file_error("file::impl::tell: error");
+
+			size_type pos=offs.QuadPart;
+			assert(pos>=0);
+			return pos;
+		}
+
+		size_type size()
+		{
+			LARGE_INTEGER s;
+			if (FALSE == GetFileSizeEx(m_file_handle,&s))
+				throw file_error("file::impl::size: error");
+			
+			size_type size=s.QuadPart;
+			assert(size>=0);
+			return size;
+		}
+	private:
+		HANDLE m_file_handle;
+	};
+}
+
+namespace libtorrent {
+
+	const file::seek_mode file::begin(file::impl::seek_begin);
+	const file::seek_mode file::end(file::impl::seek_end);
+
+	const file::open_mode file::in(file::impl::read_flag);
+	const file::open_mode file::out(file::impl::write_flag);
+
+	file::file()
+		: m_impl(new libtorrent::file::impl())
+	{
+	}
+	file::file(boost::filesystem::path const& p, open_mode m)
+		: m_impl(new libtorrent::file::impl())
+	{
+		open(p,m);
+	}
+
+	file::~file()
+	{
+	}
+
+	void file::open(boost::filesystem::path const& p, open_mode m)
+	{
+		m_impl->open(p.native_file_string().c_str(),impl::open_flags(m.m_mask));
+	}
+
+	void file::close()
+	{
+		m_impl->close();
+	}
+
+	file::size_type file::write(const char* buffer, file::size_type num_bytes)
+	{
+		return m_impl->write(buffer,num_bytes);
+	}
+
+	file::size_type file::read(char* buffer, file::size_type num_bytes)
+	{
+		return m_impl->read(buffer,num_bytes);
+	}
+
+	void file::seek(file::size_type pos, seek_mode m)
+	{
+		m_impl->seek(pos,impl::seek_mode(m.m_val));
+	}
+	
+	file::size_type file::tell()
+	{
+		return m_impl->tell();
+	}
+}