VeraCrypt/src/Platform/File.h

/*
 Derived from source code of TrueCrypt 7.1a, which is
 Copyright (c) 2008-2012 TrueCrypt Developers Association and which is governed
 by the TrueCrypt License 3.0.

 Modifications and additions to the original source code (contained in this file)
 and all other portions of this file are Copyright (c) 2013-2026 AM Crypto
 and are governed by the Apache License 2.0 the full text of which is
 contained in the file License.txt included in VeraCrypt binary and source
 code distribution packages.
*/

#ifndef TC_HEADER_Platform_File
#define TC_HEADER_Platform_File

#include "PlatformBase.h"
#include "Buffer.h"
#include "FilesystemPath.h"
#include "SystemException.h"

#ifdef TC_LINUX
#define TC_REQUESTER_HELPER_CMDLINE_OPTION "--requester-helper"
#endif

namespace VeraCrypt
{
	class File
	{
	public:
		enum FileOpenMode
		{
			CreateReadWrite,
			CreateWrite,
			OpenRead,
			OpenWrite,
			OpenReadWrite
		};

		enum FileShareMode
		{
			ShareNone,
			ShareRead,
			ShareReadWrite,
			ShareReadWriteIgnoreLock
		};

		enum FileOpenFlags
		{
			// Bitmap
			FlagsNone = 0,
			PreserveTimestamps = 1 << 0,
			DisableWriteCaching = 1 << 1,
			// Linux: when root is denied access to an existing file, open it with
			// the credentials of the user who requested elevation.
			AllowRequesterAccess = 1 << 2
		};

#ifdef TC_WINDOWS
		typedef FILE* SystemFileHandleType;
#else
		typedef int SystemFileHandleType;
#endif

		File () : FileIsOpen (false), mFileOpenFlags (FlagsNone), SharedHandle (false), FileHandle (0)
#ifndef TC_WINDOWS
				,AccTime(0), ModTime (0)
#endif
#ifdef TC_LINUX
				,RequesterBacked (false), ReleaseOnly (false), RequesterUserId (0), RequesterGroupId (0)
#endif
		 { }
		virtual ~File ();

		void AssignSystemHandle (SystemFileHandleType openFileHandle, bool sharedHandle = true)
		{
			if (FileIsOpen)
				Close();
			FileHandle = openFileHandle;
			FileIsOpen = true;
			SharedHandle = sharedHandle;
		}

		void Close ();
		static void Copy (const FilePath &sourcePath, const FilePath &destinationPath, bool preserveTimestamps = true);
		void Delete ();
		void Flush () const;
		uint32 GetDeviceSectorSize () const;
		static size_t GetOptimalReadSize () { return OptimalReadSize; }
		static size_t GetOptimalWriteSize ()  { return OptimalWriteSize; }
		uint64 GetPartitionDeviceStartOffset () const;
		bool IsOpen () const { return FileIsOpen; }
#ifdef TC_LINUX
		// Internal, freshly executed process; called before core/UI initialization.
		static int RunRequesterHelperService (const char *socketDescriptor);
		// The descriptor was opened with the requester's credentials (AllowRequesterAccess).
		bool IsRequesterBacked () const { return RequesterBacked; }
		// For copies held by processes that do not serve the volume: release the
		// descriptor without restoring timestamps through a requester process.
		void SetReleaseOnly () { ReleaseOnly = true; }
#endif
		FilePath GetPath () const;
		uint64 Length () const;
		void Open (const FilePath &path, FileOpenMode mode = OpenRead, FileShareMode shareMode = ShareReadWrite, FileOpenFlags flags = FlagsNone);
		uint64 Read (const BufferPtr &buffer) const;
		void ReadCompleteBuffer (const BufferPtr &buffer) const;
		uint64 ReadAt (const BufferPtr &buffer, uint64 position) const;
		void SeekAt (uint64 position) const;
		void SeekEnd (int ofset) const;
#ifndef TC_WINDOWS
		void SetCloseOnExec () const;
#endif
		void SetLength (uint64 length) const;
		void Write (const ConstBufferPtr &buffer) const;
		void Write (const ConstBufferPtr &buffer, size_t length) const { Write (buffer.GetRange (0, length)); }
		void WriteAt (const ConstBufferPtr &buffer, uint64 position) const;

	protected:
		void ValidateState () const;

		static const size_t OptimalReadSize = 256 * 1024;
		static const size_t OptimalWriteSize = 256 * 1024;

		bool FileIsOpen;
		FileOpenFlags mFileOpenFlags;
		bool SharedHandle;
		FilePath Path;
		SystemFileHandleType FileHandle;

#ifdef TC_WINDOWS
#else
		time_t AccTime;
		time_t ModTime;
#endif
#ifdef TC_LINUX
		bool OpenAsRequester (const FilePath &path, int sysFlags);
		void RestoreTimestampsAsRequester () const;

		bool RequesterBacked;
		bool ReleaseOnly;
		uid_t RequesterUserId;
		gid_t RequesterGroupId;
#endif

	private:
		File (const File &);
		File &operator= (const File &);
	};
}

#endif // TC_HEADER_Platform_File