BoxedAppSDK_CreateVirtualFileBasedOnIStream

Description

The function creates a virtual file, the behavior of which is determined by the implementation of the standard interface IStream. The arguments of BoxedAppSDK_CreateVirtualFileBasedOnIStream are similar to the arguments of the winapi function CreateFile.

BoxedAppSDK_CreateVirtualFile creates a file with the contents located in the shared memory. This is the easiest way to create a virtual file, which is sufficient for the majority of cases. However, sometimes you may need to have a virtual file with its data stored in other places: database, encrypted file or the Internet. For that purpose, BoxedApp SDK allows creating a virtual file, based on the implementation of the standard interface IStream: BoxedAppSDK_CreateVirtualFileBasedOnIStream.

Reading from such file takes the method IStream::Read(); writing to it calls IStream::Write().

Creating a new handle that points to such file requires IStream::Clone(), which returns IStream with its own current pointer.

To set and get the current position in that file, BoxedApp uses IStream::Seek().

To resize the file, it uses IStream::SetSize(). To get the size of the file, it can call the method IStream::Stat().

Syntax

C++


    HANDLE __stdcall BoxedAppSDK_CreateVirtualFileBasedOnIStream(
        LPCTSTR szPath,
        DWORD dwDesiredAccess,
        DWORD dwShareMode,
        LPSECURITY_ATTRIBUTES lpSecurityAttributes,
        DWORD dwCreationDisposition,
        DWORD dwFlagsAndAttributes,
        HANDLE hTemplateFile,
        LPSTREAM pStream);

Delphi


    function BoxedAppSDK_CreateVirtualFileBasedOnIStream(
        lpFileName: PAnsiChar;
        dwDesiredAccess, dwShareMode: Integer;
        lpSecurityAttributes: PSecurityAttributes;
        dwCreationDisposition, dwFlagsAndAttributes: DWORD;
        hTemplateFile: THandle;
        pStream: IStream): THandle; stdcall;

    function BoxedAppSDK_CreateVirtualFileBasedOnIStreamA(
        lpFileName: PAnsiChar;
        dwDesiredAccess, dwShareMode: Integer;
        lpSecurityAttributes: PSecurityAttributes;
        dwCreationDisposition, dwFlagsAndAttributes: DWORD;
        hTemplateFile: THandle;
        pStream: IStream): THandle; stdcall;

    function BoxedAppSDK_CreateVirtualFileBasedOnIStreamW(
        lpFileName: PWideChar;
        dwDesiredAccess, dwShareMode: Integer;
        lpSecurityAttributes: PSecurityAttributes;
        dwCreationDisposition, dwFlagsAndAttributes: DWORD;
        hTemplateFile: THandle;
        pStream: IStream): THandle; stdcall;

Parameters

lpFileName

The name, relative or full path of the virtual file to be created.

dwDesiredAccess

The requested access.

dwShareMode

The sharing mode.

lpSecurityAttributes

A pointer to a SECURITY_ATTRIBUTES structure that optionally specifies security descriptor, and whether the file handle can be inherited by child processes. It's ignored by BoxedApp currently.

dwCreationDisposition

An action to take on a virtual file that exists or doesn't exist.

dwFlagsAndAttributes

Combination of FILE_FLAG_* and FILE_ATTRIBUTE_*. You can pass 0.

pStream

The virtual file will read and write data from this stream.

See Also