URLDownloadToCacheFile Function

---

Downloads data into the Internet cache and returns the file name of the cache location for retrieving the bits.

Syntax

HRESULT URLDownloadToCacheFile(
    LPUNKNOWN lpUnkcaller,
    LPCSTR szURL,
    LPTSTR szFileName,
    DWORD dwBufLength,
    DWORD dwReserved,
    IBindStatusCallback *pBSC
);

Parameters

lpUnkcaller

Address of the controlling IUnknown interface of the calling ActiveX® component (if the caller is an ActiveX component). If the caller is not an ActiveX component, this value can be set to NULL. Otherwise, the caller is a COM object that is contained in another component (such as an ActiveX control within the context of an HTML page). This parameter represents the outermost IUnknown of the calling component. The function attempts the download within the context of the ActiveX client framework and allows the caller's container to receive callbacks on the progress of the download.

szURL

Address of a string value that contains the URL to be downloaded. This cannot be set to NULL.

szFileName

Address of a string value that contains the name of the downloaded file. This cannot be set to NULL.

dwBufLength

Unsigned long integer value that contains the size of the szFileName buffer.

dwReserved

Reserved. Must be set to zero.

pBSC

Address of the caller's IBindStatusCallback interface. URLDownloadToCacheFile calls this interface's IBindStatusCallback::OnProgress method on a connection activity, including the arrival of data. IBindStatusCallback::OnDataAvailable is never called. Implementing IBindStatusCallback::OnProgress allows a caller to implement a user interface or other progress monitoring functionality. It also allows the download operation to be canceled by returning E_ABORT from the IBindStatusCallback::OnProgress call. This can be set to NULL.

Return Value

Returns one of the following values:

E_FAIL	The operation failed.
E_OUTOFMEMORY	The buffer length is invalid or there was insufficient memory to complete the operation.
S_OK	The operation succeeded.

Remarks

The client can choose to be notified of progress through a notification callback.

This function always returns a file name if the download operation succeeds. If the given URL is a "file:" URL, URLDownloadToCacheFile directly returns the file name for the "file:" URL rather than making a copy to the cache. If the given URL is an Internet URL ("http:", "ftp:"), URLDownloadToCacheFile downloads this file and returns the local file name of the cached copy. Using this function ensures that a file name is returned without unnecessary copying of data.

Function Information

Windows NT	Use version 4.0. Implemented as ANSI and Unicode functions.
Windows	Use Windows 95 and later. Implemented as ANSI and Unicode functions.
Header	Urlmon.h
Import Library	Urlmon.lib
Minimum availability	Internet Explorer 3.0