InternetSetFilePointer Function

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Sets a file position for InternetReadFile. This is a synchronous call; however, subsequent calls to InternetReadFile might block or return pending if the data is not available from the cache and the server does not support random access.

Syntax

DWORD InternetSetFilePointer(
    IN HINTERNET hFile,
    IN LONG lDistanceToMove,
    IN PVOID pReserved,
    IN DWORD dwMoveMethod,
    IN DWORD dwContext
);

Parameters

hFile

Valid HINTERNET handle returned from a previous call to InternetOpenUrl (on an HTTP or HTTPS URL) or HttpOpenRequest (using the GET or HEAD method and passed to HttpSendRequest or HttpSendRequestEx). This handle must not have been created with the INTERNET_FLAG_DONT_CACHE or INTERNET_FLAG_NO_CACHE_WRITE value set.

lDistanceToMove

Long integer value that contains the number of bytes to move the file pointer. A positive value moves the pointer forward in the file; a negative value moves it backward.

pReserved

Reserved. Must be set to NULL.

dwMoveMethod

Unsigned long integer value that indicates the starting point for the file pointer move. This can be one of the following values:

FILE_BEGIN

Starting point is zero or the beginning of the file. If FILE_BEGIN is specified, lDistanceToMove is interpreted as an unsigned location for the new file pointer.

FILE_CURRENT

Current value of the file pointer is the starting point.

FILE_END

Current end-of-file position is the starting point. This method fails if the content length is unknown.

dwContext

Reserved. Must be set to zero.

Return Value

Returns the current file position if the function succeeds, or -1 otherwise.

Remarks

This function cannot be used once the end of the file has been reached by InternetReadFile.

For HINTERNET handles created by HttpOpenRequest and sent by HttpSendRequestEx, a call to HttpEndRequest must be made on the handle before InternetSetFilePointer is used.

InternetSetFilePointer cannot be used reliably if the content length is unknown, and it cannot be used reliably with chunked transfers.

Function Information

Windows NT	Use version 4.0. Implemented only as an ANSI function.
Windows	Use Windows 95 and later. Implemented only as an ANSI function.
Header	Wininet.h
Import library	Wininet.lib
Minimum availability	Internet Explorer 3.0

Windows CE

Windows CE	Use version 2.12 and later
Minimum availability	Internet Explorer 4.0

See Also

Microsoft Win32 Internet Functions Overview, Common Functions, Microsoft Win32 Internet Functions Reference, General Win32 Internet Functions