InternetReadFile Function

Reads data from a handle opened by the InternetOpenUrl, FtpOpenFile, GopherOpenFile, or HttpOpenRequest function.

Syntax

BOOL InternetReadFile(
    IN HINTERNET hFile,
    IN LPVOID lpBuffer,
    IN DWORD dwNumberOfBytesToRead,
    OUT LPDWORD lpdwNumberOfBytesRead
);

Parameters

hFile

Valid HINTERNET handle returned from a previous call to InternetOpenUrl, FtpOpenFile, GopherOpenFile, or HttpOpenRequest.

lpBuffer

Address of a buffer that receives the data read.

dwNumberOfBytesToRead

Unsigned long integer value that contains the number of bytes to read.

lpdwNumberOfBytesRead

Address of an unsigned long integer variable that receives the number of bytes read. InternetReadFile sets this value to zero before doing any work or error checking.

Return Value

Returns TRUE if successful, or FALSE otherwise. To get extended error information, call GetLastError. An application can also use InternetGetLastResponseInfo when necessary.

Remarks

If the return value is TRUE and the number of bytes read is zero, the transfer has been completed and there are no more bytes to read on the handle. This is analogous to reaching EOF in a local file.

The buffer pointed to by lpBuffer is not always filled by calls to InternetReadFile (sufficient data might not have arrived from the server). When reading HTML data, for the first read posted, the buffer must be large enough to hold the HTML headers. When reading HTML-encoded directory entries, the buffer must be large enough to hold at least one complete entry.

When the item being read is also being cached by a Win32® Internet function, the application must ensure that a read is made for end-of-file so the cache file is committed correctly.

This function always fulfills the user's request. If more data is requested than is available, the function waits until enough data to complete the request is available. The only time that less data is returned than requested is when the end of the file has been reached.

This function can also be used to retrieve FTP and Gopher directory listings as an HTML document on a handle opened by InternetOpenUrl. The INTERNET_FLAG_RAW_DATA value must not have been specified in the call to InternetOpenUrl.

If the HINTERNET handle stored in hFile was created by HttpOpenRequest and sent by HttpSendRequestEx, a call to HttpEndRequest must be made on the handle before InternetReadFile is used.

Function Information

Windows NT	Use version 4.0 and later. 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

See Also

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

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