Q46524: PRB: File Handles Cannot Be Shared Between Programs or DLLs

Article: Q46524
Product(s): Microsoft Windows Software Development Kit
Version(s): WINDOWS:3.0,3.1
Operating System(s): 
Keyword(s): kb16bitonly
Last Modified: 06-NOV-1999

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The information in this article applies to:

- Microsoft Windows Software Development Kit (SDK) versions 3.0, 3.1 
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SYMPTOMS
========

Assume that there are two applications, A and B. Application A calls a
Dynamic-Link Library (DLL) to open a file. The file pointer (FILE *pFile) is
stored on the data segment of the DLL. Application A then calls a function in
the DLL to read the record "n" of this file properly. However, if Application B
calls the same function in the DLL to read the same record, the record appears
as random characters.

RESOLUTION
==========

File handles cannot be shared between applications or DLLs. Each application has
its own file handle table. When an fopen() call is made, a file is taken out of
the application's program segment prefix (PSP). For two separate applications to
use the same file, each application must make its own fopen() call, file I/O
calls, and fclose() call.

Additional query words: 3.00 no32bi 3.10

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Keywords          : kb16bitonly 
Technology        : kbAudDeveloper kbWin3xSearch kbSDKSearch kbWinSDKSearch kbWinSDK300 kbWinSDK310
Version           : WINDOWS:3.0,3.1

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