FIX: Error message when a Visual C++ 2005 application tries to open a file in debug mode in Visual Studio 2005 Service Pack 1: "Too many open files"

Consider the following scenario:

• You create a C++ application in Microsoft Visual Studio 2005 Service Pack 1 (SP1).
• The application uses the C run-time library to open a file.
• You compile the application, and then you run the application in debug mode.
• The application opens several files successfully.
• The application opens another file unsuccessfully more than 512 times.

In this scenario, the application may be unable to open any more files, even if the paths are valid. When this problem occurs, you receive the following error message:

Hotfix information

A supported hotfix is now available from Microsoft. However, it is intended to correct only the problem that is described in this article. Apply it only to systems that are experiencing this specific problem. This hotfix may receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next Visual Studio 2005 service pack that contains this hotfix.

To resolve this problem immediately, contact Microsoft Customer Support Services to obtain the hotfix. For a complete list of Microsoft Customer Support Services telephone numbers and information about support costs, visit the following Microsoft Web site:Note In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

Prerequisites

You must have Visual Studio 2005 Service Pack 1 (SP1) installed to apply this hotfix.

Restart requirement

You do not have to restart the computer after you apply this hotfix.

File information

The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time item in Control Panel.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

Steps to reproduce the problem

To reproduce the problem, follow these steps:

1. Paste the following code example into a Microsoft Visual C++ 2005 console application.

   #include <stdio.h>
   #include <stdlib.h>
   
   int main(int argc, char*argv[])
   {
       int i;
       struct FILE* f;
   
       for (i=0; i<513; ++i)
           if (i<17)
               f=fopen(argv[0], "r");
           else
               f=fopen("This file does not exist", "r");
   
       printf("Error number is: %u", errno);
   
       return 0;
   }
   

2. Compile the application, and then run the application in debug mode. Notice that error number 24 is returned. Error number 24 displays a "Too many open files" error message.