FIX: The select( ) function and the write( ) function do not handle the non-blocking serial I/O correctly

The migration of the Portable Operating System Interface for UNIX (POSIX) subsystems from SCO to Interix is held up because of one of the following conditions:

• The select() function incorrectly indicates that the serial port is ready for the write operation even though it is not yet ready. The select() function also does not work when you set the action parameter of the tcflow() function to TCOOFF or TCOON.
  
  Note The TCOOFF action parameter value is for suspending output. The TCOON action parameter value is for restarting suspended output.
• The write() function blocks when the serial device is not ready. This behavior occurs even if the O_NONBLOCK flag is set. This problem can occur at the start of the write operation or if the device is disconnected during the write operation.

Hotfix information

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site: Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.

Restart requirement

You must restart your computer because the POSIX subsystem is replaced when you apply this hotfix.

Hotfix replacement information

This hotfix does not replace any other hotfixes.

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 tool in Control Panel.

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

For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

For additional information about Windows Services for UNIX, visit the following Microsoft Web site: