From: Charlie Savage <redmine@...>
Date: 2009-02-23T12:44:32+09:00
Subject: [ruby-core:22345] [Bug #1162] Build Assertion Failure with VC+++ - Incorrect flushing of stdout/stderr

Issue #1162 has been updated by Charlie Savage.


>It is a compile time flag and irrelevant to debug built msvcrt.

Not sure what you mean.  VC2008 (and earlier versions) set the -RTC1 flag by default when creating debug builds of C/C++ projects.  The -RTC1 flag causes the binary to use a debug version of the C runtime libraries.  These libraries are helpful in diagnosing memory problems or other incorrect usages of the C runtime library.

Since the Ruby build process depends on creating a working version of miniruby.exe, setting -RTC1 means you can't build a debug version of Ruby because miniruby crashes when invoked with an assertion error.

> It does mention about FlushFileBuffers() only, not _commit().
> And says just it returns an error, not make the process
> crashed.

Well commit calls FlushFileBuffers, so its seems that documentation is applicable.  And when you look at the documentation for _commit it says http://msdn.microsoft.com/en-us/library/17618685(VS.80).aspx

If fd is an invalid file descriptor, the invalid parameter handler is invoked, as described in Parameter Validation. If execution is allowed to continue...

In a debug build, execution is *not* allowed to continue because an assertion error is raised.

> Feel free to call it a bug or a paranoiac false assertion of
> msvcrt, and now disabled already, at r22337.

r22337 does not fix the problem.  Try it with a debug build using VC2008 using the standard values set by VC2008 (/Od /D "WIN32" /D "_DEBUG" /Gm /EHsc /RTC1 /MDd /W3 /c /ZI /TP).  It will crash.  

I still consider this a bug - Ruby is passing an invalid file handle to commit. In a release build this will generate a "Invalid handle error" error code which Ruby ignores.  In a debug build it triggers an assertion failure that causes Ruby to crash.

Once again the fix is simple and only affects windows:

#ifdef _WIN32
-	  fsync(fptr->fd);
+    if (io != rb_stdout && io != rb_stderr)
+	    fsync(fptr->fd);
 #endif

The only new line of code is the if statement.

So, I really think this is the way to solve the problem and r22337 should be reverted.

Thanks,

Charlie





is used by default VC2008 is of 

Yes, its a compile time flag.  What do you mean though its irrelevant to a debug built msvcrt?  
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