Java Built with Unsupported Old Compilers

When I turned off DLL loading from the current working directory to defeat DLL pre-loading luring attacks, one of the things I discovered was that the Java plug-in was broken in Firefox and Chrome. This problem of Java finding its C library is not new at all. The tubes are choked with posts and bug reports about getting various things that are dependent on Java to work when msvcr71.dll can’t be found. The new CWDIllegalInDllSearch = 0xFFFFFFFF option just exacerbates an existing deployment problem.

PS> cd 'C:\Program Files (x86)\Java\jre6\bin\new_plugin'
PS> dumpbin /dependents .\npjp2.dll
Microsoft (R) COFF/PE Dumper Version 10.00.30319.01
Copyright (C) Microsoft Corporation.  All rights reserved.

Dump of file .\npjp2.dll

File Type: DLL

  Image has the following dependencies:



        6000 .data
        3000 .rdata
        1000 .reloc
        7000 .rsrc
        4000 .text

The root of the Mozilla-compatible browser Java plugin problem is npj2.dll which is dynamically linked to msvcr71.dll. Because it is a plugin, the DLL loading is done by Windows on behalf of the executable and  (Chrome or Firefox) rather than the plugin. The new_plugin directory includes msvcr71.dll which probably helped if a browser changed its CWD to the new_plugin directory when loading npj2.dll but with searching CWD out of the picture it doesn’t.

Java simply doesn’t do a good job of loading its C runtime correctly on Windows. It’s not a new problem. I don’t understand why don’t just change a switch on the complier to /MT instead of /MD and statically link the C runtime into jpjp2.dll. That would make the whole problem go away.

There are also some other oddities here. There are 2 different C runtimes used in the 32-bit version of Java 6 for Windows. For some reason they are redistributing msvcr71.dll (C runtime from Visual Studio .NET 2003) and also msvcrt.dll which is supposed to be the name of the private C runtime used by Windows components. However, the msvcrt.dll in the Java directory is actually the C runtime from Visual Studio 6 or possibly a very old Platform SDK.

By implication Oracle/Sun is using the C/C++ optimizing compiler from Visual Studio 6 (1998) and Visual Studio .NET 2003 to build the 32-bit version of Java. Holy cow those are 5 and 3 versions back from the current compilers and between 12 and 7 years old. I’m pretty sure that Visual Studio 6 is no longer supported and unfortunately both predate the side-by-side C runtime distribution system that starts with Visual Studio 2005.

The x64 version of Java is even stranger. It links against a Microsoft  x64 C runtime library called msvcrt.dll. Again this is the name reserved for the private Windows platform C runtime but this msvcrt.dll has file version 6.10.2207.0 either from a very old version of the Windows Platform SDK that provided x64 compilation support prior to Visual Studio 2005 or from a tool chain that was available by request (and is no longer available) for Visual Studio 2003.

It seems like the Java team has made a bit of a fetish of using really old compilers for the Microsoft platforms. I can understand that there is a risk of breaking stuff when upgrading a tool chain but this has been taken a bit to the extreme by the Java build team. There is a cost to testing a huge platform like Java when building with a new tool chain. Sun was cash-constrained and, although popular, Java SE didn’t really make them any money directly.

Good News for Java 7 (Probably)

It looks like the problem is being addressed. OpenJDK 7 builds, it looks like Oracle is upgrading to the C/C++ compiler from Visual Studio 2010.

BEGIN WARNING: At this time (Spring/Summer 2010) JDK 7 is starting a transition to use the newest VS2010 Microsoft compilers. These build instructions are updated to show where we are going. We have a QA process to go through before official builds actually use VS2010. So for now, official builds are still using VS2003. No other compilers are known to build the entire JDK, including non-open portions. So for now you should be able to build with either VS2003 or VS2010. We do not guarantee that VS2008 will work, although there is sufficient makefile support to make at least basic JDK builds plausible. Visual Studio 2010 Express compilers are now able to build all the open source repositories, but this is 32 bit only. To build 64 bit Windows binaries use the the 7.1 Windows SDK.END WARNING.

The 32-bit OpenJDK Windows build requires Microsoft Visual Studio C++ 2010 (VS2010) Professional Edition or Express compiler. The compiler and other tools are expected to reside in the location defined by the variable VS100COMNTOOLS which is set by the Microsoft Visual Studio installer.

So maybe in 2011 Java will have its C runtime library sorted out by virtue of having a supported global mechanism to register the Visual Studio 2010 C runtime.


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