One of the most common problems that people face when porting applications from Windows to Linux using Mono are paths.

The Problem

Windows developers are used to a case-insensitive file system, which means that they might create a file called "mydata" in one place, and try to access it somewhere else as "MyData" or as "MYDATA". This of course breaks on most Unix setups because Windows is case insensitive[1].

Another problem is that developers on Windows are known to hardcode the directory separator character in their source code ("\") instead of using Path.DirectorySeparator and using Path.Combine for combining this paths. This is a problem because "\" is a valid file name components on Unix. This means that if an application hardcodes for example "Logs\access_log", in Unix this will not store the contents in the "Logs" directory as the file "access_log". Instead, it will store the results in a file called "Logs\access_log".

Only a few applications cope with drive letters, but they might still pose a problem as the colon is a valid filename in Unix, which means that "A:\file" is a valid filename in the current directory.

Although .NET provides the tools to write code that is portable, in practice, they do not use these features (the exception is Path.Combine, which some people use, as it is genuinely useful on its own).

The Usual Solution

When moving applications from Windows to Linux, it is always necessary to run the application, run its test suite, and validate that the application works as intended. With the path problems described above, the process above included a number of iterations to fix the assumptions made by programmers about the file system.

This process could be time consuming, because identifying where the mistakes were made could take some time, the program might fail with FileNotFound exceptions (when referencing files that were not there), data would show up empty (listing contents of a directory that had nothing, as all the data went elsewhere) but it was doable.

This process works as long as you have the source code to all the components that you are porting, but if you were using a third-party library that you had no source code for, you would not be able to fix the problems.

The New Solution

This week, Dick Porter introduced a portability layer into Mono that will address those problems without requiring changes to your code. This will remove a large component of the porting cycle as a whole class of obnoxious problems are gone.

The new portability framework is enabled by setting the environment variable MONO_IOMAP (which we will likely rename to something shorter) to one of the following values:

• case: makes all file system access case insensitive.
• drive: strips drive name from pathnames.
• all: enables both case and drive.

In addition, if any of those options are enabled, the directory separator mapping is also turned on. So this basically means that you have to type this, or include this in your script that launches your application:

	$ export MONO_IOMAP=all
	$ mono myapp.exe
	

For ASP.NET applications hosted with mod_mono, you can add the following directive to your Apache configuration file:

	MonoSetEnv MONO_IOMAP=all
	

This new feature will appear in Mono 1.1.18.

The downside is that Mono will have to do some extra work when coping with your file system, to search for case insensitive file names. So if your application is still a portable application, you will be much better off without this switch.

[1] Some Linux file systems are case insensitive, and some folks have used a combination of hacks, including doing loopback CIFS mounts to get case sensitivity issues out of the way; OS X does not have this particular problem, but it still has the others.

Dave Winer did post about the new bill in Congress, two posts:

• How Bush Goes
• His follow-up

Lluis Sánchez ofrecerá una charla sobre Mono y MonoDevelop en la Facultad de Ciencias en la UNAM.

La cita es este Miércoles 4 de Octubre a las 5pm en el anfiteatro Alfredo Barrera de la Facultad de Ciencias.

Lluis es el desarrollador principal de MonoDevelop hoy en dia, y ha sido responsable de la integración del nuevo diseñador de formas Stetic, y es responsable de varios componentes importantes en Mono como Remoting, Serialización y los servicios de Web.

I just downloaded and installed the Avalon-based the New York Times reader.

This is one nice Avalon application, it distinguishes itself from all the samples that I have seen because it lacks a video playing in the background, and the buttons have not been rotated 30 degrees. It is one cute application, and I might have to eat my own words if someone from the New York Times developer team starts raving about their experience.

A few years ago, before the Ajax revolution, it was to me pretty clear that Flash based frameworks and Avalon would pose a real threat to the web as we know it. Unlike the Web, developing applications with Flash or Avalon could be a more consistent developer experience than the combination of HTML, HTTP, CSS and JavaScript and the dozen other elements that must be mastered to create modern web applications. At least, they have a certain appeal to some developer segments.

Robert O'Callahan from Novell weighs in on this subject, and offers a few alternatives on how things could be improved on the web world.

Of course, the real solution is for someone to implement an open source Avalon stack to run on top of Mono. No applause, just throw money.

Or developers.

An updated version of the US Constitution was unveiled last week, a good summary is here.

I have only noticed the commentary on a few political web sites about the impact of the new legislation, I was expecting everyone to be up in arms about it.

The New York Times article Editorial has a good summary of the problems:

Here’s what happens when this irresponsible Congress railroads a profoundly important bill to serve the mindless politics of a midterm election: The Bush administration uses Republicans’ fear of losing their majority to push through ghastly ideas about antiterrorism that will make American troops less safe and do lasting damage to our 217-year-old nation of laws — while actually doing nothing to protect the nation from terrorists. Democrats betray their principles to avoid last-minute attack ads. Our democracy is the big loser.

Republicans say Congress must act right now to create procedures for charging and trying terrorists — because the men accused of plotting the 9/11 attacks are available for trial. That’s pure propaganda. Those men could have been tried and convicted long ago, but President Bush chose not to. He held them in illegal detention, had them questioned in ways that will make real trials very hard, and invented a transparently illegal system of kangaroo courts to convict them.

It was only after the Supreme Court issued the inevitable ruling striking down Mr. Bush’s shadow penal system that he adopted his tone of urgency. It serves a cynical goal: Republican strategists think they can win this fall, not by passing a good law but by forcing Democrats to vote against a bad one so they could be made to look soft on terrorism.

Last week, the White House and three Republican senators announced a terrible deal on this legislation that gave Mr. Bush most of what he wanted, including a blanket waiver for crimes Americans may have committed in the service of his antiterrorism policies. Then Vice President Dick Cheney and his willing lawmakers rewrote the rest of the measure so that it would give Mr. Bush the power to jail pretty much anyone he wants for as long as he wants without charging them, to unilaterally reinterpret the Geneva Conventions, to authorize what normal people consider torture, and to deny justice to hundreds of men captured in error.

These are some of the bill’s biggest flaws:

Enemy Combatants: A dangerously broad definition of “illegal enemy combatant” in the bill could subject legal residents of the United States, as well as foreign citizens living in their own countries, to summary arrest and indefinite detention with no hope of appeal. The president could give the power to apply this label to anyone he wanted.

The Geneva Conventions: The bill would repudiate a half-century of international precedent by allowing Mr. Bush to decide on his own what abusive interrogation methods he considered permissible. And his decision could stay secret — there’s no requirement that this list be published.

Habeas Corpus: Detainees in U.S. military prisons would lose the basic right to challenge their imprisonment. These cases do not clog the courts, nor coddle terrorists. They simply give wrongly imprisoned people a chance to prove their innocence.

Judicial Review: The courts would have no power to review any aspect of this new system, except verdicts by military tribunals. The bill would limit appeals and bar legal actions based on the Geneva Conventions, directly or indirectly. All Mr. Bush would have to do to lock anyone up forever is to declare him an illegal combatant and not have a trial.

Coerced Evidence: Coerced evidence would be permissible if a judge considered it reliable — already a contradiction in terms — and relevant. Coercion is defined in a way that exempts anything done before the passage of the 2005 Detainee Treatment Act, and anything else Mr. Bush chooses.

Secret Evidence: American standards of justice prohibit evidence and testimony that is kept secret from the defendant, whether the accused is a corporate executive or a mass murderer. But the bill as redrafted by Mr. Cheney seems to weaken protections against such evidence.

Offenses:The definition of torture is unacceptably narrow, a virtual reprise of the deeply cynical memos the administration produced after 9/11. Rape and sexual assault are defined in a retrograde way that covers only forced or coerced activity, and not other forms of nonconsensual sex. The bill would effectively eliminate the idea of rape as torture.

There is not enough time to fix these bills, especially since the few Republicans who call themselves moderates have been whipped into line, and the Democratic leadership in the Senate seems to have misplaced its spine. If there was ever a moment for a filibuster, this was it.

We don’t blame the Democrats for being frightened. The Republicans have made it clear that they’ll use any opportunity to brand anyone who votes against this bill as a terrorist enabler. But Americans of the future won’t remember the pragmatic arguments for caving in to the administration.

They’ll know that in 2006, Congress passed a tyrannical law that will be ranked with the low points in American democracy, our generation’s version of the Alien and Sedition Acts.

New York Times
Antiterrorism Bill on Detainees, Geneva Conventions Rushing Off a Cliff
September 28th, 2006.

And of course, the problem is that these new provision are easily misused and abused: like the DMCA is misused and abused; like the war-on-drugs legislation is misused and abused and like the Patriot Act is misused and abused.

Amy and David Goodman recently published Static: Government Liars, Media Cheerleaders and the People Who Fight Back a book that quotes extensively from the interviews they have done on their radio program on Democracy Now. The book is packed with first-hand accounts of people who have received the short end of the stick.

Scott has an interesting post detailing the risks of SQL injection.

I made that mistake myself when I wrote the contributions web service for Monodoc. Until a few months ago, our Monodoc service had this very problem. Pablo Orduña contacted me off-line and even provided fixes to our web service to fix the issue. Highly recommended reading for anyone writing web apps.

Annotations of George speech is over at billmon.

Hugo's speech at the UN raises a few good points:

And we must recall in this room that in just a few days there will be another anniversary. Thirty years will have passed from this other horrendous terrorist attack on the Cuban plane, where 73 innocents died, a Cubana de Aviacion airliner.

And where is the biggest terrorist of this continent who took the responsibility for blowing up the plane? He spent a few years in jail in Venezuela. Thanks to CIA and then government officials, he was allowed to escape, and he lives here in this country, protected by the government.

And he was convicted. He has confessed to his crime. But the U.S. government has double standards. It protects terrorism when it wants to.

And this is to say that Venezuela is fully committed to combating terrorism and violence. And we are one of the people who are fighting for peace.

Luis Posada Carriles is the name of that terrorist who is protected here. And other tremendously corrupt people who escaped from Venezuela are also living here under protection: a group that bombed various embassies, that assassinated people during the coup. They kidnapped me and they were going to kill me, but I think God reached down and our people came out into the streets and the army was too, and so I'm here today.

But these people who led that coup are here today in this country protected by the American government. And I accuse the American government of protecting terrorists and of having a completely cynical discourse.

Then he raises the issue of the veto:

Point three, the immediate suppression -- and that is something everyone's calling for -- of the anti-democratic mechanism known as the veto, the veto on decisions of the Security Council. Let me give you a recent example. The immoral veto of the United States allowed the Israelis, with impunity, to destroy Lebanon. Right in front of all of us as we stood there watching, a resolution in the council was prevented.

Worth reading the whole thing.

My Firenze Talk will be held in a new location: Universitá degli Studi di Firenze - Facoltá di Ingegneria, in l'aula è la 008 di viale Morgagni at 3pm.

A flier is available here.

Michael Lehman has uploaded the videos from the various presentations that we had at the Lang.NET Symposium.

My favorites:

• John Gough on running Ruby on the CLR.
• Mike Barnett on Spec# (Programming with contracts).
• Anders Hejlsberg on the new LINQ extensions. A great introduction to the new data and XML processing facilities in C# 3.0 and how these are built on top of a few small changes to the language.
• Dom Syme talks on F# and delivers a great live demo.
• Jim Hugunin shows IronPython, this was done very close to 1.0
• Jim and Cory on SecondLife. I absolutely loved Jim's presentation.
• John Lam on bridging the Ruby interpreter and the CLR (different from John's presentation. He also pulls an incredible demo with Ruby and Avalon.

There are more talks there, but I missed a few of those talks (one of the talks uses Mono's C# compiler as the base for their research.

And my own presentation here, the usual Mono stuff that I talk about.

Cory does a fantastic presentation on what SecondLife is on this video from the Lang.NET Symposium.

Jim then talks about the work that they have been doing to use Mono as the virtual machine to run their scripts. Jim is an excellent presenter.

This is a must-watch presentation for programmers.