Ted's Mozilla Blog

I’ve been doing some work on Firefox Mobile lately, and I keep winding up in situations where I have a URL that I want to load on my mobile device. It’s a pain to type URLs in with a virtual keyboard (or a tiny keyboard), so people have taken to using QR codes to encode them, and there are lots of mobile apps that can read the codes and load the URL contained within. Conveniently, the Google Charts API supports generating QR codes, so I threw together a tiny bookmarklet that generates a QR code of the page you’re currently viewing. Go to this page and drag it to your bookmarks toolbar to use it, then just click it whenever you’re viewing a URL that you need to view on your device. I’ve been using Barcode Scanner on Android to read them, and it works pretty well.

Last week I managed to find myself a little bit of time for a project I had been meaning to get to: bzexport. bzexport is a Mercurial extension that allows you to attach patches from your Mercurial patch queue to bugzilla from the Mercurial command line. It’s the obvious companion to the qimportbz extension. You can read the README for details on installing and using the extension, but the short form is:

hg bzexport [REV] [BUG]

where REV is the name of a currently applied patch from your queue, and BUG is a bug number to attach it to. Of course, the extension is smarter than just that, and if you leave off those parameters it will default to working on the topmost patch in your queue, and it will attempt to deduce the bug number from the commit message in the patch. (Standard notation used at Mozilla should work, i.e. “bug 12345 – some text”, “b=12345 some text” etc.)

bzexport attempts to be clever and borrow your Bugzilla login cookies from your default Firefox profile so that you don’t have to provide authentication details. This does not currently work on the Mercurial shipped with MozillaBuild, so you’ll have to provide your username and password in your .hgrc as described in the README if you intend to use it under MozillaBuild’s hg.

bzexport relies on Gerv‘s excellent BzAPI, so hats off to Gerv for that! Also, patches for additional functionality are welcome.

On a personal project of mine, I have a need to generate thumbnails of web pages. Until recently my solution was to use Firefox running in Xvfb, a virtual X server. This is not an ideal solution, as it requires you to have lots of X client libraries installed on your server. Additionally, Firefox is not intended for this purpose, so there are lots of ways for things to go wrong.

Because of this, I’d been following Chris Lord‘s work on the offscreen branch of Mozilla for some time, but never tried it out until recently. The offscreen branch provides a widget backend for Mozilla that can render web content to an offscreen buffer. Chris wrote it in support of Clutter, which is a pretty neat use case. Conveniently, he also provided a sample embedding client application called moz-headless-screenshot. This is a simple command line tool that takes a URL, image size, and output filename and generates a PNG screenshot of the webpage. This being exactly what I wanted, and having my poorly-written Firefox+Xvfb solution fall apart due to a server migration, I decided to give his solution a shot.

I hit a few speed bumps on the way, since there wasn’t much documentation to be found on actually building and using moz-headless-screenshot. I’ve attempted to fix this my providing detailed steps and a Makefile in my own moz-headless-screenshot repository. I’ve also modified the code slightly such that it’s easier to run (at least in my use case). I have heard from others over the years that have this same need, so hopefully someone else finds it useful!

I have been remiss in blogging, but as of a few weeks ago, we have two new Build Config peers:

• Mitchell Field <mitchell.field@live.com.au>
• Kyle Huey <me@kylehuey.com>

Both are available for reviewing build system patches.

MozillaBuild 1.5 has been released:
http://ftp.mozilla.org/pub/mozilla.org/mozilla/libraries/win32/MozillaBuildSetup-1.5.exe

The major highlights include:

• A newer Mercurial (1.5.4)
• Support for Visual C++ 2010
• A newer Python (2.6.5)

You can see the full list of dependent bugs,  as well as the full list of committed changes.

As usual, bugs can be filed at bugzilla.mozilla.org.

I’d like to announce the birth of our first child, Isabella Grace-Ann Mielczarek:

She was born at 1:12 PM on Saturday, April 10th, weighing in at 7 lbs 8 oz. Mom and baby are doing great, and we just brought her home this morning. There are more photos available on my website.

I’ll be taking paternity leave starting today and returning April 26th. In the mean time, if you need help with:

• Build system/Breakpad symbols or processing issues—See Jim Blandy
• Breakpad client issues—See Chris Jones
• Unit testing issues—See Clint Talbert

I often find myself landing patches on our 1.9.2 and 1.9.1 branches, both of which are in Mercurial repositories. This generally involves getting a changeset from the mozilla-central repository into one of these repositories, and also amending the changeset message to include the name of the person who gave me approval to land. There was some discussion recently on how it’s kind of a pain to do that. I’ve cooked up an easy solution for my own needs, perhaps it will serve yours as well.

I use “hg transplant” to get changesets from one repository to another. This assumes that you have local clones of both the source repository (mozilla-central in this case) and the destination repository (mozilla-1.9.2 or 1.9.1, usually). Assuming you had both clones side-by-side in a directory, you could run the transplant command in the destination repository’s working directory like so (where xxx is the changeset identifier of the changeset you want transplanted, you can also specify more than one changeset):

hg transplant -s ../mozilla-central xxx

The transplant command conveniently includes a “–filter” option that will let you alter the commit message or patch while transplanting. This requires you to have some sort of script for transplant to run. Here’s what I’m using (on Linux):

#!/bin/sh

if test -n "$APPEND"; then
 echo " $APPEND" >> "$1";
else
 if test -n "$EDITOR"; then
 $EDITOR "$1";
 else
 editor "$1";
 fi
fi

Save this as “transplant.sh” somewhere (and ensure that it’s executable), then in your ~/.hgrc, add a section:

[transplant]
filter = /path/to/transplant.sh

Now, when you run “hg transplant”, by default it will open an editor to edit the commit message for each changeset, allowing you to add approval information. But, even better, transplant.sh will append the contents of the “APPEND” variable if set, so you can run transplant like so to quickly append approval information:

APPEND="a=someone" hg transplant -s ../mozilla-central xxx

I find that this saves me a bunch of time, so hopefully it’s useful to someone else!

Some time ago, Lukas Blakk implemented support for a source server on our Windows builds as a class project in Dave Humphrey‘s class at Seneca College. Of course, soon after that we switched our main VCS from CVS to Mercurial, which broke all of her hard work. Thankfully, we got another one of Dave’s students, Jesse Valianes, to fix things to make it work with Mercurial. We landed his patch, but as it turns out we never enabled a setting on our build machines to make it actually work. However, when we finally tried to do so, I found out that another patch we had landed in the interim had broken things. I finally landed a fix for that, and we flipped it back on, and so today’s trunk build is source-enabled again.

If you have no idea what any of this means, it means you can download a Windows nightly build, attach a debugger, have it download the debug symbols automatically from our symbol server, and the debugger will download the matching source for you automatically.

I hope to get this backported to our 1.9.2 and 1.9.1 branches ASAP, so that our 3.5.x and 3.6 release builds will be similarly debuggable.

I recently landed some changes (on trunk and 1.9.2) to the way Firefox packaging works. There are two immediate consequences of this you should be aware of:

1. Mac builds now use a packaging manifest just like Windows and Linux. If you add a file that you intend to ship on Mac, it needs to wind up in a packaging manifest. (bug 463605)
2. All the  packaging manifest files have been combined into one single file: browser/installer/package-manifest.in. This should save everyone some time and annoyance. (bug 511642)

These changes had no effect on applications other than Firefox.

MozillaBuild 1.4 is now available for download. This release focused primarily on compatibility with systems running the x64 edition of Windows. It also contains a few other niceties such as a newer version of Mercurial and other tools, and support for all known Microsoft SDKs. You can view the full list of changes from version 1.3 here.