My original topic was Setting up your own update server to deploy Firefox patches. I think what I am going to do is split things up into two sections – Creating Firefox Update files and setting up a Firefox Update Server. So…
Creating Firefox Update Files (MARs)
Firefox 22.214.171.124 and 126.96.36.199 were released yesterday (March 21, 2007), and at some point in the next few days, if you use Firefox, you’ll receive a message telling you that an update is available. Alternatively, you can go to Help->Check for Updates… and Firefox will connect to an update server to check to see if there is an update available. If you deploy Firefox in a large corporation, you might want to either prevent your users from getting Firefox updates until you have certified them, or you might want to push your own updates to Firefox that include additional function. Today we’re going to talk a little about how the update process works and how you can create your own update files. In the next installment we’ll talk more about how the update process works and how to push updates to your users.
In the distant past, whenever there was an update to Firefox, users had to download a new installer and basically reinstall Firefox. To solve this problem, a new update system for Firefox was created. This system uses a file format called MAR which is short for Mozilla Archive. The MAR file contains the binary diffs for files that have changed in the update, or if the bzipped diffs are larger than the file they are patching, it contains the entire file. Whenever a new version of Firefox is released, two MAR files are created as can be seen with Firefox 188.8.131.52. The partial MAR is used to upgrade users directly from Firefox 184.108.40.206 to Firefox 220.127.116.11. The complete MAR is used if the partial upgrade could not be applied correctly or if you are on a version of Firefox that is more than one version behind.
To provide an update server within your enterprise, you’ll have to create your own MAR files based on your custom Firefox builds. Today we’re going to talk about creating those files.
Before we get started, we need to make a few fixes to our build tree. Basically the problem is that the update packaging scripts weren’t working with the MozillaBuild tools in Firefox 18.104.22.168. First we need to patch the update files. Download the patch from bug 373121 and place it in the
mozilla/tools/update-packaging directory. Then type:
patch < bugmsysupdate-packaging-1.8.patch
Once this change has been made, we need to make a small change to our build tools. Go to the
mozilla-build/msys/bin directory and copy the file
bash.exe. (Future versions of MozillaBuild will have bash.exe.) Alternatively, you can just grab the latest version of MozillaBuild (1.1).
OK, now we’re ready to get started. First we need to build the diff utility we need. Go to the
mozilla/obj/other-licenses/bsdiff directory and type
make. Next we’re going to build the full MAR file. This is the easy part. Go to the
mozilla/obj/tools/update-packaging directory and type
make. Once this process completes, if you look in the
mozilla/obj/dist/update directory, you’ll see the file
firefox-22.214.171.124.en-US.win32.complete.mar. This is the complete MAR file we talked about earlier.
Creating the partial MAR file requires a little more work. Since a partial MAR is a diff between two versions of Firefox, we’ll need to have the two versions of Firefox we want to diff against in separate directories so that we can create the partial MAR. If you want to create a partial MAR against your own custom Firefox 126.96.36.199, you’ll need to create a new build tree and build Firefox 188.8.131.52 using the instructions in the first post. (Change FIREFOX_2_0_0_2_RELEASE to FIREFOX_2_0_0_3_RELEASE) We’re going to take a shortcut and use the files that were created as part of the official Firefox 184.108.40.206 release.
The partial MARs are created by diffing the contents of two complete MAR files. So what we’ll need to do is create two directories and unpack the complete MAR files into those directories. Let’s make two directories. For convenience, we’ll put them under the mozilla/tools/update-packaging directory. One we’ll call
ff2002 and the other we’ll call
ff2003. Copy the complete MAR that you created above into ff2002 and download the complete MAR for Firefox 220.127.116.11 and put it into ff2003.
In order to unpack the MAR files, there are tools in the mozilla/tools/update-packaging directory. There is a PERL script called unwrap_full_update.pl and a shell script called unwrap_full_update.sh. Either one can be used. The tools assume that mar.exe is in the path or pointed to by an environment variable. Let’s go ahead and put it in the path by copying mar.exe from
mozilla-build/moztools-180compat/bin. (Ugly I know, but convenient). Now we need to go to the ff2002 directory where we put the MAR file and unpack it. The unwrap scripts work in the current directory, so running them will look something like this:
perl ../unwrap_full_update.pl firefox-18.104.22.168.en-US.win32.complete.mar
sh ../unwrap_full_update.sh firefox-22.214.171.124.en-US.win32.complete.mar
Once you have unpacked the MAR file, delete the original MAR file or move it out of the way so that we don’t diff it. Then do the same process for the 126.96.36.199 MAR file.
Creating the partial MAR is actually done using make, so once we’ve unpacked the MAR files, we’ll need to go back to the
mozilla/obj/tools/update-packaging directory. There are a few environment variables we need to set in order to tell the partial MAR packaging what to do.
- SRC_BUILD_ID and DST_BUILD_ID
- These names aren’t totally accurate. They are actually the version numbers of the two builds. They will be used to name the output MAR file. For our builds, they are 188.8.131.52 and 184.108.40.206
- SRC_BUILD and DST_BUILD
- These actually point to the locations of the files we just unpackaged.
SRC_BUILD_ID=220.127.116.11; export SRC_BUILD_ID; DST_BUILD_ID=18.104.22.168; export DST_BUILD_ID; SRC_BUILD=../../../tools/update-packaging/ff2002; export SRC_BUILD; DST_BUILD=../../../tools/update-packaging/ff2003; export DST_BUILD;
And that’s it! In the
mozilla/obj/dist/update directory, you’ll see the file
firefox-22.214.171.124.en-US.win32.partial.126.96.36.199-188.8.131.52.mar. Which is the partial MAR between Firefox 184.108.40.206 and Firefox 220.127.116.11.
Obviously in this post I chose to place files in certain locations that made it easier to describe the process. With the information I have presented, you might find a way to simplify this process. If you have better ideas on how to do this stuff, please let me know. I’m going to look at making changes to the build process to try to simplify this.
Next time we’ll talk about how to get those files to our users.