Recently I just found the script stop working for no good reason, because the proxy server I’m using is working, and I tried manually choose a proxy server (by entering its address and port into my browser directly) it also worked, so apparently there is something wrong with the script.

However, it has been a while since I last commit my changes to this script back to git. So there are some changes I wish to keep and I don’t want to do a binary search to find out the problem (Yep, I’m a lazy guy).

A few googling got me a tool called pactester, which turned out to be very useful. Basically it’s a Perl wrap of SpiderMonkey JavaScript engine. Since the proxy autoconfiguration script is just a subset of plain JavaScript, it can safely executes that with SpiderMonkey and find out where is the problem.

So I installed it and did one test:

$ pactester -p ~/Documents/Miscs/proxy.pac -u 'http://blog.iphone-dev.org'
Use of uninitialized value in numeric ne (!=) at pactester line 137.
Error: SyntaxError: missing ) after condition at line 98:
     if (dnsDomainIs(host, "cubes.fr") return "SOCKS 127.0.0.1:7777";

So that’s the problem. Fixed it, everything is back to normal again!

That’s a small tip on debugging a complex pac script, hope it helps.

今天实在是受不了 CVS 了：在 mozilla 这么大的树上用 cvs diff 简直是自虐，于是找来 mozilla cvs trunk 的 git mirror 来 clone，上次 clone 过一次发现缺东西不能编译，因为 mozilla cvs 树里有些东西是作为 external item 放在别的地方的，比如 nsprpub，但 git mirror (和 hg mirror) 都没有镜像这些。

因为看 mozilla.dev.platform 上有人贴了一个 gitmo 的脚本还方便，以为不会出问题的，结果还是出问题了。

为什么呢？因为 git 的 mirror 是用那个 repository 的几个 branch 来存这些 external items 的，每次我要用到这些 external items 来编译的时候，就把 checkout -b 一个 本地的 branch 出来，remote 的一个 branch 给 merge 进来，然后编译，问题是这些个 remote branch 的镜像更新似乎不如 CVS 上的勤，结果跟主干上的代码就不一致了。

虽然归根结地还是 mozilla 土鳖：CVS 这种原始社会的玩意早该淘汰了，但经验之谈是：除非对 Mozilla 的代码树结构以及它的编译系统很熟悉，否则如果自己要编译 Firefox 还是直接从 CVS 上取最省事，出问题的概率最小。

哦，顺便说一句，最近解决了一个 Firefox 3 在 Mac OS X 10.5 上的一个比较严重的 bug，涉及中文字体的载入和顺序，patch 已经进入主干，最新的 nightly build 中也已经包含，不妨试试。