Mac OS X 对于非开发人员提供了很好的体验，对于Web开发人员也很厚道。不但提供了Apache Web Server、FTP Server，还集成了很多开发环境：C、Python、PHP等等，而且版本比较新，扩展也很完善。可套餐终归是不如单点。在产品经理的各式各样需求前面，终于还是闹饥荒了。

不久之前由于需要PHP扩展的freetype模块，但是系统本身没有内建，所以只能自己动手。首先想到的是编译成动态扩展库的方式，按照装各种lib都很顺畅，也成功的编译gd.so文件。但是由于系统的PHP已经内建了gd，再load此文件会报错，google一番无解，所以只好放弃。重新编译吧，没有别的办法了。编译过程比较顺利，和Linux下过程一样，不在啰嗦了。但是重启Apache的时候出现下面的提示：

httpd: Syntax error on line 117 of /private/etc/apache2/httpd.conf: Cannot load /usr/libexec/apache2/libphp5.so into server: dlopen(/usr/libexec/apache2/libphp5.so, 10): Symbol not found: __cg_png_create_info_struct
Referenced from: /System/Library/Frameworks/ApplicationServices.framework/Versions/A/Frameworks/ImageIO.framework/Versions/A/ImageIO
Expected in: /usr/lib/libpng15.15.dylib
in /System/Library/Frameworks/ApplicationServices.framework/Versions/A/Frameworks/ImageIO.framework/Versions/A/ImageIObogon:php-5.3.6

这下麻烦了，提示语法错误，貌似是没有找到“__cg_png_create_info_struct”。花费了很多时间google，最后终于找到了解决办法：

sudo ln -sf /System/Library/Frameworks/ApplicationServices.framework/Versions/A/Frameworks/ImageIO.framework/Versions/A/Resources/libPng.dylib /usr/lib/libpng.dylib

然后重新启动Apache，一切正常！

为什么这样就可以了呢？这是因为当OSX需要载入libPng.dylib的时候，系统总是去搜索/usr/lib/。我想这可能是因为在重新编译libpng之后，新的文件与mac系统不兼容所致。我们生成一个新的符号链接，强制OSX去使用系统的libpng.dyld就解决了这个问题。相似的问题也可以很容易的解决，比如下面的错误：

dyld: Symbol not found: _gll_noop
Referenced from:
/System/Library/Frameworks/OpenGL.framework/Versions/A/OpenGL
Expected in: /opt/local/lib/libGL.dylib

dyld: Symbol not found: __cg_jpeg_resync_to_restart
Referenced from:
/System/Library/Frameworks/ApplicationServices.framework/Versions/A/Frameworks/ImageIO.framework/Versions/A/ImageIO
Expected in: /opt/local/lib/libJPEG.dylib

dyld: lazy symbol binding failed: Symbol not found: __cg_TIFFSetErrorHandler
Referenced from: /System/Library/Frameworks/ApplicationServices.framework/Versions/A/Frameworks/ImageIO.framework/Versions/A/ImageIO
Expected in: /opt/local/lib/libTIFF.dylib

dyld: Symbol not found: __cg_png_create_info_struct
Referenced from: /System/Library/Frameworks/ApplicationServices.framework/Versions/A/Frameworks/ImageIO.framework/Versions/A/ImageIO
Expected in: /optlocal/lib/libPng.dylib
Then congratulations, you’ve discovered that OSX and MacPorts are incompatible with each other for these libraries! For example, Macport’s libjpeg contains the symbol _jpeg_resync_to_restart, but not what Apple is looking for, __cg_jpeg_resync_to_restart.

解决办法，照猫画虎：

sudo ln -sf /System/Library/Frameworks/OpenGL.framework/Versions/A/Libraries/libGL.dylib /opt/local/lib/libGL.dylib

sudo ln -sf /System/Library/Frameworks/ApplicationServices.framework/Versions/A/Frameworks/ImageIO.framework/Versions/A/Resources/libTIFF.dylib /opt/local/lib/libtiff.dylib

sudo ln -sf /System/Library/Frameworks/ApplicationServices.framework/Versions/A/Frameworks/ImageIO.framework/Versions/A/Resources/libJPEG.dylib /opt/local/lib/libjpeg.dylib

参考：http://lists.macosforge.org/pipermail/macports-users/2010-November/022662.html