Cross compiling FreeTDS to iPhone

Question

Since this question is unanswered and I spent the majority of a semester figuring it I thought I would post how to Cross compiling FreeTDS 0.91 to iPhone ARMv6, ARMv7 architecture. This was done using Xcode 4.2 and iOS 5 SDK.

The reason this question is asked it because you are developing an app for an iOS device that requires connecting to an Mircosoft SQL Sever, which requires using the Tabular Data Stream (TDS) protocol as it is Microsoft proprietary.

I will also mention that you need some level of technical skill to even attempt this. This is a very condensed version of what took me nearly two months to figure out (I left all the things you shouldn't do).

Other documentation relating to this:

Basic How To on using FreeTDS http://www.freetds.org/userguide/samplecode.htm

Microsoft's TDS API documentation http://msdn.microsoft.com/en-us/library/aa936985(v=sql.80)

See my answer below.

Also see saskathex answer for Xcode 4.5 updated files.

Answer 1

For those like me that will spend hours finding the documentation for these standard configure flags (for running ./configure make make install)

        ./configure --build is used for specifing the architecture you want to complie for         ./configure --host is used to specify the ark of the machine doing the compileing (running xcode)         ./configure --target seems to be an alias 

Now then to solving the problem.

1) Get the latest version of the FreeTDS http://www.freetds.org/

2) The next step is to make your own bash shell files that correctly run the FreeTDS ./configure. You will need two as the simulator is i386/i686 architecture and an apple device (iPhone, iPod, etc.) is ARM architecture. Also, your compiler files/version within the iPhone development directories may be different, just find what makes logical sense and has similar naming convention. The mac host architecture is supplied with the command uname -p.

Here is my example for building for use on the simulator (i386) build_for_simulator_i386.sh:

 #!/bin/sh   #unset some shell variables  unset CC  unset CFLAGS  unset CPP   export buildPath=`pwd`   # make i386 (Simulator) target  export CC=/Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin/i686-apple-darwin11-llvm-gcc-4.2   export CFLAGS="-isysroot /Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator5.0.sdk"   # if you want Windows Authentication (NTLM) support you must use at least tds version 7  # the default is 5  ./configure --build=i386 --host=i386 --target=i386 --with-tdsver=7.1  

Example for configuring for ARM compilation (build_for_device_armv7.sh):

 #!/bin/sh   # unset some shell variables  unset CC  unset CFLAGS  unset CPP   export buildPath=`pwd`   # make arm target  export CC=/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/arm-apple-darwin10-llvm-gcc-4.2   export CFLAGS="-isysroot /Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS5.0.sdk"   export CPP=/usr/bin/cpp    ./configure --build=arm-apple-darwin10 --host=x86_64-apple-darwin11.3.0 --target=armv7 --with-tdsver=7.1 

3) Next cd to the root freetds directory that resulted from unzipping the freetds download, mine was freetds_0.91

4) Run one of your scripts. You can only compile for ONE architecture at a time

 sh build_for_(desiered build)           this runs ./configure for you with the correct options         (tds version 7 required for NTLM authentication) 

5) Once the configure process completes you have to hack the configuration file. Open freetds_0.91/include/config.h then on line 172 change #define HAVE_ICONV 1 to #define HAVE_ICONV 0

6) If you previously ran ./configure, make, make install then run these commands. Especially if your switching architectures as you will get errors running make without doing this

    sudo make clean     sudo make uninstall 

7) Perform the compilation using make

    make all     sudo make install 

The make procedure does through some error on purpose, but if you see errors within six or seven lines of shell prompt, once it returns, you have problems and need to fix them before proceeding. Lets just say lots of things can go wrong at this point.

8) After installing the binary complied file that is the culmination of all the little .o files that freetds makes is /usr/local/lib/libsybdb.a Trust me you don't want to pull a .o file for just the library you want. Copy /usr/local/lib/libsybdb.a to the appropriate folder in your project. What I did was have two separate folders, one per architecture, named "compiled_freetds-0.91_simulator_i386" and "compiled_freetds-0.91_device_armv7."

9) Since you want to make you life easy and have xcode figure out which compiled file to use follow this subset of steps to perform the dynamic linking.

 a) Select you project settings on the left had side of xcode   (the blue think with the name of your project on it)   b) Select the Target (usual the same name as your app)    c) Navigate to **build settings**, scroll down to **linking > other linker flags**   d) On the left side of Other Linker Flags a mouse over will reveal an expander,      expanding will reveal Debug and Release rows.   e) Add the appriate architectures by selecting the plus on the right side of   either Debug or Release.  When the new row appears select the architecture,   double click the first editable field from the right to open  an entry box   that you can then drag the appropriate  complied file into it to be dynamically       linked.  You must do this for both files and when done correctly the file   under ARMv7 will be used when building for the device and the one for Any iOS     Simulator SDK will be used when running on the simulator.  **Note:** You may also need to add the -all_load flag to resolve linking issues. 

10) The final step which seems to avoid problem of dynamic linking error involving libsybdb.5.dylib when running code on device is to make uninstall. Also, when running on the device you will also get lots of warnings, in increments of 36, about CPU_SUBTYPE_ARM_ALL being deprecated, that is normal, but annoying.

    sudo make uninstall   

I hope this helps.