Thursday, 8 January 2015

OpenSSL - Debug build configuration for mingw32

I've just submitted a patch to OpenSSL, to include a debug build configuration for mingw32, as it currently lacks one.

Not only have I done the obvious - removed optimizations and add the -g compiler option, but I've also used debug-Cygwin as a starting point to include a set of debug #defines for OpenSSL. You can find the patch here.

At first, I sent it to the openssl-dev mailing list. Later, I find out there was already an issue open for this on OpenSSL's RT.

Anyway, the patch makes the changes below.


This is the script called from the command line for configuration, which will generate the makefile.

The patch adds MSYS* to the script's platform guessing mechanism, allowing us to build on MSYS2. It wasn't really necessary for the debug configuration, but I like to have the ability to build on MSYS2.


Configure is a perl script that is called by config.

The patch adds the mingw32 debug configuration (debug-mingw), and changes the part of the script that defines the executable extension, to look for /mingw/ instead of /^mingw/, which then makes it work correctly with both mingw configurations.

As a side note, I think it would have been better to name the debug configurations as <platform-debug>, rather than <debug-platform>, but I don't know the reasons behind this, so I might be wrong.

This file is a base for the final makefile.

The patch changes platform checks from mingw and mingw* to .*mingw and *mingw*. Curious, now that I'm writing this, it's the first time I've noticed the incoherence. I'll probably go back to the testing board and change that to *ming* on both.


This file is used when we're building shared libraries (DLLs on mingw).

This is where I was more bold with the changes. The original file was always passing -Wl,-s to the linker, meaning it would clear the symbols from the object files. However, on a debug build we want to keep the symbols, that's the main reason for wanting a debug build in the first place.

So, the patch not only adds a check for .*mingw instead of mingw, it also changes the linker arguments for the debug configuration, excluding the -s.

And that's it. Not that much work, but a lot of experimenting. And, since shell script and make are not the most user-friendly debugging experiences, it has required a lot of creative experimenting.

Hope someone finds it useful.

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