[CMake] Anyone gotten OpenSSL to build as an external project?

[kent williams]

This shouldn't be a big deal -- something like this should work:

ExternalProject_add(OpenSSL
   URL "http://www.openssl.org/source/openssl-1.0.0c.tar.gz"
   URL_MD5 ff8fb85610aef328315a9decbb2712e4
   CONFIGURE_COMMAND ./config --prefix="${CMAKE_CURRENT_BINARY_DIR}/OpenSSL"
   BUILD_IN_SOURCE 1
    INSTALL_DIR "${CMAKE_CURRENT_BINARY_DIR}/OpenSSL"
  )
set(OPENSSL_INCLUDE_DIR "${CMAKE_CURRENT_BINARY_DIR}/OpenSSL/include")
link_directories("${CMAKE_CURRENT_BINARY_DIR}/OpenSSL/libs)
set(OPENSSL_LIBRARIES ssl ssleay32 ssleay32MD)

The problem is that OpenSSL doesn't handle configuration scripts in
the usual way -- the configure script wants you to specify your
platform/compiler string.

They provide an 'automatic' script instead called config, so

config --prefix=...

Does mostly what you want, but they make you handle the OS X 64-bit
case manually -- it wants you to run configure and tell it explicitly
about the platform:

./Configure darwin64-x86_64-cc

This is kind of crazy, but OK, whatever. So I need to try and figure
out at configure time if it's an OS X build and if it's a 64 bit
build.  I can use

if(APPLE)

to detect an Mac platform, but there's no way I can figure out to
determine if the currently selected build type is 64 bits.  And I
think that the stock OpenSSL distribution would completely lose its
mind if you tried to configure a Universal Binary build!

Any suggestions?