How to download boost using their SHA256 Hash through CMake? - c++

Question

I am trying to add boost as an external project to my project. However when I add the URL to boosts releases and use their hash, I get a hash mismatch even if I have copied it straight from their website. Link here for latest release. Here is my boostExternal.cmake file:
#---------------------------------------------------------------------------
# Get and build boost
SET_PROPERTY(DIRECTORY PROPERTY "EP_BASE" ${ep_base})
SET(boost_GIT_TAG "origin/master")
set( Boost_Bootstrap_Command )
if( UNIX )
set( Boost_url "https://dl.bintray.com/boostorg/release/1.70.0/source/boost_1_70_0.tar.gz")
set( Boost_Hash "SHA256=882b48708d211a5f48e60b0124cf5863c1534cd544ecd0664bb534a4b5d506e9")
set( Boost_Bootstrap_Command ./bootstrap.sh )
set( Boost_b2_Command ./b2 )
elseif( WIN32 )
set( Boost_url "https://dl.bintray.com/boostorg/release/1.70.0/source/boost_1_70_0.zip")
set( Boost_Hash "SHA256=48f379b2e90dd1084429aae87d6bdbde9670139fa7569ee856c8c86dd366039d")
set( Boost_Bootstrap_Command bootstrap.bat )
set( Boost_b2_Command b2.exe )
endif()
ExternalProject_Add(Boost_external_Download
URL ${Boost_url}
URL_HASH ${Boost_Hash}
BUILD_IN_SOURCE 1
UPDATE_COMMAND ""
PATCH_COMMAND ""
CONFIGURE_COMMAND ${Boost_Bootstrap_Command}
BUILD_COMMAND ${Boost_b2_Command} install
--with-system
--with-chrono
--with-filesystem
--disable-icu
--prefix=${CMAKE_BINARY_DIR}/Boost
--threading=single,multi
--link=shared
--variant=release
-j8
INSTALL_COMMAND ""
INSTALL_DIR ""
)
#CACHE PATH "" seems to write the path to a file that I can set
#library paths to.
set(Boost_LIBRARY_DIR ${CMAKE_BINARY_DIR}/Boost/lib CACHE PATH "")
if(WIN32)
set(Boost_INCLUDE_DIR ${CMAKE_BINARY_DIR}/Boost/include/boost-1_70 CACHE PATH "")
set(BOOST_ROOT ${CMAKE_BINARY_DIR}/Boost)
else()
set(Boost_INCLUDE_DIR ${CMAKE_BINARY_DIR}/Boost/include CACHE PATH "")
endif()
ExternalProject_Get_Property(Boost_external_Download BINARY_DIR)
SET(Boost_DIR ${BINARY_DIR} CACHE PATH "")
add_library(Boost_external SHARED IMPORTED)
message(STATUS "Boost_DIR: ${Boost_DIR}")
But when I call this cmake file, I get the error:
-- verifying file...
file='/home/sailanarmo/Documents/build/Superbuild/Download/Boost_external_Download/boost_1_70_0.tar.gz'
-- SHA256 hash of
/home/sailanarmo/Documents/build/Superbuild/Download/Boost_external_Download/boost_1_70_0.tar.gz
does not match expected value
expected: '882b48708d211a5f48e60b0124cf5863c1534cd544ecd0664bb534a4b5d506e9'
actual: 'e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855'
-- File already exists but hash mismatch. Removing...
Which doesn't make sense because I have put in the correct hash and the correct protocol within the .cmake file. However the actual doesn't seem to match what I have pasted in. Am I doing something wrong?

Answer 1

I found the reason.
When building CMake, you have to configure SSL support otherwise CMake will not allow the https protocol to be used. To do that you will need to configure CMake as the following:
./bootstrap --system-curl
make
sudo make install
This will use Linux's system curl which should be configured with SSL Support. However, instead of re-installing CMake manually. I decided to drop the s in the https. Which means I changed https://dl.bintray.com/boostorg/release/1.70.0/source/boost_1_70_0.tar.gz to http://dl.bintray.com/boostorg/release/1.70.0/source/boost_1_70_0.tar.gz and it downloaded and compiled just fine.