Setup Buildzlib VS17

Article
01/25/2017

Creating a zlib/libzip compression library for CNTK

We use the following installation paths in our instructions:

libzip sources: c:\local\src\libzip-1.1.3
zlib sources: c:\local\src\zlib\zlib-1.2.8
Build directory for zlib and libzip binaries: c:\local\zlib-vs17

You can use any paths you like, but note the remark on target folder for binaries below.

Install CMake. Include CMake binaries folder to your PATH
Download libzip source code and unpack to c:\local\src\libzip-1.1.3
Download zlib source code and unpack it to c:\local\src\zlib\zlib-1.2.8

There are two ways to build the lib/libzip compression library for CNTK, either through a batch file or manually.

Building through a batch file

In the directory Tools\devInstall\Windows you find the batch file buildZlibVS17.bat. This batch file takes three parameters to build the CNTK Protobuf library. The first parameter is the directory of the libzip source files you unpacked above, the second parameter is the directory of the zlib source files,the third parameter is the destination directory for the created library. In our case follow these steps from a standard Windows command prompt:

c:
cd \repos\cntk\Tools\devInstall\Windows
buildZlibVS17 c:\local\src\libzip-1.1.3 c:\local\src\zlib\zlib-1.2.8 c:\local\zlib-vs17

Set the environment variable ZLIB_PATH to the location of the created library (this is the third parameter in the command invocation above, not the sources location!

setx ZLIB_PATH c:\local\zlib-vs17

Manual build steps for a CNTK compression library

The following aspects are important:

Build commands for zlib and libzip should use the same target folder for binaries (specified via -DCMAKE_INSTALL_PREFIX parameter in cmake command below)
Build order is important. You should build zlib first because libzip is dependent on it

Command prompt environment for build

Note

If VS2017INSTALLDIR environment variable was not set by the Visual Studio installer, set it manually. The exact installation directory depends on both the version (2017 in this case) and offering (Community, Enterprise, etc) of Visual Studio, according to the following pattern: C:\Program Files (x86)\Microsoft Visual Studio\<version>\<offering>.

For Visual Studio 2017 Enterprise edition, run:

setx VS2017INSTALLDIR "C:\Program Files (x86)\Microsoft Visual Studio\2017\Enterprise"

For Visual Studio 2017 Community edition, run:

setx VS2017INSTALLDIR "C:\Program Files (x86)\Microsoft Visual Studio\2017\Community"

Launch a 64-bit Visual Studio 2017 development environment. The most convenient way is to execute the batch file vcvarsall.bat in the Visual Studio directory with the required parameters from a standard windows command shell:

    "%VS2017INSTALLDIR%\VC\Auxiliary\Build\vcvarsall.bat" amd64 --vcvars_ver=14.11

If you can't find this batch file on your system, please revisit the installation of VS2017, and make sure you have the 'VC++ version 15.4 v14.11 toolset' option selected.

Building zlib

Execute the following commands from VS2017 x64 Native Tools Command Prompt:

cd c:\local\src\zlib\zlib-1.2.8
mkdir build
cd build
cmake .. -G"Visual Studio 15" -DCMAKE_INSTALL_PREFIX="c:\local\zlib-vs17"
msbuild /P:Configuration=Release INSTALL.vcxproj

Building libzip

Execute the following commands from VS2017 x64 Native Tools Command Prompt:

cd c:\local\src\libzip-1.1.3
mkdir build
cd build
cmake .. -G"Visual Studio 15 Win64" -DCMAKE_INSTALL_PREFIX="c:\local\zlib-vs17"
msbuild libzip.sln /t:zip /P:Configuration=Release
cmake -DBUILD_TYPE=Release -P cmake_install.cmake

MSBuild command above may generate some warnings. It is expected and may be ignored.

The last cmake command from the list above will generate the following error:

CMake Error at src/cmake_install.cmake:34 (file):
  file INSTALL cannot find "C:/libzip/build/src/Release/zipcmp.exe".

It is expected and may be ignored - all required binaries (zip.dll and zlib.dll) should be already in c:\local\zlib-vs17

Preparing the environment

Set the following environment variable:

setx ZLIB_PATH c:\local\zlib-vs17

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