Linker error in libz on Ubuntu 16.04

[nethraravindran]

Linking ./.build/x86_64-unknown-linux/debug/KituraPackageTests.xctest
/root/Kitura/.build/x86_64-unknown-linux/debug/NIOHTTP1.build/HTTPResponseCompressor.swift.o:/root/Kitura/.build/x86_64-unknown-linux/debug/NIOHTTP1.build/HTTPResponseCompressor.swift.o:function _T08NIOHTTP122HTTPResponseCompressorC19deinitializeEncoder33_E8A369BA8CC72FD6D05117C456504CA2LLyyF: error: undefined reference to 'deflateEnd'
/root/Kitura/.build/x86_64-unknown-linux/debug/NIOHTTP1.build/HTTPResponseCompressor.swift.o:/root/Kitura/.build/x86_64-unknown-linux/debug/NIOHTTP1.build/HTTPResponseCompressor.swift.o:function _T08NIOHTTP119PartialHTTPResponse33_E8A369BA8CC72FD6D05117C456504CA2LLV12compressBody3NIO10ByteBufferVSgSC10z_stream_sVz10compressor_AF0oP9AllocatorV9allocators5Int32V4flagtF: error: undefined reference to 'deflateBound'
/root/Kitura/.build/x86_64-unknown-linux/debug/NIOHTTP1.build/HTTPResponseCompressor.swift.o:/root/Kitura/.build/x86_64-unknown-linux/debug/NIOHTTP1.build/HTTPResponseCompressor.swift.o:function _T0SC10z_stream_sV8NIOHTTP1E15deflateToBuffer33_E8A369BA8CC72FD6D05117C456504CA2LLs5Int32V3NIO04ByteE0Vz6buffer_AG4flagtFSis016UnsafeMutableRawE7PointerVcfU_: error: undefined reference to 'deflate'
/root/Kitura/.build/x86_64-unknown-linux/debug/NIOHTTP1.build/HTTPResponseCompressor.swift.o:/root/Kitura/.build/x86_64-unknown-linux/debug/NIOHTTP1.build/HTTPResponseCompressor.swift.o:function CNIOZlib_deflateInit2: error: undefined reference to 'deflateInit2_'
clang: error: linker command failed with exit code 1 (use -v to see invocation)
<unknown>:0: error: link command failed with exit code 1 (use -v to see invocation)

swift test -Xlinker -lz is used as a temporary work-around for the above issue.

[pushkarnk]

@nethraravindran Does this happen on both 14.04 and 16.04?

[nethraravindran]

@pushkarnk No, this doesn't happen on 14.04

[pushkarnk]

I found a handful of projects/forums in which this problem was discussed:

https://elixirforum.com/t/ubuntu-exec-erlexec-not-found/10499/6
ncmpcpp/ncmpcpp#138
TrinityCore/TrinityCore#19074
grpc/grpc#11768

All of them talk about solving the problem using -lz but there's no drill-down into why this problem didn't show up on Ubuntu 14.04.

On Ubuntu 16.04, I ran ldconfig and I can see libz present in the search path:

ldconfig -v | grep "libz"
	libz.so.1 -> libz.so.1.2.8

[ianpartridge]

Does the linking still fail if we add CNIOZlib to the dependencies of the KituraNet target?

[weissi]

That sounds to me like either zlib or pkg-config isn't installed. You can test this by running

pkg-config --libs zlib

which should output

-lz

Or (on Debian systems) you should be able to see if zlib is installed with development headers like this

dpkg -l zlib1g-dev

[pushkarnk]

Thanks @weissi - Didn't know about pkg-config necessity. The xenial docker images have zlib installed (as seen in the ldconfig output), but not pkg-config. Simply installing pkg-config resolves the problem 🤔

[pushkarnk]

And I can see that the trusty images (Ubuntu 14.04) have pkg-config pre-installed.

[pushkarnk]

@nethraravindran Can we try adding pkg-config to the apt-get install .... list in build.sh

[nethraravindran]

@pushkarnk Sure! Have created the PR :https://github.com/IBM-Swift/Kitura-NIO/pull/77

[nethraravindran]

PR merged. Closing this issue.