[Bug 1780233] Re: libpng16-16 needs ZLIB_1.2.9 but package does not install it

[Andreas Nicolai]

Bug appears to be related to software build and linked against different
version of libz:

Analysis:

Output of ld when trying to build an application that uses libpng16:

/usr/lib/x86_64-linux-gnu/libpng16.so.16: undefined reference to `inflateReset2 at ZLIB_1.2.3.4'
/usr/lib/x86_64-linux-gnu/libpng16.so.16: undefined reference to `inflateValidate at ZLIB_1.2.9'

Output of ldd (same output as above):

> ldd /usr/lib/x86_64-linux-gnu/libpng16.so.16
	linux-vdso.so.1 (0x00007ffeda752000)
	libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007f0dd35dd000)
	libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f0dd323f000)
	libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f0dd2e4e000)
	/lib64/ld-linux-x86-64.so.2 (0x00007f0dd3a2c000)

checking for missing symbols:

> readelf  --syms /usr/lib/x86_64-linux-gnu/libpng16.so.16 | grep inflateReset2
     9: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND inflateReset2 at ZLIB_1.2.3.4 (4)

Ok, symbol appears to be there. Why does ld pop up the error?

--> linker command line references an older z-lib earlier on in the
library dependencies -> hence, zlib from system is not used (though
required by libpng16).

Solution: remove linker dependency to custom libz (remove "-lz") and try
linking against system libz.

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https://bugs.launchpad.net/bugs/1780233

Title:
  libpng16-16 needs ZLIB_1.2.9 but package does not install it

Status in libpng1.6 package in Ubuntu:
  Invalid

Bug description:
  Since upgrading from 16.04 to 18.04, some programs that depend on
  libpng16.so.16 do not work with the error

  ImportError: /opt/yann/pyzo-4.5.1/lib/python3.5/../libz.so.1: version
  `ZLIB_1.2.9' not found (required by /usr/lib/x86_64-linux-
  gnu/libpng16.so.16)

  Reinstalling the libpng16-16 package does not improve things.

  ProblemType: Bug
  DistroRelease: Ubuntu 18.04
  Package: libpng16-16 1.6.34-1
  ProcVersionSignature: Ubuntu 4.15.0-24.26-generic 4.15.18
  Uname: Linux 4.15.0-24-generic x86_64
  NonfreeKernelModules: nvidia_modeset nvidia
  ApportVersion: 2.20.9-0ubuntu7.2
  Architecture: amd64
  CurrentDesktop: XFCE
  Date: Thu Jul  5 13:19:44 2018
  Dependencies:
   gcc-8-base 8-20180414-1ubuntu2
   libc6 2.27-3ubuntu1
   libgcc1 1:8-20180414-1ubuntu2
   zlib1g 1:1.2.11.dfsg-0ubuntu2
  InstallationDate: Installed on 2016-09-07 (665 days ago)
  InstallationMedia: Xubuntu 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1)
  SourcePackage: libpng1.6
  UpgradeStatus: Upgraded to bionic on 2018-07-01 (3 days ago)

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