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6.16. Zlib-1.2.1

The Zlib package contains compression and un-compression routines used by some programs.

Approximate build time: 0.1 SBU

Required disk space: 1.5 MB

Zlib installation depends on: Binutils, Coreutils, GCC, Glibc, Make, and Sed

6.16.1. Installation of Zlib

The following patch fixes a Denial of Service vulnerability in the Zlib compression library:

patch -Np1 -i ../zlib-1.2.1-security-1.patch


Zlib is known to build its shared library incorrectly if CFLAGS is specified in the environment. If using a specified CFLAGS variable, be sure to add the -fPIC directive to the CFLAGS variable for the duration of the configure command below, then remove it afterwards.

Prepare Zlib for compilation:

./configure --prefix=/usr --shared

Compile the package:


To test the results, issue: make check.

Install the shared library:

make install

Build the static library:

make clean
./configure --prefix=/usr

To test the results again, issue: make check.

Install the static library:

make install

Fix the permissions on the static library:

chmod 644 /usr/lib/libz.a

It is good policy and common practice to place important libraries into the /lib directory. This is most important in scenarios where /usr is on a separate partition. Essentially, the run-time components of any libraries that are used by programs in /bin or /sbin should reside in /lib so that they are on the root partition and available in the event of /usr being inaccessible.

For the above reason, move the run-time components of the shared Zlib into /lib:

mv /usr/lib/libz.so.* /lib

Fix the /usr/lib/libz.so symlink:

ln -sf ../../lib/libz.so.1 /usr/lib/libz.so

6.16.2. Contents of Zlib

Installed libraries: libz[a,so]

Short Descriptions


Contains compression and un-compression functions used by some programs