build: configure: Allow to disable support for libgeoip and zlib

Allow users to explicitely disable linking against libgeoip and zlib, as
they are completely optional, e.g:

  DISABLE_GEOIP=1 ./configure && make
  DISABLE_ZLIB=1 ./configure && make

This change should also help to increase build coverage once we use
these options in the Travis CI setup.

Signed-off-by: Tobias Klauser <tklauser@distanz.ch>

2 files changed, 21 insertions, 0 deletions

diff --git a/INSTALL b/INSTALL
index 9c000de..79ccfd2 100644
--- a/INSTALL
+++ b/INSTALL
@@ -72,11 +72,22 @@ The installation (deinstallation) process is fairly simple:
 
   (# make uninstall)
 
+The configure script can be influenced by setting certain environment
+variables, e.g. CC or CROSS_COMPILE.
+
+The use of the optional libGeoIP and libz libraries can be explicitely
+disabled by setting the corresponding variables for the configure
+script:
+
+  $ DISABLE_GEOIP=1 ./configure
+  $ DISABLE_ZLIB=1 ./configure
+
 In order to remove all build files from the source tree:
 
   $ make clean
 
 In any case "make help" will give you some pointers of what can be done.
+
 To bring the source tree into a pristine state, there are two options.
 The first one will remove all build and build config file, the latter will
 also remove any manually added files:
diff --git a/configure b/configure
index 067b675..105b1ec 100755
--- a/configure
+++ b/configure
@@ -333,6 +333,11 @@ check_libgeoip()
 {
 	echo -n "[*] Checking libGeoIP ... "
 
+	if [ "$DISABLE_GEOIP" == "1" ] ; then
+		echo "[DISABLED]"
+		return
+	fi
+
 	cat > $TMPDIR/geoiptest.c << EOF
 #include <GeoIP.h>
 #include <GeoIPCity.h>
@@ -397,6 +402,11 @@ check_zlib()
 {
 	echo -n "[*] Checking libz ... "
 
+	if [ "$DISABLE_ZLIB" == "1" ] ; then
+		echo "[DISABLED]"
+		return
+	fi
+
 	cat > $TMPDIR/ztest.c << EOF
 #include "zlib.h"