autotools: Use explicit zlib dependency build flags

Use pkg-config if a zlib.pc file is available.

Remove the now redundant AC_TRY_LINK_FUNC test (there are no linker flags
for GTK+ here).

Change-Id: I7de744749eba7231ae0097b975144b76ffcf1bdb
Reviewed-on: https://code.wireshark.org/review/14263
Petri-Dish: João Valverde <j@v6e.pt>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: João Valverde <j@v6e.pt>

1 files changed, 40 insertions, 60 deletions

diff --git a/acinclude.m4 b/acinclude.m4
index b432d4cea2..b467ef75bf 100644
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -593,31 +593,45 @@ AC_DEFUN([AC_WIRESHARK_PCAP_REMOTE_CHECK],
 AC_DEFUN([AC_WIRESHARK_ZLIB_CHECK],
 [
 	AC_WIRESHARK_PUSH_FLAGS
+	ac_ws_saved_LIBS="$LIBS"
 
-	if test "x$zlib_dir" != "x"
+	if test "x$zlib_dir" = "x"
 	then
-	  #
-	  # The user specified a directory in which zlib resides,
-	  # so add the "include" subdirectory of that directory to
-	  # the include file search path and the "lib" subdirectory
-	  # of that directory to the library search path.
-	  #
-	  # XXX - if there's also a zlib in a directory that's
-	  # already in CPPFLAGS or LDFLAGS, this won't make us find
-	  # the version in the specified directory, as the compiler
-	  # and/or linker will search that other directory before it
-	  # searches the specified directory.
-	  #
-	  CPPFLAGS="$CPPFLAGS -I$zlib_dir/include"
-	  AC_WIRESHARK_ADD_DASH_L(LDFLAGS, $zlib_dir/lib)
+	  PKG_WIRESHARK_CHECK_SYSTEM_MODULES(ZLIB, [zlib], [zlib_found=yes], [zlib_found=no])
+	fi
+
+	if test x"$zlib_found" != xyes; then
+	  if test "x$zlib_dir" != "x"; then
+	    #
+	    # The user specified a directory in which zlib resides,
+	    # so add the "include" subdirectory of that directory to
+	    # the include file search path and the "lib" subdirectory
+	    # of that directory to the library search path.
+	    #
+	    ZLIB_CFLAGS="-I$zlib_dir/include"
+	    AC_WIRESHARK_ADD_DASH_L(ZLIB_LIBS, [$zlib_dir/lib])
+	  fi
+	  AX_APPEND_FLAG(-lz, ZLIB_LIBS)
 	fi
 
 	#
-	# Make sure we have "zlib.h".  If we don't, it means we probably
-	# don't have zlib, so don't use it.
+	# Make sure we have "zlib.h".
 	#
-	AC_CHECK_HEADER(zlib.h,,
+	CPPFLAGS="$ZLIB_CFLAGS $CPPFLAGS"
+	AC_CHECK_HEADERS(zlib.h,
 	  [
+	    #
+	    # We link with zlib to support uncompression of
+	    # gzipped network traffic, e.g. in an HTTP request
+	    # or response body.
+	    #
+	    have_zlib=yes
+	  ],
+	  [
+	    have_zlib=no
+	    ZLIB_CFLAGS=""
+	    ZLIB_LIBS=""
+
 	    if test "x$zlib_dir" != "x"
 	    then
 	      #
@@ -641,58 +655,24 @@ AC_DEFUN([AC_WIRESHARK_ZLIB_CHECK],
 		# We couldn't find the header file; don't use the
 		# library, as it's probably not present.
 		#
-		want_zlib=no
+		AC_MSG_NOTICE(zlib.h not found - disabling gzip compression and decompression)
 	      fi
 	    fi
 	  ])
 
-	if test "x$want_zlib" != "xno"
+	if test "x$have_zlib" != "xno"
 	then
 		#
-		# Well, we at least have the zlib header file.
-		# We link with zlib to support uncompression of
-		# gzipped network traffic, e.g. in an HTTP request
-		# or response body.
-		#
-		if test "x$zlib_dir" != "x"
-		then
-		  WS_CPPFLAGS="$WS_CPPFLAGS -I$zlib_dir/include"
-		  AC_WIRESHARK_ADD_DASH_L(WS_LDFLAGS, $zlib_dir/lib)
-		fi
-		LIBS="$LIBS -lz"
-		AC_DEFINE(HAVE_LIBZ, 1, [Define to use libz library])
-		#
 		# Check for "inflatePrime()" in zlib, which we need
 		# in order to read compressed capture files.
 		#
-		AC_CHECK_FUNCS(inflatePrime)
-
-		if test "x$ac_cv_func_inflatePrime" = "xyes" ; then
-			#
-			# Now check for "inflatePrime()" in zlib when
-			# linking with the linker flags for GTK+
-			# applications; people often grab XFree86 source
-			# and build and install it on their systems,
-			# and they appear sometimes to misconfigure
-			# XFree86 so that, even on systems with zlib,
-			# it assumes there is no zlib, so the XFree86
-			# build process builds and installs its
-			# own zlib in the X11 library directory.
-			#
-			# The zlib in at least some versions of XFree86
-			# is an older version that may lack "inflatePrime()",
-			# and that's the zlib with which Wireshark gets
-			# linked, so the build of Wireshark fails.
-			#
-			AC_MSG_CHECKING([for inflatePrime missing when linking with X11])
-			AC_TRY_LINK_FUNC(inflatePrime, AC_MSG_RESULT(no),
-			  [
-			    AC_MSG_RESULT(yes)
-			    AC_MSG_ERROR(old zlib found when linking with X11 - get rid of old zlib.)
-			  ])
-		fi
+		LIBS="$ZLIB_LIBS $LIBS"
+		AC_CHECK_FUNCS(inflatePrime,[],
+		  [AC_MSG_NOTICE(inflatePrime not found - disabling gzipped capture file support)])
 	fi
-
+	AC_SUBST(ZLIB_CFLAGS)
+	AC_SUBST(ZLIB_LIBS)
+	LIBS="$ac_ws_saved_LIBS"
 	AC_WIRESHARK_POP_FLAGS
 ])