zlib 1.0.8 - the version that comes with X11 - does have "gzseek()",

even if it doesn't have "gzgets()", so one might think we could use it
by using our own replacement for "gzgets()".

One would be wrong to think so, however, as the "gzseek()" it has
doesn't actually work when reading uncompressed files.

zlib 1.0.9 has "gzgets()", and fixes that bug, so we rever to checking
for "gzgets()" rather than "gzseek()", so that we don't accept pre-1.0.9
versions of zlib, and we get rid of our "gzgets()" replacement.

svn path=/trunk/; revision=4702

1 files changed, 25 insertions, 14 deletions

diff --git a/acinclude.m4 b/acinclude.m4
index 42d7063b21..a150529277 100644
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -2,7 +2,7 @@ dnl Macros that test for specific features.
 dnl This file is part of the Autoconf packaging for Ethereal.
 dnl Copyright (C) 1998-2000 by Gerald Combs.
 dnl
-dnl $Id: acinclude.m4,v 1.41 2002/02/02 21:07:40 guy Exp $
+dnl $Id: acinclude.m4,v 1.42 2002/02/06 09:58:29 guy Exp $
 dnl
 dnl This program is free software; you can redistribute it and/or modify
 dnl it under the terms of the GNU General Public License as published by
@@ -367,26 +367,37 @@ AC_DEFUN(AC_ETHEREAL_ZLIB_CHECK,
 		#
 		# Well, we at least have the zlib header file.
 		#
-		# Check for "gzseek()" in zlib, because we need it, but
+		# Check for "gzgets()" in zlib, because we need it, but
 		# some older versions of zlib don't have it.  It appears
 		# from the zlib ChangeLog that any released version of zlib
-		# with "gzseek()" should have the other routines we
-		# depend on, such as "gztell()", and "zError()".
-		# (I think they may also get "gzgets()", in which case
-		# we can get rid of our own private "gzgets()"
-		# implementation, as any zlib that's adequate for our
-		# purposes will have "gzgets()".)
+		# with "gzgets()" should have the other routines we
+		# depend on, such as "gzseek()", "gztell()", and "zError()".
 		#
-		AC_CHECK_LIB(z, gzseek,,enable_zlib=no)
+		# Another reason why we require "gzgets()" is that
+		# some versions of zlib that didn't have it, such
+		# as 1.0.8, had a bug in "gzseek()" that meant that it
+		# doesn't work correctly on uncompressed files; this
+		# means we cannot use version 1.0.8.  (Unfortunately,
+		# that's the version that comes with recent X11 source,
+		# and many people who install XFree86 on their Slackware
+		# boxes don't realize that they should configure it to
+		# use the native zlib rather than building and installing
+		# the crappy old version that comes with XFree86.)
+		#
+		# I.e., we can't just avoid using "gzgets()", as
+		# versions of zlib without "gzgets()" are likely to have
+		# a broken "gzseek()".
+		#
+		AC_CHECK_LIB(z, gzgets,,enable_zlib=no)
 	fi
 
 	if test x$enable_zlib != xno
 	then
 		#
 		# Well, we at least have the zlib header file and a zlib
-		# with "gzseek()".
+		# with "gzgets()".
 		#
-		# Now check for "gzseek()" in zlib when linking with the
+		# Now check for "gzgets()" in zlib when linking with the
 		# linker flags for GTK+ applications; people often grab
 		# XFree86 source and build and install it on their systems,
 		# and they appear sometimes to misconfigure XFree86 so that,
@@ -395,15 +406,15 @@ AC_DEFUN(AC_ETHEREAL_ZLIB_CHECK,
 		# own zlib in the X11 library directory.
 		#
 		# The XFree86 zlib is an older version that lacks
-		# "gzseek()", and that's the zlib with which Ethereal
+		# "gzgets()", and that's the zlib with which Ethereal
 		# gets linked, so the build of Ethereal fails.
 		#
 		ac_save_CFLAGS="$CFLAGS"
 		ac_save_LIBS="$LIBS"
 		CFLAGS="$CFLAGS $GTK_CFLAGS"
 		LIBS="$GTK_LIBS -lz $LIBS"
-		AC_MSG_CHECKING([for gzseek missing when linking with X11])
-	        AC_TRY_LINK_FUNC(gzseek, AC_MSG_RESULT(no),
+		AC_MSG_CHECKING([for gzgets missing when linking with X11])
+	        AC_TRY_LINK_FUNC(gzgets, AC_MSG_RESULT(no),
 		  [
 		    AC_MSG_RESULT(yes)
 		    AC_MSG_ERROR(old zlib found when linking with X11 - get rid of old zlib.)