From 3a025ef673d37858a32ddc1c6ea224a668248272 Mon Sep 17 00:00:00 2001
From: Christos Zoulas <christos@zoulas.com>
Date: Fri, 13 May 2016 23:02:28 +0000
Subject: [PATCH] From Mike Frysinger: The current configure logic will
 autodetect & use zlib if it's found. If the user wants to disable zlib
 support, they have no way to do so easily.  Conversely, if they want to make
 sure zlib is always included, there's no way to do so.  Add a configure flag
 for both.

---
 configure.ac   | 22 ++++++++++++++++++++--
 src/compress.c |  5 ++---
 2 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/configure.ac b/configure.ac
index 3c5f9221..cc407feb 100644
--- a/configure.ac
+++ b/configure.ac
@@ -34,6 +34,11 @@ fi], [
   AC_DEFINE([ELFCORE], 1, [Define for ELF core file support])
 ])
 
+AC_MSG_CHECKING(for zlib support)
+AC_ARG_ENABLE(zlib,
+[AS_HELP_STRING([--disable-zlib], [disable zlib compression support @<:@default=auto@:>@])])
+AC_MSG_RESULT($enable_zlib)
+
 AC_MSG_CHECKING(for file formats in man section 5)
 AC_ARG_ENABLE(fsect-man5,
 [  --enable-fsect-man5      enable file formats in man section 5],
@@ -84,7 +89,9 @@ AC_CHECK_HEADERS(stdint.h fcntl.h locale.h stdint.h inttypes.h unistd.h)
 AC_CHECK_HEADERS(stddef.h utime.h wchar.h wctype.h limits.h)
 AC_CHECK_HEADERS(getopt.h err.h xlocale.h signal.h)
 AC_CHECK_HEADERS(sys/mman.h sys/stat.h sys/types.h sys/utime.h sys/time.h)
-AC_CHECK_HEADERS(zlib.h)
+if test "$enable_zlib" != "no"; then
+  AC_CHECK_HEADERS(zlib.h)
+fi
 AC_CHECK_TYPE([sig_t],[AC_DEFINE([HAVE_SIG_T],1,[Have sig_t type])],,[
 #ifdef HAVE_SIGNAL_H
 #include <signal.h>
@@ -148,7 +155,9 @@ dnl Provide implementation of some required functions if necessary
 AC_REPLACE_FUNCS(getopt_long asprintf vasprintf strlcpy strlcat getline ctime_r asctime_r localtime_r gmtime_r pread strcasestr fmtcheck dprintf)
 
 dnl Checks for libraries
-AC_CHECK_LIB(z,gzopen)
+if test "$enable_zlib" != "no"; then
+  AC_CHECK_LIB(z, gzopen)
+fi
 if test "$MINGW" = 1; then
   AC_CHECK_LIB(gnurx,regexec,,AC_MSG_ERROR([libgnurx is required to build file(1) with MinGW]))
 fi
@@ -156,5 +165,14 @@ fi
 dnl See if we are cross-compiling
 AM_CONDITIONAL(IS_CROSS_COMPILE, test "$cross_compiling" = yes)
 
+dnl Final sanity checks
+if test "$enable_zlib" = "yes"; then
+  if test "$ac_cv_header_zlib_h$ac_cv_lib_z_gzopen" != "yesyes"; then
+    AC_MSG_ERROR([zlib support requested but not found])
+  fi
+elif  test "$ac_cv_header_zlib_h$ac_cv_lib_z_gzopen" = "yesyes"; then
+  AC_DEFINE([ZLIBSUPPORT], 1, [Enable zlib compression support])
+fi
+
 AC_CONFIG_FILES([Makefile src/Makefile magic/Makefile tests/Makefile doc/Makefile python/Makefile])
 AC_OUTPUT
diff --git a/src/compress.c b/src/compress.c
index 979443bb..1988fe78 100644
--- a/src/compress.c
+++ b/src/compress.c
@@ -35,7 +35,7 @@
 #include "file.h"
 
 #ifndef lint
-FILE_RCSID("@(#)$File: compress.c,v 1.96 2016/04/20 00:00:26 christos Exp $")
+FILE_RCSID("@(#)$File: compress.c,v 1.97 2016/05/13 23:02:28 christos Exp $")
 #endif
 
 #include "magic.h"
@@ -62,10 +62,9 @@ typedef void (*sig_t)(int);
 #if defined(HAVE_SYS_TIME_H)
 #include <sys/time.h>
 #endif
-#if defined(HAVE_ZLIB_H) && defined(HAVE_LIBZ)
+#if defined(HAVE_ZLIB_H)
 #define BUILTIN_DECOMPRESS
 #include <zlib.h>
-#define ZLIBSUPPORT
 #endif
 #ifdef DEBUG
 int tty = -1;
-- 
2.40.0