From 048b9cb7910cf2f04f73483dd9755aeb50017e6b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Andr=C3=A9=20Draszik?= <andre.draszik@jci.com>
Date: Thu, 2 Jan 2020 13:40:50 +0100
Subject: [PATCH] Allow using a system-installed libpng
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Patch stolen (and some typos corrected) from debian patch,
which itself was a backport from:
  http://hg.openjdk.java.net/jdk9/jdk9/rev/bfc1c131e540
  http://hg.openjdk.java.net/jdk9/jdk9/jdk/rev/5e503831b142

Issues fixed on top of debian patch:
  * the default when --with-libpng= is not given works
  * using the bundled libpng works

Upstream-Status: Backport

Signed-off-by: André Draszik <andre.draszik@jci.com>
Signed-off-by: Richard Leitner <richard.leitner@skidata.com>

---
 common/autoconf/libraries.m4 | 41 ++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/common/autoconf/libraries.m4 b/common/autoconf/libraries.m4
index d2732eb8..727f0181 100644
--- a/common/autoconf/libraries.m4
+++ b/common/autoconf/libraries.m4
@@ -843,6 +843,47 @@ AC_DEFUN_ONCE([LIB_SETUP_MISC_LIBS],
   fi
   AC_SUBST(USE_EXTERNAL_LIBGIF)
 
+  ###############################################################################
+  #
+  # Check for the png library
+  #
+
+  AC_ARG_WITH(libpng, [AS_HELP_STRING([--with-libpng],
+     [use libpng from build system or OpenJDK source (system, bundled) @<:@bundled@:>@])])
+
+  AC_CHECK_LIB(png, png_sig_cmp,
+               [ LIBPNG_FOUND=yes ],
+               [ LIBPNG_FOUND=no ])
+
+  AC_MSG_CHECKING([for which libpng to use])
+
+  # default is bundled
+  DEFAULT_LIBPNG=bundled
+
+  #
+  # if user didn't specify, use DEFAULT_LIBPNG
+  #
+  if test "x${with_libpng}" = "x"; then
+      with_libpng=${DEFAULT_LIBPNG}
+  fi
+
+
+  if test "x${with_libpng}" = "xbundled"; then
+      USE_EXTERNAL_LIBPNG=false
+      AC_MSG_RESULT([bundled])
+  elif test "x${with_libpng}" = "xsystem"; then
+      if test "x${LIBPNG_FOUND}" = "xyes"; then
+          USE_EXTERNAL_LIBPNG=true
+          AC_MSG_RESULT([system])
+      else
+          AC_MSG_RESULT([system not found])
+          AC_MSG_ERROR([--with-libpng=system specified, but no libpng found!])
+      fi
+  else
+      AC_MSG_ERROR([Invalid value of --with-libpng: ${with_libpng}, use 'system' or 'bundled'])
+  fi
+  AC_SUBST(USE_EXTERNAL_LIBPNG)
+
   ###############################################################################
   #
   # Check for the zlib library