Autoconf test for JNI include dir

Question

I'm working on a configuration script for a JNI wrapper. One of the configuration parameters is the path to jni.h . What's a good quick-and-dirty Autoconf test for whether this parameter is set correctly for C++ compilation? You can assume you're running on Linux and g++ is available.

Alternatively, is there a way to get javah (or a supporting tool) to give me this path directly?

Answer 1

Then there is the easy way: http://www.gnu.org/software/autoconf-archive/ax_jni_include_dir.html

Sometimes it is best to just use the standard recipies.

Answer 2

Checking for headers is easy; just use AC_CHECK_HEADER . If it's in a weird place (ie, one the compiler doesn't know about), it's entirely reasonable to expect users to set CPPFLAGS .

The hard part is actually locating libjvm . You typically don't want to link with this; but you may want to default to a location to dlopen it from if JAVA_HOME is not set at run time.

But I don't have a better solution than requiring that JAVA_HOME be set at configure time. There's just too much variation in how this stuff is deployed across various OSes (even just Linux distributions). This is what I do:

AC_CHECK_HEADER([jni.h], [have_jni=yes])
AC_ARG_VAR([JAVA_HOME], [Java Runtime Environment (JRE) location])
AC_ARG_ENABLE([java-feature],
              [AC_HELP_STRING([--disable-java-feature],
                              [disable Java feature])])
case $target_cpu in
     x86_64) JVM_ARCH=amd64 ;;
     i?86)   JVM_ARCH=i386 ;;
     *)      JVM_ARCH=$target_cpu ;;
esac
AC_SUBST([JVM_ARCH])
AS_IF([test X$enable_java_feature != Xno],
[AS_IF([test X$have_jni != Xyes],
       [AC_MSG_FAILURE([The Java Native Interface is required for Java feature.])])
AS_IF([test -z "$JAVA_HOME"],
[AC_MSG_WARN([JAVA_HOME has not been set.  JAVA_HOME must be set at run time to locate libjvm.])],
[save_LDFLAGS=$LDFLAGS
LDFLAGS="-L$JAVA_HOME/lib/$JVM_ARCH/client -L$JAVA_HOME/lib/$JVM_ARCH/server $LDFLAGS"
AC_CHECK_LIB([jvm], [JNI_CreateJavaVM], [LIBS=$LIBS],
             [AC_MSG_WARN([no libjvm found at JAVA_HOME])])
LDFLAGS=$save_LDFLAGS
])])

Answer 3

FYI - the patch below against the latest ax_jni_include_dir.m4 works for me on Macos 11.1.

--- a/m4/ax_jni_include_dir.m4
+++ b/m4/ax_jni_include_dir.m4
@@ -73,13 +73,19 @@ fi
 
 case "$host_os" in
         darwin*)        # Apple Java headers are inside the Xcode bundle.
-            macos_version=$(sw_vers -productVersion | sed -n -e 's/^@<:@0-9@:>@
*.\(@<:@0-9@:>@*\).@<:@0-9@:>@*/\1/p')
-            if @<:@ "$macos_version" -gt "7" @:>@; then
-                _JTOPDIR="$(xcrun --show-sdk-path)/System/Library/Frameworks/JavaVM.framework"
-                _JINC="$_JTOPDIR/Headers"
+            major_macos_version=$(sw_vers -productVersion | sed -n -e 's/^\(@<:@0-9@:>@*\).@<:@0-9@:>@*.@<:@0-9@:>@*/\1/p')
+            if @<:@ "$major_macos_version" -gt "10" @:>@; then
+                _JTOPDIR="$(/usr/libexec/java_home)"
+                _JINC="$_JTOPDIR/include"
             else
-                _JTOPDIR="/System/Library/Frameworks/JavaVM.framework"
-                _JINC="$_JTOPDIR/Headers"
+                macos_version=$(sw_vers -productVersion | sed -n -e 's/^@<:@0-9@:>@*.\(@<:@0-9@:>@*\).@<:@0-9@:>@*/\1/p')
+                if @<:@ "$macos_version" -gt "7" @:>@; then
+                    _JTOPDIR="$(xcrun --show-sdk-path)/System/Library/Frameworks/JavaVM.framework"
+                    _JINC="$_JTOPDIR/Headers"
+                else
+                    _JTOPDIR="/System/Library/Frameworks/JavaVM.framework"
+                    _JINC="$_JTOPDIR/Headers"
+                fi
             fi
             ;;
         *) _JINC="$_JTOPDIR/include";;