dependency: Add JDK system dependency

The JDK system dependency is important for detecting JDK include paths
that may be useful when developing a JNI interface.

13 files changed, 193 insertions, 7 deletions

diff --git a/docs/markdown/Machine-files.md b/docs/markdown/Machine-files.md
index 39e02a6..6c0b051 100644
--- a/docs/markdown/Machine-files.md
+++ b/docs/markdown/Machine-files.md
@@ -236,6 +236,7 @@ section.
   `exe_wrapper` specified in `[binaries]` to run generated executables in CMake
   subprojects. This setting has no effect if the `exe_wrapper` was not specified.
   The default value is `true`. (*new in 0.56.0*)
+- `java_home` is an absolute path pointing to the root of a Java installation.
 
 ### CMake variables
 
diff --git a/docs/markdown/snippets/jdk-system-dependency.md b/docs/markdown/snippets/jdk-system-dependency.md
new file mode 100644
index 0000000..bccd16e
--- /dev/null
+++ b/docs/markdown/snippets/jdk-system-dependency.md
@@ -0,0 +1,16 @@
+## JDK System Dependency
+
+When building projects such as those interacting with the JNI, you need access
+to a few header files located in a Java installation. This system dependency
+will add the correct include paths to your target. It assumes that either
+`JAVA_HOME` will be set to a valid Java installation, or the default `javac` on
+your system is a located in the `bin` directory of a Java installation. Note:
+symlinks are resolved.
+
+```meson
+jdk = dependency('jdk', version : '>=1.8')
+```
+
+Currently this system dependency only works on `linux`, `win32`, and `darwin`.
+This can easily be extended given the correct information about your compiler
+and platform in an issue.
diff --git a/mesonbuild/dependencies/__init__.py b/mesonbuild/dependencies/__init__.py
index afd4adc..722ede4 100644
--- a/mesonbuild/dependencies/__init__.py
+++ b/mesonbuild/dependencies/__init__.py
@@ -21,7 +21,9 @@ from .base import (  # noqa: F401
     InternalDependency, PkgConfigDependency, CMakeDependency,
     find_external_dependency, get_dep_identifier, packages,
     _packages_accept_language, DependencyFactory)
-from .dev import ValgrindDependency, gmock_factory, gtest_factory, llvm_factory, zlib_factory
+from .dev import (
+    ValgrindDependency, JDKSystemDependency, gmock_factory, gtest_factory,
+    llvm_factory, zlib_factory)
 from .coarrays import coarray_factory
 from .mpi import mpi_factory
 from .scalapack import scalapack_factory
@@ -196,6 +198,7 @@ packages.update({
     'llvm': llvm_factory,
     'valgrind': ValgrindDependency,
     'zlib': zlib_factory,
+    'jdk': JDKSystemDependency,
 
     'boost': BoostDependency,
     'cuda': CudaDependency,
diff --git a/mesonbuild/dependencies/dev.py b/mesonbuild/dependencies/dev.py
index 2ac91b1..e9181bd 100644
--- a/mesonbuild/dependencies/dev.py
+++ b/mesonbuild/dependencies/dev.py
@@ -18,6 +18,8 @@
 import glob
 import os
 import re
+import pathlib
+import shutil
 import typing as T
 
 from .. import mesonlib, mlog
@@ -32,6 +34,7 @@ from ..compilers.c import AppleClangCCompiler
 from ..compilers.cpp import AppleClangCPPCompiler
 
 if T.TYPE_CHECKING:
+    from ..envconfig import MachineInfo
     from .. environment import Environment
 
 
@@ -505,6 +508,59 @@ class ZlibSystemDependency(ExternalDependency):
         return [DependencyMethods.SYSTEM]
 
 
+class JDKSystemDependency(ExternalDependency):
+    def __init__(self, environment: 'Environment', kwargs: T.Dict[str, T.Any]):
+        super().__init__('jdk', environment, kwargs)
+
+        m = self.env.machines[self.for_machine]
+
+        if 'java' not in environment.coredata.compilers[self.for_machine]:
+            environment.detect_compiler_for('java', self.for_machine)
+        self.javac = environment.coredata.compilers[self.for_machine]['java']
+        self.version = self.javac.version
+
+        if 'version' in kwargs and not version_compare(self.version, kwargs['version']):
+            mlog.error(f'Incorrect JDK version found ({self.version}), wanted {kwargs["version"]}')
+            self.is_found = False
+            return
+
+        self.java_home = environment.properties[self.for_machine].get_java_home()
+        if not self.java_home:
+            self.java_home = pathlib.Path(shutil.which(self.javac.exelist[0])).resolve().parents[1]
+
+        platform_include_dir = self.__machine_info_to_platform_include_dir(m)
+        if platform_include_dir is None:
+            mlog.error("Could not find a JDK platform include directory for your OS, please open an issue or provide a pull request.")
+            self.is_found = False
+            return
+
+        java_home_include = self.java_home / 'include'
+        self.compile_args.append(f'-I{java_home_include}')
+        self.compile_args.append(f'-I{java_home_include / platform_include_dir}')
+        self.is_found = True
+
+    @staticmethod
+    def get_methods() -> T.List[DependencyMethods]:
+        return [DependencyMethods.SYSTEM]
+
+    @staticmethod
+    def __machine_info_to_platform_include_dir(m: 'MachineInfo') -> T.Optional[str]:
+        """Translates the machine information to the platform-dependent include directory
+
+        When inspecting a JDK release tarball or $JAVA_HOME, inside the `include/` directory is a
+        platform dependent folder that must be on the target's include path in addition to the
+        parent `include/` directory.
+        """
+        if m.is_linux():
+            return 'linux'
+        elif m.is_windows():
+            return 'win32'
+        elif m.is_darwin():
+            return 'darwin'
+
+        return None
+
+
 llvm_factory = DependencyFactory(
     'LLVM',
     [DependencyMethods.CMAKE, DependencyMethods.CONFIG_TOOL],
diff --git a/mesonbuild/envconfig.py b/mesonbuild/envconfig.py
index f2792c5..c6a4df3 100644
--- a/mesonbuild/envconfig.py
+++ b/mesonbuild/envconfig.py
@@ -136,9 +136,9 @@ class CMakeSkipCompilerTest(Enum):
 class Properties:
     def __init__(
             self,
-            properties: T.Optional[T.Dict[str, T.Union[str, bool, int, T.List[str]]]] = None,
+            properties: T.Optional[T.Dict[str, T.Optional[T.Union[str, bool, int, T.List[str]]]]] = None,
     ):
-        self.properties = properties or {}  # type: T.Dict[str, T.Union[str, bool, int, T.List[str]]]
+        self.properties = properties or {}  # type: T.Dict[str, T.Optional[T.Union[str, bool, int, T.List[str]]]]
 
     def has_stdlib(self, language: str) -> bool:
         return language + '_stdlib' in self.properties
@@ -210,13 +210,17 @@ class Properties:
         assert isinstance(res, bool)
         return res
 
+    def get_java_home(self) -> T.Optional[Path]:
+        value = T.cast(T.Optional[str], self.properties.get('java_home'))
+        return Path(value) if value else None
+
     def __eq__(self, other: object) -> bool:
         if isinstance(other, type(self)):
             return self.properties == other.properties
         return NotImplemented
 
     # TODO consider removing so Properties is less freeform
-    def __getitem__(self, key: str) -> T.Union[str, bool, int, T.List[str]]:
+    def __getitem__(self, key: str) -> T.Optional[T.Union[str, bool, int, T.List[str]]]:
         return self.properties[key]
 
     # TODO consider removing so Properties is less freeform
@@ -224,7 +228,7 @@ class Properties:
         return item in self.properties
 
     # TODO consider removing, for same reasons as above
-    def get(self, key: str, default: T.Union[str, bool, int, T.List[str]] = None) -> T.Union[str, bool, int, T.List[str]]:
+    def get(self, key: str, default: T.Optional[T.Union[str, bool, int, T.List[str]]] = None) -> T.Optional[T.Union[str, bool, int, T.List[str]]]:
         return self.properties.get(key, default)
 
 class MachineInfo:
diff --git a/mesonbuild/environment.py b/mesonbuild/environment.py
index 54f608d..fc9b703 100644
--- a/mesonbuild/environment.py
+++ b/mesonbuild/environment.py
@@ -881,12 +881,13 @@ class Environment:
                 self.binaries[for_machine].binaries.setdefault(name, mesonlib.split_args(p_env))
 
     def _set_default_properties_from_env(self) -> None:
-        """Properties which can alkso be set from the environment."""
+        """Properties which can also be set from the environment."""
         # name, evar, split
         opts: T.List[T.Tuple[str, T.List[str], bool]] = [
             ('boost_includedir', ['BOOST_INCLUDEDIR'], False),
             ('boost_librarydir', ['BOOST_LIBRARYDIR'], False),
             ('boost_root', ['BOOST_ROOT', 'BOOSTROOT'], True),
+            ('java_home', ['JAVA_HOME'], False),
         ]
 
         for (name, evars, split), for_machine in itertools.product(opts, MachineChoice):
@@ -944,7 +945,7 @@ class Environment:
     def is_library(self, fname):
         return is_library(fname)
 
-    def lookup_binary_entry(self, for_machine: MachineChoice, name: str) -> T.List[str]:
+    def lookup_binary_entry(self, for_machine: MachineChoice, name: str) -> T.Optional[T.List[str]]:
         return self.binaries[for_machine].lookup_entry(name)
 
     @staticmethod
diff --git a/test cases/java/9 jdk/lib/com_mesonbuild_JdkTest.c b/test cases/java/9 jdk/lib/com_mesonbuild_JdkTest.c
new file mode 100644
index 0000000..075e37b
--- /dev/null
+++ b/test cases/java/9 jdk/lib/com_mesonbuild_JdkTest.c
@@ -0,0 +1,9 @@
+#include <jni.h>
+
+#include "com_mesonbuild_JdkTest.h"
+
+JNIEXPORT jint JNICALL Java_com_mesonbuild_JdkTest_jdk_1test
+  (JNIEnv *env, jclass clazz)
+{
+    return (jint)0xdeadbeef;
+}
diff --git a/test cases/java/9 jdk/lib/com_mesonbuild_JdkTest.h b/test cases/java/9 jdk/lib/com_mesonbuild_JdkTest.h
new file mode 100644
index 0000000..40083ac
--- /dev/null
+++ b/test cases/java/9 jdk/lib/com_mesonbuild_JdkTest.h
@@ -0,0 +1,21 @@
+/* DO NOT EDIT THIS FILE - it is machine generated */
+#include <jni.h>
+/* Header for class com_mesonbuild_JdkTest */
+
+#ifndef _Included_com_mesonbuild_JdkTest
+#define _Included_com_mesonbuild_JdkTest
+#ifdef __cplusplus
+extern "C" {
+#endif
+/*
+ * Class:     com_mesonbuild_JdkTest
+ * Method:    jdk_test
+ * Signature: ()I
+ */
+JNIEXPORT jint JNICALL Java_com_mesonbuild_JdkTest_jdk_1test
+  (JNIEnv *, jclass);
+
+#ifdef __cplusplus
+}
+#endif
+#endif
diff --git a/test cases/java/9 jdk/lib/meson.build b/test cases/java/9 jdk/lib/meson.build
new file mode 100644
index 0000000..a947769
--- /dev/null
+++ b/test cases/java/9 jdk/lib/meson.build
@@ -0,0 +1,14 @@
+sources = files(
+  'native.c',
+  'com_mesonbuild_JdkTest.c',
+)
+
+jdkjava = shared_module(
+  'jdkjava',
+  sources,
+  dependencies : [jdk],
+)
+
+jdkjava_dep = declare_dependency(
+  link_with : jdkjava,
+)
diff --git a/test cases/java/9 jdk/lib/native.c b/test cases/java/9 jdk/lib/native.c
new file mode 100644
index 0000000..0b5e718
--- /dev/null
+++ b/test cases/java/9 jdk/lib/native.c
@@ -0,0 +1,11 @@
+#include <jni.h>
+
+JNIEXPORT jint JNICALL
+JNI_OnLoad(JavaVM *vm, void *reserved)
+{
+    return JNI_VERSION_1_8;
+}
+
+JNIEXPORT void JNICALL
+JNI_OnUnload(JavaVM *vm, void *reserved)
+{}
diff --git a/test cases/java/9 jdk/meson.build b/test cases/java/9 jdk/meson.build
new file mode 100644
index 0000000..310ba5e
--- /dev/null
+++ b/test cases/java/9 jdk/meson.build
@@ -0,0 +1,18 @@
+project('jdkjava', ['c', 'java'])
+
+if build_machine.system() == 'cygwin'
+  error('MESON_SKIP_TEST: cygwin test failures')
+endif
+
+if build_machine.system() == 'windows' and build_machine.cpu_family() == 'x86'
+  error('MESON_SKIP_TEST: failing builds on 32bit Windows because a 32bit JDK isn not available in the Azure Pipelines Windows images')
+endif
+
+fs = import('fs')
+
+java = find_program('java')
+
+jdk = dependency('jdk', version : '>=1.8')
+
+subdir('lib')
+subdir('src')
diff --git a/test cases/java/9 jdk/src/com/mesonbuild/JdkTest.java b/test cases/java/9 jdk/src/com/mesonbuild/JdkTest.java
new file mode 100644
index 0000000..35c47ce
--- /dev/null
+++ b/test cases/java/9 jdk/src/com/mesonbuild/JdkTest.java
@@ -0,0 +1,15 @@
+package com.mesonbuild;
+
+public final class JdkTest {
+    private static native int jdk_test();
+
+    public static void main(String[] args) {
+        if (jdk_test() != 0xdeadbeef) {
+            throw new RuntimeException("jdk_test() did not return 0");
+        }
+    }
+
+    static {
+        System.loadLibrary("jdkjava");
+    }
+}
diff --git a/test cases/java/9 jdk/src/meson.build b/test cases/java/9 jdk/src/meson.build
new file mode 100644
index 0000000..d1b9ee3
--- /dev/null
+++ b/test cases/java/9 jdk/src/meson.build
@@ -0,0 +1,17 @@
+jdkjar = jar(
+  'jdkjar',
+  'com' / 'mesonbuild' / 'JdkTest.java',
+  main_class : 'com.mesonbuild.JdkTest',
+)
+
+test(
+  'jdktest',
+  java,
+  args: [
+    '-Djava.library.path=@0@'.format(fs.parent(jdkjava.full_path())),
+    '-jar',
+    jdkjar,
+  ],
+  protocol : 'exitcode',
+  depends : [jdkjava],
+)