unix/modjni: "jni" module to interface to JNI-compliant JavaVM.

This includes Android Dalvik VM for example.

Example usage:

import jni
System = jni.cls("java/lang/System")
System.out.println("Hello, Java!")

unix/Makefile

@@ -101,6 +101,11 @@ LDFLAGS_MOD += $(LIBFFI_LDFLAGS_MOD)
 SRC_MOD += modffi.c
 endif
 
+ifeq ($(MICROPY_PY_JNI),1)
+# Path for 64-bit OpenJDK, should be adjusted for other JDKs
+CFLAGS_MOD += -I/usr/lib/jvm/java-7-openjdk-amd64/include -DMICROPY_PY_JNI=1
+SRC_MOD += modjni.c
+endif
 
 # source files
 SRC_C = \

unix/modjni.c

+/*
+ * This file is part of the Micro Python project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2015 Paul Sokolovsky
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <assert.h>
+#include <string.h>
+#include <errno.h>
+#include <dlfcn.h>
+
+#include "py/nlr.h"
+#include "py/runtime.h"
+#include "py/binary.h"
+
+#include <jni.h>
+
+#define JJ(call, ...) (*env)->call(env, __VA_ARGS__)
+
+static JavaVM *jvm;
+static JNIEnv *env;
+static jclass String_class;
+static jmethodID Class_getField_mid;
+static jmethodID Class_getMethods_mid;
+static jmethodID Class_getConstructors_mid;
+static jmethodID Method_getName_mid;
+static jmethodID Method_toString_mid;
+
+STATIC const mp_obj_type_t jobject_type;
+STATIC const mp_obj_type_t jmethod_type;
+
+STATIC mp_obj_t call_method(jobject obj, const char *name, jarray methods, bool is_constr, mp_uint_t n_args, const mp_obj_t *args);
+
+typedef struct _mp_obj_jclass_t {
+    mp_obj_base_t base;
+    jclass cls;
+} mp_obj_jclass_t;
+
+typedef struct _mp_obj_jobject_t {
+    mp_obj_base_t base;
+    jobject obj;
+} mp_obj_jobject_t;
+
+typedef struct _mp_obj_jmethod_t {
+    mp_obj_base_t base;
+    jobject obj;
+    jmethodID meth;
+    qstr name;
+} mp_obj_jmethod_t;
+
+// jclass
+
+STATIC void jclass_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
+    (void)kind;
+    mp_obj_jclass_t *self = self_in;
+    // Variable value printed as cast to int
+    mp_printf(print, "<jclass @%p>", self->cls);
+}
+
+STATIC void jclass_attr(mp_obj_t self_in, qstr attr_in, mp_obj_t *dest) {
+    if (dest[0] == MP_OBJ_NULL) {
+        // load attribute
+        mp_obj_jclass_t *self = self_in;
+        const char *attr = qstr_str(attr_in);
+
+        jstring field_name = JJ(NewStringUTF, attr);
+        jobject field = JJ(CallObjectMethod, self->cls, Class_getField_mid, field_name);
+        jfieldID field_id = JJ(FromReflectedField, field);
+        jobject obj = JJ(GetStaticObjectField, self->cls, field_id);
+
+        mp_obj_jobject_t *o = m_new_obj(mp_obj_jobject_t);
+        o->base.type = &jobject_type;
+        o->obj = obj;
+        dest[0] = o;
+    }
+}
+
+STATIC mp_obj_t jclass_call(mp_obj_t self_in, mp_uint_t n_args, mp_uint_t n_kw, const mp_obj_t *args) {
+    if (n_kw != 0) {
+        nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError, "kwargs not supported"));
+    }
+    mp_obj_jclass_t *self = self_in;
+
+    jarray methods = JJ(CallObjectMethod, self->cls, Class_getConstructors_mid);
+
+    return call_method(self->cls, NULL, methods, true, n_args, args);
+}
+
+STATIC const mp_map_elem_t jclass_locals_dict_table[] = {
+//    { MP_OBJ_NEW_QSTR(MP_QSTR_get), (mp_obj_t)&ffivar_get_obj },
+//    { MP_OBJ_NEW_QSTR(MP_QSTR_set), (mp_obj_t)&ffivar_set_obj },
+};
+
+STATIC MP_DEFINE_CONST_DICT(jclass_locals_dict, jclass_locals_dict_table);
+
+STATIC const mp_obj_type_t jclass_type = {
+    { &mp_type_type },
+    .name = MP_QSTR_jclass,
+    .print = jclass_print,
+    .attr = jclass_attr,
+    .call = jclass_call,
+    .locals_dict = (mp_obj_t)&jclass_locals_dict,
+};
+
+
+// jobject
+
+STATIC void jobject_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
+    (void)kind;
+    mp_obj_jobject_t *self = self_in;
+    // Variable value printed as cast to int
+    mp_printf(print, "<jobject @%p>", self->obj);
+}
+
+STATIC void jobject_attr(mp_obj_t self_in, qstr attr_in, mp_obj_t *dest) {
+    if (dest[0] == MP_OBJ_NULL) {
+        // load attribute
+        mp_obj_jobject_t *self = self_in;
+
+        mp_obj_jmethod_t *o = m_new_obj(mp_obj_jmethod_t);
+        o->base.type = &jmethod_type;
+        o->name = attr_in;
+        o->meth = NULL;
+        o->obj = self->obj;
+        dest[0] = o;
+    }
+}
+
+STATIC const mp_obj_type_t jobject_type = {
+    { &mp_type_type },
+    .name = MP_QSTR_jobject,
+    .print = jobject_print,
+    .attr = jobject_attr,
+//    .locals_dict = (mp_obj_t)&jobject_locals_dict,
+};
+
+// jmethod
+
+STATIC void jmethod_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
+    (void)kind;
+    mp_obj_jmethod_t *self = self_in;
+    // Variable value printed as cast to int
+    mp_printf(print, "<jmethod '%s'>", qstr_str(self->name));
+}
+
+#define MATCH(s, static) ((!strncmp(s, static, sizeof(static) - 1)) && (s += sizeof(static) - 1))
+
+#define CHECK_TYPE(java_type_name) \
+                if (strncmp(arg_types, java_type_name, sizeof(java_type_name) - 1) != 0) { \
+                    found = false; \
+                    break; \
+                } \
+                arg_types += sizeof(java_type_name) - 1;
+
+STATIC const char *strprev(const char *s, char c) {
+    while (*s != c) {
+        s--;
+    }
+    return s;
+}
+
+STATIC mp_obj_t call_method(jobject obj, const char *name, jarray methods, bool is_constr, mp_uint_t n_args, const mp_obj_t *args) {
+    jvalue jargs[n_args];
+//    printf("methods=%p\n", methods);
+    jsize num_methods = JJ(GetArrayLength, methods);
+    for (int i = 0; i < num_methods; i++) {
+        jobject meth = JJ(GetObjectArrayElement, methods, i);
+        jobject name_o = JJ(CallObjectMethod, meth, Method_toString_mid);
+        const char *decl = JJ(GetStringUTFChars, name_o, NULL);
+        const char *arg_types = strchr(decl, '(') + 1;
+        //const char *arg_types_end = strchr(arg_types, ')');
+//        printf("method[%d]=%p %s\n", i, meth, decl);
+
+        const char *meth_name = NULL;
+        const char *ret_type = NULL;
+        if (!is_constr) {
+            meth_name = strprev(arg_types, '.') + 1;
+            ret_type = strprev(meth_name, ' ') - 1;
+            ret_type = strprev(ret_type, ' ') + 1;
+
+            int name_len = strlen(name);
+            if (strncmp(name, meth_name, name_len/*arg_types - meth_name - 1*/) || meth_name[name_len] != '('/*(*/) {
+                continue;
+            }
+        }
+//        printf("method[%d]=%p %s\n", i, meth, decl);
+//        printf("!!!%s\n", arg_types);
+//        printf("name=%p meth_name=%s\n", name, meth_name);
+
+        bool found = true;
+        for (int i = 0; i < n_args; i++) {
+            mp_obj_t arg = args[i];
+            mp_obj_type_t *type = mp_obj_get_type(arg);
+            if (type == &mp_type_str) {
+//                CHECK_TYPE("java.lang.String");
+                if (MATCH(arg_types, "java.lang.String") || MATCH(arg_types, "java.lang.Object")) {
+                    jargs[i].l = JJ(NewStringUTF, mp_obj_str_get_str(arg));
+                } else {
+                    found = false;
+                }
+            } else if (type == &mp_type_int) {
+                CHECK_TYPE("long");
+                jargs[i].j = mp_obj_get_int(arg);
+            } else {
+                nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError, "arg type not supported"));
+            }
+
+            if (*arg_types == ',') {
+                arg_types++;
+            }
+        }
+
+        if (found) {
+//            printf("found!\n");
+            jmethodID method_id = JJ(FromReflectedMethod, meth);
+            jobject res;
+            if (is_constr) {
+                res = JJ(NewObjectA, obj, method_id, jargs);
+                mp_obj_jobject_t *o;
+ret_object:
+                o = m_new_obj(mp_obj_jobject_t);
+                o->base.type = &jobject_type;
+                o->obj = res;
+                return o;
+            } else {
+                res = JJ(CallObjectMethodA, obj, method_id, jargs);
+                mp_obj_t ret = MP_OBJ_NULL;
+                if (strncmp(ret_type, "void", 4) == 0) {
+                    ret = mp_const_none;
+                } else if (strncmp(ret_type, "int", sizeof("int") - 1) == 0) {
+                    ret = mp_obj_new_int((mp_int_t)res);
+                } else if (strncmp(ret_type, "java.lang.String", sizeof("java.lang.String") - 1) == 0) {
+ret_string:;
+                    const char *s = JJ(GetStringUTFChars, res, NULL);
+                    ret = mp_obj_new_str(s, strlen(s), false);
+                    JJ(ReleaseStringUTFChars, res, s);
+                } else if (strncmp(ret_type, "java.lang.Object", sizeof("java.lang.Object") - 1) == 0) {
+                    if (JJ(IsInstanceOf, res, String_class)) {
+                        goto ret_string;
+                    } else {
+                        goto ret_object;
+                    }
+                }
+                JJ(ReleaseStringUTFChars, name_o, decl);
+                if (ret != MP_OBJ_NULL) {
+                    return ret;
+                }
+                nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError, "cannot handle return type"));
+            }
+        }
+
+        JJ(ReleaseStringUTFChars, name_o, decl);
+    }
+
+    nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError, "method not found"));
+}
+
+
+STATIC mp_obj_t jmethod_call(mp_obj_t self_in, mp_uint_t n_args, mp_uint_t n_kw, const mp_obj_t *args) {
+    if (n_kw != 0) {
+        nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError, "kwargs not supported"));
+    }
+    mp_obj_jmethod_t *self = self_in;
+
+    const char *name = qstr_str(self->name);
+//    jstring meth_name = JJ(NewStringUTF, name);
+
+    jclass obj_class = JJ(GetObjectClass, self->obj);
+    jarray methods = JJ(CallObjectMethod, obj_class, Class_getMethods_mid);
+
+    return call_method(self->obj, name, methods, false, n_args, args);
+}
+
+STATIC const mp_obj_type_t jmethod_type = {
+    { &mp_type_type },
+    .name = MP_QSTR_jmethod,
+    .print = jmethod_print,
+    .call = jmethod_call,
+//    .attr = jobject_attr,
+//    .locals_dict = (mp_obj_t)&jobject_locals_dict,
+};
+
+#ifdef __ANDROID__
+#define LIBJVM_SO "libdvm.so"
+#else
+#define LIBJVM_SO "libjvm.so"
+#endif
+
+STATIC void create_jvm() {
+    JavaVMInitArgs args;
+    JavaVMOption options;
+    options.optionString = "-Djava.class.path=.";
+    args.version = JNI_VERSION_1_6;
+    args.nOptions = 1;
+    args.options = &options;
+    args.ignoreUnrecognized = 0;
+
+    if (env) {
+        return;
+    }
+
+    void *libjvm = dlopen(LIBJVM_SO, RTLD_NOW | RTLD_GLOBAL);
+    if (!libjvm) {
+        nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_OSError, "unable to load libjvm.so, use LD_LIBRARY_PATH"));
+    }
+    int (*_JNI_CreateJavaVM)(void*, void**, void*) = dlsym(libjvm, "JNI_CreateJavaVM");
+
+    int st = _JNI_CreateJavaVM(&jvm, (void**)&env, &args);
+    if (st < 0 || !env) {
+        nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_OSError, "unable to create JVM"));
+    }
+
+    jclass class_class = JJ(FindClass, "java/lang/Class");
+    jclass method_class = JJ(FindClass, "java/lang/reflect/Method");
+    String_class = JJ(FindClass, "java/lang/String");
+
+    Class_getField_mid = (*env)->GetMethodID(env, class_class, "getField",
+                                     "(Ljava/lang/String;)Ljava/lang/reflect/Field;");
+    Class_getMethods_mid = (*env)->GetMethodID(env, class_class, "getMethods",
+                                     "()[Ljava/lang/reflect/Method;");
+    Class_getConstructors_mid = (*env)->GetMethodID(env, class_class, "getConstructors",
+                                     "()[Ljava/lang/reflect/Constructor;");
+    Method_getName_mid = (*env)->GetMethodID(env, method_class, "getName",
+                                     "()Ljava/lang/String;");
+    Method_toString_mid = (*env)->GetMethodID(env, method_class, "toString",
+                                     "()Ljava/lang/String;");
+}
+
+STATIC mp_obj_t mod_jni_cls(mp_obj_t cls_name_in) {
+    const char *cls_name = mp_obj_str_get_str(cls_name_in);
+    if (!env) {
+        create_jvm();
+    }
+    jclass cls = JJ(FindClass, cls_name);
+
+    mp_obj_jclass_t *o = m_new_obj(mp_obj_jclass_t);
+    o->base.type = &jclass_type;
+    o->cls = cls;
+    return o;
+}
+MP_DEFINE_CONST_FUN_OBJ_1(mod_jni_cls_obj, mod_jni_cls);
+
+STATIC const mp_map_elem_t mp_module_jni_globals_table[] = {
+    { MP_OBJ_NEW_QSTR(MP_QSTR___name__), MP_OBJ_NEW_QSTR(MP_QSTR_jni) },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_cls), (mp_obj_t)&mod_jni_cls_obj },
+};
+
+STATIC MP_DEFINE_CONST_DICT(mp_module_jni_globals, mp_module_jni_globals_table);
+
+const mp_obj_module_t mp_module_jni = {
+    .base = { &mp_type_module },
+    .name = MP_QSTR_jni,
+    .globals = (mp_obj_dict_t*)&mp_module_jni_globals,
+};

unix/mpconfigport.h

@@ -123,12 +123,18 @@ extern const struct _mp_obj_module_t mp_module_time;
 extern const struct _mp_obj_module_t mp_module_termios;
 extern const struct _mp_obj_module_t mp_module_socket;
 extern const struct _mp_obj_module_t mp_module_ffi;
+extern const struct _mp_obj_module_t mp_module_jni;
 
 #if MICROPY_PY_FFI
 #define MICROPY_PY_FFI_DEF { MP_OBJ_NEW_QSTR(MP_QSTR_ffi), (mp_obj_t)&mp_module_ffi },
 #else
 #define MICROPY_PY_FFI_DEF
 #endif
+#if MICROPY_PY_JNI
+#define MICROPY_PY_JNI_DEF { MP_OBJ_NEW_QSTR(MP_QSTR_jni), (mp_obj_t)&mp_module_jni },
+#else
+#define MICROPY_PY_JNI_DEF
+#endif
 #if MICROPY_PY_TIME
 #define MICROPY_PY_TIME_DEF { MP_OBJ_NEW_QSTR(MP_QSTR_utime), (mp_obj_t)&mp_module_time },
 #else
@@ -147,6 +153,7 @@ extern const struct _mp_obj_module_t mp_module_ffi;
 
 #define MICROPY_PORT_BUILTIN_MODULES \
     MICROPY_PY_FFI_DEF \
+    MICROPY_PY_JNI_DEF \
     MICROPY_PY_TIME_DEF \
     MICROPY_PY_SOCKET_DEF \
     { MP_OBJ_NEW_QSTR(MP_QSTR__os), (mp_obj_t)&mp_module_os }, \

unix/mpconfigport.mk

@@ -20,3 +20,6 @@ MICROPY_PY_SOCKET = 1
 
 # ffi module requires libffi (libffi-dev Debian package)
 MICROPY_PY_FFI = 1
+
+# jni module requires JVM/JNI
+MICROPY_PY_JNI = 0

unix/qstrdefsport.h

@@ -102,3 +102,11 @@ Q(B9600)
 Q(B57600)
 Q(B115200)
 #endif
+
+#if MICROPY_PY_JNI
+Q(jni)
+Q(cls)
+Q(jclass)
+Q(jobject)
+Q(jmethod)
+#endif