1 /*
2 * copyright (C) 2011 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include <signal.h>
18 #include <stdio.h>
19 #include <stdlib.h>
20 #include <string.h>
21 #include <algorithm>
22 #include <memory>
23
24 #include "base/fast_exit.h"
25 #include "jni.h"
26 #include "nativehelper/JniInvocation.h"
27 #include "nativehelper/ScopedLocalRef.h"
28 #include "nativehelper/toStringArray.h"
29
30 namespace art {
31
32 // Determine whether or not the specified method is public.
IsMethodPublic(JNIEnv * env,jclass c,jmethodID method_id)33 static bool IsMethodPublic(JNIEnv* env, jclass c, jmethodID method_id) {
34 ScopedLocalRef<jobject> reflected(env, env->ToReflectedMethod(c, method_id, JNI_FALSE));
35 if (reflected.get() == nullptr) {
36 fprintf(stderr, "Failed to get reflected method\n");
37 return false;
38 }
39 // We now have a Method instance. We need to call its
40 // getModifiers() method.
41 jclass method_class = env->FindClass("java/lang/reflect/Method");
42 if (method_class == nullptr) {
43 fprintf(stderr, "Failed to find class java.lang.reflect.Method\n");
44 return false;
45 }
46 jmethodID mid = env->GetMethodID(method_class, "getModifiers", "()I");
47 if (mid == nullptr) {
48 fprintf(stderr, "Failed to find java.lang.reflect.Method.getModifiers\n");
49 return false;
50 }
51 int modifiers = env->CallIntMethod(reflected.get(), mid);
52 static const int PUBLIC = 0x0001; // java.lang.reflect.Modifiers.PUBLIC
53 if ((modifiers & PUBLIC) == 0) {
54 fprintf(stderr, "Modifiers mismatch\n");
55 return false;
56 }
57 return true;
58 }
59
InvokeMain(JNIEnv * env,char ** argv)60 static int InvokeMain(JNIEnv* env, char** argv) {
61 // We want to call main() with a String array with our arguments in
62 // it. Create an array and populate it. Note argv[0] is not
63 // included.
64 ScopedLocalRef<jobjectArray> args(env, toStringArray(env, argv + 1));
65 if (args.get() == nullptr) {
66 env->ExceptionDescribe();
67 return EXIT_FAILURE;
68 }
69
70 // Find [class].main(String[]).
71
72 // Convert "com.android.Blah" to "com/android/Blah".
73 std::string class_name(argv[0]);
74 std::replace(class_name.begin(), class_name.end(), '.', '/');
75
76 ScopedLocalRef<jclass> klass(env, env->FindClass(class_name.c_str()));
77 if (klass.get() == nullptr) {
78 fprintf(stderr, "Unable to locate class '%s'\n", class_name.c_str());
79 env->ExceptionDescribe();
80 return EXIT_FAILURE;
81 }
82
83 jmethodID method = env->GetStaticMethodID(klass.get(), "main", "([Ljava/lang/String;)V");
84 if (method == nullptr) {
85 fprintf(stderr, "Unable to find static main(String[]) in '%s'\n", class_name.c_str());
86 env->ExceptionDescribe();
87 return EXIT_FAILURE;
88 }
89
90 // Make sure the method is public. JNI doesn't prevent us from
91 // calling a private method, so we have to check it explicitly.
92 if (!IsMethodPublic(env, klass.get(), method)) {
93 fprintf(stderr, "Sorry, main() is not public in '%s'\n", class_name.c_str());
94 env->ExceptionDescribe();
95 return EXIT_FAILURE;
96 }
97
98 // Invoke main().
99 env->CallStaticVoidMethod(klass.get(), method, args.get());
100
101 // Check whether there was an uncaught exception. We don't log any uncaught exception here;
102 // detaching this thread will do that for us, but it will clear the exception (and invalidate
103 // our JNIEnv), so we need to check here.
104 return env->ExceptionCheck() ? EXIT_FAILURE : EXIT_SUCCESS;
105 }
106
107 // Parse arguments. Most of it just gets passed through to the runtime.
108 // The JNI spec defines a handful of standard arguments.
dalvikvm(int argc,char ** argv)109 static int dalvikvm(int argc, char** argv) {
110 setvbuf(stdout, nullptr, _IONBF, 0);
111
112 // Skip over argv[0].
113 argv++;
114 argc--;
115
116 // If we're adding any additional stuff, e.g. function hook specifiers,
117 // add them to the count here.
118 //
119 // We're over-allocating, because this includes the options to the runtime
120 // plus the options to the program.
121 int option_count = argc;
122 std::unique_ptr<JavaVMOption[]> options(new JavaVMOption[option_count]());
123
124 // Copy options over. Everything up to the name of the class starts
125 // with a '-' (the function hook stuff is strictly internal).
126 //
127 // [Do we need to catch & handle "-jar" here?]
128 bool need_extra = false;
129 const char* lib = nullptr;
130 const char* what = nullptr;
131 int curr_opt, arg_idx;
132 for (curr_opt = arg_idx = 0; arg_idx < argc; arg_idx++) {
133 if (argv[arg_idx][0] != '-' && !need_extra) {
134 break;
135 }
136 if (strncmp(argv[arg_idx], "-XXlib:", strlen("-XXlib:")) == 0) {
137 lib = argv[arg_idx] + strlen("-XXlib:");
138 continue;
139 }
140
141 options[curr_opt++].optionString = argv[arg_idx];
142
143 // Some options require an additional argument.
144 need_extra = false;
145 if (strcmp(argv[arg_idx], "-classpath") == 0 || strcmp(argv[arg_idx], "-cp") == 0) {
146 need_extra = true;
147 what = argv[arg_idx];
148 }
149 }
150
151 if (need_extra) {
152 fprintf(stderr, "%s must be followed by an additional argument giving a value\n", what);
153 return EXIT_FAILURE;
154 }
155
156 if (curr_opt > option_count) {
157 fprintf(stderr, "curr_opt(%d) > option_count(%d)\n", curr_opt, option_count);
158 abort();
159 return EXIT_FAILURE;
160 }
161
162 // Find the JNI_CreateJavaVM implementation.
163 JniInvocation jni_invocation;
164 if (!jni_invocation.Init(lib)) {
165 fprintf(stderr, "Failed to initialize JNI invocation API from %s\n", lib);
166 return EXIT_FAILURE;
167 }
168
169 JavaVMInitArgs init_args;
170 init_args.version = JNI_VERSION_1_6;
171 init_args.options = options.get();
172 init_args.nOptions = curr_opt;
173 init_args.ignoreUnrecognized = JNI_FALSE;
174
175 // Start the runtime. The current thread becomes the main thread.
176 JavaVM* vm = nullptr;
177 JNIEnv* env = nullptr;
178 if (JNI_CreateJavaVM(&vm, &env, &init_args) != JNI_OK) {
179 fprintf(stderr, "Failed to initialize runtime (check log for details)\n");
180 return EXIT_FAILURE;
181 }
182
183 // Make sure they provided a class name. We do this after
184 // JNI_CreateJavaVM so that things like "-help" have the opportunity
185 // to emit a usage statement.
186 if (arg_idx == argc) {
187 fprintf(stderr, "Class name required\n");
188 return EXIT_FAILURE;
189 }
190
191 int rc = InvokeMain(env, &argv[arg_idx]);
192
193 #if defined(NDEBUG)
194 // The DestroyJavaVM call will detach this thread for us. In debug builds, we don't want to
195 // detach because detaching disables the CheckSafeToLockOrUnlock checking.
196 if (vm->DetachCurrentThread() != JNI_OK) {
197 fprintf(stderr, "Warning: unable to detach main thread\n");
198 rc = EXIT_FAILURE;
199 }
200 #endif
201
202 if (vm->DestroyJavaVM() != 0) {
203 fprintf(stderr, "Warning: runtime did not shut down cleanly\n");
204 rc = EXIT_FAILURE;
205 }
206
207 return rc;
208 }
209
210 } // namespace art
211
212 // TODO(b/141622862): stop leaks
__asan_default_options()213 extern "C" const char *__asan_default_options() {
214 return "detect_leaks=0";
215 }
216
main(int argc,char ** argv)217 int main(int argc, char** argv) {
218 // Do not allow static destructors to be called, since it's conceivable that
219 // daemons may still awaken (literally).
220 art::FastExit(art::dalvikvm(argc, argv));
221 }
222