1/*
2 * Copyright (C) 2008 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#define LOG_TAG "UEventObserver"
18//#define LOG_NDEBUG 0
19
20#include "utils/Log.h"
21
22#include "hardware_legacy/uevent.h"
23#include "jni.h"
24#include "JNIHelp.h"
25#include "core_jni_helpers.h"
26
27#include <utils/Mutex.h>
28#include <utils/Vector.h>
29#include <utils/String8.h>
30#include <ScopedUtfChars.h>
31
32namespace android {
33
34static Mutex gMatchesMutex;
35static Vector<String8> gMatches;
36
37static void nativeSetup(JNIEnv *env, jclass clazz) {
38    if (!uevent_init()) {
39        jniThrowException(env, "java/lang/RuntimeException",
40                "Unable to open socket for UEventObserver");
41    }
42}
43
44static bool isMatch(const char* buffer, size_t length) {
45    AutoMutex _l(gMatchesMutex);
46
47    for (size_t i = 0; i < gMatches.size(); i++) {
48        const String8& match = gMatches.itemAt(i);
49
50        // Consider all zero-delimited fields of the buffer.
51        const char* field = buffer;
52        const char* end = buffer + length + 1;
53        do {
54            if (strstr(field, match.string())) {
55                ALOGV("Matched uevent message with pattern: %s", match.string());
56                return true;
57            }
58            field += strlen(field) + 1;
59        } while (field != end);
60    }
61    return false;
62}
63
64static jstring nativeWaitForNextEvent(JNIEnv *env, jclass clazz) {
65    char buffer[1024];
66
67    for (;;) {
68        int length = uevent_next_event(buffer, sizeof(buffer) - 1);
69        if (length <= 0) {
70            return NULL;
71        }
72        buffer[length] = '\0';
73
74        ALOGV("Received uevent message: %s", buffer);
75
76        if (isMatch(buffer, length)) {
77            // Assume the message is ASCII.
78            jchar message[length];
79            for (int i = 0; i < length; i++) {
80                message[i] = buffer[i];
81            }
82            return env->NewString(message, length);
83        }
84    }
85}
86
87static void nativeAddMatch(JNIEnv* env, jclass clazz, jstring matchStr) {
88    ScopedUtfChars match(env, matchStr);
89
90    AutoMutex _l(gMatchesMutex);
91    gMatches.add(String8(match.c_str()));
92}
93
94static void nativeRemoveMatch(JNIEnv* env, jclass clazz, jstring matchStr) {
95    ScopedUtfChars match(env, matchStr);
96
97    AutoMutex _l(gMatchesMutex);
98    for (size_t i = 0; i < gMatches.size(); i++) {
99        if (gMatches.itemAt(i) == match.c_str()) {
100            gMatches.removeAt(i);
101            break; // only remove first occurrence
102        }
103    }
104}
105
106static const JNINativeMethod gMethods[] = {
107    { "nativeSetup", "()V",
108            (void *)nativeSetup },
109    { "nativeWaitForNextEvent", "()Ljava/lang/String;",
110            (void *)nativeWaitForNextEvent },
111    { "nativeAddMatch", "(Ljava/lang/String;)V",
112            (void *)nativeAddMatch },
113    { "nativeRemoveMatch", "(Ljava/lang/String;)V",
114            (void *)nativeRemoveMatch },
115};
116
117
118int register_android_os_UEventObserver(JNIEnv *env)
119{
120    FindClassOrDie(env, "android/os/UEventObserver");
121
122    return RegisterMethodsOrDie(env, "android/os/UEventObserver", gMethods, NELEM(gMethods));
123}
124
125}   // namespace android
126