app_main.cpp revision d1e127e141a8080477f3b3becb792f138ca9ab65 
1/*
2 * Main entry of app process.
3 *
4 * Starts the interpreted runtime, then starts up the application.
5 *
6 */
7
8#define LOG_TAG "appproc"
9
10#include <binder/IPCThreadState.h>
11#include <binder/ProcessState.h>
12#include <utils/Log.h>
13#include <cutils/memory.h>
14#include <cutils/process_name.h>
15#include <cutils/properties.h>
16#include <cutils/trace.h>
17#include <android_runtime/AndroidRuntime.h>
18#include <private/android_filesystem_config.h>  // for AID_SYSTEM
19
20#include <stdlib.h>
21#include <stdio.h>
22#include <unistd.h>
23
24namespace android {
25
26void app_usage()
27{
28    fprintf(stderr,
29        "Usage: app_process [java-options] cmd-dir start-class-name [options]\n");
30}
31
32class AppRuntime : public AndroidRuntime
33{
34public:
35    AppRuntime(char* argBlockStart, const size_t argBlockLength)
36        : AndroidRuntime(argBlockStart, argBlockLength)
37        , mClass(NULL)
38    {
39    }
40
41    void setClassNameAndArgs(const String8& className, int argc, char * const *argv) {
42        mClassName = className;
43        for (int i = 0; i < argc; ++i) {
44             mArgs.add(String8(argv[i]));
45        }
46    }
47
48    virtual void onVmCreated(JNIEnv* env)
49    {
50        if (mClassName.isEmpty()) {
51            return; // Zygote. Nothing to do here.
52        }
53
54        /*
55         * This is a little awkward because the JNI FindClass call uses the
56         * class loader associated with the native method we're executing in.
57         * If called in onStarted (from RuntimeInit.finishInit because we're
58         * launching "am", for example), FindClass would see that we're calling
59         * from a boot class' native method, and so wouldn't look for the class
60         * we're trying to look up in CLASSPATH. Unfortunately it needs to,
61         * because the "am" classes are not boot classes.
62         *
63         * The easiest fix is to call FindClass here, early on before we start
64         * executing boot class Java code and thereby deny ourselves access to
65         * non-boot classes.
66         */
67        char* slashClassName = toSlashClassName(mClassName.string());
68        mClass = env->FindClass(slashClassName);
69        if (mClass == NULL) {
70            ALOGE("ERROR: could not find class '%s'\n", mClassName.string());
71        }
72        free(slashClassName);
73
74        mClass = reinterpret_cast<jclass>(env->NewGlobalRef(mClass));
75    }
76
77    virtual void onStarted()
78    {
79        sp<ProcessState> proc = ProcessState::self();
80        ALOGV("App process: starting thread pool.\n");
81        proc->startThreadPool();
82
83        AndroidRuntime* ar = AndroidRuntime::getRuntime();
84        ar->callMain(mClassName, mClass, mArgs);
85
86        IPCThreadState::self()->stopProcess();
87    }
88
89    virtual void onZygoteInit()
90    {
91        // Re-enable tracing now that we're no longer in Zygote.
92        atrace_set_tracing_enabled(true);
93
94        sp<ProcessState> proc = ProcessState::self();
95        ALOGV("App process: starting thread pool.\n");
96        proc->startThreadPool();
97    }
98
99    virtual void onExit(int code)
100    {
101        if (mClassName.isEmpty()) {
102            // if zygote
103            IPCThreadState::self()->stopProcess();
104        }
105
106        AndroidRuntime::onExit(code);
107    }
108
109
110    String8 mClassName;
111    Vector<String8> mArgs;
112    jclass mClass;
113};
114
115}
116
117using namespace android;
118
119static size_t computeArgBlockSize(int argc, char* const argv[]) {
120    // TODO: This assumes that all arguments are allocated in
121    // contiguous memory. There isn't any documented guarantee
122    // that this is the case, but this is how the kernel does it
123    // (see fs/exec.c).
124    //
125    // Also note that this is a constant for "normal" android apps.
126    // Since they're forked from zygote, the size of their command line
127    // is the size of the zygote command line.
128    //
129    // We change the process name of the process by over-writing
130    // the start of the argument block (argv[0]) with the new name of
131    // the process, so we'd mysteriously start getting truncated process
132    // names if the zygote command line decreases in size.
133    uintptr_t start = reinterpret_cast<uintptr_t>(argv[0]);
134    uintptr_t end = reinterpret_cast<uintptr_t>(argv[argc - 1]);
135    end += strlen(argv[argc - 1]);
136
137    return (end - start);
138}
139
140static void maybeCreateDalvikCache() {
141#if defined(__aarch64__)
142    static const char kInstructionSet[] = "arm64";
143#elif defined(__x86_64__)
144    static const char kInstructionSet[] = "x86_64";
145#elif defined(__arm__)
146    static const char kInstructionSet[] = "arm";
147#elif defined(__x86__)
148    static const char kInstructionSet[] = "x86";
149#elif defined (__mips__)
150    static const char kInstructionSet[] = "mips";
151#else
152#error "Unknown instruction set"
153#endif
154    const char* androidRoot = getenv("ANDROID_DATA");
155    LOG_ALWAYS_FATAL_IF(androidRoot == NULL, "ANDROID_DATA environment variable unset");
156
157    char dalvikCacheDir[PATH_MAX];
158    const int numChars = snprintf(dalvikCacheDir, PATH_MAX,
159            "%s/dalvik-cache/%s", androidRoot, kInstructionSet);
160    LOG_ALWAYS_FATAL_IF((numChars >= PATH_MAX || numChars < 0),
161            "Error constructing dalvik cache : %s", strerror(errno));
162
163    int result = mkdir(dalvikCacheDir, 0771);
164    LOG_ALWAYS_FATAL_IF((result < 0 && errno != EEXIST),
165            "Error creating cache dir %s : %s", dalvikCacheDir, strerror(errno));
166
167    // We always perform these steps because the directory might
168    // already exist, with wider permissions and a different owner
169    // than we'd like.
170    result = chown(dalvikCacheDir, AID_SYSTEM, AID_SYSTEM);
171    LOG_ALWAYS_FATAL_IF((result < 0), "Error changing dalvik-cache ownership : %s", strerror(errno));
172
173    result = chmod(dalvikCacheDir, 0771);
174    LOG_ALWAYS_FATAL_IF((result < 0),
175            "Error changing dalvik-cache permissions : %s", strerror(errno));
176}
177
178#if defined(__LP64__)
179static const char ABI_LIST_PROPERTY[] = "ro.product.cpu.abilist64";
180static const char ZYGOTE_NICE_NAME[] = "zygote64";
181#else
182static const char ABI_LIST_PROPERTY[] = "ro.product.cpu.abilist32";
183static const char ZYGOTE_NICE_NAME[] = "zygote";
184#endif
185
186int main(int argc, char* const argv[])
187{
188    AppRuntime runtime(argv[0], computeArgBlockSize(argc, argv));
189    // Process command line arguments
190    // ignore argv[0]
191    argc--;
192    argv++;
193
194    // Everything up to '--' or first non '-' arg goes to the vm.
195    //
196    // The first argument after the VM args is the "parent dir", which
197    // is currently unused.
198    //
199    // After the parent dir, we expect one or more the following internal
200    // arguments :
201    //
202    // --zygote : Start in zygote mode
203    // --start-system-server : Start the system server.
204    // --application : Start in application (stand alone, non zygote) mode.
205    // --nice-name : The nice name for this process.
206    //
207    // For non zygote starts, these arguments will be followed by
208    // the main class name. All remaining arguments are passed to
209    // the main method of this class.
210    //
211    // For zygote starts, all remaining arguments are passed to the zygote.
212    // main function.
213
214
215    int i = runtime.addVmArguments(argc, argv);
216
217    // Parse runtime arguments.  Stop at first unrecognized option.
218    bool zygote = false;
219    bool startSystemServer = false;
220    bool application = false;
221    const char* niceName = NULL;
222    String8 className;
223
224    ++i;  // Skip unused "parent dir" argument.
225    while (i < argc) {
226        const char* arg = argv[i++];
227        if (strcmp(arg, "--zygote") == 0) {
228            zygote = true;
229            niceName = ZYGOTE_NICE_NAME;
230        } else if (strcmp(arg, "--start-system-server") == 0) {
231            startSystemServer = true;
232        } else if (strcmp(arg, "--application") == 0) {
233            application = true;
234        } else if (strncmp(arg, "--nice-name=", 12) == 0) {
235            niceName = arg + 12;
236        } else if (strncmp(arg, "--", 2) != 0) {
237            className.setTo(arg);
238            break;
239        } else {
240            --i;
241            break;
242        }
243    }
244
245    Vector<String8> args;
246    if (!className.isEmpty()) {
247        // We're not in zygote mode, the only argument we need to pass
248        // to RuntimeInit is the application argument.
249        //
250        // The Remainder of args get passed to startup class main(). Make
251        // copies of them before we overwrite them with the process name.
252        args.add(application ? String8("application") : String8("tool"));
253        runtime.setClassNameAndArgs(className, argc - i, argv + i);
254    } else {
255        // We're in zygote mode.
256        maybeCreateDalvikCache();
257
258        if (startSystemServer) {
259            args.add(String8("start-system-server"));
260        }
261
262        char prop[PROP_VALUE_MAX];
263        if (property_get(ABI_LIST_PROPERTY, prop, NULL) == 0) {
264            LOG_ALWAYS_FATAL("app_process: Unable to determine ABI list from property %s.",
265                ABI_LIST_PROPERTY);
266            return 11;
267        }
268
269        String8 abiFlag("--abi-list=");
270        abiFlag.append(prop);
271        args.add(abiFlag);
272
273        // In zygote mode, pass all remaining arguments to the zygote
274        // main() method.
275        for (; i < argc; ++i) {
276            args.add(String8(argv[i]));
277        }
278    }
279
280    if (niceName && *niceName) {
281        runtime.setArgv0(niceName);
282        set_process_name(niceName);
283    }
284
285    if (zygote) {
286        runtime.start("com.android.internal.os.ZygoteInit", args);
287    } else if (className) {
288        runtime.start("com.android.internal.os.RuntimeInit", args);
289    } else {
290        fprintf(stderr, "Error: no class name or --zygote supplied.\n");
291        app_usage();
292        LOG_ALWAYS_FATAL("app_process: no class name or --zygote supplied.");
293        return 10;
294    }
295}
296