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#include <sys/prctl.h>
24
25namespace android {
26
27void app_usage()
28{
29    fprintf(stderr,
30        "Usage: app_process [java-options] cmd-dir start-class-name [options]\n");
31}
32
33class AppRuntime : public AndroidRuntime
34{
35public:
36    AppRuntime(char* argBlockStart, const size_t argBlockLength)
37        : AndroidRuntime(argBlockStart, argBlockLength)
38        , mClass(NULL)
39    {
40    }
41
42    void setClassNameAndArgs(const String8& className, int argc, char * const *argv) {
43        mClassName = className;
44        for (int i = 0; i < argc; ++i) {
45             mArgs.add(String8(argv[i]));
46        }
47    }
48
49    virtual void onVmCreated(JNIEnv* env)
50    {
51        if (mClassName.isEmpty()) {
52            return; // Zygote. Nothing to do here.
53        }
54
55        /*
56         * This is a little awkward because the JNI FindClass call uses the
57         * class loader associated with the native method we're executing in.
58         * If called in onStarted (from RuntimeInit.finishInit because we're
59         * launching "am", for example), FindClass would see that we're calling
60         * from a boot class' native method, and so wouldn't look for the class
61         * we're trying to look up in CLASSPATH. Unfortunately it needs to,
62         * because the "am" classes are not boot classes.
63         *
64         * The easiest fix is to call FindClass here, early on before we start
65         * executing boot class Java code and thereby deny ourselves access to
66         * non-boot classes.
67         */
68        char* slashClassName = toSlashClassName(mClassName.string());
69        mClass = env->FindClass(slashClassName);
70        if (mClass == NULL) {
71            ALOGE("ERROR: could not find class '%s'\n", mClassName.string());
72        }
73        free(slashClassName);
74
75        mClass = reinterpret_cast<jclass>(env->NewGlobalRef(mClass));
76    }
77
78    virtual void onStarted()
79    {
80        sp<ProcessState> proc = ProcessState::self();
81        ALOGV("App process: starting thread pool.\n");
82        proc->startThreadPool();
83
84        AndroidRuntime* ar = AndroidRuntime::getRuntime();
85        ar->callMain(mClassName, mClass, mArgs);
86
87        IPCThreadState::self()->stopProcess();
88    }
89
90    virtual void onZygoteInit()
91    {
92        // Re-enable tracing now that we're no longer in Zygote.
93        atrace_set_tracing_enabled(true);
94
95        sp<ProcessState> proc = ProcessState::self();
96        ALOGV("App process: starting thread pool.\n");
97        proc->startThreadPool();
98    }
99
100    virtual void onExit(int code)
101    {
102        if (mClassName.isEmpty()) {
103            // if zygote
104            IPCThreadState::self()->stopProcess();
105        }
106
107        AndroidRuntime::onExit(code);
108    }
109
110
111    String8 mClassName;
112    Vector<String8> mArgs;
113    jclass mClass;
114};
115
116}
117
118using namespace android;
119
120static size_t computeArgBlockSize(int argc, char* const argv[]) {
121    // TODO: This assumes that all arguments are allocated in
122    // contiguous memory. There isn't any documented guarantee
123    // that this is the case, but this is how the kernel does it
124    // (see fs/exec.c).
125    //
126    // Also note that this is a constant for "normal" android apps.
127    // Since they're forked from zygote, the size of their command line
128    // is the size of the zygote command line.
129    //
130    // We change the process name of the process by over-writing
131    // the start of the argument block (argv[0]) with the new name of
132    // the process, so we'd mysteriously start getting truncated process
133    // names if the zygote command line decreases in size.
134    uintptr_t start = reinterpret_cast<uintptr_t>(argv[0]);
135    uintptr_t end = reinterpret_cast<uintptr_t>(argv[argc - 1]);
136    end += strlen(argv[argc - 1]) + 1;
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(__i386__)
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, 0711);
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_ROOT, AID_ROOT);
171    LOG_ALWAYS_FATAL_IF((result < 0), "Error changing dalvik-cache ownership : %s", strerror(errno));
172
173    result = chmod(dalvikCacheDir, 0711);
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    if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) < 0) {
189        // Older kernels don't understand PR_SET_NO_NEW_PRIVS and return
190        // EINVAL. Don't die on such kernels.
191        if (errno != EINVAL) {
192            LOG_ALWAYS_FATAL("PR_SET_NO_NEW_PRIVS failed: %s", strerror(errno));
193            return 12;
194        }
195    }
196
197    AppRuntime runtime(argv[0], computeArgBlockSize(argc, argv));
198    // Process command line arguments
199    // ignore argv[0]
200    argc--;
201    argv++;
202
203    // Everything up to '--' or first non '-' arg goes to the vm.
204    //
205    // The first argument after the VM args is the "parent dir", which
206    // is currently unused.
207    //
208    // After the parent dir, we expect one or more the following internal
209    // arguments :
210    //
211    // --zygote : Start in zygote mode
212    // --start-system-server : Start the system server.
213    // --application : Start in application (stand alone, non zygote) mode.
214    // --nice-name : The nice name for this process.
215    //
216    // For non zygote starts, these arguments will be followed by
217    // the main class name. All remaining arguments are passed to
218    // the main method of this class.
219    //
220    // For zygote starts, all remaining arguments are passed to the zygote.
221    // main function.
222    //
223    // Note that we must copy argument string values since we will rewrite the
224    // entire argument block when we apply the nice name to argv0.
225
226    int i;
227    for (i = 0; i < argc; i++) {
228        if (argv[i][0] != '-') {
229            break;
230        }
231        if (argv[i][1] == '-' && argv[i][2] == 0) {
232            ++i; // Skip --.
233            break;
234        }
235        runtime.addOption(strdup(argv[i]));
236    }
237
238    // Parse runtime arguments.  Stop at first unrecognized option.
239    bool zygote = false;
240    bool startSystemServer = false;
241    bool application = false;
242    String8 niceName;
243    String8 className;
244
245    ++i;  // Skip unused "parent dir" argument.
246    while (i < argc) {
247        const char* arg = argv[i++];
248        if (strcmp(arg, "--zygote") == 0) {
249            zygote = true;
250            niceName = ZYGOTE_NICE_NAME;
251        } else if (strcmp(arg, "--start-system-server") == 0) {
252            startSystemServer = true;
253        } else if (strcmp(arg, "--application") == 0) {
254            application = true;
255        } else if (strncmp(arg, "--nice-name=", 12) == 0) {
256            niceName.setTo(arg + 12);
257        } else if (strncmp(arg, "--", 2) != 0) {
258            className.setTo(arg);
259            break;
260        } else {
261            --i;
262            break;
263        }
264    }
265
266    Vector<String8> args;
267    if (!className.isEmpty()) {
268        // We're not in zygote mode, the only argument we need to pass
269        // to RuntimeInit is the application argument.
270        //
271        // The Remainder of args get passed to startup class main(). Make
272        // copies of them before we overwrite them with the process name.
273        args.add(application ? String8("application") : String8("tool"));
274        runtime.setClassNameAndArgs(className, argc - i, argv + i);
275    } else {
276        // We're in zygote mode.
277        maybeCreateDalvikCache();
278
279        if (startSystemServer) {
280            args.add(String8("start-system-server"));
281        }
282
283        char prop[PROP_VALUE_MAX];
284        if (property_get(ABI_LIST_PROPERTY, prop, NULL) == 0) {
285            LOG_ALWAYS_FATAL("app_process: Unable to determine ABI list from property %s.",
286                ABI_LIST_PROPERTY);
287            return 11;
288        }
289
290        String8 abiFlag("--abi-list=");
291        abiFlag.append(prop);
292        args.add(abiFlag);
293
294        // In zygote mode, pass all remaining arguments to the zygote
295        // main() method.
296        for (; i < argc; ++i) {
297            args.add(String8(argv[i]));
298        }
299    }
300
301    if (!niceName.isEmpty()) {
302        runtime.setArgv0(niceName.string());
303        set_process_name(niceName.string());
304    }
305
306    if (zygote) {
307        runtime.start("com.android.internal.os.ZygoteInit", args);
308    } else if (className) {
309        runtime.start("com.android.internal.os.RuntimeInit", args);
310    } else {
311        fprintf(stderr, "Error: no class name or --zygote supplied.\n");
312        app_usage();
313        LOG_ALWAYS_FATAL("app_process: no class name or --zygote supplied.");
314        return 10;
315    }
316}
317