app_main.cpp revision 55471dcd0f843e79d8665c63165720eca6a9c980
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]); 137 138 return (end - start); 139} 140 141static void maybeCreateDalvikCache() { 142#if defined(__aarch64__) 143 static const char kInstructionSet[] = "arm64"; 144#elif defined(__x86_64__) 145 static const char kInstructionSet[] = "x86_64"; 146#elif defined(__arm__) 147 static const char kInstructionSet[] = "arm"; 148#elif defined(__i386__) 149 static const char kInstructionSet[] = "x86"; 150#elif defined (__mips__) 151 static const char kInstructionSet[] = "mips"; 152#else 153#error "Unknown instruction set" 154#endif 155 const char* androidRoot = getenv("ANDROID_DATA"); 156 LOG_ALWAYS_FATAL_IF(androidRoot == NULL, "ANDROID_DATA environment variable unset"); 157 158 char dalvikCacheDir[PATH_MAX]; 159 const int numChars = snprintf(dalvikCacheDir, PATH_MAX, 160 "%s/dalvik-cache/%s", androidRoot, kInstructionSet); 161 LOG_ALWAYS_FATAL_IF((numChars >= PATH_MAX || numChars < 0), 162 "Error constructing dalvik cache : %s", strerror(errno)); 163 164 int result = mkdir(dalvikCacheDir, 0711); 165 LOG_ALWAYS_FATAL_IF((result < 0 && errno != EEXIST), 166 "Error creating cache dir %s : %s", dalvikCacheDir, strerror(errno)); 167 168 // We always perform these steps because the directory might 169 // already exist, with wider permissions and a different owner 170 // than we'd like. 171 result = chown(dalvikCacheDir, AID_ROOT, AID_ROOT); 172 LOG_ALWAYS_FATAL_IF((result < 0), "Error changing dalvik-cache ownership : %s", strerror(errno)); 173 174 result = chmod(dalvikCacheDir, 0711); 175 LOG_ALWAYS_FATAL_IF((result < 0), 176 "Error changing dalvik-cache permissions : %s", strerror(errno)); 177} 178 179#if defined(__LP64__) 180static const char ABI_LIST_PROPERTY[] = "ro.product.cpu.abilist64"; 181static const char ZYGOTE_NICE_NAME[] = "zygote64"; 182#else 183static const char ABI_LIST_PROPERTY[] = "ro.product.cpu.abilist32"; 184static const char ZYGOTE_NICE_NAME[] = "zygote"; 185#endif 186 187int main(int argc, char* const argv[]) 188{ 189 if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) < 0) { 190 // Older kernels don't understand PR_SET_NO_NEW_PRIVS and return 191 // EINVAL. Don't die on such kernels. 192 if (errno != EINVAL) { 193 LOG_ALWAYS_FATAL("PR_SET_NO_NEW_PRIVS failed: %s", strerror(errno)); 194 return 12; 195 } 196 } 197 198 AppRuntime runtime(argv[0], computeArgBlockSize(argc, argv)); 199 // Process command line arguments 200 // ignore argv[0] 201 argc--; 202 argv++; 203 204 // Everything up to '--' or first non '-' arg goes to the vm. 205 // 206 // The first argument after the VM args is the "parent dir", which 207 // is currently unused. 208 // 209 // After the parent dir, we expect one or more the following internal 210 // arguments : 211 // 212 // --zygote : Start in zygote mode 213 // --start-system-server : Start the system server. 214 // --application : Start in application (stand alone, non zygote) mode. 215 // --nice-name : The nice name for this process. 216 // 217 // For non zygote starts, these arguments will be followed by 218 // the main class name. All remaining arguments are passed to 219 // the main method of this class. 220 // 221 // For zygote starts, all remaining arguments are passed to the zygote. 222 // main function. 223 224 225 int i = runtime.addVmArguments(argc, argv); 226 227 // Parse runtime arguments. Stop at first unrecognized option. 228 bool zygote = false; 229 bool startSystemServer = false; 230 bool application = false; 231 const char* niceName = NULL; 232 String8 className; 233 234 ++i; // Skip unused "parent dir" argument. 235 while (i < argc) { 236 const char* arg = argv[i++]; 237 if (strcmp(arg, "--zygote") == 0) { 238 zygote = true; 239 niceName = ZYGOTE_NICE_NAME; 240 } else if (strcmp(arg, "--start-system-server") == 0) { 241 startSystemServer = true; 242 } else if (strcmp(arg, "--application") == 0) { 243 application = true; 244 } else if (strncmp(arg, "--nice-name=", 12) == 0) { 245 niceName = arg + 12; 246 } else if (strncmp(arg, "--", 2) != 0) { 247 className.setTo(arg); 248 break; 249 } else { 250 --i; 251 break; 252 } 253 } 254 255 Vector<String8> args; 256 if (!className.isEmpty()) { 257 // We're not in zygote mode, the only argument we need to pass 258 // to RuntimeInit is the application argument. 259 // 260 // The Remainder of args get passed to startup class main(). Make 261 // copies of them before we overwrite them with the process name. 262 args.add(application ? String8("application") : String8("tool")); 263 runtime.setClassNameAndArgs(className, argc - i, argv + i); 264 } else { 265 // We're in zygote mode. 266 maybeCreateDalvikCache(); 267 268 if (startSystemServer) { 269 args.add(String8("start-system-server")); 270 } 271 272 char prop[PROP_VALUE_MAX]; 273 if (property_get(ABI_LIST_PROPERTY, prop, NULL) == 0) { 274 LOG_ALWAYS_FATAL("app_process: Unable to determine ABI list from property %s.", 275 ABI_LIST_PROPERTY); 276 return 11; 277 } 278 279 String8 abiFlag("--abi-list="); 280 abiFlag.append(prop); 281 args.add(abiFlag); 282 283 // In zygote mode, pass all remaining arguments to the zygote 284 // main() method. 285 for (; i < argc; ++i) { 286 args.add(String8(argv[i])); 287 } 288 } 289 290 if (niceName && *niceName) { 291 runtime.setArgv0(niceName); 292 set_process_name(niceName); 293 } 294 295 if (zygote) { 296 runtime.start("com.android.internal.os.ZygoteInit", args); 297 } else if (className) { 298 runtime.start("com.android.internal.os.RuntimeInit", args); 299 } else { 300 fprintf(stderr, "Error: no class name or --zygote supplied.\n"); 301 app_usage(); 302 LOG_ALWAYS_FATAL("app_process: no class name or --zygote supplied."); 303 return 10; 304 } 305} 306