/* * native public static int nativeForkSystemServer(int uid, int gid, * int[] gids, int debugFlags, int[][] rlimits, * long permittedCapabilities, long effectiveCapabilities); */ staticvoidDalvik_dalvik_system_Zygote_forkSystemServer( const u4* args, JValue* pResult) { pid_t pid; // 根据参数，fork一个子进程 pid = forkAndSpecializeCommon(args, true); /* The zygote process checks whether the child process has died or not. */ if (pid > 0) { int status; ALOGI("System server process %d has been created", pid); // 保存system_server的进程id gDvm.systemServerPid = pid; /* There is a slight window that the system server process has crashed * but it went unnoticed because we haven't published its pid yet. So * we recheck here just to make sure that all is well. */ if (waitpid(pid, &status, WNOHANG) == pid) { // 如果system_server退出了，Zygote直接kill自己 ALOGE("System server process %d has died. Restarting Zygote!", pid); kill(getpid(), SIGKILL); } } RETURN_INT(pid); }
for (int i = 0; prctl(PR_CAPBSET_READ, i, 0, 0, 0) >= 0; i++) { err = prctl(PR_CAPBSET_DROP, i, 0, 0, 0); if (err < 0) { if (errno == EINVAL) { ALOGW("PR_CAPBSET_DROP %d failed: %s. " "Please make sure your kernel is compiled with " "file capabilities support enabled.", i, strerror(errno)); } else { ALOGE("PR_CAPBSET_DROP %d failed: %s.", i, strerror(errno)); dvmAbort(); } } }
#endif/* HAVE_ANDROID_OS */
if (mountMode != MOUNT_EXTERNAL_NONE) { err = mountEmulatedStorage(uid, mountMode); if (err < 0) { ALOGE("cannot mountExternalStorage(): %s", strerror(errno));
if (errno == ENOTCONN || errno == EROFS) { // When device is actively encrypting, we get ENOTCONN here // since FUSE was mounted before the framework restarted. // When encrypted device is booting, we get EROFS since // FUSE hasn't been created yet by init. // In either case, continue without external storage. } else { dvmAbort(); } } } // 将list数组中所标明的组加入到目前进程的组设置中 err = setgroupsIntarray(gids); if (err < 0) { ALOGE("cannot setgroups(): %s", strerror(errno)); dvmAbort(); } // 设置资源限制 err = setrlimitsFromArray(rlimits); if (err < 0) { ALOGE("cannot setrlimit(): %s", strerror(errno)); dvmAbort(); } // 设置指定进程组id err = setresgid(gid, gid, gid); if (err < 0) { ALOGE("cannot setresgid(%d): %s", gid, strerror(errno)); dvmAbort(); } // 设置用户id err = setresuid(uid, uid, uid); if (err < 0) { ALOGE("cannot setresuid(%d): %s", uid, strerror(errno)); dvmAbort(); }
if (needsNoRandomizeWorkaround()) { int current = personality(0xffffFFFF); int success = personality((ADDR_NO_RANDOMIZE | current)); if (success == -1) { ALOGW("Personality switch failed. current=%d error=%d\n", current, errno); } } // 设置Linux功能标识 err = setCapabilities(permittedCapabilities, effectiveCapabilities); if (err != 0) { ALOGE("cannot set capabilities (%llx,%llx): %s", permittedCapabilities, effectiveCapabilities, strerror(err)); dvmAbort(); }
err = setSELinuxContext(uid, isSystemServer, seInfo, niceName); if (err < 0) { ALOGE("cannot set SELinux context: %s\n", strerror(errno)); dvmAbort(); } // These free(3) calls are safe because we know we're only ever forking // a single-threaded process, so we know no other thread held the heap // lock when we forked. free(seInfo); free(niceName);
/* * Our system thread ID has changed. Get the new one. */ Thread* thread = dvmThreadSelf(); thread->systemTid = dvmGetSysThreadId();
/* configure additional debug options */ enableDebugFeatures(debugFlags); // 将信号量机制设为默认 unsetSignalHandler(); // 子进程不支持Zygote gDvm.zygote = false; // 检查虚拟机初始化是否成功 if (!dvmInitAfterZygote()) { ALOGE("error in post-zygote initialization"); dvmAbort(); } } elseif (pid > 0) { /* the parent process */ free(seInfo); free(niceName); }
