static void android_os_Debug_dumpNativeBacktraceToFile(JNIEnv* env, jobject clazz,
    jint pid, jstring fileName)
{
    if (fileName == NULL) {
        jniThrowNullPointerException(env, NULL);
        return;
    }
    const jchar* str = env->GetStringCritical(fileName, 0);
    String8 fileName8;
    if (str) {
        fileName8 = String8((char16_t*)str, env->GetStringLength(fileName));
        env->ReleaseStringCritical(fileName, str);
    }

    int fd = open(fileName8.string(), O_CREAT | O_WRONLY | O_NOFOLLOW, 0666);  /* -rw-rw-rw- */
    if (fd < 0) {
        fprintf(stderr, "Can't open %s: %s\n", fileName8.string(), strerror(errno));
        return;
    }

    if (lseek(fd, 0, SEEK_END) < 0) {
        fprintf(stderr, "lseek: %s\n", strerror(errno));
    } else {
        dump_backtrace_to_file(pid, fd);
    }

    close(fd);
}
static int do_explicit_dump(pid_t tid, bool dump_backtrace) {
  fprintf(stdout, "Sending request to dump task %d.\n", tid);

  if (dump_backtrace) {
    fflush(stdout);
    if (dump_backtrace_to_file(tid, fileno(stdout)) < 0) {
      fputs("Error dumping backtrace.\n", stderr);
      return 1;
    }
  } else {
    char tombstone_path[PATH_MAX];
    if (dump_tombstone(tid, tombstone_path, sizeof(tombstone_path)) < 0) {
      fputs("Error dumping tombstone.\n", stderr);
      return 1;
    }
    fprintf(stderr, "Tombstone written to: %s\n", tombstone_path);
  }
  return 0;
}
ECode CDebug::DumpNativeBacktraceToFile(
    /* [in] */ Int32 pid,
    /* [in] */ const String& file)
{
    if (file.IsNull()) {
        //jniThrowNullPointerException(env, NULL);
        return E_NULL_POINTER_EXCEPTION;
    }

    int fd = open(file.string(), O_CREAT | O_WRONLY | O_NOFOLLOW, 0666);  /* -rw-rw-rw- */
    if (fd < 0) {
        fprintf(stderr, "Can't open %s: %s\n", file.string(), strerror(errno));
        return NOERROR;
    }

    if (lseek(fd, 0, SEEK_END) < 0) {
        fprintf(stderr, "lseek: %s\n", strerror(errno));
    } else {
        dump_backtrace_to_file(pid, fd);
    }

    close(fd);
    return NOERROR;
}
/* dump Dalvik and native stack traces, return the trace file location (NULL if none) */
const char *dump_traces() {
    const char* result = NULL;

    char traces_path[PROPERTY_VALUE_MAX] = "";
    property_get("dalvik.vm.stack-trace-file", traces_path, "");
    if (!traces_path[0]) return NULL;

    /* move the old traces.txt (if any) out of the way temporarily */
    char anr_traces_path[PATH_MAX];
    strlcpy(anr_traces_path, traces_path, sizeof(anr_traces_path));
    strlcat(anr_traces_path, ".anr", sizeof(anr_traces_path));
    if (rename(traces_path, anr_traces_path) && errno != ENOENT) {
        fprintf(stderr, "rename(%s, %s): %s\n", traces_path, anr_traces_path, strerror(errno));
        return NULL;  // Can't rename old traces.txt -- no permission? -- leave it alone instead
    }

    /* make the directory if necessary */
    char anr_traces_dir[PATH_MAX];
    strlcpy(anr_traces_dir, traces_path, sizeof(anr_traces_dir));
    char *slash = strrchr(anr_traces_dir, '/');
    if (slash != NULL) {
        *slash = '\0';
        if (!mkdir(anr_traces_dir, 0775)) {
            chown(anr_traces_dir, AID_SYSTEM, AID_SYSTEM);
            chmod(anr_traces_dir, 0775);
        } else if (errno != EEXIST) {
            fprintf(stderr, "mkdir(%s): %s\n", anr_traces_dir, strerror(errno));
            return NULL;
        }
    }

    /* create a new, empty traces.txt file to receive stack dumps */
    int fd = open(traces_path, O_CREAT | O_WRONLY | O_TRUNC | O_NOFOLLOW, 0666);  /* -rw-rw-rw- */
    if (fd < 0) {
        fprintf(stderr, "%s: %s\n", traces_path, strerror(errno));
        return NULL;
    }
    int chmod_ret = fchmod(fd, 0666);
    if (chmod_ret < 0) {
        fprintf(stderr, "fchmod on %s failed: %s\n", traces_path, strerror(errno));
        close(fd);
        return NULL;
    }

    /* walk /proc and kill -QUIT all Dalvik processes */
    DIR *proc = opendir("/proc");
    if (proc == NULL) {
        fprintf(stderr, "/proc: %s\n", strerror(errno));
        goto error_close_fd;
    }

    /* use inotify to find when processes are done dumping */
    int ifd = inotify_init();
    if (ifd < 0) {
        fprintf(stderr, "inotify_init: %s\n", strerror(errno));
        goto error_close_fd;
    }

    int wfd = inotify_add_watch(ifd, traces_path, IN_CLOSE_WRITE);
    if (wfd < 0) {
        fprintf(stderr, "inotify_add_watch(%s): %s\n", traces_path, strerror(errno));
        goto error_close_ifd;
    }

    struct dirent *d;
    int dalvik_found = 0;
    while ((d = readdir(proc))) {
        int pid = atoi(d->d_name);
        if (pid <= 0) continue;

        char path[PATH_MAX];
        char data[PATH_MAX];
        snprintf(path, sizeof(path), "/proc/%d/exe", pid);
        ssize_t len = readlink(path, data, sizeof(data) - 1);
        if (len <= 0) {
            continue;
        }
        data[len] = '\0';

        if (!strcmp(data, "/system/bin/app_process")) {
            /* skip zygote -- it won't dump its stack anyway */
            snprintf(path, sizeof(path), "/proc/%d/cmdline", pid);
            int fd = open(path, O_RDONLY);
            len = read(fd, data, sizeof(data) - 1);
            close(fd);
            if (len <= 0) {
                continue;
            }
            data[len] = '\0';
            if (!strcmp(data, "zygote")) {
                continue;
            }

            ++dalvik_found;
            if (kill(pid, SIGQUIT)) {
                fprintf(stderr, "kill(%d, SIGQUIT): %s\n", pid, strerror(errno));
                continue;
            }

            /* wait for the writable-close notification from inotify */
            struct pollfd pfd = { ifd, POLLIN, 0 };
            int ret = poll(&pfd, 1, 200);  /* 200 msec timeout */
            if (ret < 0) {
                fprintf(stderr, "poll: %s\n", strerror(errno));
            } else if (ret == 0) {
                fprintf(stderr, "warning: timed out dumping pid %d\n", pid);
            } else {
                struct inotify_event ie;
                read(ifd, &ie, sizeof(ie));
            }
        } else if (should_dump_native_traces(data)) {
            /* dump native process if appropriate */
            if (lseek(fd, 0, SEEK_END) < 0) {
                fprintf(stderr, "lseek: %s\n", strerror(errno));
            } else {
                dump_backtrace_to_file(pid, fd);
            }
        }
    }

    if (dalvik_found == 0) {
        fprintf(stderr, "Warning: no Dalvik processes found to dump stacks\n");
    }

    static char dump_traces_path[PATH_MAX];
    strlcpy(dump_traces_path, traces_path, sizeof(dump_traces_path));
    strlcat(dump_traces_path, ".bugreport", sizeof(dump_traces_path));
    if (rename(traces_path, dump_traces_path)) {
        fprintf(stderr, "rename(%s, %s): %s\n", traces_path, dump_traces_path, strerror(errno));
        goto error_close_ifd;
    }
    result = dump_traces_path;

    /* replace the saved [ANR] traces.txt file */
    rename(anr_traces_path, traces_path);

error_close_ifd:
    close(ifd);
error_close_fd:
    close(fd);
    return result;
}
bool SFWatchDog::threadLoop() {
    XLOGV("[%s]", __func__);

    {
        Mutex::Autolock _l(mScreenLock);
    }

    nsecs_t stopTime = 1;
    if (isSFThreadHang(&stopTime)) {
        char cmds[256];
        static uint32_t rtt_ct = SW_WATCHDOG_RTTCOUNT;
        if (rtt_ct > 0) {
            rtt_ct --;
        } else {
            XLOGD("[SF-WD] swap rtt dump file");

            // swap rtt dump file
            snprintf(cmds, sizeof(cmds), "mv %s.txt %s_1.txt", RTT_DUMP, RTT_DUMP);
            system(cmds);

            rtt_ct = SW_WATCHDOG_RTTCOUNT;
        }

        // append SurfaceFlinger rtt information to rtt file
        char filename[100];
        snprintf(filename, sizeof(filename), "%s.txt", RTT_DUMP);
        int fd = open(filename, O_CREAT | O_WRONLY | O_NOFOLLOW, 0666);  /* -rw-rw-rw- */
        if (fd < 0) {
            ALOGE("Can't open %s: %s\n", filename, strerror(errno));
            return true;
        }

        if (lseek(fd, 0, SEEK_END) < 0) {
            fprintf(stderr, "lseek: %s\n", strerror(errno));
        } else {
            dump_backtrace_to_file(getpid(), fd);
        }

        close(fd);

        XLOGD("[SF-WD] dump rtt file: %s.txt", RTT_DUMP);
        XLOGW("[SF-WD] ============================================");
    } else {
        stopTime = 1;
    }

    getProperty();

    char value[PROPERTY_VALUE_MAX];
    snprintf(value, sizeof(value), "%" PRId64 " ", stopTime);
    if (stopTime < 0 || stopTime >= 2147483247) {
        volatile nsecs_t tmpStopTime = stopTime;
        XLOGD("[SF-WD] tmpStopTime=(%" PRId64 ", %" PRId64 ")", tmpStopTime, stopTime);
        abort();
    }

    uint32_t ret = property_set("service.sf.status", value);
    if (mUpdateCount) {
        if (mShowLog)
            XLOGV("[SF-WD] mUpdateCount: %d", mUpdateCount);
#if 0
        aee_ioctl_wdt_kick(WDT_SETBY_SF);
#endif
        mUpdateCount = 0;
    }
    //else {
    //	XLOGV("[SF-WD] mUpdateCount not update!!!!!: %d", mUpdateCount);
    //	aee_ioctl_wdt_kick(WDT_SETBY_SF_NEED_NOT_UPDATE);
    //}
    usleep(mTimer * 1000);
    return true;
}