### CMake Build
```bash
mkdir build
cd build

cmake .. -DCMAKE_INSTALL_PREFIX=./install/ -G "Visual Studio 17 2022" -A x64

PATH=$PATH:/c/dev/Qt/Tools/mingw810_64/bin/
cmake .. -G "MinGW Makefiles" -DCMAKE_MAKE_PROGRAM=mingw32-make -DCMAKE_INSTALL_PREFIX=./install/

PATH=$PATH:/c/dev/Qt/Tools/mingw810_64/bin/
cmake .. -G "Ninja" -DCMAKE_INSTALL_PREFIX=./install/

cmake --build .
cmake --install .
```

### 判断操作系统
```cmake
IF (CMAKE_SYSTEM_NAME MATCHES "Linux")

ELSEIF (CMAKE_SYSTEM_NAME MATCHES "Windows")

ELSEIF (CMAKE_SYSTEM_NAME MATCHES "FreeBSD")

ELSE ()
MESSAGE(STATUS "other platform: ${CMAKE_SYSTEM_NAME}")
ENDIF (CMAKE_SYSTEM_NAME MATCHES "Linux")
```

```cmake
if(WIN32)
    # todo: windows action
elseif(APPLE)
    # todo: mac action
elseif(UNIX)
    # todo: linux action
endif()
```

### 判断编译器
```cmake
if ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang")
# using Clang
elseif ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")
# using GCC
elseif ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Intel")
# using Intel C++
elseif ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "MSVC")
# using Visual Studio C++
endif()
```


CMake 笔记

## 安装 Elastic Stack

> CenOS 7

```shell
rpm --import https://artifacts.elastic.co/GPG-KEY-elasticsearch

# ES 7
cat << EOF > /etc/yum.repos.d/elasticsearch.repo
[elasticsearch]
name=Elasticsearch repository for 7.x packages
baseurl=https://mirrors.tuna.tsinghua.edu.cn/elasticstack/7.x/yum
gpgcheck=1
gpgkey=https://artifacts.elastic.co/GPG-KEY-elasticsearch
enabled=1
autorefresh=1
type=rpm-md
EOF

# ES 8
cat << EOF > /etc/yum.repos.d/elasticsearch.repo
[elasticsearch]
name=Elasticsearch repository for 8.x packages
baseurl=https://mirrors.tuna.tsinghua.edu.cn/elasticstack/8.x/yum
gpgcheck=1
gpgkey=https://artifacts.elastic.co/GPG-KEY-elasticsearch
enabled=1
autorefresh=1
type=rpm-md
EOF

yum install -y elasticsearch kibana logstash

systemctl daemon-reload
systemctl enable elasticsearch.service
systemctl enable kibana.service
systemctl enable logstash.service
```

> Ubuntu

```shell
sudo apt install apt-transport-https
wget -qO - https://artifacts.elastic.co/GPG-KEY-elasticsearch | sudo apt-key add -
# ES 7
echo "deb https://mirrors.tuna.tsinghua.edu.cn/elasticstack/7.x/apt stable main" | sudo tee /etc/apt/sources.list.d/elastic-7.x.list
# ES 8
echo "deb https://mirrors.tuna.tsinghua.edu.cn/elasticstack/8.x/apt stable main" | sudo tee /etc/apt/sources.list.d/elastic-8.x.list
sudo apt update && sudo apt install -y elasticsearch kibana logstash

systemctl daemon-reload
systemctl enable elasticsearch.service
systemctl enable kibana.service
systemctl enable logstash.service
```

## 建立中文索引

> IK Analysis for Elasticsearch

```shell
ES_VERSION=7.6.1 JAVA_HOME=/usr/share/elasticsearch/jdk/ \
/usr/share/elasticsearch/bin/elasticsearch-plugin install \
https://get.infini.cloud/elasticsearch/analysis-ik/$ES_VERSION
```

* 建立 mapping 的时候， 增加 analyzer 属性 IK分词器（ik_max_word / ik_smart）
    * ik_max_word ：会将文本做最细粒度的拆分
    * ik_smart ：会将文本做最粗粒度的拆分

> Pinyin Analysis for Elasticsearch

```shell
ES_VERSION=7.6.1 JAVA_HOME=/usr/share/elasticsearch/jdk/ \
/usr/share/elasticsearch/bin/elasticsearch-plugin install \
https://get.infini.cloud/elasticsearch/analysis-pinyin/$ES_VERSION
```

## 开放外网访问

```shell
cat << EOF >>  /etc/elasticsearch/elasticsearch.yml
network.host: 0.0.0.0
http.port: 9200
discovery.type: single-node
EOF

systemctl restart elasticsearch.service
```

## 遇到的问题

> "Validation Failed: 1: this action would add [2] shards, but this cluster currently has [1903]/[1000] maximum normal shards open;"

```shell
cat << EOF >>  /etc/elasticsearch/elasticsearch.yml
cluster.max_shards_per_node: 10000
EOF

systemctl restart elasticsearch.service
```

> Error enabling rule: could not create API key - feature_not_enabled_exception: [feature_not_enabled_exception] Reason: api keys are not enabled

```bash
cat << EOF >>  /etc/elasticsearch/elasticsearch.yml
xpack.security.authc.api_key.enabled: true
EOF

systemctl restart elasticsearch.service
```


```bash
/usr/share/kibana/bin/kibana-encryption-keys generate

cat << EOF >>  /etc/kibana/kibana.yml
xpack.encryptedSavedObjects.encryptionKey: b9d7e558c8e03ca80e698384189d4751
xpack.reporting.encryptionKey: ca8c1a3551bfba02cf0ffd3dbb0df52b
xpack.security.encryptionKey: d0b8fe87528c2da203ac402bf7d6308c
EOF

systemctl restart kibana.service
```

ElasticStack 笔记

## Java 在加载和卸载动态库

> 当动态库被加载时这个函数被系统调用
```c
JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM *jvm, void *reserved) {
	JNIEnv *env = NULL;
	if ((*jvm)->GetEnv(jvm, (void **) &env, JNI_VERSION_1_4) != JNI_OK)
		return JNI_ERR;
	
	// my code...
	
	return JNI_VERSION_1_4;
}
```

> 当动态库被卸载时这个函数被系统调用
```c
JNIEXPORT void JNI_OnUnload(JavaVM* vm, void* reserved) {
	// my code ...
}
```

## JNI 注册本地函数

1. 通过 FindClass() 查找 Java 中的 class 引用。
```c
jclass clazz = (*env)->FindClass(env, "")
```
2. 通过 RegisterNatives() 注册本地函数。
```c
JNINativeMethod methods[] = {
        {"getText", "()Ljava/lang/String;", getText}
};
(*env)->RegisterNatives(env, clazz, &methods, sizeof(methods)/sizeof((methods)[0]));
```
3. 关于 RegisterNatives() 中的 JNINativeMethod 结构体。
```c
typedef struct {
    const char* name;
    const char* signature;
    void*       fnPtr;
} JNINativeMethod;

// name: 需要注册的 Java 函数名
// signature: 函数参数和返回值类型
// fnPtr: 需要注册的 C 函数指针
```

Android NDK (JNI) 笔记

我自己搭建的 Nginx Web Server 想要提供 HTTPS 连接方式，但是觉得不想花钱去找知名 CA 证书中心 (e.g. AWS Certificate Manager) 购买证书。于是我想通过 Self-Signed 的方式来解决我的需求：



1. 首先生成 Self-Signed CA 证书：
```shell
openssl req \
        -newkey rsa:2048 -nodes -keyout self-ca.key \
        -x509 -days 365 -out self-ca.crt
```
2. 生成 Nginx Web Server 需要的 Private Key & CSR ：
```shell
openssl req \
        -newkey rsa:2048 -nodes -keyout nginx.key \
        -out nginx.csr
```
3. 利用 Self-Signed CA 证书，来签发业务所需要的 CRT 证书：
```shell
openssl x509 \
        -req -in nginx.csr \
        -out nginx.crt \
        -CAcreateserial -days 365 \
        -CA self-ca.crt -CAkey self-ca.key
```

经过了上面 3 个步奏后，你就得到了 self-ca.crt & self-ca.key ，以及由它签发出来的 nginx.crt & nginx.key 。
如何使用上面 4 个文件：首先将 nginx.crt & nginx.key 部署在 Nginx Web Server 上，然后将 self-ca.crt 发布给客户端即可。客户端就可以通过 self-ca.crt 与业务服务器建立 SSL/TLS 安全连接。


### 生成私钥及证书
```shell
openssl req -newkey rsa:4096 -nodes -keyout server.key -x509 -days 365 -out server.crt -subj "/C=CN/ST=st/L=l/O=o/OU=ou/CN=cn/emailAddress=xxx@xxx.com"
```


### 生成随机密码
```shell
openssl rand -base64 32
```

OpenSSL 一些笔记

### 软件源的替换
```shell
# sed -i 's_https\?://mirrors.vsean.net/openwrt_https://mirrors.tuna.tsinghua.edu.cn/openwrt_' /etc/opkg/distfeeds.conf
# sed -i 's_https\?://downloads.openwrt.org_https://mirrors.tuna.tsinghua.edu.cn/openwrt_' /etc/opkg/distfeeds.conf

sed -e 's,https://downloads.immortalwrt.org,https://mirrors.ustc.edu.cn/immortalwrt,g' \
-e 's,https://mirrors.vsean.net/openwrt,https://mirrors.ustc.edu.cn/immortalwrt,g' \
-i.bak /etc/opkg/distfeeds.conf
```

### 安装必备软件
```shell
opkg update && opkg install luci-theme-argon luci-i18n-argon-config-zh-cn kmod-usb-net-rndis kmod-usb-net-ipheth usbmuxd

# opkg update && opkg install luci-app-homeproxy luci-i18n-homeproxy-zh-cn ip-full kmod-tun
# opkg update && opkg install luci-app-openclash
```

### 更新所有软件包
```shell
opkg update && opkg list-upgradable | cut -f 1 -d ' ' | xargs -r opkg upgrade
```

### 刷机教程 (OpenWrt & ImmortalWrt Git提交记录)

#### 128M
```
mediatek: add support for Cudy TR3000 v1
Hardware:
 - SoC: MediaTek MT7981B
 - CPU: 2x 1.3 GHz Cortex-A53
 - Flash: 128 MiB SPI NAND
 - RAM: 512 MiB
 - WLAN: 2.4 GHz, 5 GHz (MediaTek MT7976CN, 802.11ax)
 - Ethernet: 1x 10/100/1000/2500 Mbps RTL8221B WAN, 1x10/100/1000 Mbps MT7981 LAN
 - USB 3.0 port
 - Buttons: 1 Reset button, 1 slider button
 - LEDs: 1x Red, 1x White
 - Serial console: internal test points, 115200 8n1
 - Power: 5 VDC, 3 A

MAC addresses:
+---------+-------------------+-----------+
|         | MAC               | Algorithm |
+---------+-------------------+-----------+
| WAN     | 80:af:ca:xx:xx:x1 | label+1   |
| LAN     | 80:af:ca:xx:xx:x0 | label     |
| WLAN 2g | 80:af:ca:xx:xx:x0 | label     |
| WLAN 5g | 82:af:ca:xx:xx:x0 |           |
+---------+-------------------+-----------+

Installation:
The installation must be done via TFTP by disassembling the router. On other occasions Cudy has distributed intermediate firmware to make installation easier, and so I recommend checking the Wiki for this device if there is a more convenient solution than the one below.

To install using TFTP:
1. Connect to UART.
2. With the router off, press the RESET button. While the router is turning on, the button should continue to be pressed for at least 5 seconds.
3. A u-boot shell will automatically open.
4. Connect to LAN and set your IP to 192.168.1.88/24. Configure a TFTP server and an OpenWrt initramfs-kernel.bin firmware file.
5. Run these steps in u-boot using the name of your file.

setenv bootfile initramfs-kernel.bin
tftpboot
bootm

6. If you can reach LuCI or SSH now, just use the sysupgrade image with the 'Keep settings' option turned off.

---
mediatek: add ubootmod layout for cudy tr3000 v1
This allows us to use the full size of nand, which increases ubi size
from 64M to 122.25M.

If you are at factory firmware, please refer commit 63b8d98 ("mediatek: add support for Cudy TR3000 v1")
to boot into OpenWrt initramfs (stock layout version).

Flash instructions:
1. Login into the device and backup everything, especially 'Factory' part.
2. Unlock mtd partitions:
   apk update && apk add kmod-mtd-rw
   insmod mtd-rw i_want_a_brick=1
2. Write new BL2 and FIP
   mtd write openwrt-mediatek-filogic-cudy_tr3000-v1-ubootmod-preloader.bin BL2
   mtd write openwrt-mediatek-filogic-cudy_tr3000-v1-ubootmod-bl31-uboot.fip FIP
4. Set static IP on your PC:
   IP 192.168.1.254/24, GW 192.168.1.1
5. Serve OpenWrt initramfs image using TFTP server.
6. Cut off the power and re-engage, wait for TFTP recovery to complete.
7. After OpenWrt has booted, perform sysupgrade.

```

#### 256M
```
mediatek: add support for Cudy TR3000  256MB  v1 flash version
This device is similar to the Cudy TR3000 v1 128MB version.
The difference is that the flash memory is 128mb and the other is 256mb

Hardware:
 - SoC: MediaTek MT7981B
 - CPU: 2x 1.3 GHz Cortex-A53
 - Flash: 256 MiB SPI NAND
 - RAM: 512 MiB
 - WLAN: 2.4 GHz, 5 GHz (MediaTek MT7976CN, 802.11ax)
 - Ethernet: 1x 10/100/1000/2500 Mbps RTL8221B WAN, 1x10/100/1000 Mbps MT7981 LAN
 - USB 3.0 port
 - Buttons: 1 Reset button, 1 slider button
 - LEDs: 1x Red, 1x White
 - Power: 5 VDC, 3 A

Installation:
Cudy has distributed intermediate firmware to make installation easier
1. Go to [Cudy CN official website](https://www.cudy.com/zh-cn/pages/download-center/tr3000-1-0) and download the intermediate firmware
2. Upgrade the intermediate firmware on the page
3. Visit the intermediate firmware 192.168.1.1 webpage and use the sysupgrade image to update

other:
If you fail to flash the device, you can use TFTP to flash back to the original firmware.
1. Ask Cudy CN official customer service for the original firmware
2. With the router off, press the RESET button. While the router is turning on, the button should continue to be pressed for at least 5 seconds.
3. A u-boot shell will automatically open.
4. Connect to LAN and set your IP to 192.168.1.88/24. Configure a TFTP server and an recovery.bin firmware file.

Signed-off-by: cheng wang <typedelta@outlook.com>
Link: openwrt/openwrt#19167
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
```