Aim Wang

2023/04/21

[C] 16進制字串與 byte 陣列戶轉

Convert between hex string and byte array.

以空間換取時間, 盡量減少計算跟比較.

static uint8_t HEX_VALUE[256] = {
//  x0 x1 x2 x3 x4 x5 x6 x7   x8 x9 xA xB xC xD xE xF
     0, 0, 0, 0, 0, 0, 0, 0,   0, 0, 0, 0, 0, 0, 0, 0,  // 0x
     0, 0, 0, 0, 0, 0, 0, 0,   0, 0, 0, 0, 0, 0, 0, 0,  // 1x
     0, 0, 0, 0, 0, 0, 0, 0,   0, 0, 0, 0, 0, 0, 0, 0,  // 2x
     0, 1, 2, 3, 4, 5, 6, 7,   8, 9, 0, 0, 0, 0, 0, 0,  // 3x
     0,10,11,12,13,14,15, 0,   0, 0, 0, 0, 0, 0, 0, 0,  // 4x
     0, 0, 0, 0, 0, 0, 0, 0,   0, 0, 0, 0, 0, 0, 0, 0,  // 5x
     0,10,11,12,13,14,15, 0,   0, 0, 0, 0, 0, 0, 0, 0,  // 6x
     0, 0, 0, 0, 0, 0, 0, 0,   0, 0, 0, 0, 0, 0, 0, 0,  // 7x
     0, 0, 0, 0, 0, 0, 0, 0,   0, 0, 0, 0, 0, 0, 0, 0,  // 8x
     0, 0, 0, 0, 0, 0, 0, 0,   0, 0, 0, 0, 0, 0, 0, 0,  // 9x
     0, 0, 0, 0, 0, 0, 0, 0,   0, 0, 0, 0, 0, 0, 0, 0,  // Ax
     0, 0, 0, 0, 0, 0, 0, 0,   0, 0, 0, 0, 0, 0, 0, 0,  // Bx
     0, 0, 0, 0, 0, 0, 0, 0,   0, 0, 0, 0, 0, 0, 0, 0,  // Cx
     0, 0, 0, 0, 0, 0, 0, 0,   0, 0, 0, 0, 0, 0, 0, 0,  // Dx
     0, 0, 0, 0, 0, 0, 0, 0,   0, 0, 0, 0, 0, 0, 0, 0,  // Ex
     0, 0, 0, 0, 0, 0, 0, 0,   0, 0, 0, 0, 0, 0, 0, 0   // Fx
};

static uint8_t HEX_CHAR[16] = {
    '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'
};

void bytes2hex(uint8_t* src, char* dest, uint8_t srcsize) {
    uint8_t flag;
    uint8_t pos;

    flag = 0;
    pos = 0;
    while (srcsize--) {
        if (flag || src[srcsize]) {
            dest[pos++] = HEX_CHAR[src[srcsize]>>4];
            dest[pos++] = HEX_CHAR[src[srcsize]&0xf];
        }
    }
}

void hex2bytes(char *src, uint8_t* dest, uint8_t destsize) {
    uint8_t     len;
    uint8_t     pos;
    uint8_t     hilo;
    uint8_t     byte;
    uint8_t     lohi[2];
    char       *cptr;

    len = strlen(src);
    if (len > (destsize* 2)) {
        return;
    }
    cptr = src + len;
    pos = 0;
    ++len;
    while (len) {
        memset(lohi, 0, 2);
        hilo = 2;
        while (hilo-- && --len) {
            lohi[hilo] = HEX_VALUE[*--cptr];
        }
        dest[pos++] = lohi[1] | (lohi[0] << 4);
    }

    return;
}

2023/03/16

Docker 筆記

列出所有 container

docker ps -a

啟動即停止 container

docker start container_id/name

docker stop container_id/name

刪除 container

docker rm container_id/name

在目前路徑執行 container 指令 (通常用於編譯)

docker --workdir $PWD container_id/name command

--------------------------------------------------------------------------------

docker --help

Usage: docker [OPTIONS] COMMAND

A self-sufficient runtime for containers

Options:
--config string Location of client config files (default "/home/jwang/.docker")
-D, --debug Enable debug mode
-H, --host list Daemon socket(s) to connect to
-l, --log-level string Set the logging level ("debug"|"info"|"warn"|"error"|"fatal") (default "info")
--tls Use TLS; implied by --tlsverify
--tlscacert string Trust certs signed only by this CA (default "/home/jwang/.docker/ca.pem")
--tlscert string Path to TLS certificate file (default "/home/jwang/.docker/cert.pem")
--tlskey string Path to TLS key file (default "/home/jwang/.docker/key.pem")
--tlsverify Use TLS and verify the remote
-v, --version Print version information and quit

Management Commands:
builder Manage builds
config Manage Docker configs
container Manage containers
engine Manage the docker engine
image Manage images
network Manage networks
node Manage Swarm nodes
plugin Manage plugins
secret Manage Docker secrets
service Manage services
stack Manage Docker stacks
swarm Manage Swarm
system Manage Docker
trust Manage trust on Docker images
volume Manage volumes

Commands:
attach Attach local standard input, output, and error streams to a running container
build Build an image from a Dockerfile
commit Create a new image from a container's changes
cp Copy files/folders between a container and the local filesystem
create Create a new container
diff Inspect changes to files or directories on a container's filesystem
events Get real time events from the server
exec Run a command in a running container
export Export a container's filesystem as a tar archive
history Show the history of an image
images List images
import Import the contents from a tarball to create a filesystem image
info Display system-wide information
inspect Return low-level information on Docker objects
kill Kill one or more running containers
load Load an image from a tar archive or STDIN
login Log in to a Docker registry
logout Log out from a Docker registry
logs Fetch the logs of a container
pause Pause all processes within one or more containers
port List port mappings or a specific mapping for the container
ps List containers
pull Pull an image or a repository from a registry
push Push an image or a repository to a registry
rename Rename a container
restart Restart one or more containers
rm Remove one or more containers
rmi Remove one or more images
run Run a command in a new container
save Save one or more images to a tar archive (streamed to STDOUT by default)
search Search the Docker Hub for images
start Start one or more stopped containers
stats Display a live stream of container(s) resource usage statistics
stop Stop one or more running containers
tag Create a tag TARGET_IMAGE that refers to SOURCE_IMAGE
top Display the running processes of a container
unpause Unpause all processes within one or more containers
update Update configuration of one or more containers
version Show the Docker version information
wait Block until one or more containers stop, then print their exit codes

Run 'docker COMMAND --help' for more information on a command.

2023/02/08

用 gdb 找 Segmentation fault 的位置

編譯 elf 時不要 strip

STRIP := /usr/bin/true

產生 coredump

ulimit -c 設定 user 的 core上限, 記憶體足夠的情況下, 直接設定成無限.

$ulimit -c unlimited

發生 Segmentation fault

讓程式發生 Segmentation fault, 如果有產生 core 檔, 會在 stdout 看到 Segmentation fault (core dumped).

core 文件會放在 /tmp/process_name.xxxxxx.core

預設存放路徑

UBUNTU 22.04: /var/lib/apport/coredump

用 gdb 載入 core

$ gdb <elf> <core>

跑到錯誤點

如果一個 page 跑不到, 直接按 c 跑到錯誤點.

--Type <RET> for more, q to quit, c to continue without paging--

用 Back Trace (bt) 查看 call stack

如果 elf 經過 strip 減肥, 會看不到 symbol.

2022/09/30

[linux shell] How to check if have root privileges.

if [ "${EUID}" -ne 0 ]; then
        echo "Please run as root"
        exit 1
fi

2022/02/14

SVN 筆記

checkout

從 server 拉來本地, 簡寫 co

checkout URL[@REV]... [PATH]

例:

svn co svn+ssh://repo/home/svn/mybranch mybranch

直接 checkout 指定版本

svn co -r version svn+ssh://repo/home/svn/mybranch mybranch

commit

將本地的修改推到 server, 簡寫 ci

commit [PATH...]

例:

svn ci file1 file2 path1/file3

copy

複製成新的 branch, 簡寫 cp

copy SRC[@REV]... DST

例:

svn cp svn+ssh://repo/home/svn/mybranch svn+ssh://repo/home/svn/newbranch

status

檔案狀態, 簡寫 st

svn st [PATH...]

例:

svn st

merge

合併,

svn merge [-c M[,N...] | -r N:M ...] SOURCE[@REV] [TARGET_WCPATH]

例: 把 trunk 的修改合併進來.

svn merge svn+ssh://repo/trunk

例: 退回 oldver. 完成後重新 commit. 可以保留原先變更的版本參考

svn merge -r 123:115 svn+ssh://repo/develop

例: 檔案退回 oldver. 完成後重新 commit 可以保留原先變更的版本參考

svn merge -r 123:115 path/filename

update

更新,

svn update [PATH...]

例:

svn up

例:

svn up -r 115

cherry-pick

摘櫻桃

svn merge -r N:M SOURCE

例: (從 repo/develop 摘取從 r98 到 r99 所做的變更)

svn merge -r 98:99 svn+ssh://repo/develop

svn merge 出現下列訊息：

svn local file obstruction incoming file add upon merge

這是因為本地跟merge源個別 add 檔案造成的, 解決方法:

先手動比較兩個版本的差異, 並將檔案修改到最終想要的版本. 然後執行

svn resolve --accept working <file>

意思是接受 working 的版本來解決衝突.