September 30, 2021 by asad akbar

struct stat and missing field initializer

If you are using following code

#include <sys/stat.h>
struct stat foo = {0};

in the modern c++, and compiler warnings (GCC: -Wall -Wextra) it is likely that you
will find following warning

<source>:4:21: warning: missing initializer for member 'stat::st_ino' [-Wmissing-field-initializers]
4 | struct stat foo = {0};
  | ^

It is due to new syntax introduced in C++11 for uniform initialization. It means that
{0} is doing initlization of just first data member of struct stat. To fix this warning
you have to use struct stat foo {};

July 3, 2021 by asad akbar

Git and word documents

If you got word documents in the git repo and tired of seeing binary diff message from git, do the following setups to fix it.

$ git diff diff --git a/hello.docx b/hello.docx index bc73959bc592..122761966158 100644 Binary files a/hello.docx and b/hello.docx differ

To see diff of what has been changed in the word document, do following:

Install docx2txt. You can download it from http://docx2txt.sourceforge.net. Follow the instructions in the INSTALL file to put it somewhere your shell can find it.
Create or append file ~/.config/git/attributes to have

*.docx diff=word

Edit .gitconfig to have following commands

[diff "word"] textconv = ~/git_docx2txt.sh

[alias] wdiff = diff --word-diff=color --unified=1

Create ~/git_docx2txt.sh with following text

!/bin/bash

docx2txt.pl "$1" -

chmod a+x ~/git_docx2txt.sh

You will have

$ git diff diff --git a/hello.docx b/hello.docx index bc73959bc592..122761966158 100644 --- a/hello.docx +++ b/hello.docx @@ -1 +1 @@ -Hello world +Hello world: View word diff in git.

$ git wdiff hello.docx diff --git a/hello.docx b/hello.docx index bc73959bc592..122761966158 100644 --- a/hello.docx +++ b/hello.docx @@ -1 +1 @@ Hello worldworld: View word diff in git.

Happy diff view.

September 6, 2020September 6, 2020 by asad akbar

Setting up cppcheck

programming, tips
c++17, programming, static-analysis, ubuntu, vscode
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To install pre-built cppcheck: http://cppcheck.sourceforge.net/

sudo apt-get update
sudo apt-get install cppcheck

In case, you want to use latest cppcheck, download and build it from the source code

wget https://github.com/danmar/cppcheck/archive/2.1.tar.gz
tar zxvf 2.1.tar.gz
cd cppcheck-2.1
mkdir build
cd build
cmake ..

P.S: In case you are interested for cppcheck GUI use cmake -DBUILD_GUI=ON ..

make
sudo make install

Once installation is complete.

which cppcheck
/usr/local/bin/cppcheck

cppcheck --version
Cppcheck 2.1

Build your cpp project with cmake and pass on an extra parameter -DCMAKE_EXPORT_COMPILE_COMMANDS=TRUE to cmake. It will produce compile_commands.json file in your build folder for the project.

Execute cppcheck -p </path/to/folder/having/compile_command.json>.

To use it in VSCode add following to the tasks.json

{
    "label": "Run cppCheck",
    "command": "/usr/local/bin/cppcheck",
    "args": [
       "--project=${workspaceRoot}/build/compile_commands.json"
    ],
    "problemMatcher": "$gcc",
}

Ref: https://gist.github.com/aakbar5/268a2072138345893b7f82590dcc3d26

February 19, 2020March 2, 2020 by asad akbar

Create .desktop file

To create .desktop file in Ubuntu

[Desktop Entry]

Type=Application

Name=EclipseC++

GenericName=Eclipse

Comment=Eclipse for development

Exec=/path/to/eclipse

Icon=/path/to/icon.xpm

Terminal=false

MimeType=text/plain;

Categories=Development;IDE

StartupNotify=true

# If you won't specify following line you may end having duplicate icons

# in Ubuntu Dock bar where first is the one you have added to Dock and the 

# other one is showing the running application. To avoid this issue you need

# to add following line in .desktop file

StartupWMClass=Eclipse

# How to determine value of StartWMClass for any application:

# – Run your application

# – Run xprop WM_CLASS from the commandline

# – Your mouse cursor will be in different shape

# – Click the window bar of the your application

# – Note down the value(s) printed on the console where you executed xprop

# – These printed values will be WM_CLASS(STRING) = "ABC", "RST", "XYZ" 

# – Use any of the string shown in "xxx" for StartupWMClass in .desktop file. For example

#   you can use ABC or RST or XYZ.

view raw

.desktop

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February 15, 2020 by asad akbar

Linux kernel & VS Code

If you are using VSCode for Linux kernel development, following setup will be useful:

Clone https://github.com/aakbar5/handy-kernel_modules. It contains the
- Makefile: to build kernel modules
- .devcontainer: to setup vscode for remote development inside the Docker container
- .vscode: From tasks build and run Qemu.
Start vscode
Open the folder having linux kernel development project
Select: Remote-Containers: Open Folder in Container… from the popup menu.
Select the folder selected in #2
Keep an eye on the vscode status bar while it is showing Opening Remote…
Once vscode is setup, your project will be ready for development in container environment.
Press CTRL+P for Tasks: Run Task
Select kmod – build task to build a kernel module setup in Makefile.
Press CTRL+P for Tasks: Run Task
Select Generate compile_commands.json from the list of tasks.
- It will run generate_compdb.py (https://github.com/aakbar5/vscode-linux-kernel) for the linux kernel and for the project workspace.
- It will generate compile_commands.json which will help you in code assistance.
Press CTRL+P for Tasks: Run Task
Select Run QEMU and wait for QEMU to be ready for use
Press CTRL+P for Tasks: Run Task and select kmod – load
- This command will copy built kernel module to QEMU.
Get back to QEMU shell in vscode terminal and use kernel module commands to test your new kernel module.
Once you are done with development, use Dev Container: Close Remote Connection option.

kernel_in_vscode

December 27, 2019December 27, 2019 by asad akbar

dup2 usage

// A simple example of how dup2 can be used

const char* msg = "Text written by standard file descriptor\n";

int fd = open("dup2_test.txt", O_RDWR | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR);

write(fd, msg, strlen(msg));

/* Map stdout to our file */    

dup2(fd, STDOUT_FILENO);

printf("Text written by dup @ stdout file descriptor\n");

close(fd);

view raw

dup2_usage.c

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December 2, 2019September 6, 2020 by asad akbar

Setting up include-what-you-need (IWYU)

programming
c, c++17, programming, static-analysis, ubuntu, vscode
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Use following instructions to install IWYU (https://include-what-you-use.org/) on Ubuntu 18.04.3 LTS:

sudo apt-get update
sudo apt-get install -y build-essential cmake git zlib1g-dev libncurses5-dev llvm-6.0-dev libclang-6.0-dev libclang-6.0-dev clang-6.0
git clone https://github.com/include-what-you-use/include-what-you-use.git iwyu.git
cd iwyu.git
git checkout clang_6.0
mkdir -p build
cd build
cmake -DIWYU_LLVM_ROOT_PATH=/usr/lib/llvm-6.0 ..
make 
make install

Once installation is complete, you will find `include-what-you-need`

# include-what-you-use --version
include-what-you-use 0.10 (git:a1878c4) based on clang version 6.0.0-1ubuntu2 (tags/RELEASE_600/final)

To execute include-what-you-need:

Build your cpp project with cmake and pass on an extra parameter -DCMAKE_EXPORT_COMPILE_COMMANDS=TRUE to cmake. It will produce `compile_commands.json` file in your build folder for the project.

Execute iwyu_tool.py -p </path/to/folder/having/compile_command.json>. It may take time depending upon the code size.

fix_includes can be used to apply recommended changes.

To use it in VSCode add following to the tasks.json

{
    "label": "Run iwyu",
    "command": "iwyu_tool.py",
    "args": [
        "-p",
        "${workspaceRoot}/build"
    ],
    "presentation": {
        "echo": true,
        "reveal": "always",
        "focus": true,
        "panel": "shared",
        "showReuseMessage": true,
        "clear": false
    },
    "problemMatcher": "$gcc"
}

Ref: https://gist.github.com/aakbar5/268a2072138345893b7f82590dcc3d26

November 5, 2019December 30, 2019 by asad akbar

symlinks in virtualbox

If you are using Windows in Virtualbox ontop of Linux based (i.e: Ubuntu) machine, you might have seen this problem that accessing symlinks in windows does not work. Instead of showing contents after resolving Linux symlinks, you will end up with “Protocol error”.

This error can be fixed using vBoxManage by setting a boolean property (SharedFoldersEnableSymlinksCreate) against each folder shared with VirtualBox based machine.

VBoxManage setextradata <VirtualMachineName> VBoxInternal2/SharedFoldersEnableSymlinksCreate/<SharedFolderName> 1

After executing above command, verify your change with following:

VBoxManage getextradata <VirtualMachineName> enumerate

October 31, 2019 by asad akbar

Ubuntu: Bash history management

# To see top commands

history | awk '{print $2}' | sort | uniq -c | sort -rn | head

# To remove a commands from history

# Replace YOUR_COMMAND with the initials of the command you want to remove from bash history

sed -i '/^YOUR_COMMAND/d' ~/.bash_history

view raw

Ubuntu: Bash history management

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October 27, 2019September 6, 2020 by asad akbar

VisualStudio code & compile_commands.json

If you are working with C/C++ in VSCode, you will find that VSCode keeps on showing

"${workspaceFolder}/build/compile_commands.json" could not be found. 'includePath' from c_cpp_properties.json will be used instead.

This message is generated by vscode-cpptools. Although it is an optional file however vscode-cpptools keeps on showing error message that it is missing.

This message can easily be fixed if you are using CMake. To do so simply add following to your CMake configuration file.

# Generate compile_commands.json
set(CMAKE_EXPORT_COMPILE_COMMANDS ON)

asadakbar

[ notes to myself ]