by asad akbar

Setting up cppcheck

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

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.

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.desktop
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by asad akbar

Linux kernel & VS Code

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

  1. 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.
  2. Start vscode
  3. Open the folder having linux kernel development project
  4. Select: Remote-Containers: Open Folder in Container… from the popup menu.
  5. Select the folder selected in #2
  6. Keep an eye on the vscode status bar while it is showing Opening Remote…
  7. Once vscode is setup, your project will be ready for development in container environment.
  8. Press CTRL+P for Tasks: Run Task
  9. Select kmod – build task to build a kernel module setup in Makefile.
  10. Press CTRL+P for Tasks: Run Task
  11. Select Generate compile_commands.json from the list of tasks.
  12. Press CTRL+P for Tasks: Run Task
  13. Select Run QEMU and wait for QEMU to be ready for use
  14. Press CTRL+P for Tasks: Run Task and select kmod – load

    • This command will copy built kernel module to QEMU.
  15. Get back to QEMU shell in vscode terminal and use kernel module commands to test your new kernel module.
  16. Once you are done with development, use Dev Container: Close Remote Connection option.

kernel_in_vscode

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);

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dup2_usage.c
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by asad akbar

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

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

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
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)
by asad akbar

Setup: FTP server

# Setup FTP server
# Instructions are tested on: Ubuntu 18.04.3 LTS
apt install -y atftpd
sudo gedit /etc/default/atftpd
# – set USE_INETD=FALSE
# – Optional: To change directory to host FTP contents, change /srv/tftp in OPTIONS line
# – Optional: To have maximum log: change –verbose=7 and append –logfile /var/log/atftpd.log
sudo mkdir -p /srv/tftp
sudo chmod -R 777 /srv/tftp
sudo chown -R nobody /srv/tftp
# Vanilla contents
# USE_INETD=true
# # OPTIONS below are used only with init script
# OPTIONS="–tftpd-timeout 300 –retry-timeout 5 –mcast-port 1758 –mcast-addr 239.239.239.0-255 –mcast-ttl 1 –maxthread 100 –verbose=5 /srv/tftp"
# After changes
# USE_INETD=false
# # OPTIONS below are used only with init script
# OPTIONS="–tftpd-timeout 300 –retry-timeout 5 –mcast-port 1758 –mcast-addr 239.239.239.0-255 –mcast-ttl 1 –maxthread 100 –verbose=7 –logfile /var/log/atftpd.log ~/tftp"
# Run the service
sudo invoke-rc.d atftpd start
# Verify atftpd is running
netstat -lnp | grep ":69 "
# Use atftp FTP client to verify atftpd
apt install -y atftp
atftp localhost
# Make sure /etc/hosts is having following mapping otherwise localhost above command will not work
# 127.0.0.1 localhost
# Download an file from FTP server
get file_name_which_is_hosted_on_ftp

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Ubuntu: Setup FTP server
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