This Bash script is designed to locate and use the...

This Bash script is designed to locate and use the clang-format tool (a code formatting tool) to recursively format C and C++ source code files in one or more specified directories. The script includes fallback mechanisms to find compatible versions of clang-format, ensuring its functionality across various system configurations. Here's a detailed breakdown of what the code does:

Steps:

1. Shebang Header:

   #!/bin/bash
   

   This defines the script as a Bash script.

2. Usage Function:

   function usage {
       echo "Usage: $0 DIR..."
       exit 1
   }
   

   This defines a helper function named usage to print a usage message if the supplied arguments are invalid.

3. Find the clang-format Command:

   FMT=""
   
   for clangfmt in clang-format{,-{4,3}.{9,8,7,6,5,4,3,2,1,0}}; do
       if which "$clangfmt" &>/dev/null; then
           FMT="$clangfmt"
           break
       fi
   done
   

   • Initializes a variable, FMT, which will store the name of the clang-format executable.
   • Uses a loop to search for clang-format or specific versioned binaries (e.g., clang-format-4.0, clang-format-3.9, etc.) in decreasing version order.
   • It uses the which command to check if the executable is available, and if found, assigns it to FMT.

4. Handle Missing clang-format:

   if [ -z "$FMT" ]; then
       echo "failed to find clang-format"
       exit 1
   fi
   

   If no clang-format executable was found, the script terminates with an error message.

5. Process Input Arguments:

   SRC_PATH="$@"
   if [ -z "$SRC_PATH" ]; then
       SRC_PATH="../../../src"
   fi
   

   • Reads directories passed as arguments into the variable SRC_PATH.
   • If no arguments were provided, defaults to the relative path ../../../src.

6. Check Validity of Directories:

   for dir in "$SRC_PATH"; do
       if [ ! -d "${dir}" ]; then
           echo "${dir} is not a directory"
           usage
       fi
   done
   

   • Iterates over all directories in SRC_PATH.
   • If any argument is not a valid directory, the script prints an error message and exits.

7. Format Code Files:

   for dir in "$SRC_PATH"; do
       pushd "${dir}" &>/dev/null
       find . \
            \( -name '*.c' \
            -o -name '*.cc' \
            -o -name '*.cpp' \
            -o -name '*.h' \
            -o -name '*.hh' \
            -o -name '*.hpp' \) \
            -exec "${FMT}" -style=file -i '{}' \;
       popd &>/dev/null
   done
   

   • For each valid directory, navigates into it using pushd, suppressing output with &>/dev/null.
   • Uses the find command to locate files with extensions commonly used for C and C++ source or header files (.c, .cc, .cpp, .h, .hh, .hpp).
   • Executes the clang-format tool on each file (-exec "${FMT}" ...) with the -style=file option (to use style settings from a .clang-format file) and the -i option (to apply changes in-place).
   • Exits the directory using popd, suppressing output.

Summary:

The script:

• Searches for the clang-format tool or its versioned alternatives.
• Ensures appropriate arguments (one or more directories) are provided.
• Defaults to ../../../src if no directories are specified.
• Validates that all provided arguments are directories.
• Recursively formats C and C++ source code files in the specified directories using clang-format.