Documenting Filenames in the Source Code with Python

Troubleshooting a web application page that is made from a crazy quilt of source code files is not always easy. Whether your application is built using ASP, PHP, ColdFusion, or something completely different, the challenge here is the same. How do you find the line of code in the source that is causing the problem if you don’t know which file to look in?

If you’re lucky, and a particular piece of error handling text or other identifying information is only found in a couple of places, using a PowerShell script like the one below will find what you’re looking for.

Get-ChildItem -Path "C:\Root folder" -Recurse | Select-String -Pattern "text to search for" | group path | select name

However, if the error text itself is not embedded in the code, but you can find the offending line of code in the rendered web page using Chrome Dev Tools or the like, you may still have a problem locating the actual line of code in source. That’s where this technique comes in. Putting the source code filenames in comments at the beginning and end of each appropriate file can make it easier to determine the origin of the problem. 

I’ve visited this topic before, and used PowerShell to do this task then. Now, I’m using Python. I was able to cobble this script together from one that traverses folders and documents their contents and one that filters the file type since, for this exercise, I only need to alter the ColdFusion (.cfm) files. 

import os
import sys

walk_dir = sys.argv[1]

print('walk_dir = ' + walk_dir)

# If your current working directory may change during script execution, it's recommended to
# immediately convert program arguments to an absolute path. Then the variable root below will
# be an absolute path as well. Example:
# walk_dir = os.path.abspath(walk_dir)
print('walk_dir (absolute) = ' + os.path.abspath(walk_dir))

for root, subdirs, files in os.walk(walk_dir):
    files = [ fi for fi in files if fi.endswith(".cfm") ]    

    for filename in files:
        file_path = os.path.join(root, filename)
        adj_file_path = file_path.replace(walk_dir,'').replace('\\','/')
        print('\t- file %s (full path: %s)' % (filename, adj_file_path))
        with open(file_path, 'rb') as f:
            f_content ="utf-8")
            f_content = '<!-- file: ' + adj_file_path + ' -->\n' + f_content + '\n<!-- end of file: ' + adj_file_path + ' -->\n'                       
        with open(file_path, 'wb') as f:
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