from wsgiref import simple_server
import falcon
import os

class FileResource:
    
    def on_get(self, req, resp):
        target_file = '/path/to/target_file.txt'
        
        if not os.access(target_file, os.R_OK):
            resp.status = falcon.HTTP_403
            resp.media = {'error': 'File access denied'}
            return
            
        resp.stream = self.file_stream(target_file)
        resp.downloadable_as = os.path.basename(target_file)
        resp.status = falcon.HTTP_200

    def file_stream(self, file_path, buffer_size=8192):
        with open(file_path, 'rb') as f:
            while True:
                segment = f.read(buffer_size)
                if not segment:
                    break
                yield segment

app = falcon.App()
file_handler = FileResource()
app.add_route('/download', file_handler)

if __name__ == '__main__':
    httpd = simple_server.make_server('0.0.0.0', 8000, app)
    httpd.serve_forever()

---

Verifying File Permissions

Use os.access() to check permissions before file operations:

import os

# Check existence and permissions for /data/sample.txt

exists = os.access("/data/sample.txt", os.F_OK)
readable = os.access("/data/sample.txt", os.R_OK)
writable = os.access("/data/sample.txt", os.W_OK)
executable = os.access("/data/sample.txt", os.X_OK)

print(f"File exists: {exists}")
print(f"Read allowed: {readable}")
print(f"Write allowed: {writable}")
print(f"Execute allowed: {executable}")

Typical output when file has read/write permisssions but not execute:

File exists: True
Read allowed: True
Write allowed: True
Execute allowed: False