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Calculates the MD5 hash of a file by reading it in chunks to handle large files efficiently.

Purpose

This function computes the MD5 checksum of a file for integrity verification, duplicate detection, or file comparison purposes. It reads files in 4KB chunks to avoid loading entire large files into memory, making it suitable for files of any size. Returns an empty string if an error occurs during processing.

Source Code

def calculate_file_hash(filepath: str) -> str:
    """Calculate MD5 hash of file"""
    try:
        hash_md5 = hashlib.md5()
        with open(filepath, "rb") as f:
            for chunk in iter(lambda: f.read(4096), b""):
                hash_md5.update(chunk)
        return hash_md5.hexdigest()
    except Exception as e:
        print(f"  ⚠ Error hashing {filepath}: {e}")
        return ""

Parameters

Parameter Details

filepath: String representing the path to the file to be hashed. Can be an absolute or relative path. The file must exist and be readable, otherwise an exception will be caught and an empty string returned.

Return Value

Type: str

Returns a string containing the hexadecimal representation of the MD5 hash (32 characters) if successful. Returns an empty string ('') if any error occurs during file reading or hashing, such as file not found, permission denied, or I/O errors.

Dependencies

• hashlib

Required Imports

import hashlib

Usage Example

import hashlib

def calculate_file_hash(filepath: str) -> str:
    """Calculate MD5 hash of file"""
    try:
        hash_md5 = hashlib.md5()
        with open(filepath, "rb") as f:
            for chunk in iter(lambda: f.read(4096), b""):
                hash_md5.update(chunk)
        return hash_md5.hexdigest()
    except Exception as e:
        print(f"  ⚠ Error hashing {filepath}: {e}")
        return ""

# Example usage
file_hash = calculate_file_hash("document.pdf")
if file_hash:
    print(f"MD5 hash: {file_hash}")
else:
    print("Failed to calculate hash")

# Example with absolute path
file_hash = calculate_file_hash("/path/to/large_file.bin")
print(f"Hash: {file_hash}")

Best Practices

• MD5 is not cryptographically secure and should not be used for security purposes; use SHA-256 or stronger algorithms for security-critical applications
• The function reads files in 4KB chunks, making it memory-efficient for large files
• Always check if the returned hash is an empty string to detect errors, as exceptions are caught and suppressed
• For better error handling in production, consider logging errors or raising exceptions instead of printing and returning empty strings
• Ensure the file path is validated before calling this function to provide better error messages to users
• Consider using pathlib.Path for more robust path handling across different operating systems

Tags

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