rdiff-backup Warning: Metadata file has no digest for file

I looked all over the internet for threads with the same error complaining about missing SHA1 sums, but no one ever seemed to have any solutions. Therefore, I decided to look at the metadata files manually and write a script to simply "fill in" the entries that had missing SHA1 sums.

You can run the script by tying fix_metadata.py <your backup directory> - The original metadata file is backed up, but so far in my testing, this seems to fix the problem. I would still like to know why so many files had missing checksums to begin with.

#!/usr/bin/python3
# Usage: fix_metadata.py <backup folder>

import re, gzip, hashlib, os, time, sys

def digest(filename, chunk=1024**2):
    #Compute sha1 digest
    h = hashlib.sha1()
    print("Calculating hash of:", filename, end='')
    count = 0
    with open(filename, 'rb') as f:
        while True:
            data = f.read(chunk)
            if data:
                h.update(data)
                count += 1
                if not count % 100:
                    print('.', end='', flush=True)
            else:
                print()
                return h.hexdigest()


os.chdir(sys.argv[1])
for meta in os.listdir('rdiff-backup-data'):
    if 'metadata' in meta and meta.endswith('.gz'):
        meta = os.path.join('rdiff-backup-data', meta)
        fixed = meta+'.fixed'
        print("Processing:", meta)
        output = gzip.open(fixed, 'w')
    else:
        continue
    
    entry = []      #Entry for a single file
    sha1 = False    #Did we find a SHA1 hash?
    updated = 0     #Number of entries updated
    with gzip.open(meta, 'rt') as f:
        for line in f:
            if line.startswith('File '):
                if entry and not sha1:
                    filename = (re.sub('^File','', entry[0])).strip()
                    if os.path.exists(filename):
                        if os.path.isfile(filename):
                            entry.insert(3, '  SHA1Digest ' + digest(filename.strip())+'\n')
                            updated += 1
                    else:
                        print("Could not find file:", filename)
                output.write(''.join(entry).encode())
                entry = []      
                sha1 = False
            if line.startswith('  SHA1Digest'):
                sha1 = True
            entry.append(line)
        if entry:
            output.write(''.join(entry).encode())
        output.close()
    if updated:
        print(updated, "files fixed")
        os.rename(meta, meta + '.'+str(int(time.time())) + '.original.bak')
        os.rename(fixed, meta)
        print('Finished:', meta)
    else:
        os.remove(fixed)