Michilis
498d7d8a7d
Uploads skip per-gallery duplicates, checksums can be backfilled, and STORAGE_BACKEND plus sync tooling make switching storage backends safe.
32 lines
1022 B
Go
32 lines
1022 B
Go
// Package checksum defines the content hash used to spot duplicate photos and
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// the backfill that fills it in for photos uploaded before it existed.
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//
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// The hash is sha256 over the untouched original bytes, hex encoded, stored in
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// photos_photos.checksum. Duplicate scope is one gallery — the unique index is
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// on (gallery_id, checksum) — so the same image may still live in several
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// galleries, each with its own row and its own stored object.
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package checksum
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import (
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"crypto/sha256"
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"encoding/hex"
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"hash"
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"io"
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)
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// New returns a fresh hasher. Upload hashes as it spools the body, so it needs
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// the writer rather than a finished reader.
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func New() hash.Hash { return sha256.New() }
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// Format renders a hasher's digest the way it is stored.
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func Format(h hash.Hash) string { return hex.EncodeToString(h.Sum(nil)) }
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// Sum reads r to EOF and returns its digest.
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func Sum(r io.Reader) (string, error) {
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h := New()
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if _, err := io.Copy(h, r); err != nil {
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return "", err
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}
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return Format(h), nil
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}
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