Improve support for headerless freezing (docs, error msgs, etc.)
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Peter Taoussanis
parent
e580fc6b2b
commit
5690a9611e
1 changed files with 48 additions and 31 deletions
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@ -383,67 +383,83 @@
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(defn- try-parse-header [ba]
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(when-let [[head-ba data-ba] (utils/ba-split ba 4)]
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(let [[head-sig* [meta-id]] (utils/ba-split head-ba 3)]
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(when (utils/ba= head-sig* head-sig)
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[data-ba (head-meta meta-id {:unrecognized-header? true})]))))
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(when (utils/ba= head-sig* head-sig) ; Appears to be well-formed
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[data-ba (head-meta meta-id {:unrecognized-meta? true})]))))
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(defn thaw
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"Deserializes a frozen object from given byte array to its original Clojure
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data type. Supports data frozen with current and all previous versions of
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Nippy. For custom types extend the Clojure reader or see `extend-thaw`."
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[^bytes ba & [{:keys [password compressor encryptor headerless-opts]
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:or {headerless-opts {:compressed? true}
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compressor snappy-compressor
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encryptor aes128-encryptor}
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data type. By default[1] supports data frozen with current and all previous
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versions of Nippy. For custom types extend the Clojure reader or see
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`extend-thaw`.
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[1] :headerless-meta provides a fallback facility for data frozen without a
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standard Nippy header (notably all Nippy v1 data). A default is provided for
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Nippy v1 thaw compatibility, but it's recommended that you _disable_ this
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fallback (`{:headerless-meta nil}`) if you're certain you won't be thawing
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headerless data."
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[^bytes ba & [{:keys [password compressor encryptor headerless-meta]
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:or {compressor snappy-compressor
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encryptor aes128-encryptor
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headerless-meta ; Recommend set to nil when possible
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{:version 1
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:compressed? true
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:encrypted? false}}
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:as opts}]]
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(let [;; headerless-opts may be nil, or contain any head-meta keys:
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headerless-opts (merge headerless-opts (:legacy-opts opts)) ; Deprecated
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(let [headerless-meta (merge headerless-meta (:legacy-opts opts)) ; Deprecated
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ex (fn [msg & [e]] (throw (Exception. (str "Thaw failed: " msg) e)))
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try-thaw-data
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(fn [data-ba {:keys [compressed? encrypted?] :as head-meta}]
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(let [password (when encrypted? password) ; => also head-meta
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compressor (if head-meta
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(when compressed? compressor)
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(when (:compressed? headerless-opts) snappy-compressor))]
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(fn [data-ba {:keys [compressed? encrypted?] :as _head-or-headerless-meta}]
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(let [password (when encrypted? password)
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compressor (when compressed? compressor)]
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(try
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(let [ba data-ba
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ba (if password (encryption/decrypt encryptor password ba) ba)
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ba (if compressor (compression/decompress compressor ba) ba)
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ba (if compressor (compression/decompress compressor ba) ba)
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stream (DataInputStream. (ByteArrayInputStream. ba))]
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(thaw-from-stream! stream))
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(catch Exception e
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(cond
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password (ex "Wrong password/encryptor?" e)
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password (if head-meta (ex "Wrong password/encryptor?" e)
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(ex "Unencrypted data?" e))
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compressor (if head-meta (ex "Encrypted data or wrong compressor?" e)
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(ex "Uncompressed data?" e))
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:else (if head-meta (ex "Corrupt data?" e)
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(ex "Compressed data?" e)))))))]
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(ex "Data may be unfrozen, corrupt, compressed &/or encrypted.")))))))]
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(if-let [[data-ba {:keys [unrecognized-header? compressed? encrypted?]
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(if-let [[data-ba {:keys [unrecognized-meta? compressed? encrypted?]
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:as head-meta}] (try-parse-header ba)]
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(cond ; Header _appears_ okay
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(and (not headerless-opts) unrecognized-header?) ; Conservative
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(ex "Unrecognized header. Data frozen with newer Nippy version?")
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(cond ; A well-formed header _appears_ to be present
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(and (not headerless-meta) ; Cautious. It's unlikely but possible the
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; header sig match was a fluke and not an
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; indication of a real, well-formed header.
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; May really be headerless.
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unrecognized-meta?)
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(ex "Unrecognized (but apparently well-formed) header. Data frozen with newer Nippy version?")
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;;; It's still possible below that the header match was a fluke, but it's
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;;; _very_ unlikely. Therefore _not_ going to incl.
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;;; `(not headerless-meta)` conditions below.
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(and compressed? (not compressor))
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(ex "Compressed data. Try again with compressor.")
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(ex "Compressed data? Try again with compressor.")
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(and encrypted? (not password))
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(if (::tools-thaw? opts) ::need-password
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(ex "Encrypted data. Try again with password."))
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(ex "Encrypted data? Try again with password."))
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:else (try (try-thaw-data data-ba head-meta)
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(catch Exception e
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(if headerless-opts
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(try (try-thaw-data ba nil)
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(if headerless-meta
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(try (try-thaw-data ba headerless-meta)
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(catch Exception _
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(throw e)))
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(throw e)))))
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;; Header definitely not okay
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(if headerless-opts
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(try-thaw-data ba nil)
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(ex "Unfrozen or corrupt data?")))))
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;; Well-formed header definitely not present
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(if headerless-meta
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(try-thaw-data ba headerless-meta)
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(ex "Data may be unfrozen, corrupt, compressed &/or encrypted.")))))
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(comment (thaw (freeze "hello"))
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(thaw (freeze "hello" {:compressor nil}))
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@ -624,4 +640,5 @@
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[ba & {:keys [compressed?]
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:or {compressed? true}}]
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(thaw ba {:headerless-opts {:compressed? compressed?}
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:compressor snappy-compressor
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:password nil}))
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