Add support for Zstandard (zstd) compression method

CHANGELOG.md

@@ -1,3 +1,10 @@
+## Zip 1.6.0
+
+* Added support for Zstandard (zstd) compression
+
+* Added a Cabal flag `-fdisable-zstd` to remove the zstd C library
+  dependency and hence support for Zstd entries.
+
 ## Zip 1.5.0
 
 * Added the `packDirRecur'` function.

Codec/Archive/Zip/Internal.hs

@@ -66,7 +66,11 @@ import System.IO
 import System.IO.Error (isDoesNotExistError)
 
 #ifdef ENABLE_BZIP2
-import qualified Data.Conduit.BZlib  as BZ
+import qualified Data.Conduit.BZlib as BZ
+#endif
+
+#ifdef ENABLE_ZSTD
+import qualified Data.Conduit.Zstd as Zstandard
 #endif
 
 ----------------------------------------------------------------------------
@@ -167,7 +171,7 @@ data MsDosTime = MsDosTime
 
 -- | “Version created by” to specify when writing archive data.
 zipVersion :: Version
-zipVersion = Version [4, 6] []
+zipVersion = Version [6, 3] []
 
 ----------------------------------------------------------------------------
 -- Higher-level operations
@@ -587,6 +591,13 @@ sinkData h compression = do
           BZ.bzip2 .| dataSink
 #else
       BZip2 -> throwM BZip2Unsupported
+#endif
+#ifdef ENABLE_ZSTD
+      Zstd ->
+        withCompression $
+          Zstandard.compress 1 .| dataSink
+#else
+      Zstd -> throwM ZstdUnsupported
 #endif
   return
     DataDescriptor
@@ -1086,6 +1097,7 @@ toCompressionMethod :: Word16 -> Maybe CompressionMethod
 toCompressionMethod 0 = Just Store
 toCompressionMethod 8 = Just Deflate
 toCompressionMethod 12 = Just BZip2
+toCompressionMethod 93 = Just Zstd
 toCompressionMethod _ = Nothing
 
 -- | Convert 'CompressionMethod' to its numeric representation as per .ZIP
@@ -1094,6 +1106,7 @@ fromCompressionMethod :: CompressionMethod -> Word16
 fromCompressionMethod Store = 0
 fromCompressionMethod Deflate = 8
 fromCompressionMethod BZip2 = 12
+fromCompressionMethod Zstd = 93
 
 -- | Check if an entry with these parameters needs Zip64 extension.
 needsZip64 :: EntryDescription -> Bool
@@ -1113,6 +1126,7 @@ getZipVersion zip64 m = max zip64ver mver
       Just Store -> [2, 0]
       Just Deflate -> [2, 0]
       Just BZip2 -> [4, 6]
+      Just Zstd -> [6, 3]
 
 -- | Return decompressing 'Conduit' corresponding to the given compression
 -- method.
@@ -1124,9 +1138,15 @@ decompressingPipe Store = C.awaitForever C.yield
 decompressingPipe Deflate = Z.decompress $ Z.WindowBits (-15)
 
 #ifdef ENABLE_BZIP2
-decompressingPipe BZip2   = BZ.bunzip2
+decompressingPipe BZip2 = BZ.bunzip2
 #else
-decompressingPipe BZip2   = throwM BZip2Unsupported
+decompressingPipe BZip2 = throwM BZip2Unsupported
+#endif
+
+#ifdef ENABLE_ZSTD
+decompressingPipe Zstd = Zstandard.decompress
+#else
+decompressingPipe Zstd = throwM ZstdUnsupported
 #endif
 
 -- | Sink that calculates CRC32 check sum for incoming stream.

Codec/Archive/Zip/Type.hs

@@ -182,6 +182,10 @@ data CompressionMethod
     Deflate
   | -- | Compressed using BZip2 algorithm
     BZip2
+  | -- | Compressed using Zstandard algorithm
+    --
+    -- @since 1.6.0
+    Zstd
   deriving (Show, Read, Eq, Ord, Enum, Bounded, Data, Typeable)
 
 ----------------------------------------------------------------------------
@@ -212,6 +216,13 @@ data ZipException
     --
     -- @since 1.3.0
   | BZip2Unsupported
+#endif
+#ifndef ENABLE_ZSTD
+    -- | Thrown when attempting to decompress a 'Zstd' entry and the
+    -- library is compiled without support for it.
+    --
+    -- @since 1.6.0
+  | ZstdUnsupported
 #endif
     ParsingFailed FilePath String
   deriving (Eq, Ord, Typeable)
@@ -228,4 +239,10 @@ instance Show ZipException where
     "the zip library has been built with bzip2 disabled."
 #endif
 
+#ifndef ENABLE_ZSTD
+  show ZstdUnsupported =
+    "Encountered a zipfile entry with Zstd compression, but " ++
+    "the zip library has been built with zstd disabled."
+#endif
+
 instance Exception ZipException

README.md

@@ -98,6 +98,7 @@ For reference, here is a [copy of the specification][specification].
 * Store (no compression, just store files “as is”)
 * [DEFLATE](deflate)
 * [Bzip2](bzip2)
+* [Zstandard](zstd)
 
 The best way to add a new compression method to the library is to write a
 conduit that will do the compression and publish it as a library. `zip` can
@@ -284,3 +285,4 @@ Distributed under BSD 3 clause license.
 [specification]: https://pkware.cachefly.net/webdocs/APPNOTE/APPNOTE-6.3.3.TXT
 [deflate]: https://en.wikipedia.org/wiki/DEFLATE
 [bzip2]: https://en.wikipedia.org/wiki/Bzip2
+[zstd]: https://en.wikipedia.org/wiki/Zstandard

tests/Main.hs

@@ -95,6 +95,9 @@ instance Arbitrary CompressionMethod where
       [ Store,
 #ifdef ENABLE_BZIP2
         BZip2,
+#endif
+#ifdef ENABLE_ZSTD
+        Zstd,
 #endif
         Deflate
       ]
@@ -386,6 +389,7 @@ versionNeededSpec =
               Store -> [2, 0]
               Deflate -> [2, 0]
               BZip2 -> [4, 6]
+              Zstd -> [6, 3]
           )
 
 addEntrySpec :: SpecWith FilePath

zip.cabal

@@ -32,6 +32,13 @@ flag disable-bzip2
     default:     False
     manual:      True
 
+flag disable-zstd
+    description:
+        Removes dependency on zstd C library and hence support for Zstandard entries.
+
+    default:     False
+    manual:      True
+
 library
     exposed-modules:
         Codec.Archive.Zip
@@ -67,6 +74,9 @@ library
     if !flag(disable-bzip2)
         build-depends: bzlib-conduit >=0.3 && <0.4
 
+    if !flag(disable-zstd)
+        build-depends: conduit-zstd >=0.0.2 && <0.1
+
     if flag(dev)
         cpp-options: -DHASKELL_ZIP_DEV_MODE
         ghc-options:
@@ -79,6 +89,9 @@ library
     if !flag(disable-bzip2)
         cpp-options: -DENABLE_BZIP2
 
+    if !flag(disable-zstd)
+        cpp-options: -DENABLE_ZSTD
+
     if os(windows)
         cpp-options: -DZIP_OS=0
 
@@ -132,3 +145,6 @@ test-suite tests
 
     if !flag(disable-bzip2)
         cpp-options: -DENABLE_BZIP2
+
+    if !flag(disable-zstd)
+        cpp-options: -DENABLE_ZSTD