Copyright	(c) Robbin C.
License	GPLv3
Maintainer	Robbin C.
Stability	unstable
Portability	portable
Safe Haskell	None
Language	Haskell2010

Codec.Archive.Zim.Parser

Contents

Functions
Exceptions
ZIM Header
ZIM Directory Entry
ZIM file format

Description

This is a library for parsing ZIM (http://openzim.org) files. ZIM files contain offline web content (eg, Wikipedia) which can be browsed locally without an Internet connection.

The API is meant to be intuitive for normal use-cases.

To get content for "A/index.htm" from ZIM file "file.zim":

> mimeContent <- "file.zim" `getContent` Url "A/index.htm"
> :t mimeContent
mimeContent :: Maybe (B8.ByteString, BL.ByteString)
> print mimeContent
Just ("text/html", "<html><head>...</html>")

The above will open the file, parse the ZIM header, lookup the MIME type and content of the URL, close the file and return the MIME type and content as a pair. Note that content is a lazy bytestring.

The above operation should suffice for a simple webserver serving a ZIM file. For finer control, it is possible to cache and reuse the file handle and the ZIM header.

> hdl <- openBinaryFile "file.zim" ReadMode
> hdr <- getHeader hdl
> :t hdr
hdr :: ZimHeader
> (hdl, hdr) `getContent` Url "A/index.htm"
Just ("text/html", "<html><head>...</html>")

ZIM files of Wikimedia Foundation (Wikipedia, Wikibooks, etc) can be found at http://ftpmirror.your.org/pub/kiwix/zim.

Below is a full example of a Scotty web server that serves a ZIM file (specified on command line) on localhost port 3000:

{-# LANGUAGE OverloadedStrings #-}

import Control.Monad.IO.Class (liftIO)
import Data.Text.Lazy (toStrict, fromStrict)
import Data.Text.Encoding (decodeUtf8, encodeUtf8)
import System.Environment (getArgs)
import Network.HTTP.Types.Status (status404)
import Web.Scotty
import Codec.Archive.Zim.Parser (getMainPageUrl, getContent, Url(..))

main :: IO ()
main = do
    [fp] <- getArgs
    scotty 3000 $ do
      get "/" (redirectToZimMainPage fp)
      get (regex "^/(./.*)$") (serveZimUrl fp)
      notFound $ text "Invalid URL!"

redirectToZimMainPage :: FilePath -> ActionM ()
redirectToZimMainPage fp = do
    res <- liftIO $ getMainPageUrl fp
    case res of
      Nothing -> do
        status status404
        text "This ZIM file has no main page specified!"
      Just (Url url) -> redirect . fromStrict $ decodeUtf8 url

serveZimUrl :: FilePath -> ActionM ()
serveZimUrl fp = do
    url <- (encodeUtf8 . toStrict) <$> param "1"
    res <- liftIO $ fp `getContent` Url url
    case res of
      Nothing -> do
        liftIO . putStrLn $ "Invalid URL: " ++ show url
        status status404
        text $ "Invalid URL!"
      Just (mimeType, content) -> do
        liftIO . putStrLn $ "Serving: " ++ show url
        setHeader "Content-Type" (fromStrict $ decodeUtf8 mimeType)
        raw content

Feedback and contributions are welcome on http://github.com/robbinch/zim-parser.

Synopsis

Functions

getHeader :: RunZim h => h -> IO ZimHeader #

getMimeList :: RunZim h => h -> IO MimeList #

getDE :: (ZimGetDE k, RunZim h) => h -> k -> IO ZimDirEnt #

getMainPageUrl :: RunZim h => h -> IO (Maybe Url) #

Returns URL of main page in ZIM. This URL can be used for redirecting to the actual page.

getCluster :: RunZim h => h -> ClusterNumber -> IO Cluster #

getBlob :: RunZim h => h -> (ClusterNumber, BlobNumber) -> IO Blob #

getContent :: (ZimGetContent k, RunZim h) => h -> k -> IO (Maybe (ByteString, ByteString)) #

Get (MIME type, Content). Note that Content is lazy.

searchDE :: (ZimSearchDE k, RunZim h) => h -> k -> IO [(Int, ZimDirEnt)] #

Search for a Directory Entry on a RunZim. When searching for a:

Url: Returns either 0 (not found) or 1 element.
Title: Returns either 0 (not found) or 1 element.
TitlePrefix: Returns either 0 (not found) or 2 elements corresponding to lower and upper bound of titles containing the prefix.

type MimeList = Array Int ByteString #

List of Mime Types

mkNsTitle :: Char -> ByteString -> Title #

Construct a Title with a Namespace.

mkNsTitlePrefix :: Char -> ByteString -> TitlePrefix #

Construct a TitlePrefix with a Namespace.

mkNsUrl :: Char -> ByteString -> Url #

Construct a Url with a Namespace.

class RunZim h #

Instances of this class represent a Zim File and are able to perform ZIM operations (getMimeList, getContent, etc). Valid instances include a Handle to a ZIM file, a FilePath to a ZIM file, or a (Handle, ZimHeader) where ZimHeader is parsed previously (so it does not need to be reparsed).

Minimal complete definition

runZim

Instances

RunZim Handle #
Methods runZim :: Handle -> (Handle -> ZimHeader -> IO a) -> IO a
RunZim FilePath #
Methods runZim :: FilePath -> (Handle -> ZimHeader -> IO a) -> IO a
RunZim (Handle, ZimHeader) #
Methods runZim :: (Handle, ZimHeader) -> (Handle -> ZimHeader -> IO a) -> IO a

class ZimGetDE k where #

Minimal complete definition

getDE

Methods

getDE :: RunZim h => h -> k -> IO ZimDirEnt #

Instances

ZimGetDE TitleIndex #
Methods getDE :: RunZim h => h -> TitleIndex -> IO ZimDirEnt #
ZimGetDE UrlIndex #
Methods getDE :: RunZim h => h -> UrlIndex -> IO ZimDirEnt #

class ZimSearchDE k where #

Minimal complete definition

searchDE

Methods

searchDE :: RunZim h => h -> k -> IO [(Int, ZimDirEnt)] #

Search for a Directory Entry on a RunZim. When searching for a:

Url: Returns either 0 (not found) or 1 element.
Title: Returns either 0 (not found) or 1 element.
TitlePrefix: Returns either 0 (not found) or 2 elements corresponding to lower and upper bound of titles containing the prefix.

Instances

ZimSearchDE TitlePrefix #
Methods searchDE :: RunZim h => h -> TitlePrefix -> IO [(Int, ZimDirEnt)] #
ZimSearchDE Title #
Methods searchDE :: RunZim h => h -> Title -> IO [(Int, ZimDirEnt)] #
ZimSearchDE Url #
Methods searchDE :: RunZim h => h -> Url -> IO [(Int, ZimDirEnt)] #

class ZimGetContent k where #

Minimal complete definition

getContent

Methods

getContent :: RunZim h => h -> k -> IO (Maybe (ByteString, ByteString)) #

Get (MIME type, Content). Note that Content is lazy.

Instances

ZimGetContent Title #
Methods getContent :: RunZim h => h -> Title -> IO (Maybe (ByteString, ByteString)) #
ZimGetContent Url #
Methods getContent :: RunZim h => h -> Url -> IO (Maybe (ByteString, ByteString)) #
ZimGetContent TitleIndex #
Methods getContent :: RunZim h => h -> TitleIndex -> IO (Maybe (ByteString, ByteString)) #
ZimGetContent UrlIndex #
Methods getContent :: RunZim h => h -> UrlIndex -> IO (Maybe (ByteString, ByteString)) #
ZimGetContent ZimDirEnt #
Methods getContent :: RunZim h => h -> ZimDirEnt -> IO (Maybe (ByteString, ByteString)) #
ZimGetContent (MimeList, Title) #
Methods getContent :: RunZim h => h -> (MimeList, Title) -> IO (Maybe (ByteString, ByteString)) #
ZimGetContent (MimeList, Url) #
Methods getContent :: RunZim h => h -> (MimeList, Url) -> IO (Maybe (ByteString, ByteString)) #
ZimGetContent (MimeList, TitleIndex) #
Methods getContent :: RunZim h => h -> (MimeList, TitleIndex) -> IO (Maybe (ByteString, ByteString)) #
ZimGetContent (MimeList, UrlIndex) #
Methods getContent :: RunZim h => h -> (MimeList, UrlIndex) -> IO (Maybe (ByteString, ByteString)) #
ZimGetContent (MimeList, ZimDirEnt) #
Methods getContent :: RunZim h => h -> (MimeList, ZimDirEnt) -> IO (Maybe (ByteString, ByteString)) #

Exceptions

data ZimException #

Other than the below, ErrorCall can be thrown by LZMA library if there is a problem with decompression.

Constructors

ZimInvalidMagic	ZIM file has invalid magic number (anything other than 72173914).
ZimParseError String	There is an error in parsing.
ZimIncompleteInput	There is insufficient bytes required to parse.
ZimInvalidIndex Int	The given index (URL, title or cluster) is out of bounds for this ZIM file.

Instances

Show ZimException #
Methods showsPrec :: Int -> ZimException -> ShowS # show :: ZimException -> String # showList :: [ZimException] -> ShowS #
Exception ZimException #
Methods toException :: ZimException -> SomeException # fromException :: SomeException -> Maybe ZimException # displayException :: ZimException -> String #

ZIM Header

data ZimHeader #

See http://www.openzim.org/wiki/ZIM_file_format#Header for more details.

Constructors

ZimHeader

Fields

zimMagicNumber :: Int
Magic Number of file (somewhat superfluous as getZimHeader will throw an exception if magic number is anything other than 72173914)
zimVersion :: Int
Version of ZIM header
zimUuid :: ByteString
UUID of file
zimArticleCount :: Int
Number of articles
zimClusterCount :: Int
Number of clusters
zimUrlPtrPos :: Integer
Position of sorted URL pointers
zimTitlePtrPos :: Integer
Position of sorted Title pointers
zimClusterPtrPos :: Integer
Position of Cluster pointers
zimMimeListPos :: Integer
Position of MIME list
zimMainPage :: Maybe Int
Index of main page
zimLayoutPage :: Maybe Int
Index of layout page
zimChecksumPos :: Integer
Position of MD5 checksum

Instances

Eq ZimHeader #
Methods (==) :: ZimHeader -> ZimHeader -> Bool # (/=) :: ZimHeader -> ZimHeader -> Bool #
Show ZimHeader #
Methods showsPrec :: Int -> ZimHeader -> ShowS # show :: ZimHeader -> String # showList :: [ZimHeader] -> ShowS #
RunZim (Handle, ZimHeader) #
Methods runZim :: (Handle, ZimHeader) -> (Handle -> ZimHeader -> IO a) -> IO a

ZIM Directory Entry

data ZimDirEntType #

There are 4 types of directory entries. Most content in a ZIM file are usually ZimArticleEntry or ZimRedirectEntry.

Constructors

ZimArticleEntry
ZimRedirectEntry
ZimLinkTarget
ZimDeletedEntry

Instances

Eq ZimDirEntType #
Methods (==) :: ZimDirEntType -> ZimDirEntType -> Bool # (/=) :: ZimDirEntType -> ZimDirEntType -> Bool #
Show ZimDirEntType #
Methods showsPrec :: Int -> ZimDirEntType -> ShowS # show :: ZimDirEntType -> String # showList :: [ZimDirEntType] -> ShowS #

data ZimDirEnt #

See http://www.openzim.org/wiki/ZIM_file_format#Directory_Entries for more details.

Constructors

ZimDirEnt

Fields

zimDeType :: ZimDirEntType
Type of this Directory Entry
zimDeMimeType :: Int
Index into MIME list given by getZimMimeList
zimDeParameterLen :: Int
Parameter Length
zimDeNamespace :: Char
Namespace
zimDeRevision :: Int
Revision
zimDeRedirectIndex :: Maybe Int
Redirect Index (only applicable for ZimRedirectEntry)
zimDeClusterNumber :: Maybe Int
Content is stored in this Cluster Number (only applicable for ZimArticleEntry)
zimDeBlobNumber :: Maybe Int
Content is stored in this Blob Number (only applicable for ZimArticleEntry)
zimDeUrl :: ByteString
URL
zimDeTitle :: ByteString
Title

Instances

Eq ZimDirEnt #
Methods (==) :: ZimDirEnt -> ZimDirEnt -> Bool # (/=) :: ZimDirEnt -> ZimDirEnt -> Bool #
Show ZimDirEnt #
Methods showsPrec :: Int -> ZimDirEnt -> ShowS # show :: ZimDirEnt -> String # showList :: [ZimDirEnt] -> ShowS #
ZimGetContent ZimDirEnt #
Methods getContent :: RunZim h => h -> ZimDirEnt -> IO (Maybe (ByteString, ByteString)) #
ZimGetContent (MimeList, ZimDirEnt) #
Methods getContent :: RunZim h => h -> (MimeList, ZimDirEnt) -> IO (Maybe (ByteString, ByteString)) #

newtype UrlIndex #

Wrapper for URL index

Constructors

UrlIndex Int

Instances

Eq UrlIndex #
Methods (==) :: UrlIndex -> UrlIndex -> Bool # (/=) :: UrlIndex -> UrlIndex -> Bool #
Ord UrlIndex #
Methods compare :: UrlIndex -> UrlIndex -> Ordering # (<) :: UrlIndex -> UrlIndex -> Bool # (<=) :: UrlIndex -> UrlIndex -> Bool # (>) :: UrlIndex -> UrlIndex -> Bool # (>=) :: UrlIndex -> UrlIndex -> Bool # max :: UrlIndex -> UrlIndex -> UrlIndex # min :: UrlIndex -> UrlIndex -> UrlIndex #
Show UrlIndex #
Methods showsPrec :: Int -> UrlIndex -> ShowS # show :: UrlIndex -> String # showList :: [UrlIndex] -> ShowS #
ZimGetContent UrlIndex #
Methods getContent :: RunZim h => h -> UrlIndex -> IO (Maybe (ByteString, ByteString)) #
ZimGetDE UrlIndex #
Methods getDE :: RunZim h => h -> UrlIndex -> IO ZimDirEnt #
ZimGetContent (MimeList, UrlIndex) #
Methods getContent :: RunZim h => h -> (MimeList, UrlIndex) -> IO (Maybe (ByteString, ByteString)) #

newtype TitleIndex #

Wrapper for Title index

Constructors

TitleIndex Int

Instances

Eq TitleIndex #
Methods (==) :: TitleIndex -> TitleIndex -> Bool # (/=) :: TitleIndex -> TitleIndex -> Bool #
Ord TitleIndex #
Methods compare :: TitleIndex -> TitleIndex -> Ordering # (<) :: TitleIndex -> TitleIndex -> Bool # (<=) :: TitleIndex -> TitleIndex -> Bool # (>) :: TitleIndex -> TitleIndex -> Bool # (>=) :: TitleIndex -> TitleIndex -> Bool # max :: TitleIndex -> TitleIndex -> TitleIndex # min :: TitleIndex -> TitleIndex -> TitleIndex #
Show TitleIndex #
Methods showsPrec :: Int -> TitleIndex -> ShowS # show :: TitleIndex -> String # showList :: [TitleIndex] -> ShowS #
ZimGetContent TitleIndex #
Methods getContent :: RunZim h => h -> TitleIndex -> IO (Maybe (ByteString, ByteString)) #
ZimGetDE TitleIndex #
Methods getDE :: RunZim h => h -> TitleIndex -> IO ZimDirEnt #
ZimGetContent (MimeList, TitleIndex) #
Methods getContent :: RunZim h => h -> (MimeList, TitleIndex) -> IO (Maybe (ByteString, ByteString)) #

newtype ClusterNumber #

Wrapper for Cluster number

Constructors

ClusterNumber Int

Instances

Eq ClusterNumber #
Methods (==) :: ClusterNumber -> ClusterNumber -> Bool # (/=) :: ClusterNumber -> ClusterNumber -> Bool #
Ord ClusterNumber #
Methods compare :: ClusterNumber -> ClusterNumber -> Ordering # (<) :: ClusterNumber -> ClusterNumber -> Bool # (<=) :: ClusterNumber -> ClusterNumber -> Bool # (>) :: ClusterNumber -> ClusterNumber -> Bool # (>=) :: ClusterNumber -> ClusterNumber -> Bool # max :: ClusterNumber -> ClusterNumber -> ClusterNumber # min :: ClusterNumber -> ClusterNumber -> ClusterNumber #
Show ClusterNumber #
Methods showsPrec :: Int -> ClusterNumber -> ShowS # show :: ClusterNumber -> String # showList :: [ClusterNumber] -> ShowS #

newtype BlobNumber #

Wrapper for Blob number

Constructors

BlobNumber Int

Instances

Eq BlobNumber #
Methods (==) :: BlobNumber -> BlobNumber -> Bool # (/=) :: BlobNumber -> BlobNumber -> Bool #
Ord BlobNumber #
Methods compare :: BlobNumber -> BlobNumber -> Ordering # (<) :: BlobNumber -> BlobNumber -> Bool # (<=) :: BlobNumber -> BlobNumber -> Bool # (>) :: BlobNumber -> BlobNumber -> Bool # (>=) :: BlobNumber -> BlobNumber -> Bool # max :: BlobNumber -> BlobNumber -> BlobNumber # min :: BlobNumber -> BlobNumber -> BlobNumber #
Show BlobNumber #
Methods showsPrec :: Int -> BlobNumber -> ShowS # show :: BlobNumber -> String # showList :: [BlobNumber] -> ShowS #

newtype Cluster #

Wrapper for Cluster

Constructors

Cluster
Fields unCluster :: ByteString

newtype Blob #

Wrapper for Blob

Constructors

Blob
Fields unBlob :: ByteString

newtype Url #

Wrapper for Url

Constructors

Url ByteString

Instances

Eq Url #
Methods (==) :: Url -> Url -> Bool # (/=) :: Url -> Url -> Bool #
Ord Url #
Methods compare :: Url -> Url -> Ordering # (<) :: Url -> Url -> Bool # (<=) :: Url -> Url -> Bool # (>) :: Url -> Url -> Bool # (>=) :: Url -> Url -> Bool # max :: Url -> Url -> Url # min :: Url -> Url -> Url #
Show Url #
Methods showsPrec :: Int -> Url -> ShowS # show :: Url -> String # showList :: [Url] -> ShowS #
ZimSearchDE Url #
Methods searchDE :: RunZim h => h -> Url -> IO [(Int, ZimDirEnt)] #
ZimGetContent Url #
Methods getContent :: RunZim h => h -> Url -> IO (Maybe (ByteString, ByteString)) #
ZimGetContent (MimeList, Url) #
Methods getContent :: RunZim h => h -> (MimeList, Url) -> IO (Maybe (ByteString, ByteString)) #

data Title #

Wrapper for Title

Instances

Eq Title #
Methods (==) :: Title -> Title -> Bool # (/=) :: Title -> Title -> Bool #
Ord Title #
Methods compare :: Title -> Title -> Ordering # (<) :: Title -> Title -> Bool # (<=) :: Title -> Title -> Bool # (>) :: Title -> Title -> Bool # (>=) :: Title -> Title -> Bool # max :: Title -> Title -> Title # min :: Title -> Title -> Title #
Show Title #
Methods showsPrec :: Int -> Title -> ShowS # show :: Title -> String # showList :: [Title] -> ShowS #
ZimSearchDE Title #
Methods searchDE :: RunZim h => h -> Title -> IO [(Int, ZimDirEnt)] #
ZimGetContent Title #
Methods getContent :: RunZim h => h -> Title -> IO (Maybe (ByteString, ByteString)) #
ZimGetContent (MimeList, Title) #
Methods getContent :: RunZim h => h -> (MimeList, Title) -> IO (Maybe (ByteString, ByteString)) #

data TitlePrefix #

Wrapper for Title Prefix

Instances

Eq TitlePrefix #
Methods (==) :: TitlePrefix -> TitlePrefix -> Bool # (/=) :: TitlePrefix -> TitlePrefix -> Bool #
Ord TitlePrefix #
Methods compare :: TitlePrefix -> TitlePrefix -> Ordering # (<) :: TitlePrefix -> TitlePrefix -> Bool # (<=) :: TitlePrefix -> TitlePrefix -> Bool # (>) :: TitlePrefix -> TitlePrefix -> Bool # (>=) :: TitlePrefix -> TitlePrefix -> Bool # max :: TitlePrefix -> TitlePrefix -> TitlePrefix # min :: TitlePrefix -> TitlePrefix -> TitlePrefix #
Show TitlePrefix #
Methods showsPrec :: Int -> TitlePrefix -> ShowS # show :: TitlePrefix -> String # showList :: [TitlePrefix] -> ShowS #
ZimSearchDE TitlePrefix #
Methods searchDE :: RunZim h => h -> TitlePrefix -> IO [(Int, ZimDirEnt)] #

ZIM file format

Following is a short summary of the ZIM file format. The authoritative reference is at http://www.openzim.org/wiki/ZIM_file_format.

1. ZIM header

This is an 80-byte header (see ZimHeader). Among other things, it contains file offsets to the below.

2. List of MIME types

This is a sequence of null-terminated strings (eg. text/html, text/javascript). The last string is zero length, so the end always consists of 2 consecutive null bytes.

3. List of URLs

This is a sequence of 8-byte file offsets, each pointing to a directory entry. This list is sorted by the directory entries' URL.

4. List of Titles

This is a sequence of 4-byte indices, each pointing to a URL above (which in turn point to a directory entry). This list is sorted by the directory entries' Title.

5. Directory Entries

This is a sequence of Directory Entries (see ZimDirEnt). The first 2 bytes determine the type of this entry, which also determine the length. Contents include:

a. MIME type

This 2-byte field means:

0xffff: This directory entry is a ZimRedirectEntry.
0xfffe: This directory entry is a ZimLinkTarget.
0xfffd: This directory entry is a ZimDeletedEntry.
any other value: This directory entry is a ZimArticleEntry and this index into the MIME list from above determines its MIME type.

b. Namespace

This single character determines the directory entry's namespace. (eg. A for articles, I for images, etc.) The comprehensive list is at http://www.openzim.org/wiki/ZIM_file_format#Namespaces.

c. Cluster and Blob number

Only for ZimArticleEntry, this is the directory entry's Cluster and Blob number. The Cluster number is a 4-byte index into the list of Clusters below. The Blob number refers to a block inside the (decompressed) cluster. Together, they provide the content of this directory entry.

d. URL and Title

These 2 null-terminated strings represent the URL and Title of this directory entry respectively. If the Title is empty, it is taken to be the same as the URL.

6. List of Clusters

This is a list of 8-byte file offsets, each pointing to a cluster in the file. -- The end of a cluster is also the start of the next cluster. Therefore, the length of a cluster is the difference between the adjacent offsets. For the last cluster, the end is the Checksum file offset, as the Checksum is always the last 16 bytes of a ZIM file.

a. Compression Type

The first byte of the cluster determines if it is uncompressed (eg. PNG image) or compressed with LZMA (eg. HTML).

0 or 1: No compression
4: Compressed with LZMA

b. List of Blobs

This is a list of 4-byte offsets, each pointing inside this cluster. The end of a blob is also the start of the next blob. Therefore, the length of a blob is the difference between the adjacent offsets. The last offset points to the end of the data area so there is always one more offset than blobs.