<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html>
<head>
<!-- Generated by HsColour, http://www.cs.york.ac.uk/fp/darcs/hscolour/ -->
<title>src/System/FileArchive/GZip.hs</title>
<link type='text/css' rel='stylesheet' href='hscolour.css' />
</head>
<body>
<pre><a name="line-1"></a><span class='hs-comment'>{- arch-tag: GZip file support in Haskell
<a name="line-2"></a>Copyright (C) 2004 John Goerzen <jgoerzen@complete.org>
<a name="line-3"></a>
<a name="line-4"></a>This program is free software; you can redistribute it and/or modify
<a name="line-5"></a>it under the terms of the GNU General Public License as published by
<a name="line-6"></a>the Free Software Foundation; either version 2 of the License, or
<a name="line-7"></a>(at your option) any later version.
<a name="line-8"></a>
<a name="line-9"></a>This program is distributed in the hope that it will be useful,
<a name="line-10"></a>but WITHOUT ANY WARRANTY; without even the implied warranty of
<a name="line-11"></a>MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
<a name="line-12"></a>GNU General Public License for more details.
<a name="line-13"></a>
<a name="line-14"></a>You should have received a copy of the GNU General Public License
<a name="line-15"></a>along with this program; if not, write to the Free Software
<a name="line-16"></a>Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
<a name="line-17"></a>-}</span>
<a name="line-18"></a>
<a name="line-19"></a><span class='hs-comment'>{- |
<a name="line-20"></a> Module : System.FileArchive.GZip
<a name="line-21"></a> Copyright : Copyright (C) 2004 John Goerzen
<a name="line-22"></a> License : GNU GPL, version 2 or above
<a name="line-23"></a>
<a name="line-24"></a> Maintainer : John Goerzen <jgoerzen@complete.org>
<a name="line-25"></a> Stability : provisional
<a name="line-26"></a> Portability: portable
<a name="line-27"></a>
<a name="line-28"></a>GZip file decompression
<a name="line-29"></a>
<a name="line-30"></a>Copyright (c) 2004 John Goerzen, jgoerzen\@complete.org
<a name="line-31"></a>
<a name="line-32"></a>The GZip format is described in RFC1952.
<a name="line-33"></a>-}</span>
<a name="line-34"></a><span class='hs-keyword'>module</span> <span class='hs-conid'>System</span><span class='hs-varop'>.</span><span class='hs-conid'>FileArchive</span><span class='hs-varop'>.</span><span class='hs-conid'>GZip</span> <span class='hs-layout'>(</span>
<a name="line-35"></a> <span class='hs-comment'>-- * GZip Files</span>
<a name="line-36"></a> <span class='hs-comment'>-- $gzipfiles</span>
<a name="line-37"></a>
<a name="line-38"></a> <span class='hs-comment'>-- * Types</span>
<a name="line-39"></a> <span class='hs-conid'>Header</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <span class='hs-conid'>Section</span><span class='hs-layout'>,</span> <span class='hs-conid'>GZipError</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span>
<a name="line-40"></a> <span class='hs-conid'>Footer</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span>
<a name="line-41"></a> <span class='hs-comment'>-- * Whole-File Processing</span>
<a name="line-42"></a> <span class='hs-varid'>decompress</span><span class='hs-layout'>,</span>
<a name="line-43"></a> <span class='hs-varid'>hDecompress</span><span class='hs-layout'>,</span>
<a name="line-44"></a> <span class='hs-varid'>read_sections</span><span class='hs-layout'>,</span>
<a name="line-45"></a> <span class='hs-comment'>-- * Section Processing</span>
<a name="line-46"></a> <span class='hs-varid'>read_header</span><span class='hs-layout'>,</span>
<a name="line-47"></a> <span class='hs-varid'>read_section</span>
<a name="line-48"></a> <span class='hs-layout'>)</span>
<a name="line-49"></a> <span class='hs-keyword'>where</span>
<a name="line-50"></a>
<a name="line-51"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Compression</span><span class='hs-varop'>.</span><span class='hs-conid'>Inflate</span> <span class='hs-layout'>(</span><span class='hs-varid'>inflate_string_remainder</span><span class='hs-layout'>)</span>
<a name="line-52"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Hash</span><span class='hs-varop'>.</span><span class='hs-conid'>CRC32</span><span class='hs-varop'>.</span><span class='hs-conid'>GZip</span> <span class='hs-layout'>(</span><span class='hs-varid'>update_crc</span><span class='hs-layout'>)</span>
<a name="line-53"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Bits</span> <span class='hs-layout'>(</span><span class='hs-layout'>(</span><span class='hs-varop'>.&.</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-54"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>Monad</span><span class='hs-varop'>.</span><span class='hs-conid'>Error</span> <span class='hs-comment'>-- (Error(), strMsg, throwError)</span>
<a name="line-55"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Char</span> <span class='hs-layout'>(</span><span class='hs-varid'>ord</span><span class='hs-layout'>)</span>
<a name="line-56"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Word</span> <span class='hs-layout'>(</span><span class='hs-conid'>Word32</span><span class='hs-conid'>()</span><span class='hs-layout'>)</span>
<a name="line-57"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Bits</span><span class='hs-varop'>.</span><span class='hs-conid'>Utils</span> <span class='hs-layout'>(</span><span class='hs-varid'>fromBytes</span><span class='hs-layout'>)</span>
<a name="line-58"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>System</span><span class='hs-varop'>.</span><span class='hs-conid'>IO</span> <span class='hs-layout'>(</span><span class='hs-varid'>hGetContents</span><span class='hs-layout'>,</span> <span class='hs-varid'>hPutStr</span><span class='hs-layout'>,</span> <span class='hs-conid'>Handle</span><span class='hs-conid'>()</span><span class='hs-layout'>)</span>
<a name="line-59"></a>
<a name="line-60"></a><a name="GZipError"></a><span class='hs-keyword'>data</span> <span class='hs-conid'>GZipError</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>CRCError</span> <span class='hs-comment'>-- ^ CRC-32 check failed</span>
<a name="line-61"></a> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>NotGZIPFile</span> <span class='hs-comment'>-- ^ Couldn't find a GZip header</span>
<a name="line-62"></a> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>UnknownMethod</span> <span class='hs-comment'>-- ^ Compressed with something other than method 8 (deflate)</span>
<a name="line-63"></a> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>UnknownError</span> <span class='hs-conid'>String</span> <span class='hs-comment'>-- ^ Other problem arose</span>
<a name="line-64"></a> <span class='hs-keyword'>deriving</span> <span class='hs-layout'>(</span><span class='hs-conid'>Eq</span><span class='hs-layout'>,</span> <span class='hs-conid'>Show</span><span class='hs-layout'>)</span>
<a name="line-65"></a>
<a name="line-66"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Error</span> <span class='hs-conid'>GZipError</span> <span class='hs-keyword'>where</span>
<a name="line-67"></a> <span class='hs-varid'>noMsg</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>UnknownError</span> <span class='hs-str'>""</span>
<a name="line-68"></a> <span class='hs-varid'>strMsg</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>UnknownError</span>
<a name="line-69"></a>
<a name="line-70"></a><a name="magic"></a><span class='hs-comment'>-- | First two bytes of file</span>
<a name="line-71"></a><span class='hs-definition'>magic</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>String</span>
<a name="line-72"></a><span class='hs-definition'>magic</span> <span class='hs-keyglyph'>=</span> <span class='hs-str'>"\x1f\x8b"</span>
<a name="line-73"></a>
<a name="line-74"></a><a name="fFHCRC"></a><span class='hs-comment'>-- | Flags</span>
<a name="line-75"></a><span class='hs-definition'>fFHCRC</span><span class='hs-layout'>,</span> <span class='hs-varid'>fFEXTRA</span><span class='hs-layout'>,</span> <span class='hs-varid'>fFNAME</span><span class='hs-layout'>,</span> <span class='hs-varid'>fFCOMMENT</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Int</span>
<a name="line-76"></a><span class='hs-comment'>-- fFTEXT = 1 :: Int</span>
<a name="line-77"></a><span class='hs-definition'>fFHCRC</span> <span class='hs-keyglyph'>=</span> <span class='hs-num'>2</span>
<a name="line-78"></a><a name="fFEXTRA"></a><span class='hs-definition'>fFEXTRA</span> <span class='hs-keyglyph'>=</span> <span class='hs-num'>4</span>
<a name="line-79"></a><a name="fFNAME"></a><span class='hs-definition'>fFNAME</span> <span class='hs-keyglyph'>=</span> <span class='hs-num'>8</span>
<a name="line-80"></a><a name="fFCOMMENT"></a><span class='hs-definition'>fFCOMMENT</span> <span class='hs-keyglyph'>=</span> <span class='hs-num'>16</span>
<a name="line-81"></a>
<a name="line-82"></a><a name="Header"></a><span class='hs-comment'>{- | The data structure representing the GZip header. This occurs
<a name="line-83"></a>at the beginning of each 'Section' on disk. -}</span>
<a name="line-84"></a><a name="Header"></a><span class='hs-keyword'>data</span> <span class='hs-conid'>Header</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Header</span> <span class='hs-layout'>{</span>
<a name="line-85"></a> <span class='hs-varid'>method</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Int</span><span class='hs-layout'>,</span> <span class='hs-comment'>-- ^ Compression method. Only 8 is defined at present.</span>
<a name="line-86"></a> <span class='hs-varid'>flags</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Int</span><span class='hs-layout'>,</span>
<a name="line-87"></a> <span class='hs-varid'>extra</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Maybe</span> <span class='hs-conid'>String</span><span class='hs-layout'>,</span>
<a name="line-88"></a> <span class='hs-varid'>filename</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Maybe</span> <span class='hs-conid'>String</span><span class='hs-layout'>,</span>
<a name="line-89"></a> <span class='hs-varid'>comment</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Maybe</span> <span class='hs-conid'>String</span><span class='hs-layout'>,</span>
<a name="line-90"></a> <span class='hs-varid'>mtime</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Word32</span><span class='hs-layout'>,</span> <span class='hs-comment'>-- ^ Modification time of the original file</span>
<a name="line-91"></a> <span class='hs-varid'>xfl</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Int</span><span class='hs-layout'>,</span> <span class='hs-comment'>-- ^ Extra flags</span>
<a name="line-92"></a> <span class='hs-varid'>os</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Int</span> <span class='hs-comment'>-- ^ Creating operating system</span>
<a name="line-93"></a> <span class='hs-layout'>}</span> <span class='hs-keyword'>deriving</span> <span class='hs-layout'>(</span><span class='hs-conid'>Eq</span><span class='hs-layout'>,</span> <span class='hs-conid'>Show</span><span class='hs-layout'>)</span>
<a name="line-94"></a>
<a name="line-95"></a><a name="Footer"></a><span class='hs-comment'>{- | Stored on-disk at the end of each section. -}</span>
<a name="line-96"></a><a name="Footer"></a><span class='hs-keyword'>data</span> <span class='hs-conid'>Footer</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Footer</span> <span class='hs-layout'>{</span>
<a name="line-97"></a> <span class='hs-varid'>size</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Word32</span><span class='hs-layout'>,</span> <span class='hs-comment'>-- ^ The size of the original, decompressed data</span>
<a name="line-98"></a> <span class='hs-varid'>crc32</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Word32</span><span class='hs-layout'>,</span> <span class='hs-comment'>-- ^ The stored GZip CRC-32 of the original, decompressed data</span>
<a name="line-99"></a> <span class='hs-varid'>crc32valid</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Bool</span> <span class='hs-comment'>-- ^ Whether or not the stored CRC-32 matches the calculated CRC-32 of the data</span>
<a name="line-100"></a> <span class='hs-layout'>}</span>
<a name="line-101"></a>
<a name="line-102"></a><a name="Section"></a><span class='hs-comment'>{- | A section represents a compressed component in a GZip file.
<a name="line-103"></a>Every GZip file has at least one. -}</span>
<a name="line-104"></a><a name="Section"></a><span class='hs-keyword'>type</span> <span class='hs-conid'>Section</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-conid'>Header</span><span class='hs-layout'>,</span> <span class='hs-conid'>String</span><span class='hs-layout'>,</span> <span class='hs-conid'>Footer</span><span class='hs-layout'>)</span>
<a name="line-105"></a>
<a name="line-106"></a><a name="split1"></a><span class='hs-definition'>split1</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-conid'>Char</span><span class='hs-layout'>,</span> <span class='hs-conid'>String</span><span class='hs-layout'>)</span>
<a name="line-107"></a><span class='hs-definition'>split1</span> <span class='hs-varid'>s</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-varid'>head</span> <span class='hs-varid'>s</span><span class='hs-layout'>,</span> <span class='hs-varid'>tail</span> <span class='hs-varid'>s</span><span class='hs-layout'>)</span>
<a name="line-108"></a>
<a name="line-109"></a><span class='hs-comment'>{- | Read a GZip file, decompressing all sections found.
<a name="line-110"></a>
<a name="line-111"></a>Writes the decompressed data stream to the given output handle.
<a name="line-112"></a>
<a name="line-113"></a>Returns Nothing if the action was successful, or Just GZipError if there
<a name="line-114"></a>was a problem. If there was a problem, the data written to the output
<a name="line-115"></a>handle should be discarded.
<a name="line-116"></a>-}</span>
<a name="line-117"></a>
<a name="line-118"></a><a name="hDecompress"></a><span class='hs-definition'>hDecompress</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Handle</span> <span class='hs-comment'>-- ^ Input handle</span>
<a name="line-119"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Handle</span> <span class='hs-comment'>-- ^ Output handle</span>
<a name="line-120"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IO</span> <span class='hs-layout'>(</span><span class='hs-conid'>Maybe</span> <span class='hs-conid'>GZipError</span><span class='hs-layout'>)</span>
<a name="line-121"></a><span class='hs-definition'>hDecompress</span> <span class='hs-varid'>infd</span> <span class='hs-varid'>outfd</span> <span class='hs-keyglyph'>=</span>
<a name="line-122"></a> <span class='hs-keyword'>do</span> <span class='hs-varid'>inc</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>hGetContents</span> <span class='hs-varid'>infd</span>
<a name="line-123"></a> <span class='hs-keyword'>let</span> <span class='hs-layout'>(</span><span class='hs-varid'>outstr</span><span class='hs-layout'>,</span> <span class='hs-varid'>err</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>decompress</span> <span class='hs-varid'>inc</span>
<a name="line-124"></a> <span class='hs-varid'>hPutStr</span> <span class='hs-varid'>outfd</span> <span class='hs-varid'>outstr</span>
<a name="line-125"></a> <span class='hs-varid'>return</span> <span class='hs-varid'>err</span>
<a name="line-126"></a>
<a name="line-127"></a><a name="decompress"></a><span class='hs-comment'>{- | Read a GZip file, decompressing all sections that are found.
<a name="line-128"></a>
<a name="line-129"></a>Returns a decompresed data stream and Nothing, or an unreliable string
<a name="line-130"></a>and Just (error). If you get anything other than Nothing, the String
<a name="line-131"></a>returned should be discarded.
<a name="line-132"></a>-}</span>
<a name="line-133"></a><span class='hs-definition'>decompress</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-conid'>String</span><span class='hs-layout'>,</span> <span class='hs-conid'>Maybe</span> <span class='hs-conid'>GZipError</span><span class='hs-layout'>)</span>
<a name="line-134"></a><span class='hs-comment'>{-
<a name="line-135"></a>decompress s =
<a name="line-136"></a> do x <- read_header s
<a name="line-137"></a> let rem = snd x
<a name="line-138"></a> return $ inflate_string rem
<a name="line-139"></a>-}</span>
<a name="line-140"></a><span class='hs-definition'>decompress</span> <span class='hs-varid'>s</span> <span class='hs-keyglyph'>=</span>
<a name="line-141"></a> <span class='hs-keyword'>let</span> <span class='hs-varid'>procs</span> <span class='hs-keyglyph'>::</span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>Section</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-conid'>String</span><span class='hs-layout'>,</span> <span class='hs-conid'>Bool</span><span class='hs-layout'>)</span>
<a name="line-142"></a> <span class='hs-varid'>procs</span> <span class='hs-conid'>[]</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-conid'>[]</span><span class='hs-layout'>,</span> <span class='hs-conid'>True</span><span class='hs-layout'>)</span>
<a name="line-143"></a> <span class='hs-varid'>procs</span> <span class='hs-layout'>(</span><span class='hs-layout'>(</span><span class='hs-keyword'>_</span><span class='hs-layout'>,</span> <span class='hs-varid'>content</span><span class='hs-layout'>,</span> <span class='hs-varid'>foot</span><span class='hs-layout'>)</span><span class='hs-conop'>:</span><span class='hs-varid'>xs</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span>
<a name="line-144"></a> <span class='hs-keyword'>let</span> <span class='hs-layout'>(</span><span class='hs-varid'>nexth</span><span class='hs-layout'>,</span> <span class='hs-varid'>nextb</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>procs</span> <span class='hs-varid'>xs</span> <span class='hs-keyword'>in</span>
<a name="line-145"></a> <span class='hs-layout'>(</span><span class='hs-varid'>content</span> <span class='hs-varop'>++</span> <span class='hs-varid'>nexth</span><span class='hs-layout'>,</span> <span class='hs-layout'>(</span><span class='hs-varid'>crc32valid</span> <span class='hs-varid'>foot</span><span class='hs-layout'>)</span> <span class='hs-varop'>&&</span> <span class='hs-varid'>nextb</span><span class='hs-layout'>)</span>
<a name="line-146"></a> <span class='hs-keyword'>in</span> <span class='hs-keyword'>case</span> <span class='hs-varid'>read_sections</span> <span class='hs-varid'>s</span> <span class='hs-keyword'>of</span>
<a name="line-147"></a> <span class='hs-conid'>Left</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-str'>""</span><span class='hs-layout'>,</span> <span class='hs-conid'>Just</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span>
<a name="line-148"></a> <span class='hs-conid'>Right</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>let</span> <span class='hs-layout'>(</span><span class='hs-varid'>decomp</span><span class='hs-layout'>,</span> <span class='hs-varid'>iscrcok</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>procs</span> <span class='hs-varid'>x</span>
<a name="line-149"></a> <span class='hs-keyword'>in</span> <span class='hs-layout'>(</span><span class='hs-varid'>decomp</span><span class='hs-layout'>,</span> <span class='hs-keyword'>if</span> <span class='hs-varid'>iscrcok</span> <span class='hs-keyword'>then</span> <span class='hs-conid'>Nothing</span> <span class='hs-keyword'>else</span> <span class='hs-conid'>Just</span> <span class='hs-conid'>CRCError</span><span class='hs-layout'>)</span>
<a name="line-150"></a>
<a name="line-151"></a><span class='hs-comment'>{-
<a name="line-152"></a>decompress s = do x <- read_sections s
<a name="line-153"></a> return $ concatMap (\(_, x, _) -> x) x
<a name="line-154"></a>-}</span>
<a name="line-155"></a>
<a name="line-156"></a><a name="read_sections"></a><span class='hs-comment'>-- | Read all sections.</span>
<a name="line-157"></a><span class='hs-definition'>read_sections</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Either</span> <span class='hs-conid'>GZipError</span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>Section</span><span class='hs-keyglyph'>]</span>
<a name="line-158"></a><span class='hs-definition'>read_sections</span> <span class='hs-conid'>[]</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Right</span> <span class='hs-conid'>[]</span>
<a name="line-159"></a><span class='hs-definition'>read_sections</span> <span class='hs-varid'>s</span> <span class='hs-keyglyph'>=</span>
<a name="line-160"></a> <span class='hs-keyword'>do</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>read_section</span> <span class='hs-varid'>s</span>
<a name="line-161"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>x</span> <span class='hs-keyword'>of</span>
<a name="line-162"></a> <span class='hs-layout'>(</span><span class='hs-varid'>sect</span><span class='hs-layout'>,</span> <span class='hs-varid'>remain</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span>
<a name="line-163"></a> <span class='hs-keyword'>do</span> <span class='hs-varid'>next</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>read_sections</span> <span class='hs-varid'>remain</span>
<a name="line-164"></a> <span class='hs-varid'>return</span> <span class='hs-varop'>$</span> <span class='hs-varid'>sect</span> <span class='hs-conop'>:</span> <span class='hs-varid'>next</span>
<a name="line-165"></a>
<a name="line-166"></a><a name="parseword"></a><span class='hs-definition'>parseword</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Word32</span>
<a name="line-167"></a><span class='hs-definition'>parseword</span> <span class='hs-varid'>s</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>fromBytes</span> <span class='hs-varop'>$</span> <span class='hs-varid'>map</span> <span class='hs-layout'>(</span><span class='hs-varid'>fromIntegral</span> <span class='hs-varop'>.</span> <span class='hs-varid'>ord</span><span class='hs-layout'>)</span> <span class='hs-varop'>$</span> <span class='hs-varid'>reverse</span> <span class='hs-varid'>s</span>
<a name="line-168"></a>
<a name="line-169"></a><a name="read_section"></a><span class='hs-comment'>-- | Read one section, returning (ThisSection, Remainder)</span>
<a name="line-170"></a><span class='hs-definition'>read_section</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Either</span> <span class='hs-conid'>GZipError</span> <span class='hs-layout'>(</span><span class='hs-conid'>Section</span><span class='hs-layout'>,</span> <span class='hs-conid'>String</span><span class='hs-layout'>)</span>
<a name="line-171"></a><span class='hs-definition'>read_section</span> <span class='hs-varid'>s</span> <span class='hs-keyglyph'>=</span>
<a name="line-172"></a> <span class='hs-keyword'>do</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>read_header</span> <span class='hs-varid'>s</span>
<a name="line-173"></a> <span class='hs-keyword'>let</span> <span class='hs-varid'>headerrem</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>snd</span> <span class='hs-varid'>x</span>
<a name="line-174"></a> <span class='hs-keyword'>let</span> <span class='hs-layout'>(</span><span class='hs-varid'>decompressed</span><span class='hs-layout'>,</span> <span class='hs-varid'>crc</span><span class='hs-layout'>,</span> <span class='hs-varid'>remainder</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>read_data</span> <span class='hs-varid'>headerrem</span>
<a name="line-175"></a> <span class='hs-keyword'>let</span> <span class='hs-layout'>(</span><span class='hs-varid'>crc32str</span><span class='hs-layout'>,</span> <span class='hs-varid'>rm</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>splitAt</span> <span class='hs-num'>4</span> <span class='hs-varid'>remainder</span>
<a name="line-176"></a> <span class='hs-keyword'>let</span> <span class='hs-layout'>(</span><span class='hs-varid'>sizestr</span><span class='hs-layout'>,</span> <span class='hs-varid'>rem2</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>splitAt</span> <span class='hs-num'>4</span> <span class='hs-varid'>rm</span>
<a name="line-177"></a> <span class='hs-keyword'>let</span> <span class='hs-varid'>filecrc32</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>parseword</span> <span class='hs-varid'>crc32str</span>
<a name="line-178"></a> <span class='hs-keyword'>let</span> <span class='hs-varid'>filesize</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>parseword</span> <span class='hs-varid'>sizestr</span>
<a name="line-179"></a> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-layout'>(</span><span class='hs-varid'>fst</span> <span class='hs-varid'>x</span><span class='hs-layout'>,</span> <span class='hs-varid'>decompressed</span><span class='hs-layout'>,</span>
<a name="line-180"></a> <span class='hs-conid'>Footer</span> <span class='hs-layout'>{</span><span class='hs-varid'>size</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>filesize</span><span class='hs-layout'>,</span> <span class='hs-varid'>crc32</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>filecrc32</span><span class='hs-layout'>,</span>
<a name="line-181"></a> <span class='hs-varid'>crc32valid</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>filecrc32</span> <span class='hs-varop'>==</span> <span class='hs-varid'>crc</span><span class='hs-layout'>}</span><span class='hs-layout'>)</span>
<a name="line-182"></a> <span class='hs-layout'>,</span><span class='hs-varid'>rem2</span><span class='hs-layout'>)</span>
<a name="line-183"></a>
<a name="line-184"></a><a name="read_data"></a><span class='hs-comment'>-- | Read the file's compressed data, returning</span>
<a name="line-185"></a><span class='hs-comment'>-- (Decompressed, Calculated CRC32, Remainder)</span>
<a name="line-186"></a><span class='hs-definition'>read_data</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-conid'>String</span><span class='hs-layout'>,</span> <span class='hs-conid'>Word32</span><span class='hs-layout'>,</span> <span class='hs-conid'>String</span><span class='hs-layout'>)</span>
<a name="line-187"></a><span class='hs-definition'>read_data</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>=</span>
<a name="line-188"></a> <span class='hs-keyword'>let</span> <span class='hs-layout'>(</span><span class='hs-varid'>decompressed1</span><span class='hs-layout'>,</span> <span class='hs-varid'>remainder</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>inflate_string_remainder</span> <span class='hs-varid'>x</span>
<a name="line-189"></a> <span class='hs-layout'>(</span><span class='hs-varid'>decompressed</span><span class='hs-layout'>,</span> <span class='hs-varid'>crc32</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>read_data_internal</span> <span class='hs-varid'>decompressed1</span> <span class='hs-num'>0</span>
<a name="line-190"></a> <span class='hs-keyword'>in</span>
<a name="line-191"></a> <span class='hs-layout'>(</span><span class='hs-varid'>decompressed</span><span class='hs-layout'>,</span> <span class='hs-varid'>crc32</span><span class='hs-layout'>,</span> <span class='hs-varid'>remainder</span><span class='hs-layout'>)</span>
<a name="line-192"></a> <span class='hs-keyword'>where</span>
<a name="line-193"></a> <span class='hs-varid'>read_data_internal</span> <span class='hs-conid'>[]</span> <span class='hs-varid'>ck</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-conid'>[]</span><span class='hs-layout'>,</span> <span class='hs-varid'>ck</span><span class='hs-layout'>)</span>
<a name="line-194"></a> <span class='hs-varid'>read_data_internal</span> <span class='hs-layout'>(</span><span class='hs-varid'>y</span><span class='hs-conop'>:</span><span class='hs-varid'>ys</span><span class='hs-layout'>)</span> <span class='hs-varid'>ck</span> <span class='hs-keyglyph'>=</span>
<a name="line-195"></a> <span class='hs-keyword'>let</span> <span class='hs-varid'>newcrc</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>update_crc</span> <span class='hs-varid'>ck</span> <span class='hs-varid'>y</span>
<a name="line-196"></a> <span class='hs-varid'>n</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>newcrc</span> <span class='hs-varop'>`seq`</span> <span class='hs-varid'>read_data_internal</span> <span class='hs-varid'>ys</span> <span class='hs-varid'>newcrc</span>
<a name="line-197"></a> <span class='hs-keyword'>in</span>
<a name="line-198"></a> <span class='hs-layout'>(</span><span class='hs-varid'>y</span> <span class='hs-conop'>:</span> <span class='hs-varid'>fst</span> <span class='hs-varid'>n</span><span class='hs-layout'>,</span> <span class='hs-varid'>snd</span> <span class='hs-varid'>n</span><span class='hs-layout'>)</span>
<a name="line-199"></a>
<a name="line-200"></a>
<a name="line-201"></a>
<a name="line-202"></a><a name="read_header"></a><span class='hs-comment'>{- | Read the GZip header. Return (Header, Remainder).
<a name="line-203"></a>-}</span>
<a name="line-204"></a><span class='hs-definition'>read_header</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Either</span> <span class='hs-conid'>GZipError</span> <span class='hs-layout'>(</span><span class='hs-conid'>Header</span><span class='hs-layout'>,</span> <span class='hs-conid'>String</span><span class='hs-layout'>)</span>
<a name="line-205"></a><span class='hs-definition'>read_header</span> <span class='hs-varid'>s</span> <span class='hs-keyglyph'>=</span>
<a name="line-206"></a> <span class='hs-keyword'>let</span> <span class='hs-varid'>ok</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Right</span> <span class='hs-str'>"ok"</span> <span class='hs-keyword'>in</span>
<a name="line-207"></a> <span class='hs-keyword'>do</span> <span class='hs-keyword'>let</span> <span class='hs-layout'>(</span><span class='hs-varid'>mag</span><span class='hs-layout'>,</span> <span class='hs-varid'>rem</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>splitAt</span> <span class='hs-num'>2</span> <span class='hs-varid'>s</span>
<a name="line-208"></a> <span class='hs-keyword'>if</span> <span class='hs-varid'>mag</span> <span class='hs-varop'>/=</span> <span class='hs-varid'>magic</span>
<a name="line-209"></a> <span class='hs-keyword'>then</span> <span class='hs-varid'>throwError</span> <span class='hs-conid'>NotGZIPFile</span>
<a name="line-210"></a> <span class='hs-keyword'>else</span> <span class='hs-varid'>ok</span>
<a name="line-211"></a> <span class='hs-keyword'>let</span> <span class='hs-layout'>(</span><span class='hs-varid'>method</span><span class='hs-layout'>,</span> <span class='hs-varid'>rem2</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>split1</span> <span class='hs-varid'>rem</span>
<a name="line-212"></a> <span class='hs-keyword'>if</span> <span class='hs-layout'>(</span><span class='hs-varid'>ord</span><span class='hs-layout'>(</span><span class='hs-varid'>method</span><span class='hs-layout'>)</span> <span class='hs-varop'>/=</span> <span class='hs-num'>8</span><span class='hs-layout'>)</span>
<a name="line-213"></a> <span class='hs-keyword'>then</span> <span class='hs-varid'>throwError</span> <span class='hs-conid'>UnknownMethod</span>
<a name="line-214"></a> <span class='hs-keyword'>else</span> <span class='hs-varid'>ok</span>
<a name="line-215"></a> <span class='hs-keyword'>let</span> <span class='hs-layout'>(</span><span class='hs-varid'>flag_S</span><span class='hs-layout'>,</span> <span class='hs-varid'>rem3</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>split1</span> <span class='hs-varid'>rem2</span>
<a name="line-216"></a> <span class='hs-keyword'>let</span> <span class='hs-varid'>flag</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>ord</span> <span class='hs-varid'>flag_S</span>
<a name="line-217"></a> <span class='hs-keyword'>let</span> <span class='hs-layout'>(</span><span class='hs-varid'>mtimea</span><span class='hs-layout'>,</span> <span class='hs-varid'>rem3a</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>splitAt</span> <span class='hs-num'>4</span> <span class='hs-varid'>rem3</span>
<a name="line-218"></a> <span class='hs-keyword'>let</span> <span class='hs-varid'>mtime</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>parseword</span> <span class='hs-varid'>mtimea</span>
<a name="line-219"></a> <span class='hs-keyword'>let</span> <span class='hs-layout'>(</span><span class='hs-varid'>xfla</span><span class='hs-layout'>,</span> <span class='hs-varid'>rem3b</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>split1</span> <span class='hs-varid'>rem3a</span>
<a name="line-220"></a> <span class='hs-keyword'>let</span> <span class='hs-varid'>xfl</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>ord</span> <span class='hs-varid'>xfla</span>
<a name="line-221"></a> <span class='hs-keyword'>let</span> <span class='hs-layout'>(</span><span class='hs-varid'>osa</span><span class='hs-layout'>,</span> <span class='hs-keyword'>_</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>split1</span> <span class='hs-varid'>rem3b</span>
<a name="line-222"></a> <span class='hs-keyword'>let</span> <span class='hs-varid'>os</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>ord</span> <span class='hs-varid'>osa</span>
<a name="line-223"></a> <span class='hs-comment'>-- skip modtime (4), extraflag (1), and os (1)</span>
<a name="line-224"></a> <span class='hs-keyword'>let</span> <span class='hs-varid'>rem4</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>drop</span> <span class='hs-num'>6</span> <span class='hs-varid'>rem3</span>
<a name="line-225"></a>
<a name="line-226"></a> <span class='hs-keyword'>let</span> <span class='hs-layout'>(</span><span class='hs-varid'>extra</span><span class='hs-layout'>,</span> <span class='hs-varid'>rem5</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span>
<a name="line-227"></a> <span class='hs-keyword'>if</span> <span class='hs-layout'>(</span><span class='hs-varid'>flag</span> <span class='hs-varop'>.&.</span> <span class='hs-varid'>fFEXTRA</span> <span class='hs-varop'>/=</span> <span class='hs-num'>0</span><span class='hs-layout'>)</span>
<a name="line-228"></a> <span class='hs-comment'>-- Skip past the extra field if we have it.</span>
<a name="line-229"></a> <span class='hs-keyword'>then</span> <span class='hs-keyword'>let</span> <span class='hs-layout'>(</span><span class='hs-varid'>xlen_S</span><span class='hs-layout'>,</span> <span class='hs-keyword'>_</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>split1</span> <span class='hs-varid'>rem4</span>
<a name="line-230"></a> <span class='hs-layout'>(</span><span class='hs-varid'>xlen2_S</span><span class='hs-layout'>,</span> <span class='hs-varid'>rem4b</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>split1</span> <span class='hs-varid'>rem4</span>
<a name="line-231"></a> <span class='hs-varid'>xlen</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-varid'>ord</span> <span class='hs-varid'>xlen_S</span><span class='hs-layout'>)</span> <span class='hs-varop'>+</span> <span class='hs-num'>256</span> <span class='hs-varop'>*</span> <span class='hs-layout'>(</span><span class='hs-varid'>ord</span> <span class='hs-varid'>xlen2_S</span><span class='hs-layout'>)</span>
<a name="line-232"></a> <span class='hs-layout'>(</span><span class='hs-varid'>ex</span><span class='hs-layout'>,</span> <span class='hs-varid'>rrem</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>splitAt</span> <span class='hs-varid'>xlen</span> <span class='hs-varid'>rem4b</span>
<a name="line-233"></a> <span class='hs-keyword'>in</span> <span class='hs-layout'>(</span><span class='hs-conid'>Just</span> <span class='hs-varid'>ex</span><span class='hs-layout'>,</span> <span class='hs-varid'>rrem</span><span class='hs-layout'>)</span>
<a name="line-234"></a> <span class='hs-keyword'>else</span> <span class='hs-layout'>(</span><span class='hs-conid'>Nothing</span><span class='hs-layout'>,</span> <span class='hs-varid'>rem4</span><span class='hs-layout'>)</span>
<a name="line-235"></a>
<a name="line-236"></a> <span class='hs-keyword'>let</span> <span class='hs-layout'>(</span><span class='hs-varid'>filename</span><span class='hs-layout'>,</span> <span class='hs-varid'>rem6</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span>
<a name="line-237"></a> <span class='hs-keyword'>if</span> <span class='hs-layout'>(</span><span class='hs-varid'>flag</span> <span class='hs-varop'>.&.</span> <span class='hs-varid'>fFNAME</span> <span class='hs-varop'>/=</span> <span class='hs-num'>0</span><span class='hs-layout'>)</span>
<a name="line-238"></a> <span class='hs-comment'>-- Skip past the null-terminated filename</span>
<a name="line-239"></a> <span class='hs-keyword'>then</span> <span class='hs-keyword'>let</span> <span class='hs-varid'>fn</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>takeWhile</span> <span class='hs-layout'>(</span><span class='hs-varop'>/=</span> <span class='hs-chr'>'\x00'</span><span class='hs-layout'>)</span> <span class='hs-varid'>rem5</span>
<a name="line-240"></a> <span class='hs-keyword'>in</span> <span class='hs-layout'>(</span><span class='hs-conid'>Just</span> <span class='hs-varid'>fn</span><span class='hs-layout'>,</span> <span class='hs-varid'>drop</span> <span class='hs-layout'>(</span><span class='hs-layout'>(</span><span class='hs-varid'>length</span> <span class='hs-varid'>fn</span><span class='hs-layout'>)</span> <span class='hs-varop'>+</span> <span class='hs-num'>1</span><span class='hs-layout'>)</span> <span class='hs-varid'>rem5</span><span class='hs-layout'>)</span>
<a name="line-241"></a> <span class='hs-keyword'>else</span> <span class='hs-layout'>(</span><span class='hs-conid'>Nothing</span><span class='hs-layout'>,</span> <span class='hs-varid'>rem5</span><span class='hs-layout'>)</span>
<a name="line-242"></a>
<a name="line-243"></a> <span class='hs-keyword'>let</span> <span class='hs-layout'>(</span><span class='hs-varid'>comment</span><span class='hs-layout'>,</span> <span class='hs-varid'>rem7</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span>
<a name="line-244"></a> <span class='hs-keyword'>if</span> <span class='hs-layout'>(</span><span class='hs-varid'>flag</span> <span class='hs-varop'>.&.</span> <span class='hs-varid'>fFCOMMENT</span> <span class='hs-varop'>/=</span> <span class='hs-num'>0</span><span class='hs-layout'>)</span>
<a name="line-245"></a> <span class='hs-comment'>-- Skip past the null-terminated comment</span>
<a name="line-246"></a> <span class='hs-keyword'>then</span> <span class='hs-keyword'>let</span> <span class='hs-varid'>cm</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>takeWhile</span> <span class='hs-layout'>(</span><span class='hs-varop'>/=</span> <span class='hs-chr'>'\x00'</span><span class='hs-layout'>)</span> <span class='hs-varid'>rem6</span>
<a name="line-247"></a> <span class='hs-keyword'>in</span> <span class='hs-layout'>(</span><span class='hs-conid'>Just</span> <span class='hs-varid'>cm</span><span class='hs-layout'>,</span> <span class='hs-varid'>drop</span> <span class='hs-layout'>(</span><span class='hs-layout'>(</span><span class='hs-varid'>length</span> <span class='hs-varid'>cm</span><span class='hs-layout'>)</span> <span class='hs-varop'>+</span> <span class='hs-num'>1</span><span class='hs-layout'>)</span> <span class='hs-varid'>rem6</span><span class='hs-layout'>)</span>
<a name="line-248"></a> <span class='hs-keyword'>else</span> <span class='hs-layout'>(</span><span class='hs-conid'>Nothing</span><span class='hs-layout'>,</span> <span class='hs-varid'>rem6</span><span class='hs-layout'>)</span>
<a name="line-249"></a>
<a name="line-250"></a> <span class='hs-varid'>rem8</span> <span class='hs-keyglyph'><-</span> <span class='hs-keyword'>if</span> <span class='hs-layout'>(</span><span class='hs-varid'>flag</span> <span class='hs-varop'>.&.</span> <span class='hs-varid'>fFHCRC</span> <span class='hs-varop'>/=</span> <span class='hs-num'>0</span><span class='hs-layout'>)</span>
<a name="line-251"></a> <span class='hs-comment'>-- Skip past the header CRC</span>
<a name="line-252"></a> <span class='hs-keyword'>then</span> <span class='hs-varid'>return</span> <span class='hs-varop'>$</span> <span class='hs-varid'>drop</span> <span class='hs-num'>2</span> <span class='hs-varid'>rem7</span>
<a name="line-253"></a> <span class='hs-keyword'>else</span> <span class='hs-varid'>return</span> <span class='hs-varid'>rem7</span>
<a name="line-254"></a>
<a name="line-255"></a> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-conid'>Header</span> <span class='hs-layout'>{</span><span class='hs-varid'>method</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>ord</span> <span class='hs-varid'>method</span><span class='hs-layout'>,</span>
<a name="line-256"></a> <span class='hs-varid'>flags</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>flag</span><span class='hs-layout'>,</span>
<a name="line-257"></a> <span class='hs-varid'>extra</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>extra</span><span class='hs-layout'>,</span>
<a name="line-258"></a> <span class='hs-varid'>filename</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>filename</span><span class='hs-layout'>,</span>
<a name="line-259"></a> <span class='hs-varid'>comment</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>comment</span><span class='hs-layout'>,</span>
<a name="line-260"></a> <span class='hs-varid'>mtime</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mtime</span><span class='hs-layout'>,</span>
<a name="line-261"></a> <span class='hs-varid'>xfl</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>xfl</span><span class='hs-layout'>,</span>
<a name="line-262"></a> <span class='hs-varid'>os</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>os</span><span class='hs-layout'>}</span><span class='hs-layout'>,</span> <span class='hs-varid'>rem8</span><span class='hs-layout'>)</span>
<a name="line-263"></a>
<a name="line-264"></a><span class='hs-comment'>----------------------------------------------------------------------</span>
<a name="line-265"></a><span class='hs-comment'>-- Documentation</span>
<a name="line-266"></a><span class='hs-comment'>----------------------------------------------------------------------</span>
<a name="line-267"></a>
<a name="line-268"></a><span class='hs-comment'>{- $gzipfiles
<a name="line-269"></a>
<a name="line-270"></a>GZip files contain one or more 'Section's. Each 'Section', on disk, begins
<a name="line-271"></a>with a GZip 'Header', then stores the compressed data itself, and finally
<a name="line-272"></a>stores a GZip 'Footer'.
<a name="line-273"></a>
<a name="line-274"></a>The 'Header' identifies the file as a GZip file, records the original
<a name="line-275"></a>modification date and time, and, in some cases, also records the original
<a name="line-276"></a>filename and comments.
<a name="line-277"></a>
<a name="line-278"></a>The 'Footer' contains a GZip CRC32 checksum over the decompressed data as
<a name="line-279"></a>well as a 32-bit length of the decompressed data. The module
<a name="line-280"></a>'Data.Hash.CRC32.GZip' is used to validate stored CRC32 values.
<a name="line-281"></a>
<a name="line-282"></a>The vast majority of GZip files contain only one 'Section'. Standard tools
<a name="line-283"></a>that work with GZip files create single-section files by default.
<a name="line-284"></a>
<a name="line-285"></a>Multi-section files can be created by simply concatenating two existing
<a name="line-286"></a>GZip files together. The standard gunzip and zcat tools will simply
<a name="line-287"></a>concatenate the decompressed data when reading these files back. The
<a name="line-288"></a>'decompress' function in this module will do the same.
<a name="line-289"></a>
<a name="line-290"></a>When reading data from this module, please use caution regarding how you access
<a name="line-291"></a>it. For instance, if you are wanting to write the decompressed stream
<a name="line-292"></a>to disk and validate its CRC32 value, you could use the 'decompress'
<a name="line-293"></a>function. However, you should process the entire stream before you check
<a name="line-294"></a>the value of the Bool it returns. Otherwise, you will force Haskell to buffer
<a name="line-295"></a>the entire file in memory just so it can check the CRC32.
<a name="line-296"></a>-}</span>
</pre></body>
</html>
