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GGTar.lua
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GGTar.lua
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-- Project: GGTar
--
-- Date: November 24, 2012
--
-- Version: 0.1
--
-- File name: GGNews.lua
--
-- Author: Graham Ranson of Glitch Games - www.glitchgames.co.uk
--
-- Update History:
--
-- 0.1 - Initial release
--
-- Comments:
--
-- This is a GGified version of the Tar module for the LuaRocks project provided
-- here - https://github.com/keplerproject/luarocks/blob/master/src/luarocks/tools/tar.lua
--
-- Copyright (C) 2012 Graham Ranson, Glitch Games Ltd.
--
-- Permission is hereby granted, free of charge, to any person obtaining a copy of this
-- software and associated documentation files (the "Software"), to deal in the Software
-- without restriction, including without limitation the rights to use, copy, modify, merge,
-- publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
-- to whom the Software is furnished to do so, subject to the following conditions:
--
-- The above copyright notice and this permission notice shall be included in all copies or
-- substantial portions of the Software.
--
-- THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
-- INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
-- PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
-- FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
-- OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
-- DEALINGS IN THE SOFTWARE.
--
----------------------------------------------------------------------------------------------------
local GGTar = {}
local GGTar_mt = { __index = GGTar }
local lfs = require( "lfs" )
local ceil = math.ceil
local tonumber = tonumber
local open = io.open
--- Initiates a new GGTar object.
-- @return The new GGTar object.
function GGTar:new()
local self = {}
setmetatable( self, GGTar_mt )
self.blocksize = 512
self.typeFlags = {}
self.typeFlags[ "0" ] = "file"
self.typeFlags[ "\0" ] = "file"
self.typeFlags[ "1" ] = "link"
self.typeFlags[ "2" ] = "symlink"
self.typeFlags[ "3" ] = "character"
self.typeFlags[ "4" ] = "block"
self.typeFlags[ "5" ] = "directory"
self.typeFlags[ "6" ] = "fifo"
self.typeFlags[ "7" ] = "contiguous"
self.typeFlags[ "x" ] = "next file"
self.typeFlags[ "g" ] = "global extended header"
self.typeFlags[ "L" ] = "long name"
self.typeFlags[ "K" ] = "long link name"
return self
end
function GGTar:getTypeFlag( flag )
return self.typeFlags[ flag ]or "unknown"
end
function GGTar:octalToNumber( octal )
local exp = 0
local number = 0
for i = #octal, 1, -1 do
local digit = tonumber( octal:sub( i, i ) )
if not digit then
break
end
number = number + ( digit * 8 ^ exp )
exp = exp + 1
end
return number
end
function GGTar:checksumHeader( block )
local sum = 256
for i = 1, 148 do
sum = sum + block:byte( i )
end
for i = 157, 500 do
sum = sum + block:byte( i )
end
return sum
end
function GGTar:nullterm( s )
return s:match( "^[^%z]*" )
end
--- Reads the header of a block.
-- @param block The block to read.
-- @return The header data.
function GGTar:readHeaderBlock( block )
local header = {}
header.name = self:nullterm( block:sub( 1, 100 ) )
header.mode = self:nullterm( block:sub( 101, 108 ) )
header.uid = self:octalToNumber( self:nullterm( block:sub( 109, 116 ) ) )
header.gid = self:octalToNumber( self:nullterm( block:sub( 117, 124 ) ) )
header.size = self:octalToNumber( self:nullterm( block:sub( 125, 136 ) ) )
header.mtime = self:octalToNumber( self:nullterm( block:sub( 137, 148 ) ) )
header.chksum = self:octalToNumber( self:nullterm( block:sub( 149, 156 ) ) )
header.typeflag = self:getTypeFlag( block:sub( 157,157 ) )
header.linkname = self:nullterm( block:sub( 158,257 ) )
header.magic = block:sub( 258, 263 )
header.version = block:sub( 264, 265 )
header.uname = self:nullterm( block:sub( 266, 297 ) )
header.gname = self:nullterm( block:sub( 298, 329 ) )
header.devmajor = self:octalToNumber( self:nullterm( block:sub( 330, 337 ) ) )
header.devminor = self:octalToNumber( self:nullterm( block:sub( 338, 345 ) ) )
header.prefix = block:sub( 346, 500 )
if header.magic ~= "ustar " and header.magic ~= "ustar\0" then
return false, "Invalid header magic " .. header.magic
end
if header.version ~= "00" and header.version ~= " \0" then
return false, "Unknown version " .. header.version
end
if not self:checksumHeader( block ) == header.chksum then
return false, "Failed header checksum"
end
return header
end
--- Extracts a tar archive.
-- @param filename Filename of the .tar file.
-- @param destDir Destination directory for the extracted files. Optional, default is system.DocumentsDirectory.
-- @param baseDir Base directory for the .tar file. Optional, default is system.DocumentsDirectory.
-- @param onComplete Function to be called on completion of the extraction. Optional.
function GGTar:untar( filename, destDir, baseDir, onComplete )
if type( filename ) ~= "string" then
return
end
local path = system.pathForFile( filename, baseDir or system.DocumentsDirectory )
local tarHandle = open( path, "rb" )
if not tarHandle then
return nil, "Error opening file " .. filename
end
local longName, longLinkName
while true do
local block
repeat
block = tarHandle:read( self.blocksize )
until( not block ) or self:checksumHeader( block ) > 256
if not block then
break
end
local header, err = self:readHeaderBlock( block )
local fileData = tarHandle:read( ceil( header.size / self.blocksize ) * self.blocksize ):sub( 1, header.size )
if header.typeflag == "long name" then
longName = self:nullterm( fileData )
elseif header.typeflag == "long link name" then
longLinkName = self:nullterm( fileData )
else
if longName then
header.name = longName
longName = nil
end
if longLinkName then
header.name = longLinkName
longLinkName = nil
end
end
local destPath = system.pathForFile( "", destdir or system.DocumentsDirectory )
local pathname = destPath .. "/" .. header.name
if header.typeflag == "directory" then
lfs.mkdir( pathname )
elseif header.typeflag == "file" then
local fileHandle = open( pathname, "wb" )
if fileHandle then
fileHandle:write( fileData )
fileHandle:close()
end
end
end
if onComplete then
onComplete()
end
return true
end
--- Destroys this GGTar object.
function GGTar:destroy()
self.blocksize = nil
self.typeFlags = nil
end
return GGTar