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|
--- A pure-Lua implementation of untar (unpacking .tar archives)
local tar = {}
local fs = require("luarocks.fs")
local dir = require("luarocks.dir")
local fun = require("luarocks.fun")
local blocksize = 512
local function get_typeflag(flag)
if flag == "0" or flag == "\0" then return "file"
elseif flag == "1" then return "link"
elseif flag == "2" then return "symlink" -- "reserved" in POSIX, "symlink" in GNU
elseif flag == "3" then return "character"
elseif flag == "4" then return "block"
elseif flag == "5" then return "directory"
elseif flag == "6" then return "fifo"
elseif flag == "7" then return "contiguous" -- "reserved" in POSIX, "contiguous" in GNU
elseif flag == "x" then return "next file"
elseif flag == "g" then return "global extended header"
elseif flag == "L" then return "long name"
elseif flag == "K" then return "long link name"
end
return "unknown"
end
local function octal_to_number(octal)
local exp = 0
local number = 0
octal = octal:gsub("%s", "")
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
local function checksum_header(block)
local sum = 256
for i = 1,148 do
local b = block:byte(i) or 0
sum = sum + b
end
for i = 157,500 do
local b = block:byte(i) or 0
sum = sum + b
end
return sum
end
local function nullterm(s)
return s:match("^[^%z]*")
end
local function read_header_block(block)
local header = {}
header.name = nullterm(block:sub(1,100))
header.mode = nullterm(block:sub(101,108)):gsub(" ", "")
header.uid = octal_to_number(nullterm(block:sub(109,116)))
header.gid = octal_to_number(nullterm(block:sub(117,124)))
header.size = octal_to_number(nullterm(block:sub(125,136)))
header.mtime = octal_to_number(nullterm(block:sub(137,148)))
header.chksum = octal_to_number(nullterm(block:sub(149,156)))
header.typeflag = get_typeflag(block:sub(157,157))
header.linkname = nullterm(block:sub(158,257))
header.magic = block:sub(258,263)
header.version = block:sub(264,265)
header.uname = nullterm(block:sub(266,297))
header.gname = nullterm(block:sub(298,329))
header.devmajor = octal_to_number(nullterm(block:sub(330,337)))
header.devminor = octal_to_number(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 %6x"):format(bestring_to_number(header.magic))
-- end
-- if header.version ~= "00" and header.version ~= " \0" then
-- return false, "Unknown version "..header.version
-- end
if not checksum_header(block) == header.chksum then
return false, "Failed header checksum"
end
return header
end
function tar.untar(filename, destdir)
assert(type(filename) == "string")
assert(type(destdir) == "string")
local tar_handle = io.open(filename, "rb")
if not tar_handle then return nil, "Error opening file "..filename end
local long_name, long_link_name
local ok, err
local make_dir = fun.memoize(fs.make_dir)
while true do
local block
repeat
block = tar_handle:read(blocksize)
until (not block) or checksum_header(block) > 256
if not block then break end
if #block < blocksize then
ok, err = nil, "Invalid block size -- corrupted file?"
break
end
local header
header, err = read_header_block(block)
if not header then
ok = false
break
end
local file_data = tar_handle:read(math.ceil(header.size / blocksize) * blocksize):sub(1,header.size)
if header.typeflag == "long name" then
long_name = nullterm(file_data)
elseif header.typeflag == "long link name" then
long_link_name = nullterm(file_data)
else
if long_name then
header.name = long_name
long_name = nil
end
if long_link_name then
header.name = long_link_name
long_link_name = nil
end
end
local pathname = dir.path(destdir, header.name)
pathname = fs.absolute_name(pathname)
if header.typeflag == "directory" then
ok, err = make_dir(pathname)
if not ok then
break
end
elseif header.typeflag == "file" then
local dirname = dir.dir_name(pathname)
if dirname ~= "" then
ok, err = make_dir(dirname)
if not ok then
break
end
end
local file_handle
file_handle, err = io.open(pathname, "wb")
if not file_handle then
ok = nil
break
end
file_handle:write(file_data)
file_handle:close()
fs.set_time(pathname, header.mtime)
if header.mode:match("[75]") then
fs.set_permissions(pathname, "exec", "all")
else
fs.set_permissions(pathname, "read", "all")
end
end
--[[
for k,v in pairs(header) do
util.printout("[\""..tostring(k).."\"] = "..(type(v)=="number" and v or "\""..v:gsub("%z", "\\0").."\""))
end
util.printout()
--]]
end
tar_handle:close()
return ok, err
end
return tar
|
