mirror of
https://git.shadowkat.net/izaya/OC-PsychOS2.git
synced 2024-11-15 09:08:09 -05:00
50 lines
1.7 KiB
Lua
50 lines
1.7 KiB
Lua
local mtar = {}
|
|
local versions = {}
|
|
versions[0] = {nlf = ">I2", flf = ">I2"} -- original version format
|
|
versions[1] = {nlf = ">I2", flf = ">I8"} -- extended file size format
|
|
mtar.versions = versions
|
|
|
|
local function cleanPath(path)
|
|
local pt = {}
|
|
for segment in path:gmatch("[^/]+") do
|
|
if segment == ".." then
|
|
pt[#pt] = nil
|
|
elseif segment ~= "." then
|
|
pt[#pt+1] = segment
|
|
end
|
|
end
|
|
return table.concat(pt,"/")
|
|
end
|
|
|
|
function mtar.genHeader(fname,len,version) -- string number -- string -- generate a header for file *fname* when provided with file length *len*
|
|
version=version or 1
|
|
return string.format("\255\255%s%s%s%s", string.char(version), string.pack(versions[version].nlf,fname:len()), fname, string.pack(versions[version].flf,len))
|
|
end
|
|
|
|
function mtar.iter(stream) -- table -- function -- Given buffer *stream*, returns an iterator suitable for use with *for* that returns, for each iteration, the file name, a function to read from the file, and the length of the file.
|
|
local remain = 0
|
|
local function read(n)
|
|
local rb = stream:read(math.min(n,remain))
|
|
remain = remain - rb:len()
|
|
return rb
|
|
end
|
|
return function()
|
|
while remain > 0 do
|
|
remain=remain-#stream:read(math.min(remain,2048))
|
|
end
|
|
local version = 0
|
|
local nlen = string.unpack(">I2", stream:read(2) or "\0\0")
|
|
if nlen == 0 then
|
|
return
|
|
elseif nlen == 65535 then -- versioned header
|
|
version = string.byte(stream:read(1))
|
|
nlen = string.unpack(versions[version].nlf, stream:read(string.packsize(versions[version].nlf)))
|
|
end
|
|
local name = cleanPath(stream:read(nlen))
|
|
remain = string.unpack(versions[version].flf, stream:read(string.packsize(versions[version].flf)))
|
|
return name, read, remain
|
|
end
|
|
end
|
|
|
|
return mtar
|