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- 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)) or ""
- remain = remain - rb:len()
- return rb
- end
- return function()
- while remain > 0 do
- remain=remain-(#stream:read(math.min(remain,2048)) or "")
- 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
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