50 lines
1.7 KiB
Lua
50 lines
1.7 KiB
Lua
local mtar = {}
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local versions = {}
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versions[0] = {nlf = ">I2", flf = ">I2"} -- original version format
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versions[1] = {nlf = ">I2", flf = ">I8"} -- extended file size format
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mtar.versions = versions
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local function cleanPath(path)
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local pt = {}
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for segment in path:gmatch("[^/]+") do
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if segment == ".." then
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pt[#pt] = nil
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elseif segment ~= "." then
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pt[#pt+1] = segment
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end
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end
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return table.concat(pt,"/")
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end
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function mtar.genHeader(fname,len,version) -- string number -- string -- generate a header for file *fname* when provided with file length *len*
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version=version or 1
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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))
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end
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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.
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local remain = 0
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local function read(n)
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local rb = stream:read(math.min(n,remain))
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remain = remain - rb:len()
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return rb
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end
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return function()
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while remain > 0 do
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remain=remain-#stream:read(math.min(remain,2048))
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end
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local version = 0
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local nlen = string.unpack(">I2", stream:read(2) or "\0\0")
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if nlen == 0 then
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return
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elseif nlen == 65535 then -- versioned header
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version = string.byte(stream:read(1))
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nlen = string.unpack(versions[version].nlf, stream:read(string.packsize(versions[version].nlf)))
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end
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local name = cleanPath(stream:read(nlen))
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remain = string.unpack(versions[version].flf, stream:read(string.packsize(versions[version].flf)))
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return name, read, remain
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end
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end
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return mtar
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