47 lines
1.1 KiB
Lua
47 lines
1.1 KiB
Lua
local mtar = {}
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local function toint(s)
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local n = 0
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local i = 1
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for p in s:gmatch(".") do
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n = n << 8
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n = n | string.byte(p)
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i=i+1
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end
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return n
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end
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local function cint(n,l)
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local t={}
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for i = 0, 7 do
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t[i+1] = (n >> (i * 8)) & 0xFF
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end
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return string.reverse(string.char(table.unpack(t)):sub(1,l))
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end
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function mtar.genHeader(fname,len) -- string number -- string -- Generates an mtar file header for a file called *name* that is *len* bytes long.
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return string.format("%s%s%s",cint(fname:len(),2),fname,cint(len,2))
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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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stream:read(remain)
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local nlen = toint(stream:read(2) or "\0\0")
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if nlen == 0 then
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return
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end
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local name = stream:read(nlen)
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local fsize = toint(stream:read(2))
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remain = fsize
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return name, read, fsize
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end
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end
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return mtar
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