146 lines
3.1 KiB
Lua
146 lines
3.1 KiB
Lua
-- module for reading serialized lua bytecode
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local bit=require('bit')
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local HEADER_MAGIC = {27, string.byte('L'), string.byte('J')}
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local FLAG_STRIP = 0x02
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local function read_u8(fp)
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return string.byte(fp:read(1))
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end
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local function read_u16(fp)
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-- TODO: endianess
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local b1 = read_u8(fp)
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local b2 = read_u8(fp)
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return bit.bor(b2*0x100, b1)
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end
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local function read_u32(fp)
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-- TODO: endianess
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local h1 = read_u16(fp)
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local h2 = read_u16(fp)
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return bit.bor(h2*0x10000, h1)
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end
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local function read_u8n(fp, n)
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return { string.byte(fp:read(n), 1, n) }
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end
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local function read_u16n(fp, n)
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local res = {}
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for i = 1, n do
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res[i] = read_u16(fp)
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end
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return res
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end
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local function read_u32n(fp, n)
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local res = {}
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for i = 1, n do
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res[i] = read_u32(fp)
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end
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return res
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end
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local function read_uleb128(fp)
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local last_byte = false
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local res = 0
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local shift = 0
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-- the bytes are read from the LSB to the MSB
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while not last_byte do
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local uleb_byte = read_u8(fp)
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res = bit.bor(res, bit.lshift(bit.band(uleb_byte, 0x7f), shift))
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if bit.band(uleb_byte, 0x80) == 0 then
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last_byte = true
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end
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end
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return res
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end
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local function read_header(fp)
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local magic = read_u8n(fp, 3)
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local version = read_u8(fp)
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local flags = read_uleb128(fp)
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local name
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local stripped
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if bit.band(flags, FLAG_STRIP) ~= 0 then
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stripped = true
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name = ''
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else
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stripped = false
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local nameLen = read_uleb128(fp)
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name = fp:read(nameLen)
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end
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return {
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magic = magic,
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version = version,
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stripped = stripped,
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name = name,
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}
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end
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local function read_proto(fp)
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local length = read_uleb128(fp)
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-- if the the last read proto was the last one
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-- we have reached the end marker, which is a zero
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-- this overlaps with a uleb128 zero representation
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if length == 0 then
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return
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end
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-- read proto header
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local flags = read_u8(fp)
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local numparams = read_u8(fp)
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local framesize = read_u8(fp)
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local numuv = read_u8(fp)
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local numkgc = read_uleb128(fp)
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local numkn = read_uleb128(fp)
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local numbc = read_uleb128(fp)
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local debugLen = 0
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local debugInfo = nil
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if bit.band(flags, FLAG_STRIP) ~= 0 then
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debugLen = read_uleb128(fp)
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-- TODO: is this correct?
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if debugLen ~= 0 then
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local firstLine = read_uleb128(fp)
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local numLine = read_uleb128(fp)
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debugInfo = {
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firstLine = firstLine,
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numLine = numLine,
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}
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end
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end
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local bcins = read_u32n(fp, numbc)
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local uvdata = read_u16n(fp, numuv)
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-- local kgc
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-- local numkn
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return {
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flags = flags,
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numparams = numparams,
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framesize = framesize,
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numuv = numuv,
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numkgc = numkgc,
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numkn = numkn,
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numbc = numbc,
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debugInfo = debugInfo,
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bcins = bcins,
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uvdata = uvdata,
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}
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end
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return {
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read_header = read_header,
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read_proto = read_proto,
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}
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