Refactor: Move to an elf module.

While here, define a elf.d.lua to help author type check configuration file.

6 files changed, 277 insertions, 0 deletions

diff --git a/elf/constants.lua b/elf/constants.lua
new file mode 100644
index 0000000..b06b275
--- /dev/null
+++ b/elf/constants.lua
@@ -0,0 +1,101 @@
+local M = {}
+
+M.VERSION = 1
+
+---@enum Osabi
+M.Osabi = {
+    sysv = 0x00,
+    hpux = 0x01,
+    netbsd = 0x02,
+    linux = 0x03,
+    hurd = 0x04,
+    solaris = 0x06,
+    aix = 0x07,
+    irix = 0x08,
+    freebsd = 0x09,
+    tru64 = 0x0a,
+    modesto = 0x0b,
+    openbsd = 0x0c,
+    openvms = 0x0d,
+    nsk = 0x0e,
+    aros = 0x0f,
+    fenixos = 0x10,
+    cloudabi = 0x11,
+    openvos = 0x12,
+}
+
+---@enum Class
+M.Class = {
+    bit32 = 0x1,
+    bit64 = 0x2,
+}
+
+---@enum Endian
+M.Endian = {
+    little = 0x1,
+    big = 0x2,
+}
+
+---@enum Type
+M.Type = {
+    none = 0x00,
+    rel = 0x01,
+    exec = 0x02,
+    dyn = 0x03,
+    core = 0x04,
+    loos = 0xfe00,
+    hios = 0xfeff,
+    loproc = 0xff00,
+    hiproc = 0xffff,
+}
+
+---@enum Machine
+M.Machine = {
+    none = 0x00,
+    m32 = 0x01,       -- AT&T WE 32100
+    sparc = 0x02,     -- SPARC
+    i386 = 0x03,      -- Intel 80386
+    m68k = 0x04,      -- Motorola 68000 (M68k)
+    m88k = 0x05,      -- Motorola 88000 (M88k)
+    mcu = 0x06,       -- Intel MCU
+    i860 = 0x07,      -- Intel 80860
+    mips = 0x08,      -- MIPS
+
+    s370 = 0x09,      -- IBM System/370
+    mipsrs3le = 0x0a, -- MIPS RS3000 Little Endian
+    parisc = 0x0f,    -- Hewlett-Packard PA-RISC
+    vpp500 = 0x11,    -- Fujitsu VPP500
+    sparc32 = 0x12,   -- Enhanced instruction set SPARC
+    i960 = 0x13,      -- Intel 80960
+    ppc = 0x14,       -- PowerPC
+    ppc64 = 0x15,     -- PowerPC (64-bit)
+    s390 = 0x16,      -- IBM System/390
+    spu = 0x17,       -- IBM SPC/SPU
+    v800 = 0x24,      -- NEC V800
+    fr20 = 0x25,      -- Fujitsu FR20
+    -- todo
+}
+
+---@enum SegmentType
+M.SegmentType = {
+    null = 0x00000000,
+    load = 0x00000001,
+    dynamic = 0x00000002,
+    interp = 0x00000003,
+    note = 0x00000004,
+    shlib = 0x00000005,
+    phdr = 0x00000006,
+    tls = 0x00000007,
+    loos = 0x60000000,
+    hios = 0x6FFFFFFF,
+    loproc = 0x70000000,
+    hiproc = 0x7FFFFFFF,
+}
+
+M.SegmentFlags = {
+    x = 0x1,
+    w = 0x2,
+    r = 0x4,
+}
+
+return M
diff --git a/elf/fmt.lua b/elf/fmt.lua
new file mode 100644
index 0000000..44498d4
--- /dev/null
+++ b/elf/fmt.lua
@@ -0,0 +1,17 @@
+local constants = require("elf.constants")
+
+local M = {}
+
+---@param endian Endian
+---@nodiscard
+function M.endian(endian)
+    return (endian == constants.Endian.big) and ">" or "<"
+end
+
+---@param class Class
+---@nodiscard
+function M.word(class)
+    return (class == constants.Class.bit64) and "I8" or "I4"
+end
+
+return M
diff --git a/elf/header.lua b/elf/header.lua
new file mode 100644
index 0000000..2a9ec68
--- /dev/null
+++ b/elf/header.lua
@@ -0,0 +1,58 @@
+local fmt = require("elf.fmt")
+
+local M = {}
+
+---@alias Magic [integer, integer, integer, integer]
+
+---@class Header
+---@field magic Magic
+---@field class Class
+---@field data Endian
+---@field ident_version integer
+---@field osabi Osabi
+---@field abiversion integer
+---@field type Type
+---@field machine Machine
+---@field version integer
+---@field entry integer
+---@field phoff integer
+---@field shoff integer
+---@field flags integer
+---@field ehsize integer
+---@field phentsize? integer
+---@field phnum? integer
+---@field shentsize integer
+---@field shnum integer
+---@field shstrndx integer
+
+---@param hdr Header
+---@return string
+---@nodiscard
+function M.pack(hdr)
+    return string.pack("BBBBBBBBBxxxxxxx" ..
+        fmt.endian(hdr.data) ..
+        "I2I2I4" ..
+        string.rep(fmt.word(hdr.class), 3) ..
+        "I4I2I2I2I2I2I2",
+        hdr.magic[1], hdr.magic[2], hdr.magic[3], hdr.magic[4],
+        hdr.class,
+        hdr.data,
+        hdr.ident_version,
+        hdr.osabi,
+        hdr.abiversion,
+        hdr.type,
+        hdr.machine,
+        hdr.version,
+        hdr.entry,
+        hdr.phoff,
+        hdr.shoff,
+        hdr.flags,
+        hdr.ehsize,
+        hdr.phentsize,
+        hdr.phnum,
+        hdr.shentsize,
+        hdr.shnum,
+        hdr.shstrndx)
+end
+
+return M
diff --git a/elf/init.lua b/elf/init.lua
new file mode 100644
index 0000000..6e6966a
--- /dev/null
+++ b/elf/init.lua
@@ -0,0 +1,20 @@
+local constants = require("elf.constants")
+local header = require("elf.header")
+local segment = require("elf.segment")
+local section = require("elf.section")
+
+local M = {}
+
+M.VERSION = constants.VERSION
+M.Class = constants.Class
+M.Endian = constants.Endian
+M.Osabi = constants.Osabi
+M.Type = constants.Type
+M.Machine = constants.Machine
+M.SegmentType = constants.SegmentType
+M.SegmentFlags = constants.SegmentFlags
+M.header = header
+M.segment = segment
+M.section = section
+
+return M
diff --git a/elf/section.lua b/elf/section.lua
new file mode 100644
index 0000000..64a91b2
--- /dev/null
+++ b/elf/section.lua
@@ -0,0 +1,16 @@
+local fmt = require("elf.fmt")
+
+local M = {}
+
+---@class Section
+
+---@param section Section
+---@param endian Endian
+---@return string
+---@nodiscard
+function M.pack(section, endian)
+    -- TODO
+    return string.pack("B", 0x1)
+end
+
+return M
diff --git a/elf/segment.lua b/elf/segment.lua
new file mode 100644
index 0000000..da8e9c6
--- /dev/null
+++ b/elf/segment.lua
@@ -0,0 +1,65 @@
+local ec = require("elf.constants")
+local fmt = require("elf.fmt")
+
+local M = {}
+
+---@class Segment
+---@field type SegmentType
+---@field flags integer
+---@field offset integer
+---@field vaddr integer
+---@field paddr integer
+---@field filesz integer
+---@field memsz integer
+---@field align integer
+
+---@param phdr Segment
+---@param endian Endian
+---@return string
+---@nodiscard
+local function pack32(phdr, endian)
+    return string.pack(
+        fmt.endian(endian) .. string.rep(fmt.word(ec.Class.bit32), 8),
+        phdr.type,
+        phdr.offset,
+        phdr.vaddr,
+        phdr.paddr,
+        phdr.filesz,
+        phdr.memsz,
+        phdr.flags,
+        phdr.align)
+end
+
+---@param phdr Segment
+---@param endian Endian
+---@return string
+---@nodiscard
+local function pack64(phdr, endian)
+    return string.pack(
+        fmt.endian(endian) .. "I4I4" .. string.rep(fmt.word(ec.Class.bit64), 6),
+        phdr.type,
+        phdr.flags,
+        phdr.offset,
+        phdr.vaddr,
+        phdr.paddr,
+        phdr.filesz,
+        phdr.memsz,
+        phdr.align)
+end
+
+---@param phdrs Segment[]
+---@param endian Endian
+---@param class Class
+---@return string
+---@nodiscard
+function M.pack(phdrs, endian, class)
+    local p = {}
+    for i, phdr in ipairs(phdrs) do
+        p[i] = (class == ec.Class.bit32) and
+            pack32(phdr, endian) or
+            pack64(phdr, endian)
+    end
+    return table.concat(p)
+end
+
+return M