ELF parser in JavaScript/CoffeeScript. Initial.

elf.coffee

@@ -0,0 +1,120 @@
+fs   = require 'fs'
+util = require 'util'
+
+bufTo16 = (buf) ->
+  rez = buf[0]
+  rez << 8
+  rez |= buf[1]
+  rez
+
+bufTo32 = (buf) ->
+  fst1 = bufTo16 buf.slice(0, 2)
+  snd1 = bufTo16 buf.slice(2, 4)
+  fst1 << 16
+  fst1 |= snd1
+  fst1
+
+getAsciiz = (buf, pos) ->
+  ans = ''
+  for c in [pos .. buf.length]
+    break if buf[c] == 0
+    ans = ans + String.fromCharCode(buf[c])
+  ans
+
+tokeniseOpcodes = (elf) ->
+  tsec = elf['.text'].section
+  elf['.text'].section = for bt in [0 ... tsec.length] by 2
+    bufTo16 new Buffer [tsec[bt], tsec[bt + 1] or 0]
+  elf
+
+fillInIdent = (elf) ->
+  idobj =
+    bit_width: (['32', '64'][elf.ident[4] - 1]) + '-bit'
+    endianness: (['Little', 'Big'][elf.ident[5] - 1]) + '-endian'
+    elf_version: (['Standard', 'Big'][elf.ident[6] - 1]) + ' ELF format'
+  elf.ident = idobj
+  elf
+
+nameSections = (elf) ->
+  sec = elf.section_headers[elf.section_strings_index].section
+  elf.section_headers = for s in elf.section_headers
+    s.name = getAsciiz sec, s.name
+    elf[s.name] = s
+    s.name
+  elf
+
+fillInSections = (elf, data) ->
+  start = elf.section_header_offset
+  secs  = for sec in [0 ... elf.section_header_count]
+    pnt = start + (sec * elf.section_header_size)
+    ans = data.slice(pnt, pnt + elf.section_header_size)
+    rez =
+      name: bufTo16 ans.slice(0, 4)
+      type: ['?'
+        'data'
+        'symbol table'
+        'string table'
+        'explicit relocation'
+        'hash table'
+        'dynamic linking'
+        'notes'
+        'empty'
+        'implicit relocation'
+        'reserved'
+        'dynamic linking symbols'
+        'reserved (processor)'
+        'reserved (processor)'
+        'index minimum'
+        'index maximum'][bufTo16 ans.slice(4, 8)]
+      flags: bufTo16 ans.slice(8, 12)
+      address: bufTo16 ans.slice(12, 16)
+      offset: bufTo16 ans.slice(16, 20)
+      size: bufTo16 ans.slice(20, 24)
+      link: bufTo16 ans.slice(24, 28)
+      info: bufTo16 ans.slice(28, 32)
+      address_align: bufTo16 ans.slice(32, 36)
+      entry_size: bufTo16 ans.slice(36, 40)
+    rez.section = data.slice(rez.offset, rez.offset + rez.size)
+    rez
+  elf.section_headers = secs
+  elf
+
+readElf = (data) ->
+  ans =
+    ident: data.slice(0, 16)
+    type: bufTo16 data.slice(16, 18)
+    machine: bufTo16 data.slice(18, 20)
+    version: bufTo32 data.slice(20, 24)
+    entry: bufTo32 data.slice(24, 28)
+    program_header_offset: bufTo32 data.slice(28, 32)
+    section_header_offset: bufTo32 data.slice(32, 36)
+    flags: bufTo32 data.slice(36, 40)
+    elf_header_size: bufTo16 data.slice(40, 42)
+    program_header_size: bufTo16 data.slice(42, 44)
+    program_header_count: bufTo16 data.slice(44, 46)
+    section_header_size: bufTo16 data.slice(46, 48)
+    section_header_count: bufTo16 data.slice(48, 50)
+    section_strings_index: bufTo16 data.slice(50, 52)
+  tokeniseOpcodes (nameSections (fillInSections (fillInIdent ans), data))
+
+# TODO:
+# Pull the component objects into that hash.
+# 1.  Program headers, say.
+
+defineElf = () ->
+  fch = process.argv[process.argv.length - 1]
+  fs.open fch, 'r', (err, fd) ->
+    if err
+      console.error err
+    else
+      d = new Buffer 18
+      fs.fstat fd, (err, stats) ->
+        d = new Buffer stats.size
+        fs.read fd, d, 0, stats.size, null, (err, num, buf) ->
+          if err
+            console.error err
+          else
+            console.log util.inspect readElf buf
+          fs.close fd
+
+defineElf()