elf-dump

#!/usr/bin/env python

import struct
import sys
import StringIO

import common_dump

class Reader:
    def __init__(self, path):
        if path == "-":
            # Snarf all the data so we can seek.
            self.file = StringIO.StringIO(sys.stdin.read())
        else:
            self.file = open(path, "rb")
        self.isLSB = None
        self.is64Bit = None

    def seek(self, pos):
        self.file.seek(pos)

    def read(self, N):
        data = self.file.read(N)
        if len(data) != N:
            raise ValueError, "Out of data!"
        return data

    def read8(self):
        return (ord(self.read(1)), 8)

    def read16(self):
        return (struct.unpack('><'[self.isLSB] + 'H', self.read(2))[0], 16)

    def read32(self):
        return (struct.unpack('><'[self.isLSB] + 'I', self.read(4))[0], 32)

    def read64(self):
        return (struct.unpack('><'[self.isLSB] + 'Q', self.read(8))[0], 64)

    def readWord(self):
        if self.is64Bit:
            return self.read64()
        else:
            return self.read32()

class StringTable:
    def __init__(self, strings):
       self.string_table = strings

    def __getitem__(self, index):
       end = self.string_table.index('\x00', index)
       return self.string_table[index:end]

class Section:
    def __init__(self, f):
        self.sh_name = f.read32()
        self.sh_type = f.read32()
        self.sh_flags = f.readWord()
        self.sh_addr = f.readWord()
        self.sh_offset = f.readWord()
        self.sh_size = f.readWord()
        self.sh_link = f.read32()
        self.sh_info = f.read32()
        self.sh_addralign = f.readWord()
        self.sh_entsize = f.readWord()

    def dump(self, shstrtab, f, strtab, dumpdata):
        print "  (('sh_name', %s)" % common_dump.HexDump(self.sh_name), "# %r" % shstrtab[self.sh_name[0]]
        print "   ('sh_type', %s)" % common_dump.HexDump(self.sh_type)
        print "   ('sh_flags', %s)" % common_dump.HexDump(self.sh_flags)
        print "   ('sh_addr', %s)" % common_dump.HexDump(self.sh_addr)
        print "   ('sh_offset', %s)" % common_dump.HexDump(self.sh_offset)
        print "   ('sh_size', %s)" % common_dump.HexDump(self.sh_size)
        print "   ('sh_link', %s)" % common_dump.HexDump(self.sh_link)
        print "   ('sh_info', %s)" % common_dump.HexDump(self.sh_info)
        print "   ('sh_addralign', %s)" % common_dump.HexDump(self.sh_addralign)
        print "   ('sh_entsize', %s)" % common_dump.HexDump(self.sh_entsize)
        if self.sh_type[0] == 2: # SHT_SYMTAB
            print "   ('_symbols', ["
            dumpSymtab(f, self, strtab)
            print "   ])"
        elif self.sh_type[0] == 4 or self.sh_type[0] == 9: # SHT_RELA / SHT_REL
            print "   ('_relocations', ["
            dumpRel(f, self, self.sh_type[0] == 4)
            print "   ])"
        elif dumpdata:
            f.seek(self.sh_offset[0])
            if self.sh_type != 8: # != SHT_NOBITS
                data = f.read(self.sh_size[0])
                print "   ('_section_data', '%s')" % common_dump.dataToHex(data)
            else:
                print "   ('_section_data', '')" 
        print "  ),"

def dumpSymtab(f, section, strtab):
    entries = section.sh_size[0] // section.sh_entsize[0]

    for index in range(entries):
        f.seek(section.sh_offset[0] + index * section.sh_entsize[0])
        print "    # Symbol %s" % index
        name = f.read32()
        print "    (('st_name', %s)" % common_dump.HexDump(name), "# %r" % strtab[name[0]]
        if not f.is64Bit:
            print "     ('st_value', %s)" % common_dump.HexDump(f.read32())
            print "     ('st_size', %s)" % common_dump.HexDump(f.read32())
        st_info = f.read8()[0]
        st_bind = (st_info >> 4, 4)
        st_type = (st_info & 0xf, 4)
        print "     ('st_bind', %s)" % common_dump.HexDump(st_bind)
        print "     ('st_type', %s)" % common_dump.HexDump(st_type)
        print "     ('st_other', %s)" % common_dump.HexDump(f.read8())
        print "     ('st_shndx', %s)" % common_dump.HexDump(f.read16())
        if f.is64Bit:
            print "     ('st_value', %s)" % common_dump.HexDump(f.read64())
            print "     ('st_size', %s)" % common_dump.HexDump(f.read64())
        print "    ),"

def dumpRel(f, section, dumprela = False):
    entries = section.sh_size[0] // section.sh_entsize[0]

    for index in range(entries):
        f.seek(section.sh_offset[0] + index * section.sh_entsize[0])
        print "    # Relocation %s" % index
        print "    (('r_offset', %s)" % common_dump.HexDump(f.readWord())
        r_info = f.readWord()[0]
        if f.is64Bit:
            r_sym = (r_info >> 32, 32)
            r_type = (r_info & 0xffffffff, 32)
        else:
            r_sym = (r_info >> 8, 24)
            r_type = (r_info & 0xff, 8)
        print "     ('r_sym', %s)" % common_dump.HexDump(r_sym)
        print "     ('r_type', %s)" % common_dump.HexDump(r_type)
        if dumprela:
            print "     ('r_addend', %s)" % common_dump.HexDump(f.readWord())
        print "    ),"

def dumpELF(path, opts):
    f = Reader(path)

    magic = f.read(4)
    assert magic == '\x7FELF'

    fileclass = f.read8()
    if fileclass[0] == 1: # ELFCLASS32
        f.is64Bit = False
    elif fileclass[0] == 2: # ELFCLASS64
        f.is64Bit = True
    else:
        raise ValueError, "Unknown file class %s" % common_dump.HexDump(fileclass)
    print "('e_indent[EI_CLASS]', %s)" % common_dump.HexDump(fileclass)

    byteordering = f.read8()
    if byteordering[0] == 1: # ELFDATA2LSB
        f.isLSB = True
    elif byteordering[0] == 2: # ELFDATA2MSB
        f.isLSB = False
    else:
        raise ValueError, "Unknown byte ordering %s" % common_dump.HexDump(byteordering)
    print "('e_indent[EI_DATA]', %s)" % common_dump.HexDump(byteordering)

    print "('e_indent[EI_VERSION]', %s)" % common_dump.HexDump(f.read8())
    print "('e_indent[EI_OSABI]', %s)" % common_dump.HexDump(f.read8())
    print "('e_indent[EI_ABIVERSION]', %s)" % common_dump.HexDump(f.read8())

    f.seek(16) # Seek to end of e_ident.

    print "('e_type', %s)" % common_dump.HexDump(f.read16())
    print "('e_machine', %s)" % common_dump.HexDump(f.read16())
    print "('e_version', %s)" % common_dump.HexDump(f.read32())
    print "('e_entry', %s)" % common_dump.HexDump(f.readWord())
    print "('e_phoff', %s)" % common_dump.HexDump(f.readWord())
    e_shoff = f.readWord()
    print "('e_shoff', %s)" % common_dump.HexDump(e_shoff)
    print "('e_flags', %s)" % common_dump.HexDump(f.read32())
    print "('e_ehsize', %s)" % common_dump.HexDump(f.read16())
    print "('e_phentsize', %s)" % common_dump.HexDump(f.read16())
    print "('e_phnum', %s)" % common_dump.HexDump(f.read16())
    e_shentsize = f.read16()
    print "('e_shentsize', %s)" % common_dump.HexDump(e_shentsize)
    e_shnum = f.read16()
    print "('e_shnum', %s)" % common_dump.HexDump(e_shnum)
    e_shstrndx = f.read16()
    print "('e_shstrndx', %s)" % common_dump.HexDump(e_shstrndx)

    # Read all section headers
    sections = []
    for index in range(e_shnum[0]):
        f.seek(e_shoff[0] + index * e_shentsize[0])
        s = Section(f)
        sections.append(s)

    # Read .shstrtab so we can resolve section names
    f.seek(sections[e_shstrndx[0]].sh_offset[0])
    shstrtab = StringTable(f.read(sections[e_shstrndx[0]].sh_size[0]))

    # Get the symbol string table
    strtab = None
    for section in sections:
        if shstrtab[section.sh_name[0]] == ".strtab":
            f.seek(section.sh_offset[0])
            strtab = StringTable(f.read(section.sh_size[0]))
            break

    print "('_sections', ["
    for index in range(e_shnum[0]):
        print "  # Section %s" % index
        sections[index].dump(shstrtab, f, strtab, opts.dumpSectionData)
    print "])"

if __name__ == "__main__":
    from optparse import OptionParser, OptionGroup
    parser = OptionParser("usage: %prog [options] {files}")
    parser.add_option("", "--dump-section-data", dest="dumpSectionData",
                      help="Dump the contents of sections",
                      action="store_true", default=False)
    (opts, args) = parser.parse_args()

    if not args:
        args.append('-')

    for arg in args:
        dumpELF(arg, opts)