[scripts] Add debugging help for linked lists and GOT

Adding in scripts that i wrote to examine GOT/PLT/DYNAMIC in shared libs, as well
as a GDB pretty-printer for util::linked_list.

scripts/print_got.py

@@ -0,0 +1,124 @@
+#!/usr/bin/env python3
+
+
+def section_header(name):
+    print()
+    print(name)
+    print("-" * 40)
+
+
+def print_dyn(elf):
+    section = elf.get_section_by_name(".dynamic")
+    if section is None:
+        return
+
+    section_header(".dynamic")
+    for tag in section.iter_tags():
+        print(tag)
+
+
+def print_got(elf, name):
+    import struct
+
+    section = elf.get_section_by_name(name)
+    if section is None:
+        return
+
+    section_header(name)
+    base_ip = section['sh_addr']
+
+    data = section.data()
+    n = section.data_size // 8
+    for i in range(n):
+        addr = struct.unpack_from("Q", data, i*8)[0]
+        print(f"[{i:2x}]: {base_ip+i*8:6x} {addr:16x}")
+
+
+def print_plt(elf):
+    from iced_x86 import Decoder, Formatter, FormatterSyntax
+
+    section_header(".plt")
+
+    section = elf.get_section_by_name(".plt")
+    n = section.data_size // 16
+    data = section.data()
+
+    frm = Formatter(FormatterSyntax.NASM)
+    frm.digit_separator = "'"
+    frm.first_operand_char_index = 8
+    frm.hex_prefix = "0x"
+    frm.hex_suffix = ""
+    frm.leading_zeros = False
+    frm.rip_relative_addresses = False
+    frm.small_hex_numbers_in_decimal = False
+    frm.uppercase_hex = False
+
+    base_ip = section['sh_addr']
+
+    for i in range(n):
+        entry = data[ i*16 : (i+1)*16 ]
+        d = Decoder(64, entry, ip=base_ip + i*16)
+
+        indent = f"[{i:2x}]:"
+        for instr in d:
+            disasm = frm.format(instr)
+            print(f"{indent:6} {instr.ip:6x} {disasm}")
+            indent = ""
+
+        print()
+
+
+def print_gnu_hash(elf):
+    hash_section = elf.get_section_by_name(".gnu.hash")
+    data = hash_section.data()
+
+    import struct
+    (nbuckets, symoff, bloom_sz, bloom_sh) = struct.unpack_from("IIII", data, 0)
+    blooms = struct.unpack_from(f"{bloom_sz}Q", data, 16)
+    buckets = struct.unpack_from(f"{nbuckets}I", data, 16+(bloom_sz*8))
+
+    p = 16 + (bloom_sz*8) + (nbuckets*4)
+    n = (len(data) - p) // 4
+    chains = struct.unpack_from(f"{n}I", data, p)
+
+    section_header(".gnu.hash")
+    print(f" Bucket Count: {nbuckets}")
+    print(f"Symbol Offset: {symoff}")
+    print(f"      Buckets: {buckets}")
+
+    print("\n  Bloom words:")
+    for i in range(len(blooms)):
+        print(f"          [{i:2}]: {blooms[i]:016x}")
+
+    print("\n       Hashes:")
+    for i in range(len(chains)):
+        h = chains[i]
+        end = ""
+        if (h & 1) == 1:
+            end = "END"
+        bloom_idx = (h>>6) % bloom_sz
+        bloom_msk = ((1<<(h%64)) | (1<<((h>>bloom_sh)%64)))
+        print(f"          [{i+symoff:2}]: {h:08x} {end:5} {bloom_idx:2}/{bloom_msk:016x}")
+
+
+def print_tables(filename):
+    from elftools.elf.elffile import ELFFile
+
+    print(filename)
+    print("=" * 50)
+
+    with open(filename, 'rb') as f:
+        elf = ELFFile(f)
+        print_got(elf, ".got")
+        print_got(elf, ".got.plt")
+        print_plt(elf)
+        print_dyn(elf)
+        print_gnu_hash(elf)
+
+    print()
+
+
+if __name__ == "__main__":
+    import sys
+    for filename in sys.argv[1:]:
+        print_tables(filename)