| 1 | #!/usr/bin/env python |
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| 2 | |
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| 3 | from __future__ import absolute_import, division, print_function |
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| 4 | |
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| 5 | import argparse |
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| 6 | import difflib |
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| 7 | import filecmp |
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| 8 | import os |
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| 9 | import subprocess |
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| 10 | import sys |
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| 11 | |
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| 12 | disassembler = 'objdump' |
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| 13 | |
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| 14 | def keep_line(line): |
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| 15 | """Returns true for lines that should be compared in the disassembly |
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| 16 | output.""" |
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| 17 | return "file format" not in line |
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| 18 | |
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| 19 | def disassemble(objfile): |
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| 20 | """Disassemble object to a file.""" |
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| 21 | p = subprocess.Popen([disassembler, '-d', objfile], |
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| 22 | stdout=subprocess.PIPE, |
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| 23 | stderr=subprocess.PIPE) |
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| 24 | (out, err) = p.communicate() |
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| 25 | if p.returncode or err: |
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| 26 | print("Disassemble failed: {}".format(objfile)) |
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| 27 | sys.exit(1) |
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| 28 | return [line for line in out.split(os.linesep) if keep_line(line)] |
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| 29 | |
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| 30 | def dump_debug(objfile): |
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| 31 | """Dump all of the debug info from a file.""" |
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| 32 | p = subprocess.Popen([disassembler, '-WliaprmfsoRt', objfile], stdout=subprocess.PIPE, stderr=subprocess.PIPE) |
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| 33 | (out, err) = p.communicate() |
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| 34 | if p.returncode or err: |
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| 35 | print("Dump debug failed: {}".format(objfile)) |
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| 36 | sys.exit(1) |
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| 37 | return [line for line in out.split(os.linesep) if keep_line(line)] |
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| 38 | |
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| 39 | def first_diff(a, b, fromfile, tofile): |
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| 40 | """Returns the first few lines of a difference, if there is one. Python |
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| 41 | diff can be very slow with large objects and the most interesting changes |
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| 42 | are the first ones. Truncate data before sending to difflib. Returns None |
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| 43 | is there is no difference.""" |
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| 44 | |
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| 45 | # Find first diff |
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| 46 | first_diff_idx = None |
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| 47 | for idx, val in enumerate(a): |
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| 48 | if val != b[idx]: |
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| 49 | first_diff_idx = idx |
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| 50 | break |
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| 51 | |
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| 52 | if first_diff_idx == None: |
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| 53 | # No difference |
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| 54 | return None |
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| 55 | |
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| 56 | # Diff to first line of diff plus some lines |
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| 57 | context = 3 |
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| 58 | diff = difflib.unified_diff(a[:first_diff_idx+context], |
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| 59 | b[:first_diff_idx+context], |
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| 60 | fromfile, |
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| 61 | tofile) |
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| 62 | difference = "\n".join(diff) |
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| 63 | if first_diff_idx + context < len(a): |
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| 64 | difference += "\n*** Diff truncated ***" |
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| 65 | return difference |
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| 66 | |
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| 67 | def compare_object_files(objfilea, objfileb): |
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| 68 | """Compare disassembly of two different files. |
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| 69 | Allowing unavoidable differences, such as filenames. |
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| 70 | Return the first difference if the disassembly differs, or None. |
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| 71 | """ |
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| 72 | disa = disassemble(objfilea) |
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| 73 | disb = disassemble(objfileb) |
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| 74 | return first_diff(disa, disb, objfilea, objfileb) |
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| 75 | |
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| 76 | def compare_debug_info(objfilea, objfileb): |
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| 77 | """Compare debug info of two different files. |
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| 78 | Allowing unavoidable differences, such as filenames. |
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| 79 | Return the first difference if the debug info differs, or None. |
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| 80 | If there are differences in the code, there will almost certainly be differences in the debug info too. |
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| 81 | """ |
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| 82 | dbga = dump_debug(objfilea) |
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| 83 | dbgb = dump_debug(objfileb) |
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| 84 | return first_diff(dbga, dbgb, objfilea, objfileb) |
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| 85 | |
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| 86 | def compare_exact(objfilea, objfileb): |
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| 87 | """Byte for byte comparison between object files. |
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| 88 | Returns True if equal, False otherwise. |
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| 89 | """ |
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| 90 | return filecmp.cmp(objfilea, objfileb) |
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| 91 | |
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| 92 | if __name__ == '__main__': |
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| 93 | parser = argparse.ArgumentParser() |
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| 94 | parser.add_argument('objfilea', nargs=1) |
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| 95 | parser.add_argument('objfileb', nargs=1) |
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| 96 | parser.add_argument('-v', '--verbose', action='store_true') |
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| 97 | args = parser.parse_args() |
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| 98 | diff = compare_object_files(args.objfilea[0], args.objfileb[0]) |
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| 99 | if diff: |
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| 100 | print("Difference detected") |
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| 101 | if args.verbose: |
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| 102 | print(diff) |
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| 103 | sys.exit(1) |
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| 104 | else: |
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| 105 | print("The same") |
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| 106 | |
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