xref: /external/lldb/examples/python/crashlog.py

#!/usr/bin/python

#----------------------------------------------------------------------
# Be sure to add the python path that points to the LLDB shared library.
# On MacOSX csh, tcsh:
#   setenv PYTHONPATH /Developer/Library/PrivateFrameworks/LLDB.framework/Resources/Python
# On MacOSX sh, bash:
#   export PYTHONPATH=/Developer/Library/PrivateFrameworks/LLDB.framework/Resources/Python
#----------------------------------------------------------------------

import lldb
import commands # commands.getoutput ('/bin/ls /tmp')
import optparse
import os
import plistlib
import pprint
import re
import sys
import time
import uuid


PARSE_MODE_NORMAL = 0
PARSE_MODE_THREAD = 1
PARSE_MODE_IMAGES = 2
PARSE_MODE_THREGS = 3
PARSE_MODE_SYSTEM = 4

class CrashLog:
    """Class that does parses darwin crash logs"""
    thread_state_regex = re.compile('^Thread ([0-9]+) crashed with')
    thread_regex = re.compile('^Thread ([0-9]+)([^:]*):(.*)')
    frame_regex = re.compile('^([0-9]+) +([^ ]+) *\t(0x[0-9a-fA-F]+) +(.*)')
    image_regex_uuid = re.compile('(0x[0-9a-fA-F]+)[- ]+(0x[0-9a-fA-F]+) +[+]?([^ ]+) +([^<]+)<([-0-9a-fA-F]+)> (.*)');
    image_regex_no_uuid = re.compile('(0x[0-9a-fA-F]+)[- ]+(0x[0-9a-fA-F]+) +[+]?([^ ]+) +([^/]+)/(.*)');
    empty_line_regex = re.compile('^$')

    class Thread:
        """Class that represents a thread in a darwin crash log"""
        def __init__(self, index):
            self.index = index
            self.frames = list()
            self.registers = dict()
            self.reason = None
            self.queue = None

        def dump(self, prefix):
            print "%sThread[%u] %s" % (prefix, self.index, self.reason)
            if self.frames:
                print "%s  Frames:" % (prefix)
                for frame in self.frames:
                    frame.dump(prefix + '    ')
            if self.registers:
                print "%s  Registers:" % (prefix)
                for reg in self.registers.keys():
                    print "%s    %-5s = %#16.16x" % (prefix, reg, self.registers[reg])

        def did_crash(self):
            return self.reason != None

        def __str__(self):
            s = "Thread[%u]" % self.index
            if self.reason:
                s += ' %s' % self.reason
            return s


    class Frame:
        """Class that represents a stack frame in a thread in a darwin crash log"""
        def __init__(self, index, pc, details):
            self.index = index
            self.pc = pc
            self.sym_ctx = None
            self.details = details

        def __str__(self):
            return "[%2u] %#16.16x %s" % (self.index, self.pc, self.details)

        def dump(self, prefix):
            print "%s%s" % (prefix, self)


    class Image:
        """Class that represents a binary images in a darwin crash log"""
        dsymForUUIDBinary = os.path.expanduser('~rc/bin/dsymForUUID')
        if not os.path.exists(dsymForUUIDBinary):
            dsymForUUIDBinary = commands.getoutput('which dsymForUUID')

        dwarfdump_uuid_regex = re.compile('UUID: ([-0-9a-fA-F]+) \(([^\(]+)\) .*')

        def __init__(self, text_addr_lo, text_addr_hi, ident, version, uuid, path):
            self.text_addr_lo = text_addr_lo
            self.text_addr_hi = text_addr_hi
            self.ident = ident
            self.version = version
            self.arch = None
            self.uuid = uuid
            self.path = path
            self.resolved_path = None
            self.dsym = None
            self.module = None

        def dump(self, prefix):
            print "%s%s" % (prefix, self)

        def __str__(self):
            return "%#16.16x %s %s" % (self.text_addr_lo, self.uuid, self.get_resolved_path())

        def get_resolved_path(self):
            if self.resolved_path:
                return self.resolved_path
            elif self.path:
                return self.path
            return None

        def get_resolved_path_basename(self):
            path = self.get_resolved_path()
            if path:
                return os.path.basename(path)
            return None

        def dsym_basename(self):
            if self.dsym:
                return os.path.basename(self.dsym)
            return None

        def fetch_symboled_executable_and_dsym(self):
            if self.resolved_path:
                # Don't load a module twice...
                return 0
            print 'Locating %s %s...' % (self.uuid, self.path),
            if os.path.exists(self.dsymForUUIDBinary):
                dsym_for_uuid_command = '%s %s' % (self.dsymForUUIDBinary, self.uuid)
                s = commands.getoutput(dsym_for_uuid_command)
                if s:
                    plist_root = plistlib.readPlistFromString (s)
                    if plist_root:
                        # pp = pprint.PrettyPrinter(indent=4)
                        # pp.pprint(plist_root)
                        plist = plist_root[self.uuid]
                        if plist:
                            if 'DBGArchitecture' in plist:
                                self.arch = plist['DBGArchitecture']
                            if 'DBGDSYMPath' in plist:
                                self.dsym = os.path.realpath(plist['DBGDSYMPath'])
                            if 'DBGSymbolRichExecutable' in plist:
                                self.resolved_path = os.path.expanduser (plist['DBGSymbolRichExecutable'])
            if not self.resolved_path and os.path.exists(self.path):
                dwarfdump_cmd_output = commands.getoutput('dwarfdump --uuid "%s"' % self.path)
                self_uuid = uuid.UUID(self.uuid)
                for line in dwarfdump_cmd_output.splitlines():
                    match = self.dwarfdump_uuid_regex.search (line)
                    if match:
                        dwarf_uuid_str = match.group(1)
                        dwarf_uuid = uuid.UUID(dwarf_uuid_str)
                        if self_uuid == dwarf_uuid:
                            self.resolved_path = self.path
                            self.arch = match.group(2)
                            break;
                if not self.resolved_path:
                    print "error: file %s '%s' doesn't match the UUID in the installed file" % (self.uuid, self.path)
                    return 0
            if (self.resolved_path and os.path.exists(self.resolved_path)) or (self.path and os.path.exists(self.path)):
                print 'ok'
                if self.path != self.resolved_path:
                    print '  exe = "%s"' % self.resolved_path
                if self.dsym:
                    print ' dsym = "%s"' % self.dsym
                return 1
            else:
                return 0

        def load_module(self):
            if not lldb.target:
                return 'error: no target'
            if self.module:
                text_section = self.module.FindSection ("__TEXT")
                if text_section:
                    error = lldb.target.SetSectionLoadAddress (text_section, self.text_addr_lo)
                    if error.Success():
                        #print 'Success: loaded %s.__TEXT = 0x%x' % (self.basename(), self.text_addr_lo)
                        return None
                    else:
                        return 'error: %s' % error.GetCString()
                else:
                    return 'error: unable to find "__TEXT" section in "%s"' % self.get_resolved_path()
            else:
                return 'error: invalid module'

        def create_target(self):
            if self.fetch_symboled_executable_and_dsym ():
                resolved_path = self.get_resolved_path();
                path_spec = lldb.SBFileSpec (resolved_path)
                #result.PutCString ('plist[%s] = %s' % (uuid, self.plist))
                error = lldb.SBError()
                lldb.target = lldb.debugger.CreateTarget (resolved_path, self.arch, None, False, error);
                if lldb.target:
                    self.module = lldb.target.FindModule (path_spec)
                    if self.module:
                        err = self.load_module()
                        if err:
                            print err
                        else:
                            return None
                    else:
                        return 'error: unable to get module for (%s) "%s"' % (self.arch, resolved_path)
                else:
                    return 'error: unable to create target for (%s) "%s"' % (self.arch, resolved_path)
            else:
                return 'error: unable to locate main executable (%s) "%s"' % (self.arch, self.path)

        def add_target_module(self):
            if lldb.target:
                if self.fetch_symboled_executable_and_dsym ():
                    resolved_path = self.get_resolved_path();
                    path_spec = lldb.SBFileSpec (resolved_path)
                    #print 'target.AddModule (path="%s", arch="%s", uuid=%s)' % (resolved_path, self.arch, self.uuid)
                    self.module = lldb.target.AddModule (resolved_path, self.arch, self.uuid)
                    if self.module:
                        err = self.load_module()
                        if err:
                            print err;
                        else:
                            return None
                    else:
                        return 'error: unable to get module for (%s) "%s"' % (self.arch, resolved_path)
            else:
                return 'error: invalid target'

    def __init__(self, path):
        """CrashLog constructor that take a path to a darwin crash log file"""
        self.path = path;
        self.info_lines = list()
        self.system_profile = list()
        self.threads = list()
        self.images = list()
        self.idents = list() # A list of the required identifiers for doing all stack backtraces
        self.crashed_thread_idx = -1
        self.version = -1
        # With possible initial component of ~ or ~user replaced by that user's home directory.
        f = open(os.path.expanduser(self.path))
        self.file_lines = f.read().splitlines()
        parse_mode = PARSE_MODE_NORMAL
        thread = None
        for line in self.file_lines:
            # print line
            line_len = len(line)
            if line_len == 0:
                if thread:
                    if parse_mode == PARSE_MODE_THREAD:
                        if thread.index == self.crashed_thread_idx:
                            thread.reason = ''
                            if self.thread_exception:
                                thread.reason += self.thread_exception
                            if self.thread_exception_data:
                                thread.reason += " (%s)" % self.thread_exception_data
                        self.threads.append(thread)
                    thread = None
                else:
                    # only append an extra empty line if the previous line
                    # in the info_lines wasn't empty
                    if len(self.info_lines) > 0 and len(self.info_lines[-1]):
                        self.info_lines.append(line)
                parse_mode = PARSE_MODE_NORMAL
                # print 'PARSE_MODE_NORMAL'
            elif parse_mode == PARSE_MODE_NORMAL:
                if line.startswith ('Process:'):
                    (self.process_name, pid_with_brackets) = line[8:].strip().split()
                    self.process_id = pid_with_brackets.strip('[]')
                elif line.startswith ('Path:'):
                    self.process_path = line[5:].strip()
                elif line.startswith ('Identifier:'):
                    self.process_identifier = line[11:].strip()
                elif line.startswith ('Version:'):
                    (self.process_version, compatability_version) = line[8:].strip().split()
                    self.process_compatability_version = compatability_version.strip('()')
                elif line.startswith ('Parent Process:'):
                    (self.parent_process_name, pid_with_brackets) = line[15:].strip().split()
                    self.parent_process_id = pid_with_brackets.strip('[]')
                elif line.startswith ('Exception Type:'):
                    self.thread_exception = line[15:].strip()
                    continue
                elif line.startswith ('Exception Codes:'):
                    self.thread_exception_data = line[16:].strip()
                    continue
                elif line.startswith ('Crashed Thread:'):
                    self.crashed_thread_idx = int(line[15:].strip().split()[0])
                    continue
                elif line.startswith ('Report Version:'):
                    self.version = int(line[15:].strip())
                    continue
                elif line.startswith ('System Profile:'):
                    parse_mode = PARSE_MODE_SYSTEM
                    continue
                elif (line.startswith ('Interval Since Last Report:') or
                      line.startswith ('Crashes Since Last Report:') or
                      line.startswith ('Per-App Interval Since Last Report:') or
                      line.startswith ('Per-App Crashes Since Last Report:') or
                      line.startswith ('Sleep/Wake UUID:') or
                      line.startswith ('Anonymous UUID:')):
                    # ignore these
                    continue
                elif line.startswith ('Thread'):
                    thread_state_match = self.thread_state_regex.search (line)
                    if thread_state_match:
                        thread_state_match = self.thread_regex.search (line)
                        thread_idx = int(thread_state_match.group(1))
                        parse_mode = PARSE_MODE_THREGS
                        thread = self.threads[thread_idx]
                    else:
                        thread_match = self.thread_regex.search (line)
                        if thread_match:
                            # print 'PARSE_MODE_THREAD'
                            parse_mode = PARSE_MODE_THREAD
                            thread_idx = int(thread_match.group(1))
                            thread = CrashLog.Thread(thread_idx)
                    continue
                elif line.startswith ('Binary Images:'):
                    parse_mode = PARSE_MODE_IMAGES
                    continue
                self.info_lines.append(line.strip())
            elif parse_mode == PARSE_MODE_THREAD:
                frame_match = self.frame_regex.search(line)
                if frame_match:
                    ident = frame_match.group(2)
                    if not ident in self.idents:
                        self.idents.append(ident)
                    thread.frames.append (CrashLog.Frame(int(frame_match.group(1)), int(frame_match.group(3), 0), frame_match.group(4)))
                else:
                    print 'error: frame regex failed for line: "%s"' % line
            elif parse_mode == PARSE_MODE_IMAGES:
                image_match = self.image_regex_uuid.search (line)
                if image_match:
                    image = CrashLog.Image (int(image_match.group(1),0),
                                            int(image_match.group(2),0),
                                            image_match.group(3).strip(),
                                            image_match.group(4).strip(),
                                            image_match.group(5),
                                            image_match.group(6))
                    self.images.append (image)
                else:
                    image_match = self.image_regex_no_uuid.search (line)
                    if image_match:
                        image = CrashLog.Image (int(image_match.group(1),0),
                                                int(image_match.group(2),0),
                                                image_match.group(3).strip(),
                                                image_match.group(4).strip(),
                                                None,
                                                image_match.group(5))
                        self.images.append (image)
                    else:
                        print "error: image regex failed for: %s" % line

            elif parse_mode == PARSE_MODE_THREGS:
                stripped_line = line.strip()
                reg_values = stripped_line.split('  ')
                for reg_value in reg_values:
                    (reg, value) = reg_value.split(': ')
                    thread.registers[reg.strip()] = int(value, 0)
            elif parse_mode == PARSE_MODE_SYSTEM:
                self.system_profile.append(line)
        f.close()

    def dump(self):
        print "Crash Log File: %s" % (self.path)
        print "\nThreads:"
        for thread in self.threads:
            thread.dump('  ')
        print "\nImages:"
        for image in self.images:
            image.dump('  ')

    def find_image_with_identifier(self, ident):
        for image in self.images:
            if image.ident == ident:
                return image
        return None

    def create_target(self):
        if not self.images:
            return 'error: no images in crash log'
        exe_path = self.images[0].get_resolved_path()
        err = self.images[0].create_target ()
        if not err:
            return None # success
        # We weren't able to open the main executable as, but we can still symbolicate
        if self.idents:
            for ident in idents:
                image = self.find_image_with_identifier (ident)
                if image:
                    err = image.create_target ()
                    if not err:
                        return None # success
        for image in self.images:
            err = image.create_target ()
            if not err:
                return None # success
        return 'error: unable to locate any executables from the crash log'

def disassemble_instructions (instructions, pc, insts_before_pc, insts_after_pc):
    lines = list()
    pc_index = -1
    comment_column = 50
    for inst_idx, inst in enumerate(instructions):
        inst_pc = inst.GetAddress().GetLoadAddress(lldb.target);
        if pc == inst_pc:
            pc_index = inst_idx
        mnemonic = inst.GetMnemonic (lldb.target)
        operands =  inst.GetOperands (lldb.target)
        comment =  inst.GetComment (lldb.target)
        #data = inst.GetData (lldb.target)
        lines.append ("%#16.16x: %8s %s" % (inst_pc, mnemonic, operands))
        if comment:
            line_len = len(lines[-1])
            if line_len < comment_column:
                lines[-1] += ' ' * (comment_column - line_len)
                lines[-1] += "; %s" % comment

    if pc_index >= 0:
        if pc_index >= insts_before_pc:
            start_idx = pc_index - insts_before_pc
        else:
            start_idx = 0
        end_idx = pc_index + insts_after_pc
        if end_idx > inst_idx:
            end_idx = inst_idx
        for i in range(start_idx, end_idx+1):
            if i == pc_index:
                print ' -> ', lines[i]
            else:
                print '    ', lines[i]

def print_module_section_data (section):
    print section
    section_data = section.GetSectionData()
    if section_data:
        ostream = lldb.SBStream()
        section_data.GetDescription (ostream, section.GetFileAddress())
        print ostream.GetData()

def print_module_section (section, depth):
    print section

    if depth > 0:
        num_sub_sections = section.GetNumSubSections()
        for sect_idx in range(num_sub_sections):
            print_module_section (section.GetSubSectionAtIndex(sect_idx), depth - 1)

def print_module_sections (module, depth):
    for sect in module.section_iter():
        print_module_section (sect, depth)

def print_module_symbols (module):
    for sym in module:
        print sym

def usage():
    print "Usage: lldb-symbolicate.py [-n name] executable-image"
    sys.exit(0)

def Symbolicate(debugger, command, result, dict):
    SymbolicateCrashLog (command.split())

def SymbolicateCrashLog(command_args):
    print 'command_args = %s' % command_args
    parser = optparse.OptionParser(description='Parses darwin crash log files and symbolicates them.')
    parser.add_option('--platform', type='string', metavar='platform', dest='platform', help='specify one platform by name')
    parser.add_option('--verbose', action='store_true', dest='verbose', help='display verbose debug info', default=False)
    parser.add_option('--no-images', action='store_false', dest='show_images', help='don\'t show images in stack frames', default=True)
    parser.add_option('--image-list', action='store_true', dest='dump_image_list', help='show image list', default=False)
    parser.add_option('--debug-delay', type='int', dest='debug_delay', metavar='NSEC', help='pause for NSEC seconds for debugger', default=0)
    parser.add_option('--crashed-only', action='store_true', dest='crashed_only', help='only symbolicate the crashed thread', default=False)
    loaded_addresses = False
    (options, args) = parser.parse_args(command_args)
    if options.verbose:
        print 'options', options
    if options.debug_delay > 0:
        print "Waiting %u seconds for debugger to attach..." % options.debug_delay
        time.sleep(options.debug_delay)
    error = lldb.SBError()
    if args:
        for crash_log_file in args:
            crash_log = CrashLog(crash_log_file)
            if options.verbose:
                crash_log.dump()
            if crash_log.images:
                err = crash_log.create_target ()
                if err:
                    print err
                else:
                    exe_module = lldb.target.GetModuleAtIndex(0)
                    image_paths = list()
                    # for i in range (1, len(crash_log.images)):
                    #     image = crash_log.images[i]
                    for ident in crash_log.idents:
                        image = crash_log.find_image_with_identifier (ident)
                        if image:
                            if image.path in image_paths:
                                print "warning: skipping %s loaded at %#16.16x duplicate entry (probably commpage)" % (image.path, image.text_addr_lo)
                            else:
                                err = image.add_target_module ()
                                if err:
                                    print err
                                else:
                                    image_paths.append(image.path)
                        else:
                            print 'error: can\'t find image for identifier "%s"' % ident

                    for line in crash_log.info_lines:
                        print line

                    # Reconstruct inlined frames for all threads for anything that has debug info
                    for thread in crash_log.threads:
                        if options.crashed_only and thread.did_crash() == False:
                            continue
                        # start a new frame list that we will fixup for each thread
                        new_thread_frames = list()
                        # Iterate through all concrete frames for a thread and resolve
                        # any parent frames of inlined functions
                        for frame_idx, frame in enumerate(thread.frames):
                            # Resolve the frame's pc into a section + offset address 'pc_addr'
                            pc_addr = lldb.target.ResolveLoadAddress (frame.pc)
                            # Check to see if we were able to resolve the address
                            if pc_addr:
                                # We were able to resolve the frame's PC into a section offset
                                # address.

                                # Resolve the frame's PC value into a symbol context. A symbol
                                # context can resolve a module, compile unit, function, block,
                                # line table entry and/or symbol. If the frame has a block, then
                                # we can look for inlined frames, which are represented by blocks
                                # that have inlined information in them
                                frame.sym_ctx = lldb.target.ResolveSymbolContextForAddress (pc_addr, lldb.eSymbolContextEverything);

                                # dump if the verbose option was specified
                                if options.verbose:
                                    print "frame.pc = %#16.16x (file_addr = %#16.16x)" % (frame.pc, pc_addr.GetFileAddress())
                                    print "frame.pc_addr = ", pc_addr
                                    print "frame.sym_ctx = "
                                    print frame.sym_ctx
                                    print

                                # Append the frame we already had from the crash log to the new
                                # frames list
                                new_thread_frames.append(frame)

                                new_frame = CrashLog.Frame (frame.index, -1, None)

                                # Try and use the current frame's symbol context to calculate a
                                # parent frame for an inlined function. If the curent frame is
                                # inlined, it will return a valid symbol context for the parent
                                # frame of the current inlined function
                                parent_pc_addr = lldb.SBAddress()
                                new_frame.sym_ctx = frame.sym_ctx.GetParentOfInlinedScope (pc_addr, parent_pc_addr)

                                # See if we were able to reconstruct anything?
                                while new_frame.sym_ctx:
                                    # We have a parent frame of an inlined frame, create a new frame
                                    # Convert the section + offset 'parent_pc_addr' to a load address
                                    new_frame.pc = parent_pc_addr.GetLoadAddress(lldb.target)
                                    # push the new frame onto the new frame stack
                                    new_thread_frames.append (new_frame)
                                    # dump if the verbose option was specified
                                    if options.verbose:
                                        print "new_frame.pc = %#16.16x (%s)" % (new_frame.pc, parent_pc_addr)
                                        print "new_frame.sym_ctx = "
                                        print new_frame.sym_ctx
                                        print
                                    # Create another new frame in case we have multiple inlined frames
                                    prev_new_frame = new_frame
                                    new_frame = CrashLog.Frame (frame.index, -1, None)
                                    # Swap the addresses so we can try another inlined lookup
                                    pc_addr = parent_pc_addr;
                                    new_frame.sym_ctx = prev_new_frame.sym_ctx.GetParentOfInlinedScope (pc_addr, parent_pc_addr)
                        # Replace our thread frames with our new list that includes parent
                        # frames for inlined functions
                        thread.frames = new_thread_frames
                    # Now iterate through all threads and display our richer stack backtraces
                    for thread in crash_log.threads:
                        this_thread_crashed = thread.did_crash()
                        if options.crashed_only and this_thread_crashed == False:
                            continue
                        print "%s" % thread
                        prev_frame_index = -1
                        for frame_idx, frame in enumerate(thread.frames):
                            details = '          %s' % frame.details
                            module = frame.sym_ctx.GetModule()
                            instructions = None
                            if module:
                                module_basename = module.GetFileSpec().GetFilename();
                                function_start_load_addr = -1
                                function_name = None
                                function = frame.sym_ctx.GetFunction()
                                block = frame.sym_ctx.GetBlock()
                                line_entry = frame.sym_ctx.GetLineEntry()
                                symbol = frame.sym_ctx.GetSymbol()
                                inlined_block = block.GetContainingInlinedBlock();
                                if inlined_block:
                                    function_name = inlined_block.GetInlinedName();
                                    block_range_idx = inlined_block.GetRangeIndexForBlockAddress (lldb.target.ResolveLoadAddress (frame.pc))
                                    if block_range_idx < lldb.UINT32_MAX:
                                        block_range_start_addr = inlined_block.GetRangeStartAddress (block_range_idx)
                                        function_start_load_addr = block_range_start_addr.GetLoadAddress (lldb.target)
                                    else:
                                        function_start_load_addr = frame.pc
                                    if this_thread_crashed and frame_idx == 0:
                                        instructions = function.GetInstructions(lldb.target)
                                elif function:
                                    function_name = function.GetName()
                                    function_start_load_addr = function.GetStartAddress().GetLoadAddress (lldb.target)
                                    if this_thread_crashed and frame_idx == 0:
                                        instructions = function.GetInstructions(lldb.target)
                                elif symbol:
                                    function_name = symbol.GetName()
                                    function_start_load_addr = symbol.GetStartAddress().GetLoadAddress (lldb.target)
                                    if this_thread_crashed and frame_idx == 0:
                                        instructions = symbol.GetInstructions(lldb.target)

                                if function_name:
                                    # Print the function or symbol name and annotate if it was inlined
                                    inline_suffix = ''
                                    if inlined_block:
                                        inline_suffix = '[inlined] '
                                    else:
                                        inline_suffix = '          '
                                    if options.show_images:
                                        details = "%s%s`%s" % (inline_suffix, module_basename, function_name)
                                    else:
                                        details = "%s" % (function_name)
                                    # Dump the offset from the current function or symbol if it is non zero
                                    function_offset = frame.pc - function_start_load_addr
                                    if function_offset > 0:
                                        details += " + %u" % (function_offset)
                                    elif function_offset < 0:
                                        defaults += " %i (invalid negative offset, file a bug) " % function_offset
                                    # Print out any line information if any is available
                                    if line_entry.GetFileSpec():
                                        details += ' at %s' % line_entry.GetFileSpec().GetFilename()
                                        details += ':%u' % line_entry.GetLine ()
                                        column = line_entry.GetColumn()
                                        if column > 0:
                                            details += ':%u' % column


                            # Only print out the concrete frame index if it changes.
                            # if prev_frame_index != frame.index:
                            #     print "[%2u] %#16.16x %s" % (frame.index, frame.pc, details)
                            # else:
                            #     print "     %#16.16x %s" % (frame.pc, details)
                            print "[%2u] %#16.16x %s" % (frame.index, frame.pc, details)
                            prev_frame_index = frame.index
                            if instructions:
                                print
                                disassemble_instructions (instructions, frame.pc, 4, 4)
                                print

                        print

                    if options.dump_image_list:
                        print "Binary Images:"
                        for image in crash_log.images:
                            print image


if __name__ == '__main__':
    # Create a new debugger instance
    lldb.debugger = lldb.SBDebugger.Create()
    SymbolicateCrashLog (sys.argv)
elif lldb.debugger:
    lldb.debugger.HandleCommand('command script add -f crashlog.Symbolicate crashlog')
    print '"crashlog" command installed, type "crashlog --help" for detailed help'