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Diffstat (limited to 'examples/python/diagnose_nsstring.py')
| -rw-r--r-- | examples/python/diagnose_nsstring.py | 171 |
1 files changed, 171 insertions, 0 deletions
diff --git a/examples/python/diagnose_nsstring.py b/examples/python/diagnose_nsstring.py new file mode 100644 index 000000000000..aca5c7f220fc --- /dev/null +++ b/examples/python/diagnose_nsstring.py @@ -0,0 +1,171 @@ +# This implements the "diagnose-nsstring" command, usually installed in the debug session like +# command script import lldb.diagnose +# it is used when NSString summary formatter fails to replicate the logic that went into LLDB making the +# decisions it did and providing some useful context information that can be used for improving the formatter + +import lldb + +def read_memory(process,location,size): + data = "" + error = lldb.SBError() + for x in range(0,size-1): + byte = process.ReadUnsignedFromMemory(x+location,1,error) + if error.fail: + data = data + "err%s" % "" if x == size-2 else ":" + else: + try: + data = data + "0x%x" % byte + if byte == 0: + data = data + "(\\0)" + elif byte == 0xa: + data = data + "(\\a)" + elif byte == 0xb: + data = data + "(\\b)" + elif byte == 0xc: + data = data + "(\\c)" + elif byte == '\n': + data = data + "(\\n)" + else: + data = data + "(%s)" % chr(byte) + if x < size-2: + data = data + ":" + except Exception as e: + print e + return data + +def diagnose_nsstring_Command_Impl(debugger,command,result,internal_dict): + """ + A command to diagnose the LLDB NSString data formatter + invoke as + (lldb) diagnose-nsstring <expr returning NSString> + e.g. + (lldb) diagnose-nsstring @"Hello world" + """ + target = debugger.GetSelectedTarget() + process = target.GetProcess() + thread = process.GetSelectedThread() + frame = thread.GetSelectedFrame() + if not target.IsValid() or not process.IsValid(): + return "unable to get target/process - cannot proceed" + options = lldb.SBExpressionOptions() + options.SetFetchDynamicValue() + error = lldb.SBError() + if frame.IsValid(): + nsstring = frame.EvaluateExpression(command,options) + else: + nsstring = target.EvaluateExpression(command,options) + print >>result,str(nsstring) + nsstring_address = nsstring.GetValueAsUnsigned(0) + if nsstring_address == 0: + return "unable to obtain the string - cannot proceed" + expression = "\ +struct $__lldb__notInlineMutable {\ + char* buffer;\ + signed long length;\ + signed long capacity;\ + unsigned int hasGap:1;\ + unsigned int isFixedCapacity:1;\ + unsigned int isExternalMutable:1;\ + unsigned int capacityProvidedExternally:1;\n\ +#if __LP64__\n\ + unsigned long desiredCapacity:60;\n\ +#else\n\ + unsigned long desiredCapacity:28;\n\ +#endif\n\ + void* contentsAllocator;\ +};\ +\ +struct $__lldb__CFString {\ + void* _cfisa;\ + uint8_t _cfinfo[4];\ + uint32_t _rc;\ + union {\ + struct __inline1 {\ + signed long length;\ + } inline1;\ + struct __notInlineImmutable1 {\ + char* buffer;\ + signed long length;\ + void* contentsDeallocator;\ + } notInlineImmutable1;\ + struct __notInlineImmutable2 {\ + char* buffer;\ + void* contentsDeallocator;\ + } notInlineImmutable2;\ + struct $__lldb__notInlineMutable notInlineMutable;\ + } variants;\ +};\ +" + + expression = expression + "*(($__lldb__CFString*) %d)" % nsstring_address + # print expression + dumped = target.EvaluateExpression(expression,options) + print >>result, str(dumped) + + little_endian = (target.byte_order == lldb.eByteOrderLittle) + ptr_size = target.addr_size + + info_bits = dumped.GetChildMemberWithName("_cfinfo").GetChildAtIndex(0 if little_endian else 3).GetValueAsUnsigned(0) + is_mutable = (info_bits & 1) == 1 + is_inline = (info_bits & 0x60) == 0 + has_explicit_length = (info_bits & (1 | 4)) != 4 + is_unicode = (info_bits & 0x10) == 0x10 + is_special = (nsstring.GetDynamicValue(lldb.eDynamicCanRunTarget).GetTypeName() == "NSPathStore2") + has_null = (info_bits & 8) == 8 + + print >>result,"\nInfo=%d\nMutable=%s\nInline=%s\nExplicit=%s\nUnicode=%s\nSpecial=%s\nNull=%s\n" % \ + (info_bits, "yes" if is_mutable else "no","yes" if is_inline else "no","yes" if has_explicit_length else "no","yes" if is_unicode else "no","yes" if is_special else "no","yes" if has_null else "no") + + + explicit_length_offset = 0 + if not has_null and has_explicit_length and not is_special: + explicit_length_offset = 2*ptr_size + if is_mutable and not is_inline: + explicit_length_offset = explicit_length_offset + ptr_size + elif is_inline: + pass + elif not is_inline and not is_mutable: + explicit_length_offset = explicit_length_offset + ptr_size + else: + explicit_length_offset = 0 + + if explicit_length_offset == 0: + print >>result,"There is no explicit length marker - skipping this step\n" + else: + explicit_length_offset = nsstring_address + explicit_length_offset + explicit_length = process.ReadUnsignedFromMemory(explicit_length_offset, 4, error) + print >>result,"Explicit length location is at 0x%x - read value is %d\n" % (explicit_length_offset,explicit_length) + + if is_mutable: + location = 2 * ptr_size + nsstring_address + location = process.ReadPointerFromMemory(location,error) + elif is_inline and has_explicit_length and not is_unicode and not is_special and not is_mutable: + location = 3 * ptr_size + nsstring_address + elif is_unicode: + location = 2 * ptr_size + nsstring_address + if is_inline: + if not has_explicit_length: + print >>result,"Unicode & Inline & !Explicit is a new combo - no formula for it" + else: + location += ptr_size + else: + location = process.ReadPointerFromMemory(location,error) + elif is_special: + location = nsstring_address + ptr_size + 4 + elif is_inline: + location = 2 * ptr_size + nsstring_address + if not has_explicit_length: + location += 1 + else: + location = 2 * ptr_size + nsstring_address + location = process.ReadPointerFromMemory(location,error) + print >>result,"Expected data location: 0x%x\n" % (location) + print >>result,"1K of data around location: %s\n" % read_memory(process,location,1024) + print >>result,"5K of data around string pointer: %s\n" % read_memory(process,nsstring_address,1024*5) + +def __lldb_init_module(debugger, internal_dict): + debugger.HandleCommand("command script add -f %s.diagnose_nsstring_Command_Impl diagnose-nsstring" % __name__) + print 'The "diagnose-nsstring" command has been installed, type "help diagnose-nsstring" for detailed help.' + +__lldb_init_module(lldb.debugger,None) +__lldb_init_module = None
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