e3930e77fc
This is a follow-up patch to 6f7835f309b9. As explained previously, when running from an IDE, it can happen that the IDE imports some lldb scripts by itself. If the user also tries to import these commands, lldb will show the following message: ``` error: cannot add command: user command exists and force replace not set ``` This message is confusing to the user, because it suggests that the command import failed and that the execution should stop. However, in this case, lldb will continue the execution with the command added previously by the user. To prevent that, this patch updates every first-party lldb-packaged custom commands to override commands that were pre-imported in lldb. Differential Revision: https://reviews.llvm.org/D140293 Signed-off-by: Med Ismail Bennani <medismail.bennani@gmail.com>
184 lines
6.8 KiB
Python
184 lines
6.8 KiB
Python
# This implements the "diagnose-nsstring" command, usually installed in the debug session like
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# command script import lldb.diagnose
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# it is used when NSString summary formatter fails to replicate the logic that went into LLDB making the
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# decisions it did and providing some useful context information that can
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# be used for improving the formatter
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import lldb
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def read_memory(process, location, size):
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data = ""
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error = lldb.SBError()
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for x in range(0, size - 1):
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byte = process.ReadUnsignedFromMemory(x + location, 1, error)
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if error.fail:
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data = data + "err%s" % "" if x == size - 2 else ":"
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else:
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try:
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data = data + "0x%x" % byte
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if byte == 0:
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data = data + "(\\0)"
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elif byte == 0xa:
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data = data + "(\\a)"
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elif byte == 0xb:
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data = data + "(\\b)"
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elif byte == 0xc:
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data = data + "(\\c)"
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elif byte == '\n':
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data = data + "(\\n)"
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else:
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data = data + "(%s)" % chr(byte)
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if x < size - 2:
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data = data + ":"
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except Exception as e:
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print(e)
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return data
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def diagnose_nsstring_Command_Impl(debugger, command, result, internal_dict):
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"""
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A command to diagnose the LLDB NSString data formatter
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invoke as
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(lldb) diagnose-nsstring <expr returning NSString>
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e.g.
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(lldb) diagnose-nsstring @"Hello world"
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"""
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target = debugger.GetSelectedTarget()
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process = target.GetProcess()
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thread = process.GetSelectedThread()
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frame = thread.GetSelectedFrame()
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if not target.IsValid() or not process.IsValid():
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return "unable to get target/process - cannot proceed"
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options = lldb.SBExpressionOptions()
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options.SetFetchDynamicValue()
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error = lldb.SBError()
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if frame.IsValid():
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nsstring = frame.EvaluateExpression(command, options)
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else:
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nsstring = target.EvaluateExpression(command, options)
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print(str(nsstring), file=result)
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nsstring_address = nsstring.GetValueAsUnsigned(0)
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if nsstring_address == 0:
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return "unable to obtain the string - cannot proceed"
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expression = "\
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struct $__lldb__notInlineMutable {\
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char* buffer;\
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signed long length;\
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signed long capacity;\
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unsigned int hasGap:1;\
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unsigned int isFixedCapacity:1;\
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unsigned int isExternalMutable:1;\
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unsigned int capacityProvidedExternally:1;\n\
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#if __LP64__\n\
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unsigned long desiredCapacity:60;\n\
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#else\n\
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unsigned long desiredCapacity:28;\n\
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#endif\n\
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void* contentsAllocator;\
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};\
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\
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struct $__lldb__CFString {\
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void* _cfisa;\
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uint8_t _cfinfo[4];\
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uint32_t _rc;\
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union {\
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struct __inline1 {\
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signed long length;\
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} inline1;\
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struct __notInlineImmutable1 {\
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char* buffer;\
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signed long length;\
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void* contentsDeallocator;\
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} notInlineImmutable1;\
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struct __notInlineImmutable2 {\
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char* buffer;\
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void* contentsDeallocator;\
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} notInlineImmutable2;\
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struct $__lldb__notInlineMutable notInlineMutable;\
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} variants;\
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};\
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"
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expression = expression + "*(($__lldb__CFString*) %d)" % nsstring_address
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# print expression
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dumped = target.EvaluateExpression(expression, options)
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print(str(dumped), file=result)
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little_endian = (target.byte_order == lldb.eByteOrderLittle)
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ptr_size = target.addr_size
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info_bits = dumped.GetChildMemberWithName("_cfinfo").GetChildAtIndex(
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0 if little_endian else 3).GetValueAsUnsigned(0)
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is_mutable = (info_bits & 1) == 1
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is_inline = (info_bits & 0x60) == 0
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has_explicit_length = (info_bits & (1 | 4)) != 4
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is_unicode = (info_bits & 0x10) == 0x10
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is_special = (
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nsstring.GetDynamicValue(
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lldb.eDynamicCanRunTarget).GetTypeName() == "NSPathStore2")
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has_null = (info_bits & 8) == 8
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print("\nInfo=%d\nMutable=%s\nInline=%s\nExplicit=%s\nUnicode=%s\nSpecial=%s\nNull=%s\n" % \
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(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"), file=result)
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explicit_length_offset = 0
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if not has_null and has_explicit_length and not is_special:
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explicit_length_offset = 2 * ptr_size
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if is_mutable and not is_inline:
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explicit_length_offset = explicit_length_offset + ptr_size
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elif is_inline:
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pass
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elif not is_inline and not is_mutable:
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explicit_length_offset = explicit_length_offset + ptr_size
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else:
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explicit_length_offset = 0
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if explicit_length_offset == 0:
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print("There is no explicit length marker - skipping this step\n", file=result)
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else:
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explicit_length_offset = nsstring_address + explicit_length_offset
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explicit_length = process.ReadUnsignedFromMemory(
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explicit_length_offset, 4, error)
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print("Explicit length location is at 0x%x - read value is %d\n" % (
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explicit_length_offset, explicit_length), file=result)
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if is_mutable:
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location = 2 * ptr_size + nsstring_address
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location = process.ReadPointerFromMemory(location, error)
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elif is_inline and has_explicit_length and not is_unicode and not is_special and not is_mutable:
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location = 3 * ptr_size + nsstring_address
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elif is_unicode:
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location = 2 * ptr_size + nsstring_address
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if is_inline:
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if not has_explicit_length:
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print("Unicode & Inline & !Explicit is a new combo - no formula for it", file=result)
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else:
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location += ptr_size
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else:
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location = process.ReadPointerFromMemory(location, error)
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elif is_special:
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location = nsstring_address + ptr_size + 4
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elif is_inline:
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location = 2 * ptr_size + nsstring_address
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if not has_explicit_length:
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location += 1
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else:
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location = 2 * ptr_size + nsstring_address
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location = process.ReadPointerFromMemory(location, error)
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print("Expected data location: 0x%x\n" % (location), file=result)
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print("1K of data around location: %s\n" % read_memory(
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process, location, 1024), file=result)
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print("5K of data around string pointer: %s\n" % read_memory(
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process, nsstring_address, 1024 * 5), file=result)
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def __lldb_init_module(debugger, internal_dict):
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debugger.HandleCommand(
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"command script add -o -f %s.diagnose_nsstring_Command_Impl diagnose-nsstring" %
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__name__)
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print('The "diagnose-nsstring" command has been installed, type "help diagnose-nsstring" for detailed help.')
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__lldb_init_module(lldb.debugger, None)
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__lldb_init_module = None
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