llvm-project/lldb/examples/summaries/cocoa/CFString.py

326 lines
12 KiB
Python

"""
LLDB AppKit formatters
part of The LLVM Compiler Infrastructure
This file is distributed under the University of Illinois Open Source
License. See LICENSE.TXT for details.
"""
# example synthetic children and summary provider for CFString (and related NSString class)
# the real code is part of the LLDB core
import lldb
import lldb.runtime.objc.objc_runtime
import lldb.formatters.Logger
def CFString_SummaryProvider (valobj,dict):
logger = lldb.formatters.Logger.Logger()
provider = CFStringSynthProvider(valobj,dict);
if provider.invalid == False:
try:
summary = provider.get_child_at_index(provider.get_child_index("content"))
if type(summary) == lldb.SBValue:
summary = summary.GetSummary()
else:
summary = '"' + summary + '"'
except:
summary = None
if summary == None:
summary = '<variable is not NSString>'
return '@'+summary
return ''
def CFAttributedString_SummaryProvider (valobj,dict):
logger = lldb.formatters.Logger.Logger()
offset = valobj.GetTarget().GetProcess().GetAddressByteSize()
pointee = valobj.GetValueAsUnsigned(0)
summary = '<variable is not NSAttributedString>'
if pointee != None and pointee != 0:
pointee = pointee + offset
child_ptr = valobj.CreateValueFromAddress("string_ptr",pointee,valobj.GetType())
child = child_ptr.CreateValueFromAddress("string_data",child_ptr.GetValueAsUnsigned(),valobj.GetType()).AddressOf()
provider = CFStringSynthProvider(child,dict);
if provider.invalid == False:
try:
summary = provider.get_child_at_index(provider.get_child_index("content")).GetSummary();
except:
summary = '<variable is not NSAttributedString>'
if summary == None:
summary = '<variable is not NSAttributedString>'
return '@'+summary
def __lldb_init_module(debugger,dict):
debugger.HandleCommand("type summary add -F CFString.CFString_SummaryProvider NSString CFStringRef CFMutableStringRef")
debugger.HandleCommand("type summary add -F CFString.CFAttributedString_SummaryProvider NSAttributedString")
class CFStringSynthProvider:
def __init__(self,valobj,dict):
logger = lldb.formatters.Logger.Logger()
self.valobj = valobj;
self.update()
# children other than "content" are for debugging only and must not be used in production code
def num_children(self):
logger = lldb.formatters.Logger.Logger()
if self.invalid:
return 0;
return 6;
def read_unicode(self, pointer,max_len=2048):
logger = lldb.formatters.Logger.Logger()
process = self.valobj.GetTarget().GetProcess()
error = lldb.SBError()
pystr = u''
# cannot do the read at once because the length value has
# a weird encoding. better play it safe here
while max_len > 0:
content = process.ReadMemory(pointer, 2, error)
new_bytes = bytearray(content)
b0 = new_bytes[0]
b1 = new_bytes[1]
pointer = pointer + 2
if b0 == 0 and b1 == 0:
break
# rearrange bytes depending on endianness
# (do we really need this or is Cocoa going to
# use Windows-compatible little-endian even
# if the target is big endian?)
if self.is_little:
value = b1 * 256 + b0
else:
value = b0 * 256 + b1
pystr = pystr + unichr(value)
# read max_len unicode values, not max_len bytes
max_len = max_len - 1
return pystr
# handle the special case strings
# only use the custom code for the tested LP64 case
def handle_special(self):
logger = lldb.formatters.Logger.Logger()
if self.is_64_bit == False:
# for 32bit targets, use safe ObjC code
return self.handle_unicode_string_safe()
offset = 12
pointer = self.valobj.GetValueAsUnsigned(0) + offset
pystr = self.read_unicode(pointer)
return self.valobj.CreateValueFromExpression("content",
"(char*)\"" + pystr.encode('utf-8') + "\"")
# last resort call, use ObjC code to read; the final aim is to
# be able to strip this call away entirely and only do the read
# ourselves
def handle_unicode_string_safe(self):
return self.valobj.CreateValueFromExpression("content",
"(char*)\"" + self.valobj.GetObjectDescription() + "\"");
def handle_unicode_string(self):
logger = lldb.formatters.Logger.Logger()
# step 1: find offset
if self.inline:
pointer = self.valobj.GetValueAsUnsigned(0) + self.size_of_cfruntime_base();
if self.explicit == False:
# untested, use the safe code path
return self.handle_unicode_string_safe();
else:
# a full pointer is skipped here before getting to the live data
pointer = pointer + self.pointer_size
else:
pointer = self.valobj.GetValueAsUnsigned(0) + self.size_of_cfruntime_base()
# read 8 bytes here and make an address out of them
try:
char_type = self.valobj.GetType().GetBasicType(lldb.eBasicTypeChar).GetPointerType()
vopointer = self.valobj.CreateValueFromAddress("dummy",pointer,char_type);
pointer = vopointer.GetValueAsUnsigned(0)
except:
return self.valobj.CreateValueFromExpression("content",
'(char*)"@\"invalid NSString\""')
# step 2: read Unicode data at pointer
pystr = self.read_unicode(pointer)
# step 3: return it
return pystr.encode('utf-8')
def handle_inline_explicit(self):
logger = lldb.formatters.Logger.Logger()
offset = 3*self.pointer_size
offset = offset + self.valobj.GetValueAsUnsigned(0)
return self.valobj.CreateValueFromExpression("content",
"(char*)(" + str(offset) + ")")
def handle_mutable_string(self):
logger = lldb.formatters.Logger.Logger()
offset = 2 * self.pointer_size
data = self.valobj.CreateChildAtOffset("content",
offset, self.valobj.GetType().GetBasicType(lldb.eBasicTypeChar).GetPointerType());
data_value = data.GetValueAsUnsigned(0)
if self.explicit and self.unicode:
return self.read_unicode(data_value).encode('utf-8')
else:
data_value = data_value + 1
return self.valobj.CreateValueFromExpression("content", "(char*)(" + str(data_value) + ")")
def handle_UTF8_inline(self):
logger = lldb.formatters.Logger.Logger()
offset = self.valobj.GetValueAsUnsigned(0) + self.size_of_cfruntime_base();
if self.explicit == False:
offset = offset + 1;
return self.valobj.CreateValueFromAddress("content",
offset, self.valobj.GetType().GetBasicType(lldb.eBasicTypeChar)).AddressOf();
def handle_UTF8_not_inline(self):
logger = lldb.formatters.Logger.Logger()
offset = self.size_of_cfruntime_base();
return self.valobj.CreateChildAtOffset("content",
offset,self.valobj.GetType().GetBasicType(lldb.eBasicTypeChar).GetPointerType());
def get_child_at_index(self,index):
logger = lldb.formatters.Logger.Logger()
logger >> "Querying for child [" + str(index) + "]"
if index == 0:
return self.valobj.CreateValueFromExpression("mutable",
str(int(self.mutable)));
if index == 1:
return self.valobj.CreateValueFromExpression("inline",
str(int(self.inline)));
if index == 2:
return self.valobj.CreateValueFromExpression("explicit",
str(int(self.explicit)));
if index == 3:
return self.valobj.CreateValueFromExpression("unicode",
str(int(self.unicode)));
if index == 4:
return self.valobj.CreateValueFromExpression("special",
str(int(self.special)));
if index == 5:
# we are handling the several possible combinations of flags.
# for each known combination we have a function that knows how to
# go fetch the data from memory instead of running code. if a string is not
# correctly displayed, one should start by finding a combination of flags that
# makes it different from these known cases, and provide a new reader function
# if this is not possible, a new flag might have to be made up (like the "special" flag
# below, which is not a real flag in CFString), or alternatively one might need to use
# the ObjC runtime helper to detect the new class and deal with it accordingly
#print 'mutable = ' + str(self.mutable)
#print 'inline = ' + str(self.inline)
#print 'explicit = ' + str(self.explicit)
#print 'unicode = ' + str(self.unicode)
#print 'special = ' + str(self.special)
if self.mutable == True:
return self.handle_mutable_string()
elif self.inline == True and self.explicit == True and \
self.unicode == False and self.special == False and \
self.mutable == False:
return self.handle_inline_explicit()
elif self.unicode == True:
return self.handle_unicode_string();
elif self.special == True:
return self.handle_special();
elif self.inline == True:
return self.handle_UTF8_inline();
else:
return self.handle_UTF8_not_inline();
def get_child_index(self,name):
logger = lldb.formatters.Logger.Logger()
logger >> "Querying for child ['" + str(name) + "']"
if name == "content":
return self.num_children() - 1;
if name == "mutable":
return 0;
if name == "inline":
return 1;
if name == "explicit":
return 2;
if name == "unicode":
return 3;
if name == "special":
return 4;
# CFRuntimeBase is defined as having an additional
# 4 bytes (padding?) on LP64 architectures
# to get its size we add up sizeof(pointer)+4
# and then add 4 more bytes if we are on a 64bit system
def size_of_cfruntime_base(self):
logger = lldb.formatters.Logger.Logger()
return self.pointer_size+4+(4 if self.is_64_bit else 0)
# the info bits are part of the CFRuntimeBase structure
# to get at them we have to skip a uintptr_t and then get
# at the least-significant byte of a 4 byte array. If we are
# on big-endian this means going to byte 3, if we are on
# little endian (OSX & iOS), this means reading byte 0
def offset_of_info_bits(self):
logger = lldb.formatters.Logger.Logger()
offset = self.pointer_size
if self.is_little == False:
offset = offset + 3;
return offset;
def read_info_bits(self):
logger = lldb.formatters.Logger.Logger()
cfinfo = self.valobj.CreateChildAtOffset("cfinfo",
self.offset_of_info_bits(),
self.valobj.GetType().GetBasicType(lldb.eBasicTypeChar));
cfinfo.SetFormat(11)
info = cfinfo.GetValue();
if info != None:
self.invalid = False;
return int(info,0);
else:
self.invalid = True;
return None;
# calculating internal flag bits of the CFString object
# this stuff is defined and discussed in CFString.c
def is_mutable(self):
logger = lldb.formatters.Logger.Logger()
return (self.info_bits & 1) == 1;
def is_inline(self):
logger = lldb.formatters.Logger.Logger()
return (self.info_bits & 0x60) == 0;
# this flag's name is ambiguous, it turns out
# we must skip a length byte to get at the data
# when this flag is False
def has_explicit_length(self):
logger = lldb.formatters.Logger.Logger()
return (self.info_bits & (1 | 4)) != 4;
# probably a subclass of NSString. obtained this from [str pathExtension]
# here info_bits = 0 and Unicode data at the start of the padding word
# in the long run using the isa value might be safer as a way to identify this
# instead of reading the info_bits
def is_special_case(self):
logger = lldb.formatters.Logger.Logger()
return self.info_bits == 0;
def is_unicode(self):
logger = lldb.formatters.Logger.Logger()
return (self.info_bits & 0x10) == 0x10;
# preparing ourselves to read into memory
# by adjusting architecture-specific info
def adjust_for_architecture(self):
logger = lldb.formatters.Logger.Logger()
self.pointer_size = self.valobj.GetTarget().GetProcess().GetAddressByteSize()
self.is_64_bit = self.pointer_size == 8
self.is_little = self.valobj.GetTarget().GetProcess().GetByteOrder() == lldb.eByteOrderLittle
# reading info bits out of the CFString and computing
# useful values to get at the real data
def compute_flags(self):
logger = lldb.formatters.Logger.Logger()
self.info_bits = self.read_info_bits();
if self.info_bits == None:
return;
self.mutable = self.is_mutable();
self.inline = self.is_inline();
self.explicit = self.has_explicit_length();
self.unicode = self.is_unicode();
self.special = self.is_special_case();
def update(self):
logger = lldb.formatters.Logger.Logger()
self.adjust_for_architecture();
self.compute_flags();