1 //===-- NSString.cpp ------------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #include "NSString.h"
10 
11 #include "lldb/Core/ValueObject.h"
12 #include "lldb/Core/ValueObjectConstResult.h"
13 #include "lldb/DataFormatters/FormattersHelpers.h"
14 #include "lldb/DataFormatters/StringPrinter.h"
15 #include "lldb/Target/Language.h"
16 #include "lldb/Target/Target.h"
17 #include "lldb/Utility/ConstString.h"
18 #include "lldb/Utility/DataBufferHeap.h"
19 #include "lldb/Utility/Endian.h"
20 #include "lldb/Utility/Status.h"
21 #include "lldb/Utility/Stream.h"
22 
23 using namespace lldb;
24 using namespace lldb_private;
25 using namespace lldb_private::formatters;
26 
27 std::map<ConstString, CXXFunctionSummaryFormat::Callback> &
28 NSString_Additionals::GetAdditionalSummaries() {
29   static std::map<ConstString, CXXFunctionSummaryFormat::Callback> g_map;
30   return g_map;
31 }
32 
33 bool lldb_private::formatters::NSStringSummaryProvider(
34     ValueObject &valobj, Stream &stream,
35     const TypeSummaryOptions &summary_options) {
36   static constexpr llvm::StringLiteral g_TypeHint("NSString");
37 
38   ProcessSP process_sp = valobj.GetProcessSP();
39   if (!process_sp)
40     return false;
41 
42   ObjCLanguageRuntime *runtime = ObjCLanguageRuntime::Get(*process_sp);
43 
44   if (!runtime)
45     return false;
46 
47   ObjCLanguageRuntime::ClassDescriptorSP descriptor(
48       runtime->GetClassDescriptor(valobj));
49 
50   if (!descriptor.get() || !descriptor->IsValid())
51     return false;
52 
53   uint32_t ptr_size = process_sp->GetAddressByteSize();
54 
55   lldb::addr_t valobj_addr = valobj.GetValueAsUnsigned(0);
56 
57   if (!valobj_addr)
58     return false;
59 
60   ConstString class_name_cs = descriptor->GetClassName();
61   llvm::StringRef class_name = class_name_cs.GetStringRef();
62 
63   if (class_name.empty())
64     return false;
65 
66   bool is_tagged_ptr = class_name == "NSTaggedPointerString" &&
67                        descriptor->GetTaggedPointerInfo();
68   // for a tagged pointer, the descriptor has everything we need
69   if (is_tagged_ptr)
70     return NSTaggedString_SummaryProvider(valobj, descriptor, stream,
71                                           summary_options);
72 
73   auto &additionals_map(NSString_Additionals::GetAdditionalSummaries());
74   auto iter = additionals_map.find(class_name_cs), end = additionals_map.end();
75   if (iter != end)
76     return iter->second(valobj, stream, summary_options);
77 
78   // if not a tagged pointer that we know about, try the normal route
79   uint64_t info_bits_location = valobj_addr + ptr_size;
80   if (process_sp->GetByteOrder() != lldb::eByteOrderLittle)
81     info_bits_location += 3;
82 
83   Status error;
84 
85   uint8_t info_bits = process_sp->ReadUnsignedIntegerFromMemory(
86       info_bits_location, 1, 0, error);
87   if (error.Fail())
88     return false;
89 
90   bool is_mutable = (info_bits & 1) == 1;
91   bool is_inline = (info_bits & 0x60) == 0;
92   bool has_explicit_length = (info_bits & (1 | 4)) != 4;
93   bool is_unicode = (info_bits & 0x10) == 0x10;
94   bool is_path_store = class_name == "NSPathStore2";
95   bool has_null = (info_bits & 8) == 8;
96 
97   size_t explicit_length = 0;
98   if (!has_null && has_explicit_length && !is_path_store) {
99     lldb::addr_t explicit_length_offset = 2 * ptr_size;
100     if (is_mutable && !is_inline)
101       explicit_length_offset =
102           explicit_length_offset + ptr_size; //  notInlineMutable.length;
103     else if (is_inline)
104       explicit_length = explicit_length + 0; // inline1.length;
105     else if (!is_inline && !is_mutable)
106       explicit_length_offset =
107           explicit_length_offset + ptr_size; // notInlineImmutable1.length;
108     else
109       explicit_length_offset = 0;
110 
111     if (explicit_length_offset) {
112       explicit_length_offset = valobj_addr + explicit_length_offset;
113       explicit_length = process_sp->ReadUnsignedIntegerFromMemory(
114           explicit_length_offset, 4, 0, error);
115     }
116   }
117 
118   const llvm::StringSet<> supported_string_classes = {
119       "NSString",     "CFMutableStringRef",
120       "CFStringRef",  "__NSCFConstantString",
121       "__NSCFString", "NSCFConstantString",
122       "NSCFString",   "NSPathStore2"};
123   if (supported_string_classes.count(class_name) == 0) {
124     // not one of us - but tell me class name
125     stream.Printf("class name = %s", class_name_cs.GetCString());
126     return true;
127   }
128 
129   llvm::StringRef prefix, suffix;
130   if (Language *language = Language::FindPlugin(summary_options.GetLanguage()))
131     std::tie(prefix, suffix) = language->GetFormatterPrefixSuffix(g_TypeHint);
132 
133   StringPrinter::ReadStringAndDumpToStreamOptions options(valobj);
134   options.SetPrefixToken(prefix.str());
135   options.SetSuffixToken(suffix.str());
136 
137   if (is_mutable) {
138     uint64_t location = 2 * ptr_size + valobj_addr;
139     location = process_sp->ReadPointerFromMemory(location, error);
140     if (error.Fail())
141       return false;
142     if (has_explicit_length && is_unicode) {
143       options.SetLocation(location);
144       options.SetTargetSP(valobj.GetTargetSP());
145       options.SetStream(&stream);
146       options.SetQuote('"');
147       options.SetSourceSize(explicit_length);
148       options.SetHasSourceSize(has_explicit_length);
149       options.SetNeedsZeroTermination(false);
150       options.SetIgnoreMaxLength(summary_options.GetCapping() ==
151                                  TypeSummaryCapping::eTypeSummaryUncapped);
152       options.SetBinaryZeroIsTerminator(false);
153       return StringPrinter::ReadStringAndDumpToStream<
154           StringPrinter::StringElementType::UTF16>(options);
155     } else {
156       options.SetLocation(location + 1);
157       options.SetTargetSP(valobj.GetTargetSP());
158       options.SetStream(&stream);
159       options.SetSourceSize(explicit_length);
160       options.SetHasSourceSize(has_explicit_length);
161       options.SetNeedsZeroTermination(false);
162       options.SetIgnoreMaxLength(summary_options.GetCapping() ==
163                                  TypeSummaryCapping::eTypeSummaryUncapped);
164       options.SetBinaryZeroIsTerminator(false);
165       return StringPrinter::ReadStringAndDumpToStream<
166           StringPrinter::StringElementType::ASCII>(options);
167     }
168   } else if (is_inline && has_explicit_length && !is_unicode &&
169              !is_path_store && !is_mutable) {
170     uint64_t location = 3 * ptr_size + valobj_addr;
171 
172     options.SetLocation(location);
173     options.SetTargetSP(valobj.GetTargetSP());
174     options.SetStream(&stream);
175     options.SetQuote('"');
176     options.SetSourceSize(explicit_length);
177     options.SetHasSourceSize(has_explicit_length);
178     options.SetIgnoreMaxLength(summary_options.GetCapping() ==
179                                TypeSummaryCapping::eTypeSummaryUncapped);
180     return StringPrinter::ReadStringAndDumpToStream<
181         StringPrinter::StringElementType::ASCII>(options);
182   } else if (is_unicode) {
183     uint64_t location = valobj_addr + 2 * ptr_size;
184     if (is_inline) {
185       if (!has_explicit_length) {
186         return false;
187       } else
188         location += ptr_size;
189     } else {
190       location = process_sp->ReadPointerFromMemory(location, error);
191       if (error.Fail())
192         return false;
193     }
194     options.SetLocation(location);
195     options.SetTargetSP(valobj.GetTargetSP());
196     options.SetStream(&stream);
197     options.SetQuote('"');
198     options.SetSourceSize(explicit_length);
199     options.SetHasSourceSize(has_explicit_length);
200     options.SetNeedsZeroTermination(!has_explicit_length);
201     options.SetIgnoreMaxLength(summary_options.GetCapping() ==
202                                TypeSummaryCapping::eTypeSummaryUncapped);
203     options.SetBinaryZeroIsTerminator(!has_explicit_length);
204     return StringPrinter::ReadStringAndDumpToStream<
205         StringPrinter::StringElementType::UTF16>(options);
206   } else if (is_path_store) {
207     // _lengthAndRefCount is the first ivar of NSPathStore2 (after the isa).
208     uint64_t length_ivar_offset = 1 * ptr_size;
209     CompilerType length_type = valobj.GetCompilerType().GetBasicTypeFromAST(
210         lldb::eBasicTypeUnsignedInt);
211     ValueObjectSP length_valobj_sp =
212         valobj.GetSyntheticChildAtOffset(length_ivar_offset, length_type, true,
213                                          ConstString("_lengthAndRefCount"));
214     if (!length_valobj_sp)
215       return false;
216     // Get the length out of _lengthAndRefCount.
217     explicit_length = length_valobj_sp->GetValueAsUnsigned(0) >> 20;
218     lldb::addr_t location = valobj.GetValueAsUnsigned(0) + ptr_size + 4;
219 
220     options.SetLocation(location);
221     options.SetTargetSP(valobj.GetTargetSP());
222     options.SetStream(&stream);
223     options.SetQuote('"');
224     options.SetSourceSize(explicit_length);
225     options.SetHasSourceSize(has_explicit_length);
226     options.SetNeedsZeroTermination(!has_explicit_length);
227     options.SetIgnoreMaxLength(summary_options.GetCapping() ==
228                                TypeSummaryCapping::eTypeSummaryUncapped);
229     options.SetBinaryZeroIsTerminator(!has_explicit_length);
230     return StringPrinter::ReadStringAndDumpToStream<
231         StringPrinter::StringElementType::UTF16>(options);
232   } else if (is_inline) {
233     uint64_t location = valobj_addr + 2 * ptr_size;
234     if (!has_explicit_length) {
235       // in this kind of string, the byte before the string content is a length
236       // byte so let's try and use it to handle the embedded NUL case
237       Status error;
238       explicit_length =
239           process_sp->ReadUnsignedIntegerFromMemory(location, 1, 0, error);
240       has_explicit_length = !(error.Fail() || explicit_length == 0);
241       location++;
242     }
243     options.SetLocation(location);
244     options.SetTargetSP(valobj.GetTargetSP());
245     options.SetStream(&stream);
246     options.SetSourceSize(explicit_length);
247     options.SetHasSourceSize(has_explicit_length);
248     options.SetNeedsZeroTermination(!has_explicit_length);
249     options.SetIgnoreMaxLength(summary_options.GetCapping() ==
250                                TypeSummaryCapping::eTypeSummaryUncapped);
251     options.SetBinaryZeroIsTerminator(!has_explicit_length);
252     if (has_explicit_length)
253       return StringPrinter::ReadStringAndDumpToStream<
254           StringPrinter::StringElementType::UTF8>(options);
255     else
256       return StringPrinter::ReadStringAndDumpToStream<
257           StringPrinter::StringElementType::ASCII>(options);
258   } else {
259     uint64_t location = valobj_addr + 2 * ptr_size;
260     location = process_sp->ReadPointerFromMemory(location, error);
261     if (error.Fail())
262       return false;
263     if (has_explicit_length && !has_null)
264       explicit_length++; // account for the fact that there is no NULL and we
265                          // need to have one added
266     options.SetLocation(location);
267     options.SetTargetSP(valobj.GetTargetSP());
268     options.SetStream(&stream);
269     options.SetSourceSize(explicit_length);
270     options.SetHasSourceSize(has_explicit_length);
271     options.SetIgnoreMaxLength(summary_options.GetCapping() ==
272                                TypeSummaryCapping::eTypeSummaryUncapped);
273     return StringPrinter::ReadStringAndDumpToStream<
274         StringPrinter::StringElementType::ASCII>(options);
275   }
276 }
277 
278 bool lldb_private::formatters::NSAttributedStringSummaryProvider(
279     ValueObject &valobj, Stream &stream, const TypeSummaryOptions &options) {
280   TargetSP target_sp(valobj.GetTargetSP());
281   if (!target_sp)
282     return false;
283   uint32_t addr_size = target_sp->GetArchitecture().GetAddressByteSize();
284   uint64_t pointer_value = valobj.GetValueAsUnsigned(0);
285   if (!pointer_value)
286     return false;
287   pointer_value += addr_size;
288   CompilerType type(valobj.GetCompilerType());
289   ExecutionContext exe_ctx(target_sp, false);
290   ValueObjectSP child_ptr_sp(valobj.CreateValueObjectFromAddress(
291       "string_ptr", pointer_value, exe_ctx, type));
292   if (!child_ptr_sp)
293     return false;
294   DataExtractor data;
295   Status error;
296   child_ptr_sp->GetData(data, error);
297   if (error.Fail())
298     return false;
299   ValueObjectSP child_sp(child_ptr_sp->CreateValueObjectFromData(
300       "string_data", data, exe_ctx, type));
301   child_sp->GetValueAsUnsigned(0);
302   if (child_sp)
303     return NSStringSummaryProvider(*child_sp, stream, options);
304   return false;
305 }
306 
307 bool lldb_private::formatters::NSMutableAttributedStringSummaryProvider(
308     ValueObject &valobj, Stream &stream, const TypeSummaryOptions &options) {
309   return NSAttributedStringSummaryProvider(valobj, stream, options);
310 }
311 
312 bool lldb_private::formatters::NSTaggedString_SummaryProvider(
313     ValueObject &valobj, ObjCLanguageRuntime::ClassDescriptorSP descriptor,
314     Stream &stream, const TypeSummaryOptions &summary_options) {
315   static constexpr llvm::StringLiteral g_TypeHint("NSString");
316 
317   if (!descriptor)
318     return false;
319   uint64_t len_bits = 0, data_bits = 0;
320   if (!descriptor->GetTaggedPointerInfo(&len_bits, &data_bits, nullptr))
321     return false;
322 
323   static const int g_MaxNonBitmaskedLen = 7; // TAGGED_STRING_UNPACKED_MAXLEN
324   static const int g_SixbitMaxLen = 9;
325   static const int g_fiveBitMaxLen = 11;
326 
327   static const char *sixBitToCharLookup = "eilotrm.apdnsIc ufkMShjTRxgC4013"
328                                           "bDNvwyUL2O856P-B79AFKEWV_zGJ/HYX";
329 
330   if (len_bits > g_fiveBitMaxLen)
331     return false;
332 
333   llvm::StringRef prefix, suffix;
334   if (Language *language = Language::FindPlugin(summary_options.GetLanguage()))
335     std::tie(prefix, suffix) = language->GetFormatterPrefixSuffix(g_TypeHint);
336 
337   // this is a fairly ugly trick - pretend that the numeric value is actually a
338   // char* this works under a few assumptions: little endian architecture
339   // sizeof(uint64_t) > g_MaxNonBitmaskedLen
340   if (len_bits <= g_MaxNonBitmaskedLen) {
341     stream << prefix;
342     stream.Printf("\"%s\"", (const char *)&data_bits);
343     stream << suffix;
344     return true;
345   }
346 
347   // if the data is bitmasked, we need to actually process the bytes
348   uint8_t bitmask = 0;
349   uint8_t shift_offset = 0;
350 
351   if (len_bits <= g_SixbitMaxLen) {
352     bitmask = 0x03f;
353     shift_offset = 6;
354   } else {
355     bitmask = 0x01f;
356     shift_offset = 5;
357   }
358 
359   std::vector<uint8_t> bytes;
360   bytes.resize(len_bits);
361   for (; len_bits > 0; data_bits >>= shift_offset, --len_bits) {
362     uint8_t packed = data_bits & bitmask;
363     bytes.insert(bytes.begin(), sixBitToCharLookup[packed]);
364   }
365 
366   stream << prefix;
367   stream.Printf("\"%s\"", &bytes[0]);
368   stream << suffix;
369   return true;
370 }
371