1 //===-- Watchpoint.cpp ------------------------------------------*- C++ -*-===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "lldb/Breakpoint/Watchpoint.h"
11 
12 #include "lldb/Breakpoint/StoppointCallbackContext.h"
13 #include "lldb/Core/Value.h"
14 #include "lldb/Core/ValueObject.h"
15 #include "lldb/Core/ValueObjectMemory.h"
16 #include "lldb/Expression/UserExpression.h"
17 #include "lldb/Symbol/ClangASTContext.h"
18 #include "lldb/Target/Process.h"
19 #include "lldb/Target/Target.h"
20 #include "lldb/Target/ThreadSpec.h"
21 #include "lldb/Utility/Stream.h"
22 
23 using namespace lldb;
24 using namespace lldb_private;
25 
26 Watchpoint::Watchpoint(Target &target, lldb::addr_t addr, uint32_t size,
27                        const CompilerType *type, bool hardware)
28     : StoppointLocation(0, addr, size, hardware), m_target(target),
29       m_enabled(false), m_is_hardware(hardware), m_is_watch_variable(false),
30       m_is_ephemeral(false), m_disabled_count(0), m_watch_read(0),
31       m_watch_write(0), m_watch_was_read(0), m_watch_was_written(0),
32       m_ignore_count(0), m_false_alarms(0), m_decl_str(), m_watch_spec_str(),
33       m_type(), m_error(), m_options(), m_being_created(true) {
34   if (type && type->IsValid())
35     m_type = *type;
36   else {
37     // If we don't have a known type, then we force it to unsigned int of the
38     // right size.
39     ClangASTContext *ast_context = target.GetScratchClangASTContext();
40     m_type = ast_context->GetBuiltinTypeForEncodingAndBitSize(eEncodingUint,
41                                                               8 * size);
42   }
43 
44   // Set the initial value of the watched variable:
45   if (m_target.GetProcessSP()) {
46     ExecutionContext exe_ctx;
47     m_target.GetProcessSP()->CalculateExecutionContext(exe_ctx);
48     CaptureWatchedValue(exe_ctx);
49   }
50   m_being_created = false;
51 }
52 
53 Watchpoint::~Watchpoint() = default;
54 
55 // This function is used when "baton" doesn't need to be freed
56 void Watchpoint::SetCallback(WatchpointHitCallback callback, void *baton,
57                              bool is_synchronous) {
58   // The default "Baton" class will keep a copy of "baton" and won't free or
59   // delete it when it goes goes out of scope.
60   m_options.SetCallback(callback, std::make_shared<UntypedBaton>(baton),
61                         is_synchronous);
62 
63   SendWatchpointChangedEvent(eWatchpointEventTypeCommandChanged);
64 }
65 
66 // This function is used when a baton needs to be freed and therefore is
67 // contained in a "Baton" subclass.
68 void Watchpoint::SetCallback(WatchpointHitCallback callback,
69                              const BatonSP &callback_baton_sp,
70                              bool is_synchronous) {
71   m_options.SetCallback(callback, callback_baton_sp, is_synchronous);
72   SendWatchpointChangedEvent(eWatchpointEventTypeCommandChanged);
73 }
74 
75 void Watchpoint::ClearCallback() {
76   m_options.ClearCallback();
77   SendWatchpointChangedEvent(eWatchpointEventTypeCommandChanged);
78 }
79 
80 void Watchpoint::SetDeclInfo(const std::string &str) { m_decl_str = str; }
81 
82 std::string Watchpoint::GetWatchSpec() { return m_watch_spec_str; }
83 
84 void Watchpoint::SetWatchSpec(const std::string &str) {
85   m_watch_spec_str = str;
86 }
87 
88 // Override default impl of StoppointLocation::IsHardware() since m_is_hardware
89 // member field is more accurate.
90 bool Watchpoint::IsHardware() const { return m_is_hardware; }
91 
92 bool Watchpoint::IsWatchVariable() const { return m_is_watch_variable; }
93 
94 void Watchpoint::SetWatchVariable(bool val) { m_is_watch_variable = val; }
95 
96 bool Watchpoint::CaptureWatchedValue(const ExecutionContext &exe_ctx) {
97   ConstString watch_name("$__lldb__watch_value");
98   m_old_value_sp = m_new_value_sp;
99   Address watch_address(GetLoadAddress());
100   if (!m_type.IsValid()) {
101     // Don't know how to report new & old values, since we couldn't make a
102     // scalar type for this watchpoint. This works around an assert in
103     // ValueObjectMemory::Create.
104     // FIXME: This should not happen, but if it does in some case we care about,
105     // we can go grab the value raw and print it as unsigned.
106     return false;
107   }
108   m_new_value_sp = ValueObjectMemory::Create(
109       exe_ctx.GetBestExecutionContextScope(), watch_name.GetStringRef(),
110       watch_address, m_type);
111   m_new_value_sp = m_new_value_sp->CreateConstantValue(watch_name);
112   return (m_new_value_sp && m_new_value_sp->GetError().Success());
113 }
114 
115 void Watchpoint::IncrementFalseAlarmsAndReviseHitCount() {
116   ++m_false_alarms;
117   if (m_false_alarms) {
118     if (m_hit_count >= m_false_alarms) {
119       m_hit_count -= m_false_alarms;
120       m_false_alarms = 0;
121     } else {
122       m_false_alarms -= m_hit_count;
123       m_hit_count = 0;
124     }
125   }
126 }
127 
128 // RETURNS - true if we should stop at this breakpoint, false if we
129 // should continue.
130 
131 bool Watchpoint::ShouldStop(StoppointCallbackContext *context) {
132   IncrementHitCount();
133 
134   if (!IsEnabled())
135     return false;
136 
137   return true;
138 }
139 
140 void Watchpoint::GetDescription(Stream *s, lldb::DescriptionLevel level) {
141   DumpWithLevel(s, level);
142 }
143 
144 void Watchpoint::Dump(Stream *s) const {
145   DumpWithLevel(s, lldb::eDescriptionLevelBrief);
146 }
147 
148 // If prefix is nullptr, we display the watch id and ignore the prefix
149 // altogether.
150 void Watchpoint::DumpSnapshots(Stream *s, const char *prefix) const {
151   if (!prefix) {
152     s->Printf("\nWatchpoint %u hit:", GetID());
153     prefix = "";
154   }
155 
156   if (m_old_value_sp) {
157     const char *old_value_cstr = m_old_value_sp->GetValueAsCString();
158     if (old_value_cstr && old_value_cstr[0])
159       s->Printf("\n%sold value: %s", prefix, old_value_cstr);
160     else {
161       const char *old_summary_cstr = m_old_value_sp->GetSummaryAsCString();
162       if (old_summary_cstr && old_summary_cstr[0])
163         s->Printf("\n%sold value: %s", prefix, old_summary_cstr);
164     }
165   }
166 
167   if (m_new_value_sp) {
168     const char *new_value_cstr = m_new_value_sp->GetValueAsCString();
169     if (new_value_cstr && new_value_cstr[0])
170       s->Printf("\n%snew value: %s", prefix, new_value_cstr);
171     else {
172       const char *new_summary_cstr = m_new_value_sp->GetSummaryAsCString();
173       if (new_summary_cstr && new_summary_cstr[0])
174         s->Printf("\n%snew value: %s", prefix, new_summary_cstr);
175     }
176   }
177 }
178 
179 void Watchpoint::DumpWithLevel(Stream *s,
180                                lldb::DescriptionLevel description_level) const {
181   if (s == nullptr)
182     return;
183 
184   assert(description_level >= lldb::eDescriptionLevelBrief &&
185          description_level <= lldb::eDescriptionLevelVerbose);
186 
187   s->Printf("Watchpoint %u: addr = 0x%8.8" PRIx64
188             " size = %u state = %s type = %s%s",
189             GetID(), GetLoadAddress(), m_byte_size,
190             IsEnabled() ? "enabled" : "disabled", m_watch_read ? "r" : "",
191             m_watch_write ? "w" : "");
192 
193   if (description_level >= lldb::eDescriptionLevelFull) {
194     if (!m_decl_str.empty())
195       s->Printf("\n    declare @ '%s'", m_decl_str.c_str());
196     if (!m_watch_spec_str.empty())
197       s->Printf("\n    watchpoint spec = '%s'", m_watch_spec_str.c_str());
198 
199     // Dump the snapshots we have taken.
200     DumpSnapshots(s, "    ");
201 
202     if (GetConditionText())
203       s->Printf("\n    condition = '%s'", GetConditionText());
204     m_options.GetCallbackDescription(s, description_level);
205   }
206 
207   if (description_level >= lldb::eDescriptionLevelVerbose) {
208     s->Printf("\n    hw_index = %i  hit_count = %-4u  ignore_count = %-4u",
209               GetHardwareIndex(), GetHitCount(), GetIgnoreCount());
210   }
211 }
212 
213 bool Watchpoint::IsEnabled() const { return m_enabled; }
214 
215 // Within StopInfo.cpp, we purposely turn on the ephemeral mode right before
216 // temporarily disable the watchpoint in order to perform possible watchpoint
217 // actions without triggering further watchpoint events. After the temporary
218 // disabled watchpoint is enabled, we then turn off the ephemeral mode.
219 
220 void Watchpoint::TurnOnEphemeralMode() { m_is_ephemeral = true; }
221 
222 void Watchpoint::TurnOffEphemeralMode() {
223   m_is_ephemeral = false;
224   // Leaving ephemeral mode, reset the m_disabled_count!
225   m_disabled_count = 0;
226 }
227 
228 bool Watchpoint::IsDisabledDuringEphemeralMode() {
229   return m_disabled_count > 1 && m_is_ephemeral;
230 }
231 
232 void Watchpoint::SetEnabled(bool enabled, bool notify) {
233   if (!enabled) {
234     if (!m_is_ephemeral)
235       SetHardwareIndex(LLDB_INVALID_INDEX32);
236     else
237       ++m_disabled_count;
238 
239     // Don't clear the snapshots for now.
240     // Within StopInfo.cpp, we purposely do disable/enable watchpoint while
241     // performing watchpoint actions.
242   }
243   bool changed = enabled != m_enabled;
244   m_enabled = enabled;
245   if (notify && !m_is_ephemeral && changed)
246     SendWatchpointChangedEvent(enabled ? eWatchpointEventTypeEnabled
247                                        : eWatchpointEventTypeDisabled);
248 }
249 
250 void Watchpoint::SetWatchpointType(uint32_t type, bool notify) {
251   int old_watch_read = m_watch_read;
252   int old_watch_write = m_watch_write;
253   m_watch_read = (type & LLDB_WATCH_TYPE_READ) != 0;
254   m_watch_write = (type & LLDB_WATCH_TYPE_WRITE) != 0;
255   if (notify &&
256       (old_watch_read != m_watch_read || old_watch_write != m_watch_write))
257     SendWatchpointChangedEvent(eWatchpointEventTypeTypeChanged);
258 }
259 
260 bool Watchpoint::WatchpointRead() const { return m_watch_read != 0; }
261 
262 bool Watchpoint::WatchpointWrite() const { return m_watch_write != 0; }
263 
264 uint32_t Watchpoint::GetIgnoreCount() const { return m_ignore_count; }
265 
266 void Watchpoint::SetIgnoreCount(uint32_t n) {
267   bool changed = m_ignore_count != n;
268   m_ignore_count = n;
269   if (changed)
270     SendWatchpointChangedEvent(eWatchpointEventTypeIgnoreChanged);
271 }
272 
273 bool Watchpoint::InvokeCallback(StoppointCallbackContext *context) {
274   return m_options.InvokeCallback(context, GetID());
275 }
276 
277 void Watchpoint::SetCondition(const char *condition) {
278   if (condition == nullptr || condition[0] == '\0') {
279     if (m_condition_ap.get())
280       m_condition_ap.reset();
281   } else {
282     // Pass nullptr for expr_prefix (no translation-unit level definitions).
283     Status error;
284     m_condition_ap.reset(m_target.GetUserExpressionForLanguage(
285         condition, llvm::StringRef(), lldb::eLanguageTypeUnknown,
286         UserExpression::eResultTypeAny, EvaluateExpressionOptions(), error));
287     if (error.Fail()) {
288       // FIXME: Log something...
289       m_condition_ap.reset();
290     }
291   }
292   SendWatchpointChangedEvent(eWatchpointEventTypeConditionChanged);
293 }
294 
295 const char *Watchpoint::GetConditionText() const {
296   if (m_condition_ap.get())
297     return m_condition_ap->GetUserText();
298   else
299     return nullptr;
300 }
301 
302 void Watchpoint::SendWatchpointChangedEvent(
303     lldb::WatchpointEventType eventKind) {
304   if (!m_being_created &&
305       GetTarget().EventTypeHasListeners(
306           Target::eBroadcastBitWatchpointChanged)) {
307     WatchpointEventData *data =
308         new Watchpoint::WatchpointEventData(eventKind, shared_from_this());
309     GetTarget().BroadcastEvent(Target::eBroadcastBitWatchpointChanged, data);
310   }
311 }
312 
313 void Watchpoint::SendWatchpointChangedEvent(WatchpointEventData *data) {
314   if (data == nullptr)
315     return;
316 
317   if (!m_being_created &&
318       GetTarget().EventTypeHasListeners(Target::eBroadcastBitWatchpointChanged))
319     GetTarget().BroadcastEvent(Target::eBroadcastBitWatchpointChanged, data);
320   else
321     delete data;
322 }
323 
324 Watchpoint::WatchpointEventData::WatchpointEventData(
325     WatchpointEventType sub_type, const WatchpointSP &new_watchpoint_sp)
326     : EventData(), m_watchpoint_event(sub_type),
327       m_new_watchpoint_sp(new_watchpoint_sp) {}
328 
329 Watchpoint::WatchpointEventData::~WatchpointEventData() = default;
330 
331 const ConstString &Watchpoint::WatchpointEventData::GetFlavorString() {
332   static ConstString g_flavor("Watchpoint::WatchpointEventData");
333   return g_flavor;
334 }
335 
336 const ConstString &Watchpoint::WatchpointEventData::GetFlavor() const {
337   return WatchpointEventData::GetFlavorString();
338 }
339 
340 WatchpointSP &Watchpoint::WatchpointEventData::GetWatchpoint() {
341   return m_new_watchpoint_sp;
342 }
343 
344 WatchpointEventType
345 Watchpoint::WatchpointEventData::GetWatchpointEventType() const {
346   return m_watchpoint_event;
347 }
348 
349 void Watchpoint::WatchpointEventData::Dump(Stream *s) const {}
350 
351 const Watchpoint::WatchpointEventData *
352 Watchpoint::WatchpointEventData::GetEventDataFromEvent(const Event *event) {
353   if (event) {
354     const EventData *event_data = event->GetData();
355     if (event_data &&
356         event_data->GetFlavor() == WatchpointEventData::GetFlavorString())
357       return static_cast<const WatchpointEventData *>(event->GetData());
358   }
359   return nullptr;
360 }
361 
362 WatchpointEventType
363 Watchpoint::WatchpointEventData::GetWatchpointEventTypeFromEvent(
364     const EventSP &event_sp) {
365   const WatchpointEventData *data = GetEventDataFromEvent(event_sp.get());
366 
367   if (data == nullptr)
368     return eWatchpointEventTypeInvalidType;
369   else
370     return data->GetWatchpointEventType();
371 }
372 
373 WatchpointSP Watchpoint::WatchpointEventData::GetWatchpointFromEvent(
374     const EventSP &event_sp) {
375   WatchpointSP wp_sp;
376 
377   const WatchpointEventData *data = GetEventDataFromEvent(event_sp.get());
378   if (data)
379     wp_sp = data->m_new_watchpoint_sp;
380 
381   return wp_sp;
382 }
383