1 //===- llvm/Support/PrettyStackTrace.h - Pretty Crash Handling --*- C++ -*-===//
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 // This file defines the PrettyStackTraceEntry class, which is used to make
10 // crashes give more contextual information about what the program was doing
11 // when it crashed.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #ifndef LLVM_SUPPORT_PRETTYSTACKTRACE_H
16 #define LLVM_SUPPORT_PRETTYSTACKTRACE_H
17 
18 #include "llvm/ADT/SmallVector.h"
19 #include "llvm/Support/Compiler.h"
20 
21 namespace llvm {
22   class raw_ostream;
23 
24   /// Enables dumping a "pretty" stack trace when the program crashes.
25   ///
26   /// \see PrettyStackTraceEntry
27   void EnablePrettyStackTrace();
28 
29   /// Enables (or disables) dumping a "pretty" stack trace when the user sends
30   /// SIGINFO or SIGUSR1 to the current process.
31   ///
32   /// This is a per-thread decision so that a program can choose to print stack
33   /// traces only on a primary thread, or on all threads that use
34   /// PrettyStackTraceEntry.
35   ///
36   /// \see EnablePrettyStackTrace
37   /// \see PrettyStackTraceEntry
38   void EnablePrettyStackTraceOnSigInfoForThisThread(bool ShouldEnable = true);
39 
40   /// PrettyStackTraceEntry - This class is used to represent a frame of the
41   /// "pretty" stack trace that is dumped when a program crashes. You can define
42   /// subclasses of this and declare them on the program stack: when they are
43   /// constructed and destructed, they will add their symbolic frames to a
44   /// virtual stack trace.  This gets dumped out if the program crashes.
45   class PrettyStackTraceEntry {
46     friend PrettyStackTraceEntry *ReverseStackTrace(PrettyStackTraceEntry *);
47 
48     PrettyStackTraceEntry *NextEntry;
49     PrettyStackTraceEntry(const PrettyStackTraceEntry &) = delete;
50     void operator=(const PrettyStackTraceEntry &) = delete;
51   public:
52     PrettyStackTraceEntry();
53     virtual ~PrettyStackTraceEntry();
54 
55     /// print - Emit information about this stack frame to OS.
56     virtual void print(raw_ostream &OS) const = 0;
57 
58     /// getNextEntry - Return the next entry in the list of frames.
59     const PrettyStackTraceEntry *getNextEntry() const { return NextEntry; }
60   };
61 
62   /// PrettyStackTraceString - This object prints a specified string (which
63   /// should not contain newlines) to the stream as the stack trace when a crash
64   /// occurs.
65   class PrettyStackTraceString : public PrettyStackTraceEntry {
66     const char *Str;
67   public:
68     PrettyStackTraceString(const char *str) : Str(str) {}
69     void print(raw_ostream &OS) const override;
70   };
71 
72   /// PrettyStackTraceFormat - This object prints a string (which may use
73   /// printf-style formatting but should not contain newlines) to the stream
74   /// as the stack trace when a crash occurs.
75   class PrettyStackTraceFormat : public PrettyStackTraceEntry {
76     llvm::SmallVector<char, 32> Str;
77   public:
78     PrettyStackTraceFormat(const char *Format, ...);
79     void print(raw_ostream &OS) const override;
80   };
81 
82   /// PrettyStackTraceProgram - This object prints a specified program arguments
83   /// to the stream as the stack trace when a crash occurs.
84   class PrettyStackTraceProgram : public PrettyStackTraceEntry {
85     int ArgC;
86     const char *const *ArgV;
87   public:
88     PrettyStackTraceProgram(int argc, const char * const*argv)
89       : ArgC(argc), ArgV(argv) {
90       EnablePrettyStackTrace();
91     }
92     void print(raw_ostream &OS) const override;
93   };
94 
95   /// Returns the topmost element of the "pretty" stack state.
96   const void *SavePrettyStackState();
97 
98   /// Restores the topmost element of the "pretty" stack state to State, which
99   /// should come from a previous call to SavePrettyStackState().  This is
100   /// useful when using a CrashRecoveryContext in code that also uses
101   /// PrettyStackTraceEntries, to make sure the stack that's printed if a crash
102   /// happens after a crash that's been recovered by CrashRecoveryContext
103   /// doesn't have frames on it that were added in code unwound by the
104   /// CrashRecoveryContext.
105   void RestorePrettyStackState(const void *State);
106 
107 } // end namespace llvm
108 
109 #endif
110