1 //===- lib/Support/ErrorHandling.cpp - Callbacks for errors ---------------===//
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 // This file defines an API used to indicate fatal error conditions.  Non-fatal
11 // errors (most of them) should be handled through LLVMContext.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "llvm/Support/ErrorHandling.h"
16 #include "llvm-c/Core.h"
17 #include "llvm/ADT/SmallVector.h"
18 #include "llvm/ADT/Twine.h"
19 #include "llvm/Config/config.h"
20 #include "llvm/Support/Debug.h"
21 #include "llvm/Support/Signals.h"
22 #include "llvm/Support/Mutex.h"
23 #include "llvm/Support/MutexGuard.h"
24 #include "llvm/Support/Threading.h"
25 #include "llvm/Support/raw_ostream.h"
26 #include <cassert>
27 #include <cstdlib>
28 
29 #if defined(HAVE_UNISTD_H)
30 # include <unistd.h>
31 #endif
32 #if defined(_MSC_VER)
33 # include <io.h>
34 # include <fcntl.h>
35 #endif
36 
37 using namespace llvm;
38 
39 static fatal_error_handler_t ErrorHandler = nullptr;
40 static void *ErrorHandlerUserData = nullptr;
41 
42 static sys::Mutex ErrorHandlerMutex;
43 
44 void llvm::install_fatal_error_handler(fatal_error_handler_t handler,
45                                        void *user_data) {
46   llvm::MutexGuard Lock(ErrorHandlerMutex);
47   assert(!ErrorHandler && "Error handler already registered!\n");
48   ErrorHandler = handler;
49   ErrorHandlerUserData = user_data;
50 }
51 
52 void llvm::remove_fatal_error_handler() {
53   llvm::MutexGuard Lock(ErrorHandlerMutex);
54   ErrorHandler = nullptr;
55   ErrorHandlerUserData = nullptr;
56 }
57 
58 void llvm::report_fatal_error(const char *Reason, bool GenCrashDiag) {
59   report_fatal_error(Twine(Reason), GenCrashDiag);
60 }
61 
62 void llvm::report_fatal_error(const std::string &Reason, bool GenCrashDiag) {
63   report_fatal_error(Twine(Reason), GenCrashDiag);
64 }
65 
66 void llvm::report_fatal_error(StringRef Reason, bool GenCrashDiag) {
67   report_fatal_error(Twine(Reason), GenCrashDiag);
68 }
69 
70 void llvm::report_fatal_error(const Twine &Reason, bool GenCrashDiag) {
71   llvm::fatal_error_handler_t handler = nullptr;
72   void* handlerData = nullptr;
73   {
74     // Only acquire the mutex while reading the handler, so as not to invoke a
75     // user-supplied callback under a lock.
76     llvm::MutexGuard Lock(ErrorHandlerMutex);
77     handler = ErrorHandler;
78     handlerData = ErrorHandlerUserData;
79   }
80 
81   if (handler) {
82     handler(handlerData, Reason.str(), GenCrashDiag);
83   } else {
84     // Blast the result out to stderr.  We don't try hard to make sure this
85     // succeeds (e.g. handling EINTR) and we can't use errs() here because
86     // raw ostreams can call report_fatal_error.
87     SmallVector<char, 64> Buffer;
88     raw_svector_ostream OS(Buffer);
89     OS << "LLVM ERROR: " << Reason << "\n";
90     StringRef MessageStr = OS.str();
91     ssize_t written = ::write(2, MessageStr.data(), MessageStr.size());
92     (void)written; // If something went wrong, we deliberately just give up.
93   }
94 
95   // If we reached here, we are failing ungracefully. Run the interrupt handlers
96   // to make sure any special cleanups get done, in particular that we remove
97   // files registered with RemoveFileOnSignal.
98   sys::RunInterruptHandlers();
99 
100   exit(1);
101 }
102 
103 void llvm::llvm_unreachable_internal(const char *msg, const char *file,
104                                      unsigned line) {
105   // This code intentionally doesn't call the ErrorHandler callback, because
106   // llvm_unreachable is intended to be used to indicate "impossible"
107   // situations, and not legitimate runtime errors.
108   if (msg)
109     dbgs() << msg << "\n";
110   dbgs() << "UNREACHABLE executed";
111   if (file)
112     dbgs() << " at " << file << ":" << line;
113   dbgs() << "!\n";
114   abort();
115 #ifdef LLVM_BUILTIN_UNREACHABLE
116   // Windows systems and possibly others don't declare abort() to be noreturn,
117   // so use the unreachable builtin to avoid a Clang self-host warning.
118   LLVM_BUILTIN_UNREACHABLE;
119 #endif
120 }
121 
122 static void bindingsErrorHandler(void *user_data, const std::string& reason,
123                                  bool gen_crash_diag) {
124   LLVMFatalErrorHandler handler =
125       LLVM_EXTENSION reinterpret_cast<LLVMFatalErrorHandler>(user_data);
126   handler(reason.c_str());
127 }
128 
129 void LLVMInstallFatalErrorHandler(LLVMFatalErrorHandler Handler) {
130   install_fatal_error_handler(bindingsErrorHandler,
131                               LLVM_EXTENSION reinterpret_cast<void *>(Handler));
132 }
133 
134 void LLVMResetFatalErrorHandler() {
135   remove_fatal_error_handler();
136 }
137