1 //===--------------------- cxa_exception_storage.cpp ----------------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is dual licensed under the MIT and the University of Illinois Open
6 // Source Licenses. See LICENSE.TXT for details.
7 //
8 //
9 //  This file implements the storage for the "Caught Exception Stack"
10 //  http://mentorembedded.github.io/cxx-abi/abi-eh.html (section 2.2.2)
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "cxa_exception.hpp"
15 
16 #include "config.h"
17 
18 #if LIBCXXABI_HAS_NO_THREADS
19 
20 namespace __cxxabiv1 {
21 extern "C" {
22     static __cxa_eh_globals eh_globals;
__cxa_get_globals()23     __cxa_eh_globals *__cxa_get_globals() { return &eh_globals; }
__cxa_get_globals_fast()24     __cxa_eh_globals *__cxa_get_globals_fast() { return &eh_globals; }
25     }
26 }
27 
28 #elif defined(HAS_THREAD_LOCAL)
29 
30 namespace __cxxabiv1 {
31 
32 namespace {
__globals()33     __cxa_eh_globals * __globals () {
34         static thread_local __cxa_eh_globals eh_globals;
35         return &eh_globals;
36         }
37     }
38 
39 extern "C" {
__cxa_get_globals()40     __cxa_eh_globals * __cxa_get_globals      () { return __globals (); }
__cxa_get_globals_fast()41     __cxa_eh_globals * __cxa_get_globals_fast () { return __globals (); }
42     }
43 }
44 
45 #else
46 
47 #include <pthread.h>
48 #include <cstdlib>          // for calloc, free
49 #include "abort_message.h"
50 
51 //  In general, we treat all pthread errors as fatal.
52 //  We cannot call std::terminate() because that will in turn
53 //  call __cxa_get_globals() and cause infinite recursion.
54 
55 namespace __cxxabiv1 {
56 namespace {
57     pthread_key_t  key_;
58     pthread_once_t flag_ = PTHREAD_ONCE_INIT;
59 
destruct_(void * p)60     void destruct_ (void *p) {
61         std::free ( p );
62         if ( 0 != ::pthread_setspecific ( key_, NULL ) )
63             abort_message("cannot zero out thread value for __cxa_get_globals()");
64         }
65 
construct_()66     void construct_ () {
67         if ( 0 != pthread_key_create ( &key_, destruct_ ) )
68             abort_message("cannot create pthread key for __cxa_get_globals()");
69         }
70 }
71 
72 extern "C" {
__cxa_get_globals()73     __cxa_eh_globals * __cxa_get_globals () {
74     //  Try to get the globals for this thread
75         __cxa_eh_globals* retVal = __cxa_get_globals_fast ();
76 
77     //  If this is the first time we've been asked for these globals, create them
78         if ( NULL == retVal ) {
79             retVal = static_cast<__cxa_eh_globals*>
80                         (std::calloc (1, sizeof (__cxa_eh_globals)));
81             if ( NULL == retVal )
82                 abort_message("cannot allocate __cxa_eh_globals");
83             if ( 0 != pthread_setspecific ( key_, retVal ) )
84                abort_message("pthread_setspecific failure in __cxa_get_globals()");
85            }
86         return retVal;
87         }
88 
89     // Note that this implementation will reliably return NULL if not
90     // preceded by a call to __cxa_get_globals().  This is an extension
91     // to the Itanium ABI and is taken advantage of in several places in
92     // libc++abi.
__cxa_get_globals_fast()93     __cxa_eh_globals * __cxa_get_globals_fast () {
94     //  First time through, create the key.
95         if (0 != pthread_once(&flag_, construct_))
96             abort_message("pthread_once failure in __cxa_get_globals_fast()");
97 //        static int init = construct_();
98         return static_cast<__cxa_eh_globals*>(::pthread_getspecific(key_));
99         }
100 
101 }
102 }
103 #endif
104