1 //===-- TargetList.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 // C Includes
11 // C++ Includes
12 // Other libraries and framework includes
13 // Project includes
14 #include "lldb/Core/Broadcaster.h"
15 #include "lldb/Core/Debugger.h"
16 #include "lldb/Core/Event.h"
17 #include "lldb/Core/Module.h"
18 #include "lldb/Core/ModuleSpec.h"
19 #include "lldb/Core/State.h"
20 #include "lldb/Core/Timer.h"
21 #include "lldb/Host/Host.h"
22 #include "lldb/Host/HostInfo.h"
23 #include "lldb/Interpreter/CommandInterpreter.h"
24 #include "lldb/Interpreter/OptionGroupPlatform.h"
25 #include "lldb/Symbol/ObjectFile.h"
26 #include "lldb/Target/Platform.h"
27 #include "lldb/Target/Process.h"
28 #include "lldb/Target/TargetList.h"
29 
30 #include "llvm/ADT/SmallString.h"
31 
32 using namespace lldb;
33 using namespace lldb_private;
34 
35 ConstString &
36 TargetList::GetStaticBroadcasterClass ()
37 {
38     static ConstString class_name ("lldb.targetList");
39     return class_name;
40 }
41 
42 //----------------------------------------------------------------------
43 // TargetList constructor
44 //----------------------------------------------------------------------
45 TargetList::TargetList(Debugger &debugger) :
46     Broadcaster(&debugger, TargetList::GetStaticBroadcasterClass().AsCString()),
47     m_target_list(),
48     m_target_list_mutex (Mutex::eMutexTypeRecursive),
49     m_selected_target_idx (0)
50 {
51     CheckInWithManager();
52 }
53 
54 //----------------------------------------------------------------------
55 // Destructor
56 //----------------------------------------------------------------------
57 TargetList::~TargetList()
58 {
59     Mutex::Locker locker(m_target_list_mutex);
60     m_target_list.clear();
61 }
62 
63 Error
64 TargetList::CreateTarget (Debugger &debugger,
65                           const char *user_exe_path,
66                           const char *triple_cstr,
67                           bool get_dependent_files,
68                           const OptionGroupPlatform *platform_options,
69                           TargetSP &target_sp)
70 {
71     return CreateTargetInternal (debugger,
72                                  user_exe_path,
73                                  triple_cstr,
74                                  get_dependent_files,
75                                  platform_options,
76                                  target_sp,
77                                  false);
78 }
79 
80 Error
81 TargetList::CreateTarget (Debugger &debugger,
82                           const char *user_exe_path,
83                           const ArchSpec& specified_arch,
84                           bool get_dependent_files,
85                           PlatformSP &platform_sp,
86                           TargetSP &target_sp)
87 {
88     return CreateTargetInternal (debugger,
89                                  user_exe_path,
90                                  specified_arch,
91                                  get_dependent_files,
92                                  platform_sp,
93                                  target_sp,
94                                  false);
95 }
96 
97 Error
98 TargetList::CreateTargetInternal (Debugger &debugger,
99                                   const char *user_exe_path,
100                                   const char *triple_cstr,
101                                   bool get_dependent_files,
102                                   const OptionGroupPlatform *platform_options,
103                                   TargetSP &target_sp,
104                                   bool is_dummy_target)
105 {
106     Error error;
107     PlatformSP platform_sp;
108 
109     // This is purposely left empty unless it is specified by triple_cstr.
110     // If not initialized via triple_cstr, then the currently selected platform
111     // will set the architecture correctly.
112     const ArchSpec arch(triple_cstr);
113     if (triple_cstr && triple_cstr[0])
114     {
115         if (!arch.IsValid())
116         {
117             error.SetErrorStringWithFormat("invalid triple '%s'", triple_cstr);
118             return error;
119         }
120     }
121 
122     ArchSpec platform_arch(arch);
123 
124     bool prefer_platform_arch = false;
125 
126     CommandInterpreter &interpreter = debugger.GetCommandInterpreter();
127 
128     // let's see if there is already an existing plaform before we go creating another...
129     platform_sp = debugger.GetPlatformList().GetSelectedPlatform();
130 
131     if (platform_options && platform_options->PlatformWasSpecified ())
132     {
133         // Create a new platform if it doesn't match the selected platform
134         if (!platform_options->PlatformMatches(platform_sp))
135         {
136             const bool select_platform = true;
137             platform_sp = platform_options->CreatePlatformWithOptions (interpreter,
138                                                                        arch,
139                                                                        select_platform,
140                                                                        error,
141                                                                        platform_arch);
142             if (!platform_sp)
143                 return error;
144         }
145     }
146 
147     if (user_exe_path && user_exe_path[0])
148     {
149         ModuleSpecList module_specs;
150         ModuleSpec module_spec;
151         module_spec.GetFileSpec().SetFile(user_exe_path, true);
152 
153         // Resolve the executable in case we are given a path to a application bundle
154         // like a .app bundle on MacOSX
155         Host::ResolveExecutableInBundle (module_spec.GetFileSpec());
156 
157         lldb::offset_t file_offset = 0;
158         lldb::offset_t file_size = 0;
159         const size_t num_specs = ObjectFile::GetModuleSpecifications (module_spec.GetFileSpec(), file_offset, file_size, module_specs);
160         if (num_specs > 0)
161         {
162             ModuleSpec matching_module_spec;
163 
164             if (num_specs == 1)
165             {
166                 if (module_specs.GetModuleSpecAtIndex(0, matching_module_spec))
167                 {
168                     if (platform_arch.IsValid())
169                     {
170                         if (platform_arch.IsCompatibleMatch(matching_module_spec.GetArchitecture()))
171                         {
172                             // If the OS or vendor weren't specified, then adopt the module's
173                             // architecture so that the platform matching can be more accurate
174                             if (!platform_arch.TripleOSWasSpecified() || !platform_arch.TripleVendorWasSpecified())
175                             {
176                                 prefer_platform_arch = true;
177                                 platform_arch = matching_module_spec.GetArchitecture();
178                             }
179                         }
180                         else
181                         {
182                             StreamString platform_arch_strm;
183                             StreamString module_arch_strm;
184 
185                             platform_arch.DumpTriple(platform_arch_strm);
186                             matching_module_spec.GetArchitecture().DumpTriple(module_arch_strm);
187                             error.SetErrorStringWithFormat("the specified architecture '%s' is not compatible with '%s' in '%s'",
188                                                            platform_arch_strm.GetString().c_str(),
189                                                            module_arch_strm.GetString().c_str(),
190                                                            module_spec.GetFileSpec().GetPath().c_str());
191                             return error;
192                         }
193                     }
194                     else
195                     {
196                         // Only one arch and none was specified
197                         prefer_platform_arch = true;
198                         platform_arch = matching_module_spec.GetArchitecture();
199                     }
200                 }
201             }
202             else
203             {
204                 if (arch.IsValid())
205                 {
206                     module_spec.GetArchitecture() = arch;
207                     if (module_specs.FindMatchingModuleSpec(module_spec, matching_module_spec))
208                     {
209                         prefer_platform_arch = true;
210                         platform_arch = matching_module_spec.GetArchitecture();
211                     }
212                 }
213                 else
214                 {
215                     // No architecture specified, check if there is only one platform for
216                     // all of the architectures.
217 
218                     typedef std::vector<PlatformSP> PlatformList;
219                     PlatformList platforms;
220                     PlatformSP host_platform_sp = Platform::GetHostPlatform();
221                     for (size_t i=0; i<num_specs; ++i)
222                     {
223                         ModuleSpec module_spec;
224                         if (module_specs.GetModuleSpecAtIndex(i, module_spec))
225                         {
226                             // See if there was a selected platform and check that first
227                             // since the user may have specified it.
228                             if (platform_sp)
229                             {
230                                 if (platform_sp->IsCompatibleArchitecture(module_spec.GetArchitecture(), false, NULL))
231                                 {
232                                     platforms.push_back(platform_sp);
233                                     continue;
234                                 }
235                             }
236 
237                             // Next check the host platform it if wasn't already checked above
238                             if (host_platform_sp && (!platform_sp || host_platform_sp->GetName() != platform_sp->GetName()))
239                             {
240                                 if (host_platform_sp->IsCompatibleArchitecture(module_spec.GetArchitecture(), false, NULL))
241                                 {
242                                     platforms.push_back(host_platform_sp);
243                                     continue;
244                                 }
245                             }
246 
247                             // Just find a platform that matches the architecture in the executable file
248                             platforms.push_back(Platform::GetPlatformForArchitecture(module_spec.GetArchitecture(), nullptr));
249                         }
250                     }
251 
252                     Platform *platform_ptr = NULL;
253                     for (const auto &the_platform_sp : platforms)
254                     {
255                         if (platform_ptr)
256                         {
257                             if (platform_ptr->GetName() != the_platform_sp->GetName())
258                             {
259                                 platform_ptr = NULL;
260                                 break;
261                             }
262                         }
263                         else
264                         {
265                             platform_ptr = the_platform_sp.get();
266                         }
267                     }
268 
269                     if (platform_ptr)
270                     {
271                         // All platforms for all modules in the exectuable match, so we can select this platform
272                         platform_sp = platforms.front();
273                     }
274                     else
275                     {
276                         // More than one platform claims to support this file, so the --platform option must be specified
277                         StreamString error_strm;
278                         std::set<Platform *> platform_set;
279                         error_strm.Printf ("more than one platform supports this executable (");
280                         for (const auto &the_platform_sp : platforms)
281                         {
282                             if (platform_set.find(the_platform_sp.get()) == platform_set.end())
283                             {
284                                 if (!platform_set.empty())
285                                     error_strm.PutCString(", ");
286                                 error_strm.PutCString(the_platform_sp->GetName().GetCString());
287                                 platform_set.insert(the_platform_sp.get());
288                             }
289                         }
290                         error_strm.Printf("), use the --platform option to specify a platform");
291                         error.SetErrorString(error_strm.GetString().c_str());
292                         return error;
293                     }
294                 }
295             }
296         }
297     }
298 
299     // If we have a valid architecture, make sure the current platform is
300     // compatible with that architecture
301     if (!prefer_platform_arch && arch.IsValid())
302     {
303         if (!platform_sp->IsCompatibleArchitecture(arch, false, &platform_arch))
304         {
305             platform_sp = Platform::GetPlatformForArchitecture(arch, &platform_arch);
306             if (!is_dummy_target && platform_sp)
307                 debugger.GetPlatformList().SetSelectedPlatform(platform_sp);
308         }
309     }
310     else if (platform_arch.IsValid())
311     {
312         // if "arch" isn't valid, yet "platform_arch" is, it means we have an executable file with
313         // a single architecture which should be used
314         ArchSpec fixed_platform_arch;
315         if (!platform_sp->IsCompatibleArchitecture(platform_arch, false, &fixed_platform_arch))
316         {
317             platform_sp = Platform::GetPlatformForArchitecture(platform_arch, &fixed_platform_arch);
318             if (!is_dummy_target && platform_sp)
319                 debugger.GetPlatformList().SetSelectedPlatform(platform_sp);
320         }
321     }
322 
323     if (!platform_arch.IsValid())
324         platform_arch = arch;
325 
326     error = TargetList::CreateTargetInternal (debugger,
327                                               user_exe_path,
328                                               platform_arch,
329                                               get_dependent_files,
330                                               platform_sp,
331                                               target_sp,
332                                               is_dummy_target);
333     return error;
334 }
335 
336 lldb::TargetSP
337 TargetList::GetDummyTarget (lldb_private::Debugger &debugger)
338 {
339     // FIXME: Maybe the dummy target should be per-Debugger
340     if (!m_dummy_target_sp || !m_dummy_target_sp->IsValid())
341     {
342         ArchSpec arch(Target::GetDefaultArchitecture());
343         if (!arch.IsValid())
344             arch = HostInfo::GetArchitecture();
345         Error err = CreateDummyTarget(debugger,
346                                       arch.GetTriple().getTriple().c_str(),
347                                       m_dummy_target_sp);
348     }
349 
350     return m_dummy_target_sp;
351 }
352 
353 Error
354 TargetList::CreateDummyTarget (Debugger &debugger,
355                                const char *specified_arch_name,
356                                lldb::TargetSP &target_sp)
357 {
358     PlatformSP host_platform_sp(Platform::GetHostPlatform());
359     return CreateTargetInternal (debugger,
360                                  (const char *) nullptr,
361                                  specified_arch_name,
362                                  false,
363                                  (const OptionGroupPlatform *) nullptr,
364                                  target_sp,
365                                  true);
366 }
367 
368 Error
369 TargetList::CreateTargetInternal (Debugger &debugger,
370                                   const char *user_exe_path,
371                                   const ArchSpec& specified_arch,
372                                   bool get_dependent_files,
373                                   lldb::PlatformSP &platform_sp,
374                                   lldb::TargetSP &target_sp,
375                                   bool is_dummy_target)
376 {
377 
378     Timer scoped_timer (__PRETTY_FUNCTION__,
379                         "TargetList::CreateTarget (file = '%s', arch = '%s')",
380                         user_exe_path,
381                         specified_arch.GetArchitectureName());
382     Error error;
383 
384     ArchSpec arch(specified_arch);
385 
386     if (arch.IsValid())
387     {
388         if (!platform_sp || !platform_sp->IsCompatibleArchitecture(arch, false, NULL))
389             platform_sp = Platform::GetPlatformForArchitecture(specified_arch, &arch);
390     }
391 
392     if (!platform_sp)
393         platform_sp = debugger.GetPlatformList().GetSelectedPlatform();
394 
395     if (!arch.IsValid())
396         arch = specified_arch;
397 
398     FileSpec file (user_exe_path, false);
399     if (!file.Exists() && user_exe_path && user_exe_path[0] == '~')
400     {
401         // we want to expand the tilde but we don't want to resolve any symbolic links
402         // so we can't use the FileSpec constructor's resolve flag
403         llvm::SmallString<64> unglobbed_path(user_exe_path);
404         FileSpec::ResolveUsername(unglobbed_path);
405 
406         if (unglobbed_path.empty())
407             file = FileSpec(user_exe_path, false);
408         else
409             file = FileSpec(unglobbed_path.c_str(), false);
410     }
411 
412     bool user_exe_path_is_bundle = false;
413     char resolved_bundle_exe_path[PATH_MAX];
414     resolved_bundle_exe_path[0] = '\0';
415     if (file)
416     {
417         if (file.GetFileType() == FileSpec::eFileTypeDirectory)
418             user_exe_path_is_bundle = true;
419 
420         if (file.IsRelative() && user_exe_path)
421         {
422             // Ignore paths that start with "./" and "../"
423             if (!((user_exe_path[0] == '.' && user_exe_path[1] == '/') ||
424                   (user_exe_path[0] == '.' && user_exe_path[1] == '.' && user_exe_path[2] == '/')))
425             {
426                 char cwd[PATH_MAX];
427                 if (getcwd (cwd, sizeof(cwd)))
428                 {
429                     std::string cwd_user_exe_path (cwd);
430                     cwd_user_exe_path += '/';
431                     cwd_user_exe_path += user_exe_path;
432                     FileSpec cwd_file (cwd_user_exe_path.c_str(), false);
433                     if (cwd_file.Exists())
434                         file = cwd_file;
435                 }
436             }
437         }
438 
439         ModuleSP exe_module_sp;
440         if (platform_sp)
441         {
442             FileSpecList executable_search_paths (Target::GetDefaultExecutableSearchPaths());
443             ModuleSpec module_spec(file, arch);
444             error = platform_sp->ResolveExecutable (module_spec,
445                                                     exe_module_sp,
446                                                     executable_search_paths.GetSize() ? &executable_search_paths : NULL);
447         }
448 
449         if (error.Success() && exe_module_sp)
450         {
451             if (exe_module_sp->GetObjectFile() == NULL)
452             {
453                 if (arch.IsValid())
454                 {
455                     error.SetErrorStringWithFormat("\"%s\" doesn't contain architecture %s",
456                                                    file.GetPath().c_str(),
457                                                    arch.GetArchitectureName());
458                 }
459                 else
460                 {
461                     error.SetErrorStringWithFormat("unsupported file type \"%s\"",
462                                                    file.GetPath().c_str());
463                 }
464                 return error;
465             }
466             target_sp.reset(new Target(debugger, arch, platform_sp, is_dummy_target));
467             target_sp->SetExecutableModule (exe_module_sp, get_dependent_files);
468             if (user_exe_path_is_bundle)
469                 exe_module_sp->GetFileSpec().GetPath(resolved_bundle_exe_path, sizeof(resolved_bundle_exe_path));
470         }
471     }
472     else
473     {
474         // No file was specified, just create an empty target with any arch
475         // if a valid arch was specified
476         target_sp.reset(new Target(debugger, arch, platform_sp, is_dummy_target));
477     }
478 
479     if (target_sp)
480     {
481         // Set argv0 with what the user typed, unless the user specified a
482         // directory. If the user specified a directory, then it is probably a
483         // bundle that was resolved and we need to use the resolved bundle path
484         if (user_exe_path)
485         {
486             // Use exactly what the user typed as the first argument when we exec or posix_spawn
487             if (user_exe_path_is_bundle && resolved_bundle_exe_path[0])
488             {
489                 target_sp->SetArg0 (resolved_bundle_exe_path);
490             }
491             else
492             {
493                 // Use resolved path
494                 target_sp->SetArg0 (file.GetPath().c_str());
495             }
496         }
497         if (file.GetDirectory())
498         {
499             FileSpec file_dir;
500             file_dir.GetDirectory() = file.GetDirectory();
501             target_sp->GetExecutableSearchPaths ().Append (file_dir);
502         }
503 
504         // Don't put the dummy target in the target list, it's held separately.
505         if (!is_dummy_target)
506         {
507             Mutex::Locker locker(m_target_list_mutex);
508             m_selected_target_idx = m_target_list.size();
509             m_target_list.push_back(target_sp);
510             // Now prime this from the dummy target:
511             target_sp->PrimeFromDummyTarget(debugger.GetDummyTarget());
512         }
513         else
514         {
515             m_dummy_target_sp = target_sp;
516         }
517     }
518 
519     return error;
520 }
521 
522 bool
523 TargetList::DeleteTarget (TargetSP &target_sp)
524 {
525     Mutex::Locker locker(m_target_list_mutex);
526     collection::iterator pos, end = m_target_list.end();
527 
528     for (pos = m_target_list.begin(); pos != end; ++pos)
529     {
530         if (pos->get() == target_sp.get())
531         {
532             m_target_list.erase(pos);
533             return true;
534         }
535     }
536     return false;
537 }
538 
539 
540 TargetSP
541 TargetList::FindTargetWithExecutableAndArchitecture
542 (
543     const FileSpec &exe_file_spec,
544     const ArchSpec *exe_arch_ptr
545 ) const
546 {
547     Mutex::Locker locker (m_target_list_mutex);
548     TargetSP target_sp;
549     bool full_match = (bool)exe_file_spec.GetDirectory();
550 
551     collection::const_iterator pos, end = m_target_list.end();
552     for (pos = m_target_list.begin(); pos != end; ++pos)
553     {
554         Module *exe_module = (*pos)->GetExecutableModulePointer();
555 
556         if (exe_module)
557         {
558             if (FileSpec::Equal (exe_file_spec, exe_module->GetFileSpec(), full_match))
559             {
560                 if (exe_arch_ptr)
561                 {
562                     if (!exe_arch_ptr->IsCompatibleMatch(exe_module->GetArchitecture()))
563                         continue;
564                 }
565                 target_sp = *pos;
566                 break;
567             }
568         }
569     }
570     return target_sp;
571 }
572 
573 TargetSP
574 TargetList::FindTargetWithProcessID (lldb::pid_t pid) const
575 {
576     Mutex::Locker locker(m_target_list_mutex);
577     TargetSP target_sp;
578     collection::const_iterator pos, end = m_target_list.end();
579     for (pos = m_target_list.begin(); pos != end; ++pos)
580     {
581         Process* process = (*pos)->GetProcessSP().get();
582         if (process && process->GetID() == pid)
583         {
584             target_sp = *pos;
585             break;
586         }
587     }
588     return target_sp;
589 }
590 
591 
592 TargetSP
593 TargetList::FindTargetWithProcess (Process *process) const
594 {
595     TargetSP target_sp;
596     if (process)
597     {
598         Mutex::Locker locker(m_target_list_mutex);
599         collection::const_iterator pos, end = m_target_list.end();
600         for (pos = m_target_list.begin(); pos != end; ++pos)
601         {
602             if (process == (*pos)->GetProcessSP().get())
603             {
604                 target_sp = *pos;
605                 break;
606             }
607         }
608     }
609     return target_sp;
610 }
611 
612 TargetSP
613 TargetList::GetTargetSP (Target *target) const
614 {
615     TargetSP target_sp;
616     if (target)
617     {
618         Mutex::Locker locker(m_target_list_mutex);
619         collection::const_iterator pos, end = m_target_list.end();
620         for (pos = m_target_list.begin(); pos != end; ++pos)
621         {
622             if (target == (*pos).get())
623             {
624                 target_sp = *pos;
625                 break;
626             }
627         }
628     }
629     return target_sp;
630 }
631 
632 uint32_t
633 TargetList::SendAsyncInterrupt (lldb::pid_t pid)
634 {
635     uint32_t num_async_interrupts_sent = 0;
636 
637     if (pid != LLDB_INVALID_PROCESS_ID)
638     {
639         TargetSP target_sp(FindTargetWithProcessID (pid));
640         if (target_sp.get())
641         {
642             Process* process = target_sp->GetProcessSP().get();
643             if (process)
644             {
645                 process->SendAsyncInterrupt();
646                 ++num_async_interrupts_sent;
647             }
648         }
649     }
650     else
651     {
652         // We don't have a valid pid to broadcast to, so broadcast to the target
653         // list's async broadcaster...
654         BroadcastEvent (Process::eBroadcastBitInterrupt, NULL);
655     }
656 
657     return num_async_interrupts_sent;
658 }
659 
660 uint32_t
661 TargetList::SignalIfRunning (lldb::pid_t pid, int signo)
662 {
663     uint32_t num_signals_sent = 0;
664     Process *process = NULL;
665     if (pid == LLDB_INVALID_PROCESS_ID)
666     {
667         // Signal all processes with signal
668         Mutex::Locker locker(m_target_list_mutex);
669         collection::iterator pos, end = m_target_list.end();
670         for (pos = m_target_list.begin(); pos != end; ++pos)
671         {
672             process = (*pos)->GetProcessSP().get();
673             if (process)
674             {
675                 if (process->IsAlive())
676                 {
677                     ++num_signals_sent;
678                     process->Signal (signo);
679                 }
680             }
681         }
682     }
683     else
684     {
685         // Signal a specific process with signal
686         TargetSP target_sp(FindTargetWithProcessID (pid));
687         if (target_sp.get())
688         {
689             process = target_sp->GetProcessSP().get();
690             if (process)
691             {
692                 if (process->IsAlive())
693                 {
694                     ++num_signals_sent;
695                     process->Signal (signo);
696                 }
697             }
698         }
699     }
700     return num_signals_sent;
701 }
702 
703 int
704 TargetList::GetNumTargets () const
705 {
706     Mutex::Locker locker (m_target_list_mutex);
707     return m_target_list.size();
708 }
709 
710 lldb::TargetSP
711 TargetList::GetTargetAtIndex (uint32_t idx) const
712 {
713     TargetSP target_sp;
714     Mutex::Locker locker (m_target_list_mutex);
715     if (idx < m_target_list.size())
716         target_sp = m_target_list[idx];
717     return target_sp;
718 }
719 
720 uint32_t
721 TargetList::GetIndexOfTarget (lldb::TargetSP target_sp) const
722 {
723     Mutex::Locker locker (m_target_list_mutex);
724     size_t num_targets = m_target_list.size();
725     for (size_t idx = 0; idx < num_targets; idx++)
726     {
727         if (target_sp == m_target_list[idx])
728             return idx;
729     }
730     return UINT32_MAX;
731 }
732 
733 uint32_t
734 TargetList::SetSelectedTarget (Target* target)
735 {
736     Mutex::Locker locker (m_target_list_mutex);
737     collection::const_iterator pos,
738         begin = m_target_list.begin(),
739         end = m_target_list.end();
740     for (pos = begin; pos != end; ++pos)
741     {
742         if (pos->get() == target)
743         {
744             m_selected_target_idx = std::distance (begin, pos);
745             return m_selected_target_idx;
746         }
747     }
748     m_selected_target_idx = 0;
749     return m_selected_target_idx;
750 }
751 
752 lldb::TargetSP
753 TargetList::GetSelectedTarget ()
754 {
755     Mutex::Locker locker (m_target_list_mutex);
756     if (m_selected_target_idx >= m_target_list.size())
757         m_selected_target_idx = 0;
758     return GetTargetAtIndex (m_selected_target_idx);
759 }
760