1 //===-- PlatformLinux.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 "PlatformLinux.h"
11 #include "lldb/Host/Config.h"
12 
13 // C Includes
14 #include <stdio.h>
15 #ifndef LLDB_DISABLE_POSIX
16 #include <sys/utsname.h>
17 #endif
18 
19 // C++ Includes
20 // Other libraries and framework includes
21 // Project includes
22 #include "lldb/Breakpoint/BreakpointLocation.h"
23 #include "lldb/Core/Debugger.h"
24 #include "lldb/Core/Error.h"
25 #include "lldb/Core/Log.h"
26 #include "lldb/Core/Module.h"
27 #include "lldb/Core/ModuleList.h"
28 #include "lldb/Core/ModuleSpec.h"
29 #include "lldb/Core/PluginManager.h"
30 #include "lldb/Core/State.h"
31 #include "lldb/Core/StreamString.h"
32 #include "lldb/Host/FileSpec.h"
33 #include "lldb/Host/HostInfo.h"
34 #include "lldb/Interpreter/OptionValueProperties.h"
35 #include "lldb/Interpreter/Property.h"
36 #include "lldb/Target/Target.h"
37 #include "lldb/Target/Process.h"
38 
39 #if defined(__linux__)
40 #include "../../Process/Linux/NativeProcessLinux.h"
41 #endif
42 
43 // Define these constants from Linux mman.h for use when targetting
44 // remote linux systems even when host has different values.
45 #define MAP_PRIVATE 2
46 #define MAP_ANON 0x20
47 
48 using namespace lldb;
49 using namespace lldb_private;
50 using namespace lldb_private::platform_linux;
51 
52 static uint32_t g_initialize_count = 0;
53 
54 //------------------------------------------------------------------
55 /// Code to handle the PlatformLinux settings
56 //------------------------------------------------------------------
57 
58 namespace
59 {
60     enum
61     {
62         ePropertyUseLlgsForLocal = 0,
63     };
64 
65     class PlatformLinuxProperties : public Properties
66     {
67     public:
68         static ConstString&
69         GetSettingName ();
70 
71         PlatformLinuxProperties();
72 
73         virtual
74         ~PlatformLinuxProperties() = default;
75 
76         bool
77         GetUseLlgsForLocal() const;
78 
79     private:
80         static const PropertyDefinition*
81         GetStaticPropertyDefinitions();
82     };
83 
84     typedef std::shared_ptr<PlatformLinuxProperties> PlatformLinuxPropertiesSP;
85 
86 } // anonymous namespace
87 
88 PlatformLinuxProperties::PlatformLinuxProperties() :
89     Properties ()
90 {
91     m_collection_sp.reset (new OptionValueProperties(GetSettingName ()));
92     m_collection_sp->Initialize (GetStaticPropertyDefinitions ());
93 }
94 
95 ConstString&
96 PlatformLinuxProperties::GetSettingName ()
97 {
98     static ConstString g_setting_name("linux");
99     return g_setting_name;
100 }
101 
102 bool
103 PlatformLinuxProperties::GetUseLlgsForLocal() const
104 {
105     const uint32_t idx = ePropertyUseLlgsForLocal;
106     return m_collection_sp->GetPropertyAtIndexAsBoolean (NULL, idx, GetStaticPropertyDefinitions()[idx].default_uint_value != 0);
107 }
108 
109 const PropertyDefinition*
110 PlatformLinuxProperties::GetStaticPropertyDefinitions()
111 {
112     static PropertyDefinition
113     g_properties[] =
114     {
115         { "use-llgs-for-local" , OptionValue::eTypeBoolean, true, true, NULL, NULL, "Control whether the platform uses llgs for local debug sessions." },
116         {  NULL        , OptionValue::eTypeInvalid, false, 0  , NULL, NULL, NULL  }
117     };
118 
119     // Allow environment variable to disable llgs-local.
120     if (getenv("PLATFORM_LINUX_DISABLE_LLGS_LOCAL"))
121         g_properties[ePropertyUseLlgsForLocal].default_uint_value = false;
122 
123     return g_properties;
124 }
125 
126 static const PlatformLinuxPropertiesSP &
127 GetGlobalProperties()
128 {
129     static PlatformLinuxPropertiesSP g_settings_sp;
130     if (!g_settings_sp)
131         g_settings_sp.reset (new PlatformLinuxProperties ());
132     return g_settings_sp;
133 }
134 
135 void
136 PlatformLinux::DebuggerInitialize (Debugger &debugger)
137 {
138     if (!PluginManager::GetSettingForPlatformPlugin (debugger, PlatformLinuxProperties::GetSettingName()))
139     {
140         const bool is_global_setting = true;
141         PluginManager::CreateSettingForPlatformPlugin (debugger,
142                                                        GetGlobalProperties()->GetValueProperties(),
143                                                        ConstString ("Properties for the PlatformLinux plug-in."),
144                                                        is_global_setting);
145     }
146 }
147 
148 
149 //------------------------------------------------------------------
150 
151 PlatformSP
152 PlatformLinux::CreateInstance (bool force, const ArchSpec *arch)
153 {
154     Log *log(GetLogIfAllCategoriesSet (LIBLLDB_LOG_PLATFORM));
155     if (log)
156     {
157         const char *arch_name;
158         if (arch && arch->GetArchitectureName ())
159             arch_name = arch->GetArchitectureName ();
160         else
161             arch_name = "<null>";
162 
163         const char *triple_cstr = arch ? arch->GetTriple ().getTriple ().c_str() : "<null>";
164 
165         log->Printf ("PlatformLinux::%s(force=%s, arch={%s,%s})", __FUNCTION__, force ? "true" : "false", arch_name, triple_cstr);
166     }
167 
168     bool create = force;
169     if (create == false && arch && arch->IsValid())
170     {
171         const llvm::Triple &triple = arch->GetTriple();
172         switch (triple.getOS())
173         {
174             case llvm::Triple::Linux:
175                 create = true;
176                 break;
177 
178 #if defined(__linux__)
179             // Only accept "unknown" for the OS if the host is linux and
180             // it "unknown" wasn't specified (it was just returned because it
181             // was NOT specified)
182             case llvm::Triple::OSType::UnknownOS:
183                 create = !arch->TripleOSWasSpecified();
184                 break;
185 #endif
186             default:
187                 break;
188         }
189     }
190 
191     if (create)
192     {
193         if (log)
194             log->Printf ("PlatformLinux::%s() creating remote-linux platform", __FUNCTION__);
195         return PlatformSP(new PlatformLinux(false));
196     }
197 
198     if (log)
199         log->Printf ("PlatformLinux::%s() aborting creation of remote-linux platform", __FUNCTION__);
200 
201     return PlatformSP();
202 }
203 
204 
205 ConstString
206 PlatformLinux::GetPluginNameStatic (bool is_host)
207 {
208     if (is_host)
209     {
210         static ConstString g_host_name(Platform::GetHostPlatformName ());
211         return g_host_name;
212     }
213     else
214     {
215         static ConstString g_remote_name("remote-linux");
216         return g_remote_name;
217     }
218 }
219 
220 const char *
221 PlatformLinux::GetPluginDescriptionStatic (bool is_host)
222 {
223     if (is_host)
224         return "Local Linux user platform plug-in.";
225     else
226         return "Remote Linux user platform plug-in.";
227 }
228 
229 ConstString
230 PlatformLinux::GetPluginName()
231 {
232     return GetPluginNameStatic(IsHost());
233 }
234 
235 void
236 PlatformLinux::Initialize ()
237 {
238     PlatformPOSIX::Initialize ();
239 
240     if (g_initialize_count++ == 0)
241     {
242 #if defined(__linux__) && !defined(__ANDROID__)
243         PlatformSP default_platform_sp (new PlatformLinux(true));
244         default_platform_sp->SetSystemArchitecture(HostInfo::GetArchitecture());
245         Platform::SetHostPlatform (default_platform_sp);
246 #endif
247         PluginManager::RegisterPlugin(PlatformLinux::GetPluginNameStatic(false),
248                                       PlatformLinux::GetPluginDescriptionStatic(false),
249                                       PlatformLinux::CreateInstance,
250                                       PlatformLinux::DebuggerInitialize);
251     }
252 }
253 
254 void
255 PlatformLinux::Terminate ()
256 {
257     if (g_initialize_count > 0)
258     {
259         if (--g_initialize_count == 0)
260         {
261             PluginManager::UnregisterPlugin (PlatformLinux::CreateInstance);
262         }
263     }
264 
265     PlatformPOSIX::Terminate ();
266 }
267 
268 Error
269 PlatformLinux::ResolveExecutable (const ModuleSpec &ms,
270                                   lldb::ModuleSP &exe_module_sp,
271                                   const FileSpecList *module_search_paths_ptr)
272 {
273     Error error;
274     // Nothing special to do here, just use the actual file and architecture
275 
276     char exe_path[PATH_MAX];
277     ModuleSpec resolved_module_spec (ms);
278 
279     if (IsHost())
280     {
281         // If we have "ls" as the exe_file, resolve the executable location based on
282         // the current path variables
283         if (!resolved_module_spec.GetFileSpec().Exists())
284         {
285             resolved_module_spec.GetFileSpec().GetPath(exe_path, sizeof(exe_path));
286             resolved_module_spec.GetFileSpec().SetFile(exe_path, true);
287         }
288 
289         if (!resolved_module_spec.GetFileSpec().Exists())
290             resolved_module_spec.GetFileSpec().ResolveExecutableLocation ();
291 
292         if (resolved_module_spec.GetFileSpec().Exists())
293             error.Clear();
294         else
295         {
296             error.SetErrorStringWithFormat("unable to find executable for '%s'", resolved_module_spec.GetFileSpec().GetPath().c_str());
297         }
298     }
299     else
300     {
301         if (m_remote_platform_sp)
302         {
303             error = GetCachedExecutable (resolved_module_spec, exe_module_sp, nullptr, *m_remote_platform_sp);
304         }
305         else
306         {
307             // We may connect to a process and use the provided executable (Don't use local $PATH).
308 
309             if (resolved_module_spec.GetFileSpec().Exists())
310                 error.Clear();
311             else
312                 error.SetErrorStringWithFormat("the platform is not currently connected, and '%s' doesn't exist in the system root.", exe_path);
313         }
314     }
315 
316     if (error.Success())
317     {
318         if (resolved_module_spec.GetArchitecture().IsValid())
319         {
320             error = ModuleList::GetSharedModule (resolved_module_spec,
321                                                  exe_module_sp,
322                                                  NULL,
323                                                  NULL,
324                                                  NULL);
325             if (error.Fail())
326             {
327                 // If we failed, it may be because the vendor and os aren't known. If that is the
328                 // case, try setting them to the host architecture and give it another try.
329                 llvm::Triple &module_triple = resolved_module_spec.GetArchitecture().GetTriple();
330                 bool is_vendor_specified = (module_triple.getVendor() != llvm::Triple::UnknownVendor);
331                 bool is_os_specified = (module_triple.getOS() != llvm::Triple::UnknownOS);
332                 if (!is_vendor_specified || !is_os_specified)
333                 {
334                     const llvm::Triple &host_triple = HostInfo::GetArchitecture(HostInfo::eArchKindDefault).GetTriple();
335 
336                     if (!is_vendor_specified)
337                         module_triple.setVendorName (host_triple.getVendorName());
338                     if (!is_os_specified)
339                         module_triple.setOSName (host_triple.getOSName());
340 
341                     error = ModuleList::GetSharedModule (resolved_module_spec,
342                                                          exe_module_sp,
343                                                          NULL,
344                                                          NULL,
345                                                          NULL);
346                 }
347             }
348 
349             // TODO find out why exe_module_sp might be NULL
350             if (!exe_module_sp || exe_module_sp->GetObjectFile() == NULL)
351             {
352                 exe_module_sp.reset();
353                 error.SetErrorStringWithFormat ("'%s' doesn't contain the architecture %s",
354                                                 resolved_module_spec.GetFileSpec().GetPath().c_str(),
355                                                 resolved_module_spec.GetArchitecture().GetArchitectureName());
356             }
357         }
358         else
359         {
360             // No valid architecture was specified, ask the platform for
361             // the architectures that we should be using (in the correct order)
362             // and see if we can find a match that way
363             StreamString arch_names;
364             for (uint32_t idx = 0; GetSupportedArchitectureAtIndex (idx, resolved_module_spec.GetArchitecture()); ++idx)
365             {
366                 error = ModuleList::GetSharedModule (resolved_module_spec,
367                                                      exe_module_sp,
368                                                      NULL,
369                                                      NULL,
370                                                      NULL);
371                 // Did we find an executable using one of the
372                 if (error.Success())
373                 {
374                     if (exe_module_sp && exe_module_sp->GetObjectFile())
375                         break;
376                     else
377                         error.SetErrorToGenericError();
378                 }
379 
380                 if (idx > 0)
381                     arch_names.PutCString (", ");
382                 arch_names.PutCString (resolved_module_spec.GetArchitecture().GetArchitectureName());
383             }
384 
385             if (error.Fail() || !exe_module_sp)
386             {
387                 if (resolved_module_spec.GetFileSpec().Readable())
388                 {
389                     error.SetErrorStringWithFormat ("'%s' doesn't contain any '%s' platform architectures: %s",
390                                                     resolved_module_spec.GetFileSpec().GetPath().c_str(),
391                                                     GetPluginName().GetCString(),
392                                                     arch_names.GetString().c_str());
393                 }
394                 else
395                 {
396                     error.SetErrorStringWithFormat("'%s' is not readable", resolved_module_spec.GetFileSpec().GetPath().c_str());
397                 }
398             }
399         }
400     }
401 
402     return error;
403 }
404 
405 Error
406 PlatformLinux::GetFileWithUUID (const FileSpec &platform_file,
407                                 const UUID *uuid_ptr, FileSpec &local_file)
408 {
409     if (IsRemote())
410     {
411         if (m_remote_platform_sp)
412             return m_remote_platform_sp->GetFileWithUUID (platform_file, uuid_ptr, local_file);
413     }
414 
415     // Default to the local case
416     local_file = platform_file;
417     return Error();
418 }
419 
420 
421 //------------------------------------------------------------------
422 /// Default Constructor
423 //------------------------------------------------------------------
424 PlatformLinux::PlatformLinux (bool is_host) :
425     PlatformPOSIX(is_host)  // This is the local host platform
426 {
427 }
428 
429 //------------------------------------------------------------------
430 /// Destructor.
431 ///
432 /// The destructor is virtual since this class is designed to be
433 /// inherited from by the plug-in instance.
434 //------------------------------------------------------------------
435 PlatformLinux::~PlatformLinux()
436 {
437 }
438 
439 bool
440 PlatformLinux::GetProcessInfo (lldb::pid_t pid, ProcessInstanceInfo &process_info)
441 {
442     bool success = false;
443     if (IsHost())
444     {
445         success = Platform::GetProcessInfo (pid, process_info);
446     }
447     else
448     {
449         if (m_remote_platform_sp)
450             success = m_remote_platform_sp->GetProcessInfo (pid, process_info);
451     }
452     return success;
453 }
454 
455 uint32_t
456 PlatformLinux::FindProcesses (const ProcessInstanceInfoMatch &match_info,
457                               ProcessInstanceInfoList &process_infos)
458 {
459     uint32_t match_count = 0;
460     if (IsHost())
461     {
462         // Let the base class figure out the host details
463         match_count = Platform::FindProcesses (match_info, process_infos);
464     }
465     else
466     {
467         // If we are remote, we can only return results if we are connected
468         if (m_remote_platform_sp)
469             match_count = m_remote_platform_sp->FindProcesses (match_info, process_infos);
470     }
471     return match_count;
472 }
473 
474 bool
475 PlatformLinux::GetSupportedArchitectureAtIndex (uint32_t idx, ArchSpec &arch)
476 {
477     if (IsHost())
478     {
479         ArchSpec hostArch = HostInfo::GetArchitecture(HostInfo::eArchKindDefault);
480         if (hostArch.GetTriple().isOSLinux())
481         {
482             if (idx == 0)
483             {
484                 arch = hostArch;
485                 return arch.IsValid();
486             }
487             else if (idx == 1)
488             {
489                 // If the default host architecture is 64-bit, look for a 32-bit variant
490                 if (hostArch.IsValid() && hostArch.GetTriple().isArch64Bit())
491                 {
492                     arch = HostInfo::GetArchitecture(HostInfo::eArchKind32);
493                     return arch.IsValid();
494                 }
495             }
496         }
497     }
498     else
499     {
500         if (m_remote_platform_sp)
501             return m_remote_platform_sp->GetSupportedArchitectureAtIndex(idx, arch);
502 
503         llvm::Triple triple;
504         // Set the OS to linux
505         triple.setOS(llvm::Triple::Linux);
506         // Set the architecture
507         switch (idx)
508         {
509             case 0: triple.setArchName("x86_64"); break;
510             case 1: triple.setArchName("i386"); break;
511             case 2: triple.setArchName("arm"); break;
512             case 3: triple.setArchName("aarch64"); break;
513             case 4: triple.setArchName("mips64"); break;
514             case 5: triple.setArchName("hexagon"); break;
515             case 6: triple.setArchName("mips"); break;
516             case 7: triple.setArchName("mips64el"); break;
517             case 8: triple.setArchName("mipsel"); break;
518             default: return false;
519         }
520         // Leave the vendor as "llvm::Triple:UnknownVendor" and don't specify the vendor by
521         // calling triple.SetVendorName("unknown") so that it is a "unspecified unknown".
522         // This means when someone calls triple.GetVendorName() it will return an empty string
523         // which indicates that the vendor can be set when two architectures are merged
524 
525         // Now set the triple into "arch" and return true
526         arch.SetTriple(triple);
527         return true;
528     }
529     return false;
530 }
531 
532 void
533 PlatformLinux::GetStatus (Stream &strm)
534 {
535     Platform::GetStatus(strm);
536 
537 #ifndef LLDB_DISABLE_POSIX
538     // Display local kernel information only when we are running in host mode.
539     // Otherwise, we would end up printing non-Linux information (when running
540     // on Mac OS for example).
541     if (IsHost())
542     {
543         struct utsname un;
544 
545         if (uname(&un))
546             return;
547 
548         strm.Printf ("    Kernel: %s\n", un.sysname);
549         strm.Printf ("   Release: %s\n", un.release);
550         strm.Printf ("   Version: %s\n", un.version);
551     }
552 #endif
553 }
554 
555 size_t
556 PlatformLinux::GetSoftwareBreakpointTrapOpcode (Target &target,
557                                                 BreakpointSite *bp_site)
558 {
559     ArchSpec arch = target.GetArchitecture();
560     const uint8_t *trap_opcode = NULL;
561     size_t trap_opcode_size = 0;
562 
563     switch (arch.GetMachine())
564     {
565     default:
566         assert(false && "CPU type not supported!");
567         break;
568 
569     case llvm::Triple::aarch64:
570         {
571             static const uint8_t g_aarch64_opcode[] = { 0x00, 0x00, 0x20, 0xd4 };
572             trap_opcode = g_aarch64_opcode;
573             trap_opcode_size = sizeof(g_aarch64_opcode);
574         }
575         break;
576     case llvm::Triple::x86:
577     case llvm::Triple::x86_64:
578         {
579             static const uint8_t g_i386_breakpoint_opcode[] = { 0xCC };
580             trap_opcode = g_i386_breakpoint_opcode;
581             trap_opcode_size = sizeof(g_i386_breakpoint_opcode);
582         }
583         break;
584     case llvm::Triple::hexagon:
585         {
586             static const uint8_t g_hex_opcode[] = { 0x0c, 0xdb, 0x00, 0x54 };
587             trap_opcode = g_hex_opcode;
588             trap_opcode_size = sizeof(g_hex_opcode);
589         }
590         break;
591     case llvm::Triple::arm:
592         {
593             // The ARM reference recommends the use of 0xe7fddefe and 0xdefe
594             // but the linux kernel does otherwise.
595             static const uint8_t g_arm_breakpoint_opcode[] = { 0xf0, 0x01, 0xf0, 0xe7 };
596             static const uint8_t g_thumb_breakpoint_opcode[] = { 0x01, 0xde };
597 
598             lldb::BreakpointLocationSP bp_loc_sp (bp_site->GetOwnerAtIndex (0));
599             AddressClass addr_class = eAddressClassUnknown;
600 
601             if (bp_loc_sp)
602                 addr_class = bp_loc_sp->GetAddress ().GetAddressClass ();
603 
604             if (addr_class == eAddressClassCodeAlternateISA
605                 || (addr_class == eAddressClassUnknown && (bp_site->GetLoadAddress() & 1)))
606             {
607                 trap_opcode = g_thumb_breakpoint_opcode;
608                 trap_opcode_size = sizeof(g_thumb_breakpoint_opcode);
609             }
610             else
611             {
612                 trap_opcode = g_arm_breakpoint_opcode;
613                 trap_opcode_size = sizeof(g_arm_breakpoint_opcode);
614             }
615         }
616         break;
617     case llvm::Triple::mips:
618     case llvm::Triple::mips64:
619         {
620             static const uint8_t g_hex_opcode[] = { 0x00, 0x00, 0x00, 0x0d };
621             trap_opcode = g_hex_opcode;
622             trap_opcode_size = sizeof(g_hex_opcode);
623         }
624         break;
625     case llvm::Triple::mipsel:
626     case llvm::Triple::mips64el:
627         {
628             static const uint8_t g_hex_opcode[] = { 0x0d, 0x00, 0x00, 0x00 };
629             trap_opcode = g_hex_opcode;
630             trap_opcode_size = sizeof(g_hex_opcode);
631         }
632         break;
633     }
634 
635     if (bp_site->SetTrapOpcode(trap_opcode, trap_opcode_size))
636         return trap_opcode_size;
637     return 0;
638 }
639 
640 int32_t
641 PlatformLinux::GetResumeCountForLaunchInfo (ProcessLaunchInfo &launch_info)
642 {
643     int32_t resume_count = 0;
644 
645     // Always resume past the initial stop when we use eLaunchFlagDebug
646     if (launch_info.GetFlags ().Test (eLaunchFlagDebug))
647     {
648         // Resume past the stop for the final exec into the true inferior.
649         ++resume_count;
650     }
651 
652     // If we're not launching a shell, we're done.
653     const FileSpec &shell = launch_info.GetShell();
654     if (!shell)
655         return resume_count;
656 
657     std::string shell_string = shell.GetPath();
658     // We're in a shell, so for sure we have to resume past the shell exec.
659     ++resume_count;
660 
661     // Figure out what shell we're planning on using.
662     const char *shell_name = strrchr (shell_string.c_str(), '/');
663     if (shell_name == NULL)
664         shell_name = shell_string.c_str();
665     else
666         shell_name++;
667 
668     if (strcmp (shell_name, "csh") == 0
669              || strcmp (shell_name, "tcsh") == 0
670              || strcmp (shell_name, "zsh") == 0
671              || strcmp (shell_name, "sh") == 0)
672     {
673         // These shells seem to re-exec themselves.  Add another resume.
674         ++resume_count;
675     }
676 
677     return resume_count;
678 }
679 
680 bool
681 PlatformLinux::UseLlgsForLocalDebugging ()
682 {
683     PlatformLinuxPropertiesSP properties_sp = GetGlobalProperties ();
684     assert (properties_sp && "global properties shared pointer is null");
685     return properties_sp ? properties_sp->GetUseLlgsForLocal () : false;
686 }
687 
688 bool
689 PlatformLinux::CanDebugProcess ()
690 {
691     if (IsHost ())
692     {
693         // The platform only does local debugging (i.e. uses llgs) when the setting indicates we do that.
694         // Otherwise, we'll use ProcessLinux/ProcessPOSIX to handle with ProcessMonitor.
695         return UseLlgsForLocalDebugging ();
696     }
697     else
698     {
699         // If we're connected, we can debug.
700         return IsConnected ();
701     }
702 }
703 
704 // For local debugging, Linux will override the debug logic to use llgs-launch rather than
705 // lldb-launch, llgs-attach.  This differs from current lldb-launch, debugserver-attach
706 // approach on MacOSX.
707 lldb::ProcessSP
708 PlatformLinux::DebugProcess (ProcessLaunchInfo &launch_info,
709                              Debugger &debugger,
710                              Target *target,       // Can be NULL, if NULL create a new target, else use existing one
711                              Error &error)
712 {
713     Log *log(GetLogIfAllCategoriesSet (LIBLLDB_LOG_PLATFORM));
714     if (log)
715         log->Printf ("PlatformLinux::%s entered (target %p)", __FUNCTION__, static_cast<void*>(target));
716 
717     // If we're a remote host, use standard behavior from parent class.
718     if (!IsHost ())
719         return PlatformPOSIX::DebugProcess (launch_info, debugger, target, error);
720 
721     //
722     // For local debugging, we'll insist on having ProcessGDBRemote create the process.
723     //
724 
725     ProcessSP process_sp;
726 
727     // Ensure we're using llgs for local debugging.
728     if (!UseLlgsForLocalDebugging ())
729     {
730         assert (false && "we're trying to debug a local process but platform.plugin.linux.use-llgs-for-local is false, should never get here");
731         error.SetErrorString ("attempted to start gdb-remote-based debugging for local process but platform.plugin.linux.use-llgs-for-local is false");
732         return process_sp;
733     }
734 
735     // Make sure we stop at the entry point
736     launch_info.GetFlags ().Set (eLaunchFlagDebug);
737 
738     // We always launch the process we are going to debug in a separate process
739     // group, since then we can handle ^C interrupts ourselves w/o having to worry
740     // about the target getting them as well.
741     launch_info.SetLaunchInSeparateProcessGroup(true);
742 
743     // Ensure we have a target.
744     if (target == nullptr)
745     {
746         if (log)
747             log->Printf ("PlatformLinux::%s creating new target", __FUNCTION__);
748 
749         TargetSP new_target_sp;
750         error = debugger.GetTargetList().CreateTarget (debugger,
751                                                        nullptr,
752                                                        nullptr,
753                                                        false,
754                                                        nullptr,
755                                                        new_target_sp);
756         if (error.Fail ())
757         {
758             if (log)
759                 log->Printf ("PlatformLinux::%s failed to create new target: %s", __FUNCTION__, error.AsCString ());
760             return process_sp;
761         }
762 
763         target = new_target_sp.get();
764         if (!target)
765         {
766             error.SetErrorString ("CreateTarget() returned nullptr");
767             if (log)
768                 log->Printf ("PlatformLinux::%s failed: %s", __FUNCTION__, error.AsCString ());
769             return process_sp;
770         }
771     }
772     else
773     {
774         if (log)
775             log->Printf ("PlatformLinux::%s using provided target", __FUNCTION__);
776     }
777 
778     // Mark target as currently selected target.
779     debugger.GetTargetList().SetSelectedTarget(target);
780 
781     // Now create the gdb-remote process.
782     if (log)
783         log->Printf ("PlatformLinux::%s having target create process with gdb-remote plugin", __FUNCTION__);
784     process_sp = target->CreateProcess (launch_info.GetListenerForProcess(debugger), "gdb-remote", nullptr);
785 
786     if (!process_sp)
787     {
788         error.SetErrorString ("CreateProcess() failed for gdb-remote process");
789         if (log)
790             log->Printf ("PlatformLinux::%s failed: %s", __FUNCTION__, error.AsCString ());
791         return process_sp;
792     }
793     else
794     {
795         if (log)
796             log->Printf ("PlatformLinux::%s successfully created process", __FUNCTION__);
797     }
798 
799     // Set the unix signals properly.
800     process_sp->SetUnixSignals (Host::GetUnixSignals ());
801 
802     // Adjust launch for a hijacker.
803     ListenerSP listener_sp;
804     if (!launch_info.GetHijackListener ())
805     {
806         if (log)
807             log->Printf ("PlatformLinux::%s setting up hijacker", __FUNCTION__);
808 
809         listener_sp.reset (new Listener("lldb.PlatformLinux.DebugProcess.hijack"));
810         launch_info.SetHijackListener (listener_sp);
811         process_sp->HijackProcessEvents (listener_sp.get ());
812     }
813 
814     // Log file actions.
815     if (log)
816     {
817         log->Printf ("PlatformLinux::%s launching process with the following file actions:", __FUNCTION__);
818 
819         StreamString stream;
820         size_t i = 0;
821         const FileAction *file_action;
822         while ((file_action = launch_info.GetFileActionAtIndex (i++)) != nullptr)
823         {
824             file_action->Dump (stream);
825             log->PutCString (stream.GetString().c_str ());
826             stream.Clear();
827         }
828     }
829 
830     // Do the launch.
831     error = process_sp->Launch(launch_info);
832     if (error.Success ())
833     {
834         // Handle the hijacking of process events.
835         if (listener_sp)
836         {
837             const StateType state = process_sp->WaitForProcessToStop (NULL, NULL, false, listener_sp.get());
838 
839             if (state == eStateStopped)
840             {
841                 if (log)
842                     log->Printf ("PlatformLinux::%s pid %" PRIu64 " state %s\n",
843                                  __FUNCTION__, process_sp->GetID (), StateAsCString (state));
844             }
845             else
846             {
847                 if (log)
848                     log->Printf ("PlatformLinux::%s pid %" PRIu64 " state is not stopped - %s\n",
849                                  __FUNCTION__, process_sp->GetID (), StateAsCString (state));
850             }
851         }
852 
853         // Hook up process PTY if we have one (which we should for local debugging with llgs).
854         int pty_fd = launch_info.GetPTY().ReleaseMasterFileDescriptor();
855         if (pty_fd != lldb_utility::PseudoTerminal::invalid_fd)
856         {
857             process_sp->SetSTDIOFileDescriptor(pty_fd);
858             if (log)
859                 log->Printf ("PlatformLinux::%s pid %" PRIu64 " hooked up STDIO pty to process", __FUNCTION__, process_sp->GetID ());
860         }
861         else
862         {
863             if (log)
864                 log->Printf ("PlatformLinux::%s pid %" PRIu64 " not using process STDIO pty", __FUNCTION__, process_sp->GetID ());
865         }
866     }
867     else
868     {
869         if (log)
870             log->Printf ("PlatformLinux::%s process launch failed: %s", __FUNCTION__, error.AsCString ());
871         // FIXME figure out appropriate cleanup here.  Do we delete the target? Do we delete the process?  Does our caller do that?
872     }
873 
874     return process_sp;
875 }
876 
877 void
878 PlatformLinux::CalculateTrapHandlerSymbolNames ()
879 {
880     m_trap_handlers.push_back (ConstString ("_sigtramp"));
881 }
882 
883 Error
884 PlatformLinux::LaunchNativeProcess (ProcessLaunchInfo &launch_info,
885                                     NativeProcessProtocol::NativeDelegate &native_delegate,
886                                     NativeProcessProtocolSP &process_sp)
887 {
888 #if !defined(__linux__)
889     return Error("Only implemented on Linux hosts");
890 #else
891     if (!IsHost ())
892         return Error("PlatformLinux::%s (): cannot launch a debug process when not the host", __FUNCTION__);
893 
894     // Retrieve the exe module.
895     lldb::ModuleSP exe_module_sp;
896     ModuleSpec exe_module_spec(launch_info.GetExecutableFile(), launch_info.GetArchitecture());
897 
898     Error error = ResolveExecutable (
899         exe_module_spec,
900         exe_module_sp,
901         NULL);
902 
903     if (!error.Success ())
904         return error;
905 
906     if (!exe_module_sp)
907         return Error("exe_module_sp could not be resolved for %s", launch_info.GetExecutableFile ().GetPath ().c_str ());
908 
909     // Launch it for debugging
910     error = process_linux::NativeProcessLinux::LaunchProcess (
911         exe_module_sp.get (),
912         launch_info,
913         native_delegate,
914         process_sp);
915 
916     return error;
917 #endif
918 }
919 
920 Error
921 PlatformLinux::AttachNativeProcess (lldb::pid_t pid,
922                                     NativeProcessProtocol::NativeDelegate &native_delegate,
923                                     NativeProcessProtocolSP &process_sp)
924 {
925 #if !defined(__linux__)
926     return Error("Only implemented on Linux hosts");
927 #else
928     if (!IsHost ())
929         return Error("PlatformLinux::%s (): cannot attach to a debug process when not the host", __FUNCTION__);
930 
931     // Launch it for debugging
932     return process_linux::NativeProcessLinux::AttachToProcess (pid, native_delegate, process_sp);
933 #endif
934 }
935 
936 uint64_t
937 PlatformLinux::ConvertMmapFlagsToPlatform(unsigned flags)
938 {
939     uint64_t flags_platform = 0;
940     if (flags & eMmapFlagsPrivate)
941         flags_platform |= MAP_PRIVATE;
942     if (flags & eMmapFlagsAnon)
943         flags_platform |= MAP_ANON;
944     return flags_platform;
945 }
946