xref: /llvm-project/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunication.cpp (revision 015d818b59dbdadc2726adc6132be1b3da4d6387)
1 //===-- GDBRemoteCommunication.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 
11 #include "GDBRemoteCommunication.h"
12 
13 // C Includes
14 #include <limits.h>
15 #include <string.h>
16 #include <sys/stat.h>
17 
18 // C++ Includes
19 // Other libraries and framework includes
20 #include "lldb/Core/ConnectionFileDescriptor.h"
21 #include "lldb/Core/Log.h"
22 #include "lldb/Core/StreamFile.h"
23 #include "lldb/Core/StreamString.h"
24 #include "lldb/Host/FileSpec.h"
25 #include "lldb/Host/Host.h"
26 #include "lldb/Host/TimeValue.h"
27 #include "lldb/Target/Process.h"
28 
29 // Project includes
30 #include "ProcessGDBRemoteLog.h"
31 
32 #if defined(__APPLE__)
33 # define DEBUGSERVER_BASENAME    "debugserver"
34 #else
35 # define DEBUGSERVER_BASENAME    "lldb-gdbserver"
36 #endif
37 
38 using namespace lldb;
39 using namespace lldb_private;
40 
41 GDBRemoteCommunication::History::History (uint32_t size) :
42     m_packets(),
43     m_curr_idx (0),
44     m_total_packet_count (0),
45     m_dumped_to_log (false)
46 {
47     m_packets.resize(size);
48 }
49 
50 GDBRemoteCommunication::History::~History ()
51 {
52 }
53 
54 void
55 GDBRemoteCommunication::History::AddPacket (char packet_char,
56                                             PacketType type,
57                                             uint32_t bytes_transmitted)
58 {
59     const size_t size = m_packets.size();
60     if (size > 0)
61     {
62         const uint32_t idx = GetNextIndex();
63         m_packets[idx].packet.assign (1, packet_char);
64         m_packets[idx].type = type;
65         m_packets[idx].bytes_transmitted = bytes_transmitted;
66         m_packets[idx].packet_idx = m_total_packet_count;
67         m_packets[idx].tid = Host::GetCurrentThreadID();
68     }
69 }
70 
71 void
72 GDBRemoteCommunication::History::AddPacket (const std::string &src,
73                                             uint32_t src_len,
74                                             PacketType type,
75                                             uint32_t bytes_transmitted)
76 {
77     const size_t size = m_packets.size();
78     if (size > 0)
79     {
80         const uint32_t idx = GetNextIndex();
81         m_packets[idx].packet.assign (src, 0, src_len);
82         m_packets[idx].type = type;
83         m_packets[idx].bytes_transmitted = bytes_transmitted;
84         m_packets[idx].packet_idx = m_total_packet_count;
85         m_packets[idx].tid = Host::GetCurrentThreadID();
86     }
87 }
88 
89 void
90 GDBRemoteCommunication::History::Dump (lldb_private::Stream &strm) const
91 {
92     const uint32_t size = GetNumPacketsInHistory ();
93     const uint32_t first_idx = GetFirstSavedPacketIndex ();
94     const uint32_t stop_idx = m_curr_idx + size;
95     for (uint32_t i = first_idx;  i < stop_idx; ++i)
96     {
97         const uint32_t idx = NormalizeIndex (i);
98         const Entry &entry = m_packets[idx];
99         if (entry.type == ePacketTypeInvalid || entry.packet.empty())
100             break;
101         strm.Printf ("history[%u] tid=0x%4.4" PRIx64 " <%4u> %s packet: %s\n",
102                      entry.packet_idx,
103                      entry.tid,
104                      entry.bytes_transmitted,
105                      (entry.type == ePacketTypeSend) ? "send" : "read",
106                      entry.packet.c_str());
107     }
108 }
109 
110 void
111 GDBRemoteCommunication::History::Dump (lldb_private::Log *log) const
112 {
113     if (log && !m_dumped_to_log)
114     {
115         m_dumped_to_log = true;
116         const uint32_t size = GetNumPacketsInHistory ();
117         const uint32_t first_idx = GetFirstSavedPacketIndex ();
118         const uint32_t stop_idx = m_curr_idx + size;
119         for (uint32_t i = first_idx;  i < stop_idx; ++i)
120         {
121             const uint32_t idx = NormalizeIndex (i);
122             const Entry &entry = m_packets[idx];
123             if (entry.type == ePacketTypeInvalid || entry.packet.empty())
124                 break;
125             log->Printf ("history[%u] tid=0x%4.4" PRIx64 " <%4u> %s packet: %s",
126                          entry.packet_idx,
127                          entry.tid,
128                          entry.bytes_transmitted,
129                          (entry.type == ePacketTypeSend) ? "send" : "read",
130                          entry.packet.c_str());
131         }
132     }
133 }
134 
135 //----------------------------------------------------------------------
136 // GDBRemoteCommunication constructor
137 //----------------------------------------------------------------------
138 GDBRemoteCommunication::GDBRemoteCommunication(const char *comm_name,
139                                                const char *listener_name,
140                                                bool is_platform) :
141     Communication(comm_name),
142 #ifdef LLDB_CONFIGURATION_DEBUG
143     m_packet_timeout (1000),
144 #else
145     m_packet_timeout (1),
146 #endif
147     m_sequence_mutex (Mutex::eMutexTypeRecursive),
148     m_public_is_running (false),
149     m_private_is_running (false),
150     m_history (512),
151     m_send_acks (true),
152     m_is_platform (is_platform),
153     m_listen_thread (LLDB_INVALID_HOST_THREAD),
154     m_listen_url ()
155 {
156 }
157 
158 //----------------------------------------------------------------------
159 // Destructor
160 //----------------------------------------------------------------------
161 GDBRemoteCommunication::~GDBRemoteCommunication()
162 {
163     if (IsConnected())
164     {
165         Disconnect();
166     }
167 }
168 
169 char
170 GDBRemoteCommunication::CalculcateChecksum (const char *payload, size_t payload_length)
171 {
172     int checksum = 0;
173 
174     for (size_t i = 0; i < payload_length; ++i)
175         checksum += payload[i];
176 
177     return checksum & 255;
178 }
179 
180 size_t
181 GDBRemoteCommunication::SendAck ()
182 {
183     Log *log (ProcessGDBRemoteLog::GetLogIfAllCategoriesSet (GDBR_LOG_PACKETS));
184     ConnectionStatus status = eConnectionStatusSuccess;
185     char ch = '+';
186     const size_t bytes_written = Write (&ch, 1, status, NULL);
187     if (log)
188         log->Printf ("<%4" PRIu64 "> send packet: %c", (uint64_t)bytes_written, ch);
189     m_history.AddPacket (ch, History::ePacketTypeSend, bytes_written);
190     return bytes_written;
191 }
192 
193 size_t
194 GDBRemoteCommunication::SendNack ()
195 {
196     Log *log (ProcessGDBRemoteLog::GetLogIfAllCategoriesSet (GDBR_LOG_PACKETS));
197     ConnectionStatus status = eConnectionStatusSuccess;
198     char ch = '-';
199     const size_t bytes_written = Write (&ch, 1, status, NULL);
200     if (log)
201         log->Printf("<%4" PRIu64 "> send packet: %c", (uint64_t)bytes_written, ch);
202     m_history.AddPacket (ch, History::ePacketTypeSend, bytes_written);
203     return bytes_written;
204 }
205 
206 GDBRemoteCommunication::PacketResult
207 GDBRemoteCommunication::SendPacket (const char *payload, size_t payload_length)
208 {
209     Mutex::Locker locker(m_sequence_mutex);
210     return SendPacketNoLock (payload, payload_length);
211 }
212 
213 GDBRemoteCommunication::PacketResult
214 GDBRemoteCommunication::SendPacketNoLock (const char *payload, size_t payload_length)
215 {
216     if (IsConnected())
217     {
218         StreamString packet(0, 4, eByteOrderBig);
219 
220         packet.PutChar('$');
221         packet.Write (payload, payload_length);
222         packet.PutChar('#');
223         packet.PutHex8(CalculcateChecksum (payload, payload_length));
224 
225         Log *log (ProcessGDBRemoteLog::GetLogIfAllCategoriesSet (GDBR_LOG_PACKETS));
226         ConnectionStatus status = eConnectionStatusSuccess;
227         size_t bytes_written = Write (packet.GetData(), packet.GetSize(), status, NULL);
228         if (log)
229         {
230             // If logging was just enabled and we have history, then dump out what
231             // we have to the log so we get the historical context. The Dump() call that
232             // logs all of the packet will set a boolean so that we don't dump this more
233             // than once
234             if (!m_history.DidDumpToLog ())
235                 m_history.Dump (log);
236 
237             log->Printf("<%4" PRIu64 "> send packet: %.*s", (uint64_t)bytes_written, (int)packet.GetSize(), packet.GetData());
238         }
239 
240         m_history.AddPacket (packet.GetString(), packet.GetSize(), History::ePacketTypeSend, bytes_written);
241 
242 
243         if (bytes_written == packet.GetSize())
244         {
245             if (GetSendAcks ())
246                 return GetAck ();
247             else
248                 return PacketResult::Success;
249         }
250         else
251         {
252             if (log)
253                 log->Printf ("error: failed to send packet: %.*s", (int)packet.GetSize(), packet.GetData());
254         }
255     }
256     return PacketResult::ErrorSendFailed;
257 }
258 
259 GDBRemoteCommunication::PacketResult
260 GDBRemoteCommunication::GetAck ()
261 {
262     StringExtractorGDBRemote packet;
263     PacketResult result = WaitForPacketWithTimeoutMicroSecondsNoLock (packet, GetPacketTimeoutInMicroSeconds ());
264     if (result == PacketResult::Success)
265     {
266         if (packet.GetResponseType() == StringExtractorGDBRemote::ResponseType::eAck)
267             return PacketResult::Success;
268         else
269             return PacketResult::ErrorSendAck;
270     }
271     return result;
272 }
273 
274 bool
275 GDBRemoteCommunication::GetSequenceMutex (Mutex::Locker& locker, const char *failure_message)
276 {
277     if (IsRunning())
278         return locker.TryLock (m_sequence_mutex, failure_message);
279 
280     locker.Lock (m_sequence_mutex);
281     return true;
282 }
283 
284 
285 bool
286 GDBRemoteCommunication::WaitForNotRunningPrivate (const TimeValue *timeout_ptr)
287 {
288     return m_private_is_running.WaitForValueEqualTo (false, timeout_ptr, NULL);
289 }
290 
291 GDBRemoteCommunication::PacketResult
292 GDBRemoteCommunication::WaitForPacketWithTimeoutMicroSecondsNoLock (StringExtractorGDBRemote &packet, uint32_t timeout_usec)
293 {
294     uint8_t buffer[8192];
295     Error error;
296 
297     Log *log (ProcessGDBRemoteLog::GetLogIfAllCategoriesSet (GDBR_LOG_PACKETS | GDBR_LOG_VERBOSE));
298 
299     // Check for a packet from our cache first without trying any reading...
300     if (CheckForPacket (NULL, 0, packet))
301         return PacketResult::Success;
302 
303     bool timed_out = false;
304     bool disconnected = false;
305     while (IsConnected() && !timed_out)
306     {
307         lldb::ConnectionStatus status = eConnectionStatusNoConnection;
308         size_t bytes_read = Read (buffer, sizeof(buffer), timeout_usec, status, &error);
309 
310         if (log)
311             log->Printf ("%s: Read (buffer, (sizeof(buffer), timeout_usec = 0x%x, status = %s, error = %s) => bytes_read = %" PRIu64,
312                          __PRETTY_FUNCTION__,
313                          timeout_usec,
314                          Communication::ConnectionStatusAsCString (status),
315                          error.AsCString(),
316                          (uint64_t)bytes_read);
317 
318         if (bytes_read > 0)
319         {
320             if (CheckForPacket (buffer, bytes_read, packet))
321                 return PacketResult::Success;
322         }
323         else
324         {
325             switch (status)
326             {
327             case eConnectionStatusTimedOut:
328             case eConnectionStatusInterrupted:
329                 timed_out = true;
330                 break;
331             case eConnectionStatusSuccess:
332                 //printf ("status = success but error = %s\n", error.AsCString("<invalid>"));
333                 break;
334 
335             case eConnectionStatusEndOfFile:
336             case eConnectionStatusNoConnection:
337             case eConnectionStatusLostConnection:
338             case eConnectionStatusError:
339                 disconnected = true;
340                 Disconnect();
341                 break;
342             }
343         }
344     }
345     packet.Clear ();
346     if (disconnected)
347         return PacketResult::ErrorDisconnected;
348     if (timed_out)
349         return PacketResult::ErrorReplyTimeout;
350     else
351         return PacketResult::ErrorReplyFailed;
352 }
353 
354 bool
355 GDBRemoteCommunication::CheckForPacket (const uint8_t *src, size_t src_len, StringExtractorGDBRemote &packet)
356 {
357     // Put the packet data into the buffer in a thread safe fashion
358     Mutex::Locker locker(m_bytes_mutex);
359 
360     Log *log (ProcessGDBRemoteLog::GetLogIfAllCategoriesSet (GDBR_LOG_PACKETS));
361 
362     if (src && src_len > 0)
363     {
364         if (log && log->GetVerbose())
365         {
366             StreamString s;
367             log->Printf ("GDBRemoteCommunication::%s adding %u bytes: %.*s",
368                          __FUNCTION__,
369                          (uint32_t)src_len,
370                          (uint32_t)src_len,
371                          src);
372         }
373         m_bytes.append ((const char *)src, src_len);
374     }
375 
376     // Parse up the packets into gdb remote packets
377     if (!m_bytes.empty())
378     {
379         // end_idx must be one past the last valid packet byte. Start
380         // it off with an invalid value that is the same as the current
381         // index.
382         size_t content_start = 0;
383         size_t content_length = 0;
384         size_t total_length = 0;
385         size_t checksum_idx = std::string::npos;
386 
387         switch (m_bytes[0])
388         {
389             case '+':       // Look for ack
390             case '-':       // Look for cancel
391             case '\x03':    // ^C to halt target
392                 content_length = total_length = 1;  // The command is one byte long...
393                 break;
394 
395             case '$':
396                 // Look for a standard gdb packet?
397                 {
398                     size_t hash_pos = m_bytes.find('#');
399                     if (hash_pos != std::string::npos)
400                     {
401                         if (hash_pos + 2 < m_bytes.size())
402                         {
403                             checksum_idx = hash_pos + 1;
404                             // Skip the dollar sign
405                             content_start = 1;
406                             // Don't include the # in the content or the $ in the content length
407                             content_length = hash_pos - 1;
408 
409                             total_length = hash_pos + 3; // Skip the # and the two hex checksum bytes
410                         }
411                         else
412                         {
413                             // Checksum bytes aren't all here yet
414                             content_length = std::string::npos;
415                         }
416                     }
417                 }
418                 break;
419 
420             default:
421                 {
422                     // We have an unexpected byte and we need to flush all bad
423                     // data that is in m_bytes, so we need to find the first
424                     // byte that is a '+' (ACK), '-' (NACK), \x03 (CTRL+C interrupt),
425                     // or '$' character (start of packet header) or of course,
426                     // the end of the data in m_bytes...
427                     const size_t bytes_len = m_bytes.size();
428                     bool done = false;
429                     uint32_t idx;
430                     for (idx = 1; !done && idx < bytes_len; ++idx)
431                     {
432                         switch (m_bytes[idx])
433                         {
434                         case '+':
435                         case '-':
436                         case '\x03':
437                         case '$':
438                             done = true;
439                             break;
440 
441                         default:
442                             break;
443                         }
444                     }
445                     if (log)
446                         log->Printf ("GDBRemoteCommunication::%s tossing %u junk bytes: '%.*s'",
447                                      __FUNCTION__, idx, idx, m_bytes.c_str());
448                     m_bytes.erase(0, idx);
449                 }
450                 break;
451         }
452 
453         if (content_length == std::string::npos)
454         {
455             packet.Clear();
456             return false;
457         }
458         else if (total_length > 0)
459         {
460 
461             // We have a valid packet...
462             assert (content_length <= m_bytes.size());
463             assert (total_length <= m_bytes.size());
464             assert (content_length <= total_length);
465             const size_t content_end = content_start + content_length;
466 
467             bool success = true;
468             std::string &packet_str = packet.GetStringRef();
469 
470 
471             if (log)
472             {
473                 // If logging was just enabled and we have history, then dump out what
474                 // we have to the log so we get the historical context. The Dump() call that
475                 // logs all of the packet will set a boolean so that we don't dump this more
476                 // than once
477                 if (!m_history.DidDumpToLog ())
478                     m_history.Dump (log);
479 
480                 bool binary = false;
481                 // Only detect binary for packets that start with a '$' and have a '#CC' checksum
482                 if (m_bytes[0] == '$' && total_length > 4)
483                 {
484                     for (size_t i=0; !binary && i<total_length; ++i)
485                     {
486                         if (isprint(m_bytes[i]) == 0)
487                             binary = true;
488                     }
489                 }
490                 if (binary)
491                 {
492                     StreamString strm;
493                     // Packet header...
494                     strm.Printf("<%4" PRIu64 "> read packet: %c", (uint64_t)total_length, m_bytes[0]);
495                     for (size_t i=content_start; i<content_end; ++i)
496                     {
497                         // Remove binary escaped bytes when displaying the packet...
498                         const char ch = m_bytes[i];
499                         if (ch == 0x7d)
500                         {
501                             // 0x7d is the escape character.  The next character is to
502                             // be XOR'd with 0x20.
503                             const char escapee = m_bytes[++i] ^ 0x20;
504                             strm.Printf("%2.2x", escapee);
505                         }
506                         else
507                         {
508                             strm.Printf("%2.2x", (uint8_t)ch);
509                         }
510                     }
511                     // Packet footer...
512                     strm.Printf("%c%c%c", m_bytes[total_length-3], m_bytes[total_length-2], m_bytes[total_length-1]);
513                     log->PutCString(strm.GetString().c_str());
514                 }
515                 else
516                 {
517                     log->Printf("<%4" PRIu64 "> read packet: %.*s", (uint64_t)total_length, (int)(total_length), m_bytes.c_str());
518                 }
519             }
520 
521             m_history.AddPacket (m_bytes.c_str(), total_length, History::ePacketTypeRecv, total_length);
522 
523             // Clear packet_str in case there is some existing data in it.
524             packet_str.clear();
525             // Copy the packet from m_bytes to packet_str expanding the
526             // run-length encoding in the process.
527             // Reserve enough byte for the most common case (no RLE used)
528             packet_str.reserve(m_bytes.length());
529             for (std::string::const_iterator c = m_bytes.begin() + content_start; c != m_bytes.begin() + content_end; ++c)
530             {
531                 if (*c == '*')
532                 {
533                     // '*' indicates RLE. Next character will give us the
534                     // repeat count and previous character is what is to be
535                     // repeated.
536                     char char_to_repeat = packet_str.back();
537                     // Number of time the previous character is repeated
538                     int repeat_count = *++c + 3 - ' ';
539                     // We have the char_to_repeat and repeat_count. Now push
540                     // it in the packet.
541                     for (int i = 0; i < repeat_count; ++i)
542                         packet_str.push_back(char_to_repeat);
543                 }
544                 else if (*c == 0x7d)
545                 {
546                     // 0x7d is the escape character.  The next character is to
547                     // be XOR'd with 0x20.
548                     char escapee = *++c ^ 0x20;
549                     packet_str.push_back(escapee);
550                 }
551                 else
552                 {
553                     packet_str.push_back(*c);
554                 }
555             }
556 
557             if (m_bytes[0] == '$')
558             {
559                 assert (checksum_idx < m_bytes.size());
560                 if (::isxdigit (m_bytes[checksum_idx+0]) ||
561                     ::isxdigit (m_bytes[checksum_idx+1]))
562                 {
563                     if (GetSendAcks ())
564                     {
565                         const char *packet_checksum_cstr = &m_bytes[checksum_idx];
566                         char packet_checksum = strtol (packet_checksum_cstr, NULL, 16);
567                         char actual_checksum = CalculcateChecksum (packet_str.c_str(), packet_str.size());
568                         success = packet_checksum == actual_checksum;
569                         if (!success)
570                         {
571                             if (log)
572                                 log->Printf ("error: checksum mismatch: %.*s expected 0x%2.2x, got 0x%2.2x",
573                                              (int)(total_length),
574                                              m_bytes.c_str(),
575                                              (uint8_t)packet_checksum,
576                                              (uint8_t)actual_checksum);
577                         }
578                         // Send the ack or nack if needed
579                         if (!success)
580                             SendNack();
581                         else
582                             SendAck();
583                     }
584                 }
585                 else
586                 {
587                     success = false;
588                     if (log)
589                         log->Printf ("error: invalid checksum in packet: '%s'\n", m_bytes.c_str());
590                 }
591             }
592 
593             m_bytes.erase(0, total_length);
594             packet.SetFilePos(0);
595             return success;
596         }
597     }
598     packet.Clear();
599     return false;
600 }
601 
602 Error
603 GDBRemoteCommunication::StartListenThread (const char *hostname, uint16_t port)
604 {
605     Error error;
606     if (IS_VALID_LLDB_HOST_THREAD(m_listen_thread))
607     {
608         error.SetErrorString("listen thread already running");
609     }
610     else
611     {
612         char listen_url[512];
613         if (hostname && hostname[0])
614             snprintf(listen_url, sizeof(listen_url), "listen://%s:%i", hostname, port);
615         else
616             snprintf(listen_url, sizeof(listen_url), "listen://%i", port);
617         m_listen_url = listen_url;
618         SetConnection(new ConnectionFileDescriptor());
619         m_listen_thread = Host::ThreadCreate (listen_url, GDBRemoteCommunication::ListenThread, this, &error);
620     }
621     return error;
622 }
623 
624 bool
625 GDBRemoteCommunication::JoinListenThread ()
626 {
627     if (IS_VALID_LLDB_HOST_THREAD(m_listen_thread))
628     {
629         Host::ThreadJoin(m_listen_thread, NULL, NULL);
630         m_listen_thread = LLDB_INVALID_HOST_THREAD;
631     }
632     return true;
633 }
634 
635 lldb::thread_result_t
636 GDBRemoteCommunication::ListenThread (lldb::thread_arg_t arg)
637 {
638     GDBRemoteCommunication *comm = (GDBRemoteCommunication *)arg;
639     Error error;
640     ConnectionFileDescriptor *connection = (ConnectionFileDescriptor *)comm->GetConnection ();
641 
642     if (connection)
643     {
644         // Do the listen on another thread so we can continue on...
645         if (connection->Connect(comm->m_listen_url.c_str(), &error) != eConnectionStatusSuccess)
646             comm->SetConnection(NULL);
647     }
648     return NULL;
649 }
650 
651 Error
652 GDBRemoteCommunication::StartDebugserverProcess (const char *hostname,
653                                                  uint16_t in_port,
654                                                  lldb_private::ProcessLaunchInfo &launch_info,
655                                                  uint16_t &out_port)
656 {
657     Log *log (ProcessGDBRemoteLog::GetLogIfAllCategoriesSet (GDBR_LOG_PROCESS));
658     if (log)
659         log->Printf ("GDBRemoteCommunication::%s(hostname=%s, in_port=%" PRIu16 ", out_port=%" PRIu16, __FUNCTION__, hostname ? hostname : "<empty>", in_port, out_port);
660 
661     out_port = in_port;
662     Error error;
663     // If we locate debugserver, keep that located version around
664     static FileSpec g_debugserver_file_spec;
665 
666     char debugserver_path[PATH_MAX];
667     FileSpec &debugserver_file_spec = launch_info.GetExecutableFile();
668 
669     // Always check to see if we have an environment override for the path
670     // to the debugserver to use and use it if we do.
671     const char *env_debugserver_path = getenv("LLDB_DEBUGSERVER_PATH");
672     if (env_debugserver_path)
673     {
674         debugserver_file_spec.SetFile (env_debugserver_path, false);
675         if (log)
676             log->Printf ("GDBRemoteCommunication::%s() gdb-remote stub exe path set from environment variable: %s", __FUNCTION__, env_debugserver_path);
677     }
678     else
679         debugserver_file_spec = g_debugserver_file_spec;
680     bool debugserver_exists = debugserver_file_spec.Exists();
681     if (!debugserver_exists)
682     {
683         // The debugserver binary is in the LLDB.framework/Resources
684         // directory.
685         if (Host::GetLLDBPath (ePathTypeSupportExecutableDir, debugserver_file_spec))
686         {
687             debugserver_file_spec.GetFilename().SetCString(DEBUGSERVER_BASENAME);
688             debugserver_exists = debugserver_file_spec.Exists();
689             if (debugserver_exists)
690             {
691                 if (log)
692                     log->Printf ("GDBRemoteCommunication::%s() found gdb-remote stub exe '%s'", __FUNCTION__, debugserver_file_spec.GetPath ().c_str ());
693 
694                 g_debugserver_file_spec = debugserver_file_spec;
695             }
696             else
697             {
698                 if (log)
699                     log->Printf ("GDBRemoteCommunication::%s() could not find gdb-remote stub exe '%s'", __FUNCTION__, debugserver_file_spec.GetPath ().c_str ());
700 
701                 g_debugserver_file_spec.Clear();
702                 debugserver_file_spec.Clear();
703             }
704         }
705     }
706 
707     if (debugserver_exists)
708     {
709         debugserver_file_spec.GetPath (debugserver_path, sizeof(debugserver_path));
710 
711         Args &debugserver_args = launch_info.GetArguments();
712         debugserver_args.Clear();
713         char arg_cstr[PATH_MAX];
714 
715         // Start args with "debugserver /file/path -r --"
716         debugserver_args.AppendArgument(debugserver_path);
717 
718         // If a host and port is supplied then use it
719         char host_and_port[128];
720         if (hostname)
721         {
722             snprintf (host_and_port, sizeof(host_and_port), "%s:%u", hostname, in_port);
723             debugserver_args.AppendArgument(host_and_port);
724         }
725         else
726         {
727             host_and_port[0] = '\0';
728         }
729 
730         // use native registers, not the GDB registers
731         debugserver_args.AppendArgument("--native-regs");
732         // make debugserver run in its own session so signals generated by
733         // special terminal key sequences (^C) don't affect debugserver
734         debugserver_args.AppendArgument("--setsid");
735 
736         char named_pipe_path[PATH_MAX];
737         named_pipe_path[0] = '\0';
738 
739         bool listen = false;
740         if (host_and_port[0])
741         {
742             // Create a temporary file to get the stdout/stderr and redirect the
743             // output of the command into this file. We will later read this file
744             // if all goes well and fill the data into "command_output_ptr"
745 
746             if (in_port == 0)
747             {
748                 // Binding to port zero, we need to figure out what port it ends up
749                 // using using a named pipe...
750                 FileSpec tmpdir_file_spec;
751                 if (Host::GetLLDBPath (ePathTypeLLDBTempSystemDir, tmpdir_file_spec))
752                 {
753                     tmpdir_file_spec.GetFilename().SetCString("debugserver-named-pipe.XXXXXX");
754                     strncpy(named_pipe_path, tmpdir_file_spec.GetPath().c_str(), sizeof(named_pipe_path));
755                 }
756                 else
757                 {
758                     strncpy(named_pipe_path, "/tmp/debugserver-named-pipe.XXXXXX", sizeof(named_pipe_path));
759                 }
760 
761                 if (::mktemp (named_pipe_path))
762                 {
763 #if defined(_WIN32)
764                     if ( false )
765 #else
766                     if (::mkfifo(named_pipe_path, 0600) == 0)
767 #endif
768                     {
769                         debugserver_args.AppendArgument("--named-pipe");
770                         debugserver_args.AppendArgument(named_pipe_path);
771                     }
772                 }
773             }
774             else
775             {
776                 listen = true;
777             }
778         }
779         else
780         {
781             // No host and port given, so lets listen on our end and make the debugserver
782             // connect to us..
783             error = StartListenThread ("127.0.0.1", 0);
784             if (error.Fail())
785                 return error;
786 
787             ConnectionFileDescriptor *connection = (ConnectionFileDescriptor *)GetConnection ();
788             // Wait for 10 seconds to resolve the bound port
789             out_port = connection->GetBoundPort(10);
790             if (out_port > 0)
791             {
792                 char port_cstr[32];
793                 snprintf(port_cstr, sizeof(port_cstr), "127.0.0.1:%i", out_port);
794                 // Send the host and port down that debugserver and specify an option
795                 // so that it connects back to the port we are listening to in this process
796                 debugserver_args.AppendArgument("--reverse-connect");
797                 debugserver_args.AppendArgument(port_cstr);
798             }
799             else
800             {
801                 error.SetErrorString ("failed to bind to port 0 on 127.0.0.1");
802                 return error;
803             }
804         }
805 
806 
807         const char *env_debugserver_log_file = getenv("LLDB_DEBUGSERVER_LOG_FILE");
808         if (env_debugserver_log_file)
809         {
810             ::snprintf (arg_cstr, sizeof(arg_cstr), "--log-file=%s", env_debugserver_log_file);
811             debugserver_args.AppendArgument(arg_cstr);
812         }
813 
814         const char *env_debugserver_log_flags = getenv("LLDB_DEBUGSERVER_LOG_FLAGS");
815         if (env_debugserver_log_flags)
816         {
817             ::snprintf (arg_cstr, sizeof(arg_cstr), "--log-flags=%s", env_debugserver_log_flags);
818             debugserver_args.AppendArgument(arg_cstr);
819         }
820 
821         // Close STDIN, STDOUT and STDERR. We might need to redirect them
822         // to "/dev/null" if we run into any problems.
823         launch_info.AppendCloseFileAction (STDIN_FILENO);
824         launch_info.AppendCloseFileAction (STDOUT_FILENO);
825         launch_info.AppendCloseFileAction (STDERR_FILENO);
826 
827         error = Host::LaunchProcess(launch_info);
828 
829         if (error.Success() && launch_info.GetProcessID() != LLDB_INVALID_PROCESS_ID)
830         {
831             if (named_pipe_path[0])
832             {
833                 File name_pipe_file;
834                 error = name_pipe_file.Open(named_pipe_path, File::eOpenOptionRead);
835                 if (error.Success())
836                 {
837                     char port_cstr[256];
838                     port_cstr[0] = '\0';
839                     size_t num_bytes = sizeof(port_cstr);
840                     error = name_pipe_file.Read(port_cstr, num_bytes);
841                     assert (error.Success());
842                     assert (num_bytes > 0 && port_cstr[num_bytes-1] == '\0');
843                     out_port = Args::StringToUInt32(port_cstr, 0);
844                     name_pipe_file.Close();
845                 }
846                 Host::Unlink(named_pipe_path);
847             }
848             else if (listen)
849             {
850 
851             }
852             else
853             {
854                 // Make sure we actually connect with the debugserver...
855                 JoinListenThread();
856             }
857         }
858     }
859     else
860     {
861         error.SetErrorStringWithFormat ("unable to locate " DEBUGSERVER_BASENAME );
862     }
863     return error;
864 }
865 
866 void
867 GDBRemoteCommunication::DumpHistory(Stream &strm)
868 {
869     m_history.Dump (strm);
870 }
871