xref: /llvm-project/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunication.cpp (revision 3c6774a172a116adf5272081c926af54fb81d384)
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 #define DEBUGSERVER_BASENAME    "debugserver"
33 
34 using namespace lldb;
35 using namespace lldb_private;
36 
37 GDBRemoteCommunication::History::History (uint32_t size) :
38     m_packets(),
39     m_curr_idx (0),
40     m_total_packet_count (0),
41     m_dumped_to_log (false)
42 {
43     m_packets.resize(size);
44 }
45 
46 GDBRemoteCommunication::History::~History ()
47 {
48 }
49 
50 void
51 GDBRemoteCommunication::History::AddPacket (char packet_char,
52                                             PacketType type,
53                                             uint32_t bytes_transmitted)
54 {
55     const size_t size = m_packets.size();
56     if (size > 0)
57     {
58         const uint32_t idx = GetNextIndex();
59         m_packets[idx].packet.assign (1, packet_char);
60         m_packets[idx].type = type;
61         m_packets[idx].bytes_transmitted = bytes_transmitted;
62         m_packets[idx].packet_idx = m_total_packet_count;
63         m_packets[idx].tid = Host::GetCurrentThreadID();
64     }
65 }
66 
67 void
68 GDBRemoteCommunication::History::AddPacket (const std::string &src,
69                                             uint32_t src_len,
70                                             PacketType type,
71                                             uint32_t bytes_transmitted)
72 {
73     const size_t size = m_packets.size();
74     if (size > 0)
75     {
76         const uint32_t idx = GetNextIndex();
77         m_packets[idx].packet.assign (src, 0, src_len);
78         m_packets[idx].type = type;
79         m_packets[idx].bytes_transmitted = bytes_transmitted;
80         m_packets[idx].packet_idx = m_total_packet_count;
81         m_packets[idx].tid = Host::GetCurrentThreadID();
82     }
83 }
84 
85 void
86 GDBRemoteCommunication::History::Dump (lldb_private::Stream &strm) const
87 {
88     const uint32_t size = GetNumPacketsInHistory ();
89     const uint32_t first_idx = GetFirstSavedPacketIndex ();
90     const uint32_t stop_idx = m_curr_idx + size;
91     for (uint32_t i = first_idx;  i < stop_idx; ++i)
92     {
93         const uint32_t idx = NormalizeIndex (i);
94         const Entry &entry = m_packets[idx];
95         if (entry.type == ePacketTypeInvalid || entry.packet.empty())
96             break;
97         strm.Printf ("history[%u] tid=0x%4.4" PRIx64 " <%4u> %s packet: %s\n",
98                      entry.packet_idx,
99                      entry.tid,
100                      entry.bytes_transmitted,
101                      (entry.type == ePacketTypeSend) ? "send" : "read",
102                      entry.packet.c_str());
103     }
104 }
105 
106 void
107 GDBRemoteCommunication::History::Dump (lldb_private::Log *log) const
108 {
109     if (log && !m_dumped_to_log)
110     {
111         m_dumped_to_log = true;
112         const uint32_t size = GetNumPacketsInHistory ();
113         const uint32_t first_idx = GetFirstSavedPacketIndex ();
114         const uint32_t stop_idx = m_curr_idx + size;
115         for (uint32_t i = first_idx;  i < stop_idx; ++i)
116         {
117             const uint32_t idx = NormalizeIndex (i);
118             const Entry &entry = m_packets[idx];
119             if (entry.type == ePacketTypeInvalid || entry.packet.empty())
120                 break;
121             log->Printf ("history[%u] tid=0x%4.4" PRIx64 " <%4u> %s packet: %s",
122                          entry.packet_idx,
123                          entry.tid,
124                          entry.bytes_transmitted,
125                          (entry.type == ePacketTypeSend) ? "send" : "read",
126                          entry.packet.c_str());
127         }
128     }
129 }
130 
131 //----------------------------------------------------------------------
132 // GDBRemoteCommunication constructor
133 //----------------------------------------------------------------------
134 GDBRemoteCommunication::GDBRemoteCommunication(const char *comm_name,
135                                                const char *listener_name,
136                                                bool is_platform) :
137     Communication(comm_name),
138 #ifdef LLDB_CONFIGURATION_DEBUG
139     m_packet_timeout (1000),
140 #else
141     m_packet_timeout (1),
142 #endif
143     m_sequence_mutex (Mutex::eMutexTypeRecursive),
144     m_public_is_running (false),
145     m_private_is_running (false),
146     m_history (512),
147     m_send_acks (true),
148     m_is_platform (is_platform),
149     m_listen_thread (LLDB_INVALID_HOST_THREAD),
150     m_listen_url ()
151 {
152 }
153 
154 //----------------------------------------------------------------------
155 // Destructor
156 //----------------------------------------------------------------------
157 GDBRemoteCommunication::~GDBRemoteCommunication()
158 {
159     if (IsConnected())
160     {
161         Disconnect();
162     }
163 }
164 
165 char
166 GDBRemoteCommunication::CalculcateChecksum (const char *payload, size_t payload_length)
167 {
168     int checksum = 0;
169 
170     for (size_t i = 0; i < payload_length; ++i)
171         checksum += payload[i];
172 
173     return checksum & 255;
174 }
175 
176 size_t
177 GDBRemoteCommunication::SendAck ()
178 {
179     Log *log (ProcessGDBRemoteLog::GetLogIfAllCategoriesSet (GDBR_LOG_PACKETS));
180     ConnectionStatus status = eConnectionStatusSuccess;
181     char ch = '+';
182     const size_t bytes_written = Write (&ch, 1, status, NULL);
183     if (log)
184         log->Printf ("<%4" PRIu64 "> send packet: %c", (uint64_t)bytes_written, ch);
185     m_history.AddPacket (ch, History::ePacketTypeSend, bytes_written);
186     return bytes_written;
187 }
188 
189 size_t
190 GDBRemoteCommunication::SendNack ()
191 {
192     Log *log (ProcessGDBRemoteLog::GetLogIfAllCategoriesSet (GDBR_LOG_PACKETS));
193     ConnectionStatus status = eConnectionStatusSuccess;
194     char ch = '-';
195     const size_t bytes_written = Write (&ch, 1, status, NULL);
196     if (log)
197         log->Printf("<%4" PRIu64 "> send packet: %c", (uint64_t)bytes_written, ch);
198     m_history.AddPacket (ch, History::ePacketTypeSend, bytes_written);
199     return bytes_written;
200 }
201 
202 GDBRemoteCommunication::PacketResult
203 GDBRemoteCommunication::SendPacket (const char *payload, size_t payload_length)
204 {
205     Mutex::Locker locker(m_sequence_mutex);
206     return SendPacketNoLock (payload, payload_length);
207 }
208 
209 GDBRemoteCommunication::PacketResult
210 GDBRemoteCommunication::SendPacketNoLock (const char *payload, size_t payload_length)
211 {
212     if (IsConnected())
213     {
214         StreamString packet(0, 4, eByteOrderBig);
215 
216         packet.PutChar('$');
217         packet.Write (payload, payload_length);
218         packet.PutChar('#');
219         packet.PutHex8(CalculcateChecksum (payload, payload_length));
220 
221         Log *log (ProcessGDBRemoteLog::GetLogIfAllCategoriesSet (GDBR_LOG_PACKETS));
222         ConnectionStatus status = eConnectionStatusSuccess;
223         size_t bytes_written = Write (packet.GetData(), packet.GetSize(), status, NULL);
224         if (log)
225         {
226             // If logging was just enabled and we have history, then dump out what
227             // we have to the log so we get the historical context. The Dump() call that
228             // logs all of the packet will set a boolean so that we don't dump this more
229             // than once
230             if (!m_history.DidDumpToLog ())
231                 m_history.Dump (log);
232 
233             log->Printf("<%4" PRIu64 "> send packet: %.*s", (uint64_t)bytes_written, (int)packet.GetSize(), packet.GetData());
234         }
235 
236         m_history.AddPacket (packet.GetString(), packet.GetSize(), History::ePacketTypeSend, bytes_written);
237 
238 
239         if (bytes_written == packet.GetSize())
240         {
241             if (GetSendAcks ())
242                 return GetAck ();
243             else
244                 return PacketResult::Success;
245         }
246         else
247         {
248             if (log)
249                 log->Printf ("error: failed to send packet: %.*s", (int)packet.GetSize(), packet.GetData());
250         }
251     }
252     return PacketResult::ErrorSendFailed;
253 }
254 
255 GDBRemoteCommunication::PacketResult
256 GDBRemoteCommunication::GetAck ()
257 {
258     StringExtractorGDBRemote packet;
259     PacketResult result = WaitForPacketWithTimeoutMicroSecondsNoLock (packet, GetPacketTimeoutInMicroSeconds ());
260     if (result == PacketResult::Success)
261     {
262         if (packet.GetResponseType() == StringExtractorGDBRemote::ResponseType::eAck)
263             return PacketResult::Success;
264         else
265             return PacketResult::ErrorSendAck;
266     }
267     return result;
268 }
269 
270 bool
271 GDBRemoteCommunication::GetSequenceMutex (Mutex::Locker& locker, const char *failure_message)
272 {
273     if (IsRunning())
274         return locker.TryLock (m_sequence_mutex, failure_message);
275 
276     locker.Lock (m_sequence_mutex);
277     return true;
278 }
279 
280 
281 bool
282 GDBRemoteCommunication::WaitForNotRunningPrivate (const TimeValue *timeout_ptr)
283 {
284     return m_private_is_running.WaitForValueEqualTo (false, timeout_ptr, NULL);
285 }
286 
287 GDBRemoteCommunication::PacketResult
288 GDBRemoteCommunication::WaitForPacketWithTimeoutMicroSecondsNoLock (StringExtractorGDBRemote &packet, uint32_t timeout_usec)
289 {
290     uint8_t buffer[8192];
291     Error error;
292 
293     Log *log (ProcessGDBRemoteLog::GetLogIfAllCategoriesSet (GDBR_LOG_PACKETS | GDBR_LOG_VERBOSE));
294 
295     // Check for a packet from our cache first without trying any reading...
296     if (CheckForPacket (NULL, 0, packet))
297         return PacketResult::Success;
298 
299     bool timed_out = false;
300     bool disconnected = false;
301     while (IsConnected() && !timed_out)
302     {
303         lldb::ConnectionStatus status = eConnectionStatusNoConnection;
304         size_t bytes_read = Read (buffer, sizeof(buffer), timeout_usec, status, &error);
305 
306         if (log)
307             log->Printf ("%s: Read (buffer, (sizeof(buffer), timeout_usec = 0x%x, status = %s, error = %s) => bytes_read = %" PRIu64,
308                          __PRETTY_FUNCTION__,
309                          timeout_usec,
310                          Communication::ConnectionStatusAsCString (status),
311                          error.AsCString(),
312                          (uint64_t)bytes_read);
313 
314         if (bytes_read > 0)
315         {
316             if (CheckForPacket (buffer, bytes_read, packet))
317                 return PacketResult::Success;
318         }
319         else
320         {
321             switch (status)
322             {
323             case eConnectionStatusTimedOut:
324                 timed_out = true;
325                 break;
326             case eConnectionStatusSuccess:
327                 //printf ("status = success but error = %s\n", error.AsCString("<invalid>"));
328                 break;
329 
330             case eConnectionStatusEndOfFile:
331             case eConnectionStatusNoConnection:
332             case eConnectionStatusLostConnection:
333             case eConnectionStatusError:
334                 disconnected = true;
335                 Disconnect();
336                 break;
337             }
338         }
339     }
340     packet.Clear ();
341     if (disconnected)
342         return PacketResult::ErrorDisconnected;
343     if (timed_out)
344         return PacketResult::ErrorReplyTimeout;
345     else
346         return PacketResult::ErrorReplyFailed;
347 }
348 
349 bool
350 GDBRemoteCommunication::CheckForPacket (const uint8_t *src, size_t src_len, StringExtractorGDBRemote &packet)
351 {
352     // Put the packet data into the buffer in a thread safe fashion
353     Mutex::Locker locker(m_bytes_mutex);
354 
355     Log *log (ProcessGDBRemoteLog::GetLogIfAllCategoriesSet (GDBR_LOG_PACKETS));
356 
357     if (src && src_len > 0)
358     {
359         if (log && log->GetVerbose())
360         {
361             StreamString s;
362             log->Printf ("GDBRemoteCommunication::%s adding %u bytes: %.*s",
363                          __FUNCTION__,
364                          (uint32_t)src_len,
365                          (uint32_t)src_len,
366                          src);
367         }
368         m_bytes.append ((const char *)src, src_len);
369     }
370 
371     // Parse up the packets into gdb remote packets
372     if (!m_bytes.empty())
373     {
374         // end_idx must be one past the last valid packet byte. Start
375         // it off with an invalid value that is the same as the current
376         // index.
377         size_t content_start = 0;
378         size_t content_length = 0;
379         size_t total_length = 0;
380         size_t checksum_idx = std::string::npos;
381 
382         switch (m_bytes[0])
383         {
384             case '+':       // Look for ack
385             case '-':       // Look for cancel
386             case '\x03':    // ^C to halt target
387                 content_length = total_length = 1;  // The command is one byte long...
388                 break;
389 
390             case '$':
391                 // Look for a standard gdb packet?
392                 {
393                     size_t hash_pos = m_bytes.find('#');
394                     if (hash_pos != std::string::npos)
395                     {
396                         if (hash_pos + 2 < m_bytes.size())
397                         {
398                             checksum_idx = hash_pos + 1;
399                             // Skip the dollar sign
400                             content_start = 1;
401                             // Don't include the # in the content or the $ in the content length
402                             content_length = hash_pos - 1;
403 
404                             total_length = hash_pos + 3; // Skip the # and the two hex checksum bytes
405                         }
406                         else
407                         {
408                             // Checksum bytes aren't all here yet
409                             content_length = std::string::npos;
410                         }
411                     }
412                 }
413                 break;
414 
415             default:
416                 {
417                     // We have an unexpected byte and we need to flush all bad
418                     // data that is in m_bytes, so we need to find the first
419                     // byte that is a '+' (ACK), '-' (NACK), \x03 (CTRL+C interrupt),
420                     // or '$' character (start of packet header) or of course,
421                     // the end of the data in m_bytes...
422                     const size_t bytes_len = m_bytes.size();
423                     bool done = false;
424                     uint32_t idx;
425                     for (idx = 1; !done && idx < bytes_len; ++idx)
426                     {
427                         switch (m_bytes[idx])
428                         {
429                         case '+':
430                         case '-':
431                         case '\x03':
432                         case '$':
433                             done = true;
434                             break;
435 
436                         default:
437                             break;
438                         }
439                     }
440                     if (log)
441                         log->Printf ("GDBRemoteCommunication::%s tossing %u junk bytes: '%.*s'",
442                                      __FUNCTION__, idx, idx, m_bytes.c_str());
443                     m_bytes.erase(0, idx);
444                 }
445                 break;
446         }
447 
448         if (content_length == std::string::npos)
449         {
450             packet.Clear();
451             return false;
452         }
453         else if (total_length > 0)
454         {
455 
456             // We have a valid packet...
457             assert (content_length <= m_bytes.size());
458             assert (total_length <= m_bytes.size());
459             assert (content_length <= total_length);
460 
461             bool success = true;
462             std::string &packet_str = packet.GetStringRef();
463 
464 
465             if (log)
466             {
467                 // If logging was just enabled and we have history, then dump out what
468                 // we have to the log so we get the historical context. The Dump() call that
469                 // logs all of the packet will set a boolean so that we don't dump this more
470                 // than once
471                 if (!m_history.DidDumpToLog ())
472                     m_history.Dump (log);
473 
474                 log->Printf("<%4" PRIu64 "> read packet: %.*s", (uint64_t)total_length, (int)(total_length), m_bytes.c_str());
475             }
476 
477             m_history.AddPacket (m_bytes.c_str(), total_length, History::ePacketTypeRecv, total_length);
478 
479             // Clear packet_str in case there is some existing data in it.
480             packet_str.clear();
481             // Copy the packet from m_bytes to packet_str expanding the
482             // run-length encoding in the process.
483             // Reserve enough byte for the most common case (no RLE used)
484             packet_str.reserve(m_bytes.length());
485             for (std::string::const_iterator c = m_bytes.begin() + content_start; c != m_bytes.begin() + content_start + content_length; ++c)
486             {
487                 if (*c == '*')
488                 {
489                     // '*' indicates RLE. Next character will give us the
490                     // repeat count and previous character is what is to be
491                     // repeated.
492                     char char_to_repeat = packet_str.back();
493                     // Number of time the previous character is repeated
494                     int repeat_count = *++c + 3 - ' ';
495                     // We have the char_to_repeat and repeat_count. Now push
496                     // it in the packet.
497                     for (int i = 0; i < repeat_count; ++i)
498                         packet_str.push_back(char_to_repeat);
499                 }
500                 else
501                 {
502                     packet_str.push_back(*c);
503                 }
504             }
505 
506             if (m_bytes[0] == '$')
507             {
508                 assert (checksum_idx < m_bytes.size());
509                 if (::isxdigit (m_bytes[checksum_idx+0]) ||
510                     ::isxdigit (m_bytes[checksum_idx+1]))
511                 {
512                     if (GetSendAcks ())
513                     {
514                         const char *packet_checksum_cstr = &m_bytes[checksum_idx];
515                         char packet_checksum = strtol (packet_checksum_cstr, NULL, 16);
516                         char actual_checksum = CalculcateChecksum (packet_str.c_str(), packet_str.size());
517                         success = packet_checksum == actual_checksum;
518                         if (!success)
519                         {
520                             if (log)
521                                 log->Printf ("error: checksum mismatch: %.*s expected 0x%2.2x, got 0x%2.2x",
522                                              (int)(total_length),
523                                              m_bytes.c_str(),
524                                              (uint8_t)packet_checksum,
525                                              (uint8_t)actual_checksum);
526                         }
527                         // Send the ack or nack if needed
528                         if (!success)
529                             SendNack();
530                         else
531                             SendAck();
532                     }
533                 }
534                 else
535                 {
536                     success = false;
537                     if (log)
538                         log->Printf ("error: invalid checksum in packet: '%s'\n", m_bytes.c_str());
539                 }
540             }
541 
542             m_bytes.erase(0, total_length);
543             packet.SetFilePos(0);
544             return success;
545         }
546     }
547     packet.Clear();
548     return false;
549 }
550 
551 Error
552 GDBRemoteCommunication::StartListenThread (const char *hostname, uint16_t port)
553 {
554     Error error;
555     if (IS_VALID_LLDB_HOST_THREAD(m_listen_thread))
556     {
557         error.SetErrorString("listen thread already running");
558     }
559     else
560     {
561         char listen_url[512];
562         if (hostname && hostname[0])
563             snprintf(listen_url, sizeof(listen_url), "listen://%s:%i", hostname, port);
564         else
565             snprintf(listen_url, sizeof(listen_url), "listen://%i", port);
566         m_listen_url = listen_url;
567         SetConnection(new ConnectionFileDescriptor());
568         m_listen_thread = Host::ThreadCreate (listen_url, GDBRemoteCommunication::ListenThread, this, &error);
569     }
570     return error;
571 }
572 
573 bool
574 GDBRemoteCommunication::JoinListenThread ()
575 {
576     if (IS_VALID_LLDB_HOST_THREAD(m_listen_thread))
577     {
578         Host::ThreadJoin(m_listen_thread, NULL, NULL);
579         m_listen_thread = LLDB_INVALID_HOST_THREAD;
580     }
581     return true;
582 }
583 
584 lldb::thread_result_t
585 GDBRemoteCommunication::ListenThread (lldb::thread_arg_t arg)
586 {
587     GDBRemoteCommunication *comm = (GDBRemoteCommunication *)arg;
588     Error error;
589     ConnectionFileDescriptor *connection = (ConnectionFileDescriptor *)comm->GetConnection ();
590 
591     if (connection)
592     {
593         // Do the listen on another thread so we can continue on...
594         if (connection->Connect(comm->m_listen_url.c_str(), &error) != eConnectionStatusSuccess)
595             comm->SetConnection(NULL);
596     }
597     return NULL;
598 }
599 
600 Error
601 GDBRemoteCommunication::StartDebugserverProcess (const char *hostname,
602                                                  uint16_t in_port,
603                                                  lldb_private::ProcessLaunchInfo &launch_info,
604                                                  uint16_t &out_port)
605 {
606     out_port = in_port;
607     Error error;
608     // If we locate debugserver, keep that located version around
609     static FileSpec g_debugserver_file_spec;
610 
611     char debugserver_path[PATH_MAX];
612     FileSpec &debugserver_file_spec = launch_info.GetExecutableFile();
613 
614     // Always check to see if we have an environment override for the path
615     // to the debugserver to use and use it if we do.
616     const char *env_debugserver_path = getenv("LLDB_DEBUGSERVER_PATH");
617     if (env_debugserver_path)
618         debugserver_file_spec.SetFile (env_debugserver_path, false);
619     else
620         debugserver_file_spec = g_debugserver_file_spec;
621     bool debugserver_exists = debugserver_file_spec.Exists();
622     if (!debugserver_exists)
623     {
624         // The debugserver binary is in the LLDB.framework/Resources
625         // directory.
626         if (Host::GetLLDBPath (ePathTypeSupportExecutableDir, debugserver_file_spec))
627         {
628             debugserver_file_spec.GetFilename().SetCString(DEBUGSERVER_BASENAME);
629             debugserver_exists = debugserver_file_spec.Exists();
630             if (debugserver_exists)
631             {
632                 g_debugserver_file_spec = debugserver_file_spec;
633             }
634             else
635             {
636                 g_debugserver_file_spec.Clear();
637                 debugserver_file_spec.Clear();
638             }
639         }
640     }
641 
642     if (debugserver_exists)
643     {
644         debugserver_file_spec.GetPath (debugserver_path, sizeof(debugserver_path));
645 
646         Args &debugserver_args = launch_info.GetArguments();
647         debugserver_args.Clear();
648         char arg_cstr[PATH_MAX];
649 
650         // Start args with "debugserver /file/path -r --"
651         debugserver_args.AppendArgument(debugserver_path);
652 
653         // If a host and port is supplied then use it
654         char host_and_port[128];
655         if (hostname)
656         {
657             snprintf (host_and_port, sizeof(host_and_port), "%s:%u", hostname, in_port);
658             debugserver_args.AppendArgument(host_and_port);
659         }
660         else
661         {
662             host_and_port[0] = '\0';
663         }
664 
665         // use native registers, not the GDB registers
666         debugserver_args.AppendArgument("--native-regs");
667         // make debugserver run in its own session so signals generated by
668         // special terminal key sequences (^C) don't affect debugserver
669         debugserver_args.AppendArgument("--setsid");
670 
671         char named_pipe_path[PATH_MAX];
672         named_pipe_path[0] = '\0';
673 
674         bool listen = false;
675         if (host_and_port[0])
676         {
677             // Create a temporary file to get the stdout/stderr and redirect the
678             // output of the command into this file. We will later read this file
679             // if all goes well and fill the data into "command_output_ptr"
680 
681             if (in_port == 0)
682             {
683                 // Binding to port zero, we need to figure out what port it ends up
684                 // using using a named pipe...
685                 FileSpec tmpdir_file_spec;
686                 if (Host::GetLLDBPath (ePathTypeLLDBTempSystemDir, tmpdir_file_spec))
687                 {
688                     tmpdir_file_spec.GetFilename().SetCString("debugserver-named-pipe.XXXXXX");
689                     strncpy(named_pipe_path, tmpdir_file_spec.GetPath().c_str(), sizeof(named_pipe_path));
690                 }
691                 else
692                 {
693                     strncpy(named_pipe_path, "/tmp/debugserver-named-pipe.XXXXXX", sizeof(named_pipe_path));
694                 }
695 
696                 if (::mktemp (named_pipe_path))
697                 {
698 #if defined(_MSC_VER)
699                     if ( false )
700 #else
701                     if (::mkfifo(named_pipe_path, 0600) == 0)
702 #endif
703                     {
704                         debugserver_args.AppendArgument("--named-pipe");
705                         debugserver_args.AppendArgument(named_pipe_path);
706                     }
707                 }
708             }
709             else
710             {
711                 listen = true;
712             }
713         }
714         else
715         {
716             // No host and port given, so lets listen on our end and make the debugserver
717             // connect to us..
718             error = StartListenThread ("localhost", 0);
719             if (error.Fail())
720                 return error;
721 
722             ConnectionFileDescriptor *connection = (ConnectionFileDescriptor *)GetConnection ();
723             out_port = connection->GetBoundPort(3);
724             assert (out_port != 0);
725             char port_cstr[32];
726             snprintf(port_cstr, sizeof(port_cstr), "localhost:%i", out_port);
727             // Send the host and port down that debugserver and specify an option
728             // so that it connects back to the port we are listening to in this process
729             debugserver_args.AppendArgument("--reverse-connect");
730             debugserver_args.AppendArgument(port_cstr);
731         }
732 
733 
734         const char *env_debugserver_log_file = getenv("LLDB_DEBUGSERVER_LOG_FILE");
735         if (env_debugserver_log_file)
736         {
737             ::snprintf (arg_cstr, sizeof(arg_cstr), "--log-file=%s", env_debugserver_log_file);
738             debugserver_args.AppendArgument(arg_cstr);
739         }
740 
741         const char *env_debugserver_log_flags = getenv("LLDB_DEBUGSERVER_LOG_FLAGS");
742         if (env_debugserver_log_flags)
743         {
744             ::snprintf (arg_cstr, sizeof(arg_cstr), "--log-flags=%s", env_debugserver_log_flags);
745             debugserver_args.AppendArgument(arg_cstr);
746         }
747 
748         // Close STDIN, STDOUT and STDERR. We might need to redirect them
749         // to "/dev/null" if we run into any problems.
750         launch_info.AppendCloseFileAction (STDIN_FILENO);
751         launch_info.AppendCloseFileAction (STDOUT_FILENO);
752         launch_info.AppendCloseFileAction (STDERR_FILENO);
753 
754         error = Host::LaunchProcess(launch_info);
755 
756         if (named_pipe_path[0])
757         {
758             File name_pipe_file;
759             error = name_pipe_file.Open(named_pipe_path, File::eOpenOptionRead);
760             if (error.Success())
761             {
762                 char port_cstr[256];
763                 port_cstr[0] = '\0';
764                 size_t num_bytes = sizeof(port_cstr);
765                 error = name_pipe_file.Read(port_cstr, num_bytes);
766                 assert (error.Success());
767                 assert (num_bytes > 0 && port_cstr[num_bytes-1] == '\0');
768                 out_port = Args::StringToUInt32(port_cstr, 0);
769                 name_pipe_file.Close();
770             }
771             Host::Unlink(named_pipe_path);
772         }
773         else if (listen)
774         {
775 
776         }
777         else
778         {
779             // Make sure we actually connect with the debugserver...
780             JoinListenThread();
781         }
782     }
783     else
784     {
785         error.SetErrorStringWithFormat ("unable to locate " DEBUGSERVER_BASENAME );
786     }
787     return error;
788 }
789 
790 void
791 GDBRemoteCommunication::DumpHistory(Stream &strm)
792 {
793     m_history.Dump (strm);
794 }
795