xref: /llvm-project/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunication.cpp (revision 912800c4006eb0caa6407fd8278f7292f617d378)
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/Log.h"
21 #include "lldb/Core/StreamFile.h"
22 #include "lldb/Core/StreamString.h"
23 #include "lldb/Host/ConnectionFileDescriptor.h"
24 #include "lldb/Host/FileSpec.h"
25 #include "lldb/Host/Host.h"
26 #include "lldb/Host/HostInfo.h"
27 #include "lldb/Host/Pipe.h"
28 #include "lldb/Host/Socket.h"
29 #include "lldb/Host/StringConvert.h"
30 #include "lldb/Host/ThreadLauncher.h"
31 #include "lldb/Host/TimeValue.h"
32 #include "lldb/Target/Process.h"
33 #include "llvm/ADT/SmallString.h"
34 
35 // Project includes
36 #include "ProcessGDBRemoteLog.h"
37 
38 #if defined(__APPLE__)
39 # define DEBUGSERVER_BASENAME    "debugserver"
40 #else
41 # define DEBUGSERVER_BASENAME    "lldb-server"
42 #endif
43 
44 using namespace lldb;
45 using namespace lldb_private;
46 
47 GDBRemoteCommunication::History::History (uint32_t size) :
48     m_packets(),
49     m_curr_idx (0),
50     m_total_packet_count (0),
51     m_dumped_to_log (false)
52 {
53     m_packets.resize(size);
54 }
55 
56 GDBRemoteCommunication::History::~History ()
57 {
58 }
59 
60 void
61 GDBRemoteCommunication::History::AddPacket (char packet_char,
62                                             PacketType type,
63                                             uint32_t bytes_transmitted)
64 {
65     const size_t size = m_packets.size();
66     if (size > 0)
67     {
68         const uint32_t idx = GetNextIndex();
69         m_packets[idx].packet.assign (1, packet_char);
70         m_packets[idx].type = type;
71         m_packets[idx].bytes_transmitted = bytes_transmitted;
72         m_packets[idx].packet_idx = m_total_packet_count;
73         m_packets[idx].tid = Host::GetCurrentThreadID();
74     }
75 }
76 
77 void
78 GDBRemoteCommunication::History::AddPacket (const std::string &src,
79                                             uint32_t src_len,
80                                             PacketType type,
81                                             uint32_t bytes_transmitted)
82 {
83     const size_t size = m_packets.size();
84     if (size > 0)
85     {
86         const uint32_t idx = GetNextIndex();
87         m_packets[idx].packet.assign (src, 0, src_len);
88         m_packets[idx].type = type;
89         m_packets[idx].bytes_transmitted = bytes_transmitted;
90         m_packets[idx].packet_idx = m_total_packet_count;
91         m_packets[idx].tid = Host::GetCurrentThreadID();
92     }
93 }
94 
95 void
96 GDBRemoteCommunication::History::Dump (lldb_private::Stream &strm) const
97 {
98     const uint32_t size = GetNumPacketsInHistory ();
99     const uint32_t first_idx = GetFirstSavedPacketIndex ();
100     const uint32_t stop_idx = m_curr_idx + size;
101     for (uint32_t i = first_idx;  i < stop_idx; ++i)
102     {
103         const uint32_t idx = NormalizeIndex (i);
104         const Entry &entry = m_packets[idx];
105         if (entry.type == ePacketTypeInvalid || entry.packet.empty())
106             break;
107         strm.Printf ("history[%u] tid=0x%4.4" PRIx64 " <%4u> %s packet: %s\n",
108                      entry.packet_idx,
109                      entry.tid,
110                      entry.bytes_transmitted,
111                      (entry.type == ePacketTypeSend) ? "send" : "read",
112                      entry.packet.c_str());
113     }
114 }
115 
116 void
117 GDBRemoteCommunication::History::Dump (lldb_private::Log *log) const
118 {
119     if (log && !m_dumped_to_log)
120     {
121         m_dumped_to_log = true;
122         const uint32_t size = GetNumPacketsInHistory ();
123         const uint32_t first_idx = GetFirstSavedPacketIndex ();
124         const uint32_t stop_idx = m_curr_idx + size;
125         for (uint32_t i = first_idx;  i < stop_idx; ++i)
126         {
127             const uint32_t idx = NormalizeIndex (i);
128             const Entry &entry = m_packets[idx];
129             if (entry.type == ePacketTypeInvalid || entry.packet.empty())
130                 break;
131             log->Printf ("history[%u] tid=0x%4.4" PRIx64 " <%4u> %s packet: %s",
132                          entry.packet_idx,
133                          entry.tid,
134                          entry.bytes_transmitted,
135                          (entry.type == ePacketTypeSend) ? "send" : "read",
136                          entry.packet.c_str());
137         }
138     }
139 }
140 
141 //----------------------------------------------------------------------
142 // GDBRemoteCommunication constructor
143 //----------------------------------------------------------------------
144 GDBRemoteCommunication::GDBRemoteCommunication(const char *comm_name,
145                                                const char *listener_name) :
146     Communication(comm_name),
147 #ifdef LLDB_CONFIGURATION_DEBUG
148     m_packet_timeout (1000),
149 #else
150     m_packet_timeout (1),
151 #endif
152     m_sequence_mutex (Mutex::eMutexTypeRecursive),
153     m_public_is_running (false),
154     m_private_is_running (false),
155     m_history (512),
156     m_send_acks (true),
157     m_listen_url ()
158 {
159 }
160 
161 //----------------------------------------------------------------------
162 // Destructor
163 //----------------------------------------------------------------------
164 GDBRemoteCommunication::~GDBRemoteCommunication()
165 {
166     if (IsConnected())
167     {
168         Disconnect();
169     }
170 }
171 
172 char
173 GDBRemoteCommunication::CalculcateChecksum (const char *payload, size_t payload_length)
174 {
175     int checksum = 0;
176 
177     for (size_t i = 0; i < payload_length; ++i)
178         checksum += payload[i];
179 
180     return checksum & 255;
181 }
182 
183 size_t
184 GDBRemoteCommunication::SendAck ()
185 {
186     Log *log (ProcessGDBRemoteLog::GetLogIfAllCategoriesSet (GDBR_LOG_PACKETS));
187     ConnectionStatus status = eConnectionStatusSuccess;
188     char ch = '+';
189     const size_t bytes_written = Write (&ch, 1, status, NULL);
190     if (log)
191         log->Printf ("<%4" PRIu64 "> send packet: %c", (uint64_t)bytes_written, ch);
192     m_history.AddPacket (ch, History::ePacketTypeSend, bytes_written);
193     return bytes_written;
194 }
195 
196 size_t
197 GDBRemoteCommunication::SendNack ()
198 {
199     Log *log (ProcessGDBRemoteLog::GetLogIfAllCategoriesSet (GDBR_LOG_PACKETS));
200     ConnectionStatus status = eConnectionStatusSuccess;
201     char ch = '-';
202     const size_t bytes_written = Write (&ch, 1, status, NULL);
203     if (log)
204         log->Printf("<%4" PRIu64 "> send packet: %c", (uint64_t)bytes_written, ch);
205     m_history.AddPacket (ch, History::ePacketTypeSend, bytes_written);
206     return bytes_written;
207 }
208 
209 GDBRemoteCommunication::PacketResult
210 GDBRemoteCommunication::SendPacket (const char *payload, size_t payload_length)
211 {
212     Mutex::Locker locker(m_sequence_mutex);
213     return SendPacketNoLock (payload, payload_length);
214 }
215 
216 GDBRemoteCommunication::PacketResult
217 GDBRemoteCommunication::SendPacketNoLock (const char *payload, size_t payload_length)
218 {
219     if (IsConnected())
220     {
221         StreamString packet(0, 4, eByteOrderBig);
222 
223         packet.PutChar('$');
224         packet.Write (payload, payload_length);
225         packet.PutChar('#');
226         packet.PutHex8(CalculcateChecksum (payload, payload_length));
227 
228         Log *log (ProcessGDBRemoteLog::GetLogIfAllCategoriesSet (GDBR_LOG_PACKETS));
229         ConnectionStatus status = eConnectionStatusSuccess;
230         const char *packet_data = packet.GetData();
231         const size_t packet_length = packet.GetSize();
232         size_t bytes_written = Write (packet_data, packet_length, status, NULL);
233         if (log)
234         {
235             size_t binary_start_offset = 0;
236             if (strncmp(packet_data, "$vFile:pwrite:", strlen("$vFile:pwrite:")) == 0)
237             {
238                 const char *first_comma = strchr(packet_data, ',');
239                 if (first_comma)
240                 {
241                     const char *second_comma = strchr(first_comma + 1, ',');
242                     if (second_comma)
243                         binary_start_offset = second_comma - packet_data + 1;
244                 }
245             }
246 
247             // If logging was just enabled and we have history, then dump out what
248             // we have to the log so we get the historical context. The Dump() call that
249             // logs all of the packet will set a boolean so that we don't dump this more
250             // than once
251             if (!m_history.DidDumpToLog ())
252                 m_history.Dump (log);
253 
254             if (binary_start_offset)
255             {
256                 StreamString strm;
257                 // Print non binary data header
258                 strm.Printf("<%4" PRIu64 "> send packet: %.*s", (uint64_t)bytes_written, (int)binary_start_offset, packet_data);
259                 const uint8_t *p;
260                 // Print binary data exactly as sent
261                 for (p = (uint8_t*)packet_data + binary_start_offset; *p != '#'; ++p)
262                     strm.Printf("\\x%2.2x", *p);
263                 // Print the checksum
264                 strm.Printf("%*s", (int)3, p);
265                 log->PutCString(strm.GetString().c_str());
266             }
267             else
268                 log->Printf("<%4" PRIu64 "> send packet: %.*s", (uint64_t)bytes_written, (int)packet_length, packet_data);
269         }
270 
271         m_history.AddPacket (packet.GetString(), packet_length, History::ePacketTypeSend, bytes_written);
272 
273 
274         if (bytes_written == packet_length)
275         {
276             if (GetSendAcks ())
277                 return GetAck ();
278             else
279                 return PacketResult::Success;
280         }
281         else
282         {
283             if (log)
284                 log->Printf ("error: failed to send packet: %.*s", (int)packet_length, packet_data);
285         }
286     }
287     return PacketResult::ErrorSendFailed;
288 }
289 
290 GDBRemoteCommunication::PacketResult
291 GDBRemoteCommunication::GetAck ()
292 {
293     StringExtractorGDBRemote packet;
294     PacketResult result = WaitForPacketWithTimeoutMicroSecondsNoLock (packet, GetPacketTimeoutInMicroSeconds ());
295     if (result == PacketResult::Success)
296     {
297         if (packet.GetResponseType() == StringExtractorGDBRemote::ResponseType::eAck)
298             return PacketResult::Success;
299         else
300             return PacketResult::ErrorSendAck;
301     }
302     return result;
303 }
304 
305 bool
306 GDBRemoteCommunication::GetSequenceMutex (Mutex::Locker& locker, const char *failure_message)
307 {
308     if (IsRunning())
309         return locker.TryLock (m_sequence_mutex, failure_message);
310 
311     locker.Lock (m_sequence_mutex);
312     return true;
313 }
314 
315 
316 bool
317 GDBRemoteCommunication::WaitForNotRunningPrivate (const TimeValue *timeout_ptr)
318 {
319     return m_private_is_running.WaitForValueEqualTo (false, timeout_ptr, NULL);
320 }
321 
322 GDBRemoteCommunication::PacketResult
323 GDBRemoteCommunication::WaitForPacketWithTimeoutMicroSecondsNoLock (StringExtractorGDBRemote &packet, uint32_t timeout_usec)
324 {
325     uint8_t buffer[8192];
326     Error error;
327 
328     Log *log (ProcessGDBRemoteLog::GetLogIfAllCategoriesSet (GDBR_LOG_PACKETS | GDBR_LOG_VERBOSE));
329 
330     // Check for a packet from our cache first without trying any reading...
331     if (CheckForPacket (NULL, 0, packet))
332         return PacketResult::Success;
333 
334     bool timed_out = false;
335     bool disconnected = false;
336     while (IsConnected() && !timed_out)
337     {
338         lldb::ConnectionStatus status = eConnectionStatusNoConnection;
339         size_t bytes_read = Read (buffer, sizeof(buffer), timeout_usec, status, &error);
340 
341         if (log)
342             log->Printf ("%s: Read (buffer, (sizeof(buffer), timeout_usec = 0x%x, status = %s, error = %s) => bytes_read = %" PRIu64,
343                          __PRETTY_FUNCTION__,
344                          timeout_usec,
345                          Communication::ConnectionStatusAsCString (status),
346                          error.AsCString(),
347                          (uint64_t)bytes_read);
348 
349         if (bytes_read > 0)
350         {
351             if (CheckForPacket (buffer, bytes_read, packet))
352                 return PacketResult::Success;
353         }
354         else
355         {
356             switch (status)
357             {
358             case eConnectionStatusTimedOut:
359             case eConnectionStatusInterrupted:
360                 timed_out = true;
361                 break;
362             case eConnectionStatusSuccess:
363                 //printf ("status = success but error = %s\n", error.AsCString("<invalid>"));
364                 break;
365 
366             case eConnectionStatusEndOfFile:
367             case eConnectionStatusNoConnection:
368             case eConnectionStatusLostConnection:
369             case eConnectionStatusError:
370                 disconnected = true;
371                 Disconnect();
372                 break;
373             }
374         }
375     }
376     packet.Clear ();
377     if (disconnected)
378         return PacketResult::ErrorDisconnected;
379     if (timed_out)
380         return PacketResult::ErrorReplyTimeout;
381     else
382         return PacketResult::ErrorReplyFailed;
383 }
384 
385 bool
386 GDBRemoteCommunication::CheckForPacket (const uint8_t *src, size_t src_len, StringExtractorGDBRemote &packet)
387 {
388     // Put the packet data into the buffer in a thread safe fashion
389     Mutex::Locker locker(m_bytes_mutex);
390 
391     Log *log (ProcessGDBRemoteLog::GetLogIfAllCategoriesSet (GDBR_LOG_PACKETS));
392 
393     if (src && src_len > 0)
394     {
395         if (log && log->GetVerbose())
396         {
397             StreamString s;
398             log->Printf ("GDBRemoteCommunication::%s adding %u bytes: %.*s",
399                          __FUNCTION__,
400                          (uint32_t)src_len,
401                          (uint32_t)src_len,
402                          src);
403         }
404         m_bytes.append ((const char *)src, src_len);
405     }
406 
407     // Parse up the packets into gdb remote packets
408     if (!m_bytes.empty())
409     {
410         // end_idx must be one past the last valid packet byte. Start
411         // it off with an invalid value that is the same as the current
412         // index.
413         size_t content_start = 0;
414         size_t content_length = 0;
415         size_t total_length = 0;
416         size_t checksum_idx = std::string::npos;
417 
418         switch (m_bytes[0])
419         {
420             case '+':       // Look for ack
421             case '-':       // Look for cancel
422             case '\x03':    // ^C to halt target
423                 content_length = total_length = 1;  // The command is one byte long...
424                 break;
425 
426             case '$':
427                 // Look for a standard gdb packet?
428                 {
429                     size_t hash_pos = m_bytes.find('#');
430                     if (hash_pos != std::string::npos)
431                     {
432                         if (hash_pos + 2 < m_bytes.size())
433                         {
434                             checksum_idx = hash_pos + 1;
435                             // Skip the dollar sign
436                             content_start = 1;
437                             // Don't include the # in the content or the $ in the content length
438                             content_length = hash_pos - 1;
439 
440                             total_length = hash_pos + 3; // Skip the # and the two hex checksum bytes
441                         }
442                         else
443                         {
444                             // Checksum bytes aren't all here yet
445                             content_length = std::string::npos;
446                         }
447                     }
448                 }
449                 break;
450 
451             default:
452                 {
453                     // We have an unexpected byte and we need to flush all bad
454                     // data that is in m_bytes, so we need to find the first
455                     // byte that is a '+' (ACK), '-' (NACK), \x03 (CTRL+C interrupt),
456                     // or '$' character (start of packet header) or of course,
457                     // the end of the data in m_bytes...
458                     const size_t bytes_len = m_bytes.size();
459                     bool done = false;
460                     uint32_t idx;
461                     for (idx = 1; !done && idx < bytes_len; ++idx)
462                     {
463                         switch (m_bytes[idx])
464                         {
465                         case '+':
466                         case '-':
467                         case '\x03':
468                         case '$':
469                             done = true;
470                             break;
471 
472                         default:
473                             break;
474                         }
475                     }
476                     if (log)
477                         log->Printf ("GDBRemoteCommunication::%s tossing %u junk bytes: '%.*s'",
478                                      __FUNCTION__, idx - 1, idx - 1, m_bytes.c_str());
479                     m_bytes.erase(0, idx - 1);
480                 }
481                 break;
482         }
483 
484         if (content_length == std::string::npos)
485         {
486             packet.Clear();
487             return false;
488         }
489         else if (total_length > 0)
490         {
491 
492             // We have a valid packet...
493             assert (content_length <= m_bytes.size());
494             assert (total_length <= m_bytes.size());
495             assert (content_length <= total_length);
496             const size_t content_end = content_start + content_length;
497 
498             bool success = true;
499             std::string &packet_str = packet.GetStringRef();
500 
501 
502             if (log)
503             {
504                 // If logging was just enabled and we have history, then dump out what
505                 // we have to the log so we get the historical context. The Dump() call that
506                 // logs all of the packet will set a boolean so that we don't dump this more
507                 // than once
508                 if (!m_history.DidDumpToLog ())
509                     m_history.Dump (log);
510 
511                 bool binary = false;
512                 // Only detect binary for packets that start with a '$' and have a '#CC' checksum
513                 if (m_bytes[0] == '$' && total_length > 4)
514                 {
515                     for (size_t i=0; !binary && i<total_length; ++i)
516                     {
517                         if (isprint(m_bytes[i]) == 0)
518                             binary = true;
519                     }
520                 }
521                 if (binary)
522                 {
523                     StreamString strm;
524                     // Packet header...
525                     strm.Printf("<%4" PRIu64 "> read packet: %c", (uint64_t)total_length, m_bytes[0]);
526                     for (size_t i=content_start; i<content_end; ++i)
527                     {
528                         // Remove binary escaped bytes when displaying the packet...
529                         const char ch = m_bytes[i];
530                         if (ch == 0x7d)
531                         {
532                             // 0x7d is the escape character.  The next character is to
533                             // be XOR'd with 0x20.
534                             const char escapee = m_bytes[++i] ^ 0x20;
535                             strm.Printf("%2.2x", escapee);
536                         }
537                         else
538                         {
539                             strm.Printf("%2.2x", (uint8_t)ch);
540                         }
541                     }
542                     // Packet footer...
543                     strm.Printf("%c%c%c", m_bytes[total_length-3], m_bytes[total_length-2], m_bytes[total_length-1]);
544                     log->PutCString(strm.GetString().c_str());
545                 }
546                 else
547                 {
548                     log->Printf("<%4" PRIu64 "> read packet: %.*s", (uint64_t)total_length, (int)(total_length), m_bytes.c_str());
549                 }
550             }
551 
552             m_history.AddPacket (m_bytes.c_str(), total_length, History::ePacketTypeRecv, total_length);
553 
554             // Clear packet_str in case there is some existing data in it.
555             packet_str.clear();
556             // Copy the packet from m_bytes to packet_str expanding the
557             // run-length encoding in the process.
558             // Reserve enough byte for the most common case (no RLE used)
559             packet_str.reserve(m_bytes.length());
560             for (std::string::const_iterator c = m_bytes.begin() + content_start; c != m_bytes.begin() + content_end; ++c)
561             {
562                 if (*c == '*')
563                 {
564                     // '*' indicates RLE. Next character will give us the
565                     // repeat count and previous character is what is to be
566                     // repeated.
567                     char char_to_repeat = packet_str.back();
568                     // Number of time the previous character is repeated
569                     int repeat_count = *++c + 3 - ' ';
570                     // We have the char_to_repeat and repeat_count. Now push
571                     // it in the packet.
572                     for (int i = 0; i < repeat_count; ++i)
573                         packet_str.push_back(char_to_repeat);
574                 }
575                 else if (*c == 0x7d)
576                 {
577                     // 0x7d is the escape character.  The next character is to
578                     // be XOR'd with 0x20.
579                     char escapee = *++c ^ 0x20;
580                     packet_str.push_back(escapee);
581                 }
582                 else
583                 {
584                     packet_str.push_back(*c);
585                 }
586             }
587 
588             if (m_bytes[0] == '$')
589             {
590                 assert (checksum_idx < m_bytes.size());
591                 if (::isxdigit (m_bytes[checksum_idx+0]) ||
592                     ::isxdigit (m_bytes[checksum_idx+1]))
593                 {
594                     if (GetSendAcks ())
595                     {
596                         const char *packet_checksum_cstr = &m_bytes[checksum_idx];
597                         char packet_checksum = strtol (packet_checksum_cstr, NULL, 16);
598                         char actual_checksum = CalculcateChecksum (packet_str.c_str(), packet_str.size());
599                         success = packet_checksum == actual_checksum;
600                         if (!success)
601                         {
602                             if (log)
603                                 log->Printf ("error: checksum mismatch: %.*s expected 0x%2.2x, got 0x%2.2x",
604                                              (int)(total_length),
605                                              m_bytes.c_str(),
606                                              (uint8_t)packet_checksum,
607                                              (uint8_t)actual_checksum);
608                         }
609                         // Send the ack or nack if needed
610                         if (!success)
611                             SendNack();
612                         else
613                             SendAck();
614                     }
615                 }
616                 else
617                 {
618                     success = false;
619                     if (log)
620                         log->Printf ("error: invalid checksum in packet: '%s'\n", m_bytes.c_str());
621                 }
622             }
623 
624             m_bytes.erase(0, total_length);
625             packet.SetFilePos(0);
626             return success;
627         }
628     }
629     packet.Clear();
630     return false;
631 }
632 
633 Error
634 GDBRemoteCommunication::StartListenThread (const char *hostname, uint16_t port)
635 {
636     Error error;
637     if (m_listen_thread.IsJoinable())
638     {
639         error.SetErrorString("listen thread already running");
640     }
641     else
642     {
643         char listen_url[512];
644         if (hostname && hostname[0])
645             snprintf(listen_url, sizeof(listen_url), "listen://%s:%i", hostname, port);
646         else
647             snprintf(listen_url, sizeof(listen_url), "listen://%i", port);
648         m_listen_url = listen_url;
649         SetConnection(new ConnectionFileDescriptor());
650         m_listen_thread = ThreadLauncher::LaunchThread(listen_url, GDBRemoteCommunication::ListenThread, this, &error);
651     }
652     return error;
653 }
654 
655 bool
656 GDBRemoteCommunication::JoinListenThread ()
657 {
658     if (m_listen_thread.IsJoinable())
659         m_listen_thread.Join(nullptr);
660     return true;
661 }
662 
663 lldb::thread_result_t
664 GDBRemoteCommunication::ListenThread (lldb::thread_arg_t arg)
665 {
666     GDBRemoteCommunication *comm = (GDBRemoteCommunication *)arg;
667     Error error;
668     ConnectionFileDescriptor *connection = (ConnectionFileDescriptor *)comm->GetConnection ();
669 
670     if (connection)
671     {
672         // Do the listen on another thread so we can continue on...
673         if (connection->Connect(comm->m_listen_url.c_str(), &error) != eConnectionStatusSuccess)
674             comm->SetConnection(NULL);
675     }
676     return NULL;
677 }
678 
679 Error
680 GDBRemoteCommunication::StartDebugserverProcess (const char *hostname,
681                                                  uint16_t in_port,
682                                                  lldb_private::ProcessLaunchInfo &launch_info,
683                                                  uint16_t &out_port)
684 {
685     Log *log (ProcessGDBRemoteLog::GetLogIfAllCategoriesSet (GDBR_LOG_PROCESS));
686     if (log)
687         log->Printf ("GDBRemoteCommunication::%s(hostname=%s, in_port=%" PRIu16 ", out_port=%" PRIu16, __FUNCTION__, hostname ? hostname : "<empty>", in_port, out_port);
688 
689     out_port = in_port;
690     Error error;
691     // If we locate debugserver, keep that located version around
692     static FileSpec g_debugserver_file_spec;
693 
694     char debugserver_path[PATH_MAX];
695     FileSpec &debugserver_file_spec = launch_info.GetExecutableFile();
696 
697     // Always check to see if we have an environment override for the path
698     // to the debugserver to use and use it if we do.
699     const char *env_debugserver_path = getenv("LLDB_DEBUGSERVER_PATH");
700     if (env_debugserver_path)
701     {
702         debugserver_file_spec.SetFile (env_debugserver_path, false);
703         if (log)
704             log->Printf ("GDBRemoteCommunication::%s() gdb-remote stub exe path set from environment variable: %s", __FUNCTION__, env_debugserver_path);
705     }
706     else
707         debugserver_file_spec = g_debugserver_file_spec;
708     bool debugserver_exists = debugserver_file_spec.Exists();
709     if (!debugserver_exists)
710     {
711         // The debugserver binary is in the LLDB.framework/Resources
712         // directory.
713         if (HostInfo::GetLLDBPath(ePathTypeSupportExecutableDir, debugserver_file_spec))
714         {
715             debugserver_file_spec.AppendPathComponent (DEBUGSERVER_BASENAME);
716             debugserver_exists = debugserver_file_spec.Exists();
717             if (debugserver_exists)
718             {
719                 if (log)
720                     log->Printf ("GDBRemoteCommunication::%s() found gdb-remote stub exe '%s'", __FUNCTION__, debugserver_file_spec.GetPath ().c_str ());
721 
722                 g_debugserver_file_spec = debugserver_file_spec;
723             }
724             else
725             {
726                 if (log)
727                     log->Printf ("GDBRemoteCommunication::%s() could not find gdb-remote stub exe '%s'", __FUNCTION__, debugserver_file_spec.GetPath ().c_str ());
728 
729                 g_debugserver_file_spec.Clear();
730                 debugserver_file_spec.Clear();
731             }
732         }
733     }
734 
735     if (debugserver_exists)
736     {
737         debugserver_file_spec.GetPath (debugserver_path, sizeof(debugserver_path));
738 
739         Args &debugserver_args = launch_info.GetArguments();
740         debugserver_args.Clear();
741         char arg_cstr[PATH_MAX];
742 
743         // Start args with "debugserver /file/path -r --"
744         debugserver_args.AppendArgument(debugserver_path);
745 
746 #if !defined(__APPLE__)
747         // First argument to lldb-server must be mode in which to run.
748         debugserver_args.AppendArgument("gdbserver");
749 #endif
750 
751         // If a host and port is supplied then use it
752         char host_and_port[128];
753         if (hostname)
754         {
755             snprintf (host_and_port, sizeof(host_and_port), "%s:%u", hostname, in_port);
756             debugserver_args.AppendArgument(host_and_port);
757         }
758         else
759         {
760             host_and_port[0] = '\0';
761         }
762 
763         // use native registers, not the GDB registers
764         debugserver_args.AppendArgument("--native-regs");
765 
766         if (launch_info.GetLaunchInSeparateProcessGroup())
767         {
768             debugserver_args.AppendArgument("--setsid");
769         }
770 
771         llvm::SmallString<PATH_MAX> named_pipe_path;
772         Pipe port_named_pipe;
773 
774         bool listen = false;
775         if (host_and_port[0])
776         {
777             // Create a temporary file to get the stdout/stderr and redirect the
778             // output of the command into this file. We will later read this file
779             // if all goes well and fill the data into "command_output_ptr"
780 
781             if (in_port == 0)
782             {
783                 // Binding to port zero, we need to figure out what port it ends up
784                 // using using a named pipe...
785                 error = port_named_pipe.CreateWithUniqueName("debugserver-named-pipe", false, named_pipe_path);
786                 if (error.Fail())
787                     return error;
788                 debugserver_args.AppendArgument("--named-pipe");
789                 debugserver_args.AppendArgument(named_pipe_path.c_str());
790             }
791             else
792             {
793                 listen = true;
794             }
795         }
796         else
797         {
798             // No host and port given, so lets listen on our end and make the debugserver
799             // connect to us..
800             error = StartListenThread ("127.0.0.1", 0);
801             if (error.Fail())
802                 return error;
803 
804             ConnectionFileDescriptor *connection = (ConnectionFileDescriptor *)GetConnection ();
805             // Wait for 10 seconds to resolve the bound port
806             out_port = connection->GetListeningPort(10);
807             if (out_port > 0)
808             {
809                 char port_cstr[32];
810                 snprintf(port_cstr, sizeof(port_cstr), "127.0.0.1:%i", out_port);
811                 // Send the host and port down that debugserver and specify an option
812                 // so that it connects back to the port we are listening to in this process
813                 debugserver_args.AppendArgument("--reverse-connect");
814                 debugserver_args.AppendArgument(port_cstr);
815             }
816             else
817             {
818                 error.SetErrorString ("failed to bind to port 0 on 127.0.0.1");
819                 return error;
820             }
821         }
822 
823         const char *env_debugserver_log_file = getenv("LLDB_DEBUGSERVER_LOG_FILE");
824         if (env_debugserver_log_file)
825         {
826             ::snprintf (arg_cstr, sizeof(arg_cstr), "--log-file=%s", env_debugserver_log_file);
827             debugserver_args.AppendArgument(arg_cstr);
828         }
829 
830         const char *env_debugserver_log_flags = getenv("LLDB_DEBUGSERVER_LOG_FLAGS");
831         if (env_debugserver_log_flags)
832         {
833             ::snprintf (arg_cstr, sizeof(arg_cstr), "--log-flags=%s", env_debugserver_log_flags);
834             debugserver_args.AppendArgument(arg_cstr);
835         }
836 
837         // Add additional args, starting with LLDB_DEBUGSERVER_EXTRA_ARG_1 until an env var doesn't come back.
838         uint32_t env_var_index = 1;
839         bool has_env_var;
840         do
841         {
842             char env_var_name[64];
843             snprintf (env_var_name, sizeof (env_var_name), "LLDB_DEBUGSERVER_EXTRA_ARG_%" PRIu32, env_var_index++);
844             const char *extra_arg = getenv(env_var_name);
845             has_env_var = extra_arg != nullptr;
846 
847             if (has_env_var)
848             {
849                 debugserver_args.AppendArgument (extra_arg);
850                 if (log)
851                     log->Printf ("GDBRemoteCommunication::%s adding env var %s contents to stub command line (%s)", __FUNCTION__, env_var_name, extra_arg);
852             }
853         } while (has_env_var);
854 
855         // Close STDIN, STDOUT and STDERR.
856         launch_info.AppendCloseFileAction (STDIN_FILENO);
857         launch_info.AppendCloseFileAction (STDOUT_FILENO);
858         launch_info.AppendCloseFileAction (STDERR_FILENO);
859 
860         // Redirect STDIN, STDOUT and STDERR to "/dev/null".
861         launch_info.AppendSuppressFileAction (STDIN_FILENO, true, false);
862         launch_info.AppendSuppressFileAction (STDOUT_FILENO, false, true);
863         launch_info.AppendSuppressFileAction (STDERR_FILENO, false, true);
864 
865         error = Host::LaunchProcess(launch_info);
866 
867         if (error.Success() && launch_info.GetProcessID() != LLDB_INVALID_PROCESS_ID)
868         {
869             if (named_pipe_path.size() > 0)
870             {
871                 error = port_named_pipe.OpenAsReader(named_pipe_path, false);
872                 if (error.Success())
873                 {
874                     char port_cstr[256];
875                     port_cstr[0] = '\0';
876                     size_t num_bytes = sizeof(port_cstr);
877                     // Read port from pipe with 10 second timeout.
878                     error = port_named_pipe.ReadWithTimeout(port_cstr, num_bytes, std::chrono::microseconds(10 * 1000000), num_bytes);
879                     if (error.Success())
880                     {
881                         assert (num_bytes > 0 && port_cstr[num_bytes-1] == '\0');
882                         out_port = StringConvert::ToUInt32(port_cstr, 0);
883                         if (log)
884                             log->Printf("GDBRemoteCommunication::%s() debugserver listens %u port", __FUNCTION__, out_port);
885                     }
886                     else
887                     {
888                         if (log)
889                             log->Printf("GDBRemoteCommunication::%s() failed to read a port value from named pipe %s: %s", __FUNCTION__, named_pipe_path.c_str(), error.AsCString());
890 
891                     }
892                     port_named_pipe.Close();
893                 }
894                 else
895                 {
896                     if (log)
897                         log->Printf("GDBRemoteCommunication::%s() failed to open named pipe %s for reading: %s", __FUNCTION__, named_pipe_path.c_str(), error.AsCString());
898                 }
899                 const auto err = port_named_pipe.Delete(named_pipe_path);
900                 if (err.Fail())
901                 {
902                     if (log)
903                         log->Printf ("GDBRemoteCommunication::%s failed to delete pipe %s: %s", __FUNCTION__, named_pipe_path.c_str(), err.AsCString());
904                 }
905             }
906             else if (listen)
907             {
908 
909             }
910             else
911             {
912                 // Make sure we actually connect with the debugserver...
913                 JoinListenThread();
914             }
915         }
916     }
917     else
918     {
919         error.SetErrorStringWithFormat ("unable to locate " DEBUGSERVER_BASENAME );
920     }
921     return error;
922 }
923 
924 void
925 GDBRemoteCommunication::DumpHistory(Stream &strm)
926 {
927     m_history.Dump (strm);
928 }
929 
930 GDBRemoteCommunication::ScopedTimeout::ScopedTimeout (GDBRemoteCommunication& gdb_comm,
931                                                       uint32_t timeout) :
932     m_gdb_comm (gdb_comm)
933 {
934     m_saved_timeout = m_gdb_comm.SetPacketTimeout (timeout);
935 }
936 
937 GDBRemoteCommunication::ScopedTimeout::~ScopedTimeout ()
938 {
939     m_gdb_comm.SetPacketTimeout (m_saved_timeout);
940 }
941