xref: /llvm-project/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunication.cpp (revision e768c4b858bd32b814baf142dd2acfeae6022638)
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/RegularExpression.h"
22 #include "lldb/Core/StreamFile.h"
23 #include "lldb/Core/StreamString.h"
24 #include "lldb/Host/ConnectionFileDescriptor.h"
25 #include "lldb/Host/FileSpec.h"
26 #include "lldb/Host/Host.h"
27 #include "lldb/Host/HostInfo.h"
28 #include "lldb/Host/Pipe.h"
29 #include "lldb/Host/Socket.h"
30 #include "lldb/Host/StringConvert.h"
31 #include "lldb/Host/ThreadLauncher.h"
32 #include "lldb/Host/TimeValue.h"
33 #include "lldb/Target/Platform.h"
34 #include "lldb/Target/Process.h"
35 #include "llvm/ADT/SmallString.h"
36 
37 // Project includes
38 #include "ProcessGDBRemoteLog.h"
39 
40 #if defined(__APPLE__)
41 # define DEBUGSERVER_BASENAME    "debugserver"
42 #else
43 # define DEBUGSERVER_BASENAME    "lldb-server"
44 #endif
45 
46 #if defined (HAVE_LIBCOMPRESSION)
47 #include <compression.h>
48 #endif
49 
50 #if defined (HAVE_LIBZ)
51 #include <zlib.h>
52 #endif
53 
54 using namespace lldb;
55 using namespace lldb_private;
56 using namespace lldb_private::process_gdb_remote;
57 
58 GDBRemoteCommunication::History::History (uint32_t size) :
59     m_packets(),
60     m_curr_idx (0),
61     m_total_packet_count (0),
62     m_dumped_to_log (false)
63 {
64     m_packets.resize(size);
65 }
66 
67 GDBRemoteCommunication::History::~History ()
68 {
69 }
70 
71 void
72 GDBRemoteCommunication::History::AddPacket (char packet_char,
73                                             PacketType type,
74                                             uint32_t bytes_transmitted)
75 {
76     const size_t size = m_packets.size();
77     if (size > 0)
78     {
79         const uint32_t idx = GetNextIndex();
80         m_packets[idx].packet.assign (1, packet_char);
81         m_packets[idx].type = type;
82         m_packets[idx].bytes_transmitted = bytes_transmitted;
83         m_packets[idx].packet_idx = m_total_packet_count;
84         m_packets[idx].tid = Host::GetCurrentThreadID();
85     }
86 }
87 
88 void
89 GDBRemoteCommunication::History::AddPacket (const std::string &src,
90                                             uint32_t src_len,
91                                             PacketType type,
92                                             uint32_t bytes_transmitted)
93 {
94     const size_t size = m_packets.size();
95     if (size > 0)
96     {
97         const uint32_t idx = GetNextIndex();
98         m_packets[idx].packet.assign (src, 0, src_len);
99         m_packets[idx].type = type;
100         m_packets[idx].bytes_transmitted = bytes_transmitted;
101         m_packets[idx].packet_idx = m_total_packet_count;
102         m_packets[idx].tid = Host::GetCurrentThreadID();
103     }
104 }
105 
106 void
107 GDBRemoteCommunication::History::Dump (Stream &strm) const
108 {
109     const uint32_t size = GetNumPacketsInHistory ();
110     const uint32_t first_idx = GetFirstSavedPacketIndex ();
111     const uint32_t stop_idx = m_curr_idx + size;
112     for (uint32_t i = first_idx;  i < stop_idx; ++i)
113     {
114         const uint32_t idx = NormalizeIndex (i);
115         const Entry &entry = m_packets[idx];
116         if (entry.type == ePacketTypeInvalid || entry.packet.empty())
117             break;
118         strm.Printf ("history[%u] tid=0x%4.4" PRIx64 " <%4u> %s packet: %s\n",
119                      entry.packet_idx,
120                      entry.tid,
121                      entry.bytes_transmitted,
122                      (entry.type == ePacketTypeSend) ? "send" : "read",
123                      entry.packet.c_str());
124     }
125 }
126 
127 void
128 GDBRemoteCommunication::History::Dump (Log *log) const
129 {
130     if (log && !m_dumped_to_log)
131     {
132         m_dumped_to_log = true;
133         const uint32_t size = GetNumPacketsInHistory ();
134         const uint32_t first_idx = GetFirstSavedPacketIndex ();
135         const uint32_t stop_idx = m_curr_idx + size;
136         for (uint32_t i = first_idx;  i < stop_idx; ++i)
137         {
138             const uint32_t idx = NormalizeIndex (i);
139             const Entry &entry = m_packets[idx];
140             if (entry.type == ePacketTypeInvalid || entry.packet.empty())
141                 break;
142             log->Printf ("history[%u] tid=0x%4.4" PRIx64 " <%4u> %s packet: %s",
143                          entry.packet_idx,
144                          entry.tid,
145                          entry.bytes_transmitted,
146                          (entry.type == ePacketTypeSend) ? "send" : "read",
147                          entry.packet.c_str());
148         }
149     }
150 }
151 
152 //----------------------------------------------------------------------
153 // GDBRemoteCommunication constructor
154 //----------------------------------------------------------------------
155 GDBRemoteCommunication::GDBRemoteCommunication(const char *comm_name, const char *listener_name)
156     : Communication(comm_name),
157 #ifdef LLDB_CONFIGURATION_DEBUG
158       m_packet_timeout(1000),
159 #else
160       m_packet_timeout(1),
161 #endif
162       m_echo_number(0),
163       m_supports_qEcho(eLazyBoolCalculate),
164       m_history(512),
165       m_send_acks(true),
166       m_compression_type(CompressionType::None),
167       m_listen_url()
168 {
169 }
170 
171 //----------------------------------------------------------------------
172 // Destructor
173 //----------------------------------------------------------------------
174 GDBRemoteCommunication::~GDBRemoteCommunication()
175 {
176     if (IsConnected())
177     {
178         Disconnect();
179     }
180 
181     // Stop the communications read thread which is used to parse all
182     // incoming packets.  This function will block until the read
183     // thread returns.
184     if (m_read_thread_enabled)
185         StopReadThread();
186 }
187 
188 char
189 GDBRemoteCommunication::CalculcateChecksum (const char *payload, size_t payload_length)
190 {
191     int checksum = 0;
192 
193     for (size_t i = 0; i < payload_length; ++i)
194         checksum += payload[i];
195 
196     return checksum & 255;
197 }
198 
199 size_t
200 GDBRemoteCommunication::SendAck ()
201 {
202     Log *log (ProcessGDBRemoteLog::GetLogIfAllCategoriesSet (GDBR_LOG_PACKETS));
203     ConnectionStatus status = eConnectionStatusSuccess;
204     char ch = '+';
205     const size_t bytes_written = Write (&ch, 1, status, NULL);
206     if (log)
207         log->Printf ("<%4" PRIu64 "> send packet: %c", (uint64_t)bytes_written, ch);
208     m_history.AddPacket (ch, History::ePacketTypeSend, bytes_written);
209     return bytes_written;
210 }
211 
212 size_t
213 GDBRemoteCommunication::SendNack ()
214 {
215     Log *log (ProcessGDBRemoteLog::GetLogIfAllCategoriesSet (GDBR_LOG_PACKETS));
216     ConnectionStatus status = eConnectionStatusSuccess;
217     char ch = '-';
218     const size_t bytes_written = Write (&ch, 1, status, NULL);
219     if (log)
220         log->Printf("<%4" PRIu64 "> send packet: %c", (uint64_t)bytes_written, ch);
221     m_history.AddPacket (ch, History::ePacketTypeSend, bytes_written);
222     return bytes_written;
223 }
224 
225 GDBRemoteCommunication::PacketResult
226 GDBRemoteCommunication::SendPacketNoLock (const char *payload, size_t payload_length)
227 {
228     if (IsConnected())
229     {
230         StreamString packet(0, 4, eByteOrderBig);
231 
232         packet.PutChar('$');
233         packet.Write (payload, payload_length);
234         packet.PutChar('#');
235         packet.PutHex8(CalculcateChecksum (payload, payload_length));
236 
237         Log *log (ProcessGDBRemoteLog::GetLogIfAllCategoriesSet (GDBR_LOG_PACKETS));
238         ConnectionStatus status = eConnectionStatusSuccess;
239         const char *packet_data = packet.GetData();
240         const size_t packet_length = packet.GetSize();
241         size_t bytes_written = Write (packet_data, packet_length, status, NULL);
242         if (log)
243         {
244             size_t binary_start_offset = 0;
245             if (strncmp(packet_data, "$vFile:pwrite:", strlen("$vFile:pwrite:")) == 0)
246             {
247                 const char *first_comma = strchr(packet_data, ',');
248                 if (first_comma)
249                 {
250                     const char *second_comma = strchr(first_comma + 1, ',');
251                     if (second_comma)
252                         binary_start_offset = second_comma - packet_data + 1;
253                 }
254             }
255 
256             // If logging was just enabled and we have history, then dump out what
257             // we have to the log so we get the historical context. The Dump() call that
258             // logs all of the packet will set a boolean so that we don't dump this more
259             // than once
260             if (!m_history.DidDumpToLog ())
261                 m_history.Dump (log);
262 
263             if (binary_start_offset)
264             {
265                 StreamString strm;
266                 // Print non binary data header
267                 strm.Printf("<%4" PRIu64 "> send packet: %.*s", (uint64_t)bytes_written, (int)binary_start_offset, packet_data);
268                 const uint8_t *p;
269                 // Print binary data exactly as sent
270                 for (p = (const uint8_t*)packet_data + binary_start_offset; *p != '#'; ++p)
271                     strm.Printf("\\x%2.2x", *p);
272                 // Print the checksum
273                 strm.Printf("%*s", (int)3, p);
274                 log->PutCString(strm.GetString().c_str());
275             }
276             else
277                 log->Printf("<%4" PRIu64 "> send packet: %.*s", (uint64_t)bytes_written, (int)packet_length, packet_data);
278         }
279 
280         m_history.AddPacket (packet.GetString(), packet_length, History::ePacketTypeSend, bytes_written);
281 
282 
283         if (bytes_written == packet_length)
284         {
285             if (GetSendAcks ())
286                 return GetAck ();
287             else
288                 return PacketResult::Success;
289         }
290         else
291         {
292             if (log)
293                 log->Printf ("error: failed to send packet: %.*s", (int)packet_length, packet_data);
294         }
295     }
296     return PacketResult::ErrorSendFailed;
297 }
298 
299 GDBRemoteCommunication::PacketResult
300 GDBRemoteCommunication::GetAck ()
301 {
302     StringExtractorGDBRemote packet;
303     PacketResult result = ReadPacket (packet, GetPacketTimeoutInMicroSeconds (), false);
304     if (result == PacketResult::Success)
305     {
306         if (packet.GetResponseType() == StringExtractorGDBRemote::ResponseType::eAck)
307             return PacketResult::Success;
308         else
309             return PacketResult::ErrorSendAck;
310     }
311     return result;
312 }
313 
314 GDBRemoteCommunication::PacketResult
315 GDBRemoteCommunication::ReadPacket (StringExtractorGDBRemote &response, uint32_t timeout_usec, bool sync_on_timeout)
316 {
317    if (m_read_thread_enabled)
318        return PopPacketFromQueue (response, timeout_usec);
319    else
320        return WaitForPacketWithTimeoutMicroSecondsNoLock (response, timeout_usec, sync_on_timeout);
321 }
322 
323 
324 // This function is called when a packet is requested.
325 // A whole packet is popped from the packet queue and returned to the caller.
326 // Packets are placed into this queue from the communication read thread.
327 // See GDBRemoteCommunication::AppendBytesToCache.
328 GDBRemoteCommunication::PacketResult
329 GDBRemoteCommunication::PopPacketFromQueue (StringExtractorGDBRemote &response, uint32_t timeout_usec)
330 {
331     auto until = std::chrono::system_clock::now() + std::chrono::microseconds(timeout_usec);
332 
333     while (true)
334     {
335         // scope for the mutex
336         {
337             // lock down the packet queue
338             std::unique_lock<std::mutex> lock(m_packet_queue_mutex);
339 
340             // Wait on condition variable.
341             if (m_packet_queue.size() == 0)
342             {
343                 std::cv_status result = m_condition_queue_not_empty.wait_until(lock, until);
344                 if (result == std::cv_status::timeout)
345                   break;
346             }
347 
348             if (m_packet_queue.size() > 0)
349             {
350                 // get the front element of the queue
351                 response = m_packet_queue.front();
352 
353                 // remove the front element
354                 m_packet_queue.pop();
355 
356                 // we got a packet
357                 return PacketResult::Success;
358             }
359          }
360 
361          // Disconnected
362          if (!IsConnected())
363              return PacketResult::ErrorDisconnected;
364 
365       // Loop while not timed out
366     }
367 
368     return PacketResult::ErrorReplyTimeout;
369 }
370 
371 
372 GDBRemoteCommunication::PacketResult
373 GDBRemoteCommunication::WaitForPacketWithTimeoutMicroSecondsNoLock (StringExtractorGDBRemote &packet, uint32_t timeout_usec, bool sync_on_timeout)
374 {
375     uint8_t buffer[8192];
376     Error error;
377 
378     Log *log (ProcessGDBRemoteLog::GetLogIfAllCategoriesSet (GDBR_LOG_PACKETS | GDBR_LOG_VERBOSE));
379 
380     // Check for a packet from our cache first without trying any reading...
381     if (CheckForPacket(NULL, 0, packet) != PacketType::Invalid)
382         return PacketResult::Success;
383 
384     bool timed_out = false;
385     bool disconnected = false;
386     while (IsConnected() && !timed_out)
387     {
388         lldb::ConnectionStatus status = eConnectionStatusNoConnection;
389         size_t bytes_read = Read (buffer, sizeof(buffer), timeout_usec, status, &error);
390 
391         if (log)
392             log->Printf ("%s: Read (buffer, (sizeof(buffer), timeout_usec = 0x%x, status = %s, error = %s) => bytes_read = %" PRIu64,
393                          __PRETTY_FUNCTION__,
394                          timeout_usec,
395                          Communication::ConnectionStatusAsCString (status),
396                          error.AsCString(),
397                          (uint64_t)bytes_read);
398 
399         if (bytes_read > 0)
400         {
401             if (CheckForPacket(buffer, bytes_read, packet) != PacketType::Invalid)
402                 return PacketResult::Success;
403         }
404         else
405         {
406             switch (status)
407             {
408             case eConnectionStatusTimedOut:
409             case eConnectionStatusInterrupted:
410                 if (sync_on_timeout)
411                 {
412                     //------------------------------------------------------------------
413                     /// Sync the remote GDB server and make sure we get a response that
414                     /// corresponds to what we send.
415                     ///
416                     /// Sends a "qEcho" packet and makes sure it gets the exact packet
417                     /// echoed back. If the qEcho packet isn't supported, we send a qC
418                     /// packet and make sure we get a valid thread ID back. We use the
419                     /// "qC" packet since its response if very unique: is responds with
420                     /// "QC%x" where %x is the thread ID of the current thread. This
421                     /// makes the response unique enough from other packet responses to
422                     /// ensure we are back on track.
423                     ///
424                     /// This packet is needed after we time out sending a packet so we
425                     /// can ensure that we are getting the response for the packet we
426                     /// are sending. There are no sequence IDs in the GDB remote
427                     /// protocol (there used to be, but they are not supported anymore)
428                     /// so if you timeout sending packet "abc", you might then send
429                     /// packet "cde" and get the response for the previous "abc" packet.
430                     /// Many responses are "OK" or "" (unsupported) or "EXX" (error) so
431                     /// many responses for packets can look like responses for other
432                     /// packets. So if we timeout, we need to ensure that we can get
433                     /// back on track. If we can't get back on track, we must
434                     /// disconnect.
435                     //------------------------------------------------------------------
436                     bool sync_success = false;
437                     bool got_actual_response = false;
438                     // We timed out, we need to sync back up with the
439                     char echo_packet[32];
440                     int echo_packet_len = 0;
441                     RegularExpression response_regex;
442 
443                     if (m_supports_qEcho == eLazyBoolYes)
444                     {
445                         echo_packet_len = ::snprintf (echo_packet, sizeof(echo_packet), "qEcho:%u", ++m_echo_number);
446                         std::string regex_str = "^";
447                         regex_str += echo_packet;
448                         regex_str += "$";
449                         response_regex.Compile(regex_str.c_str());
450                     }
451                     else
452                     {
453                         echo_packet_len = ::snprintf (echo_packet, sizeof(echo_packet), "qC");
454                         response_regex.Compile("^QC[0-9A-Fa-f]+$");
455                     }
456 
457                     PacketResult echo_packet_result = SendPacketNoLock (echo_packet, echo_packet_len);
458                     if (echo_packet_result == PacketResult::Success)
459                     {
460                         const uint32_t max_retries = 3;
461                         uint32_t successful_responses = 0;
462                         for (uint32_t i=0; i<max_retries; ++i)
463                         {
464                             StringExtractorGDBRemote echo_response;
465                             echo_packet_result = WaitForPacketWithTimeoutMicroSecondsNoLock (echo_response, timeout_usec, false);
466                             if (echo_packet_result == PacketResult::Success)
467                             {
468                                 ++successful_responses;
469                                 if (response_regex.Execute(echo_response.GetStringRef().c_str()))
470                                 {
471                                     sync_success = true;
472                                     break;
473                                 }
474                                 else if (successful_responses == 1)
475                                 {
476                                     // We got something else back as the first successful response, it probably is
477                                     // the  response to the packet we actually wanted, so copy it over if this
478                                     // is the first success and continue to try to get the qEcho response
479                                     packet = echo_response;
480                                     got_actual_response = true;
481                                 }
482                             }
483                             else if (echo_packet_result == PacketResult::ErrorReplyTimeout)
484                                 continue;   // Packet timed out, continue waiting for a response
485                             else
486                                 break;      // Something else went wrong getting the packet back, we failed and are done trying
487                         }
488                     }
489 
490                     // We weren't able to sync back up with the server, we must abort otherwise
491                     // all responses might not be from the right packets...
492                     if (sync_success)
493                     {
494                         // We timed out, but were able to recover
495                         if (got_actual_response)
496                         {
497                             // We initially timed out, but we did get a response that came in before the successful
498                             // reply to our qEcho packet, so lets say everything is fine...
499                             return PacketResult::Success;
500                         }
501                     }
502                     else
503                     {
504                         disconnected = true;
505                         Disconnect();
506                     }
507                 }
508                 timed_out = true;
509                 break;
510             case eConnectionStatusSuccess:
511                 //printf ("status = success but error = %s\n", error.AsCString("<invalid>"));
512                 break;
513 
514             case eConnectionStatusEndOfFile:
515             case eConnectionStatusNoConnection:
516             case eConnectionStatusLostConnection:
517             case eConnectionStatusError:
518                 disconnected = true;
519                 Disconnect();
520                 break;
521             }
522         }
523     }
524     packet.Clear ();
525     if (disconnected)
526         return PacketResult::ErrorDisconnected;
527     if (timed_out)
528         return PacketResult::ErrorReplyTimeout;
529     else
530         return PacketResult::ErrorReplyFailed;
531 }
532 
533 bool
534 GDBRemoteCommunication::DecompressPacket ()
535 {
536     Log *log (ProcessGDBRemoteLog::GetLogIfAllCategoriesSet (GDBR_LOG_PACKETS));
537 
538     if (!CompressionIsEnabled())
539         return true;
540 
541     size_t pkt_size = m_bytes.size();
542 
543     // Smallest possible compressed packet is $N#00 - an uncompressed empty reply, most commonly indicating
544     // an unsupported packet.  Anything less than 5 characters, it's definitely not a compressed packet.
545     if (pkt_size < 5)
546         return true;
547 
548     if (m_bytes[0] != '$' && m_bytes[0] != '%')
549         return true;
550     if (m_bytes[1] != 'C' && m_bytes[1] != 'N')
551         return true;
552 
553     size_t hash_mark_idx = m_bytes.find ('#');
554     if (hash_mark_idx == std::string::npos)
555         return true;
556     if (hash_mark_idx + 2 >= m_bytes.size())
557         return true;
558 
559     if (!::isxdigit (m_bytes[hash_mark_idx + 1]) || !::isxdigit (m_bytes[hash_mark_idx + 2]))
560         return true;
561 
562     size_t content_length = pkt_size - 5;    // not counting '$', 'C' | 'N', '#', & the two hex checksum chars
563     size_t content_start = 2;                // The first character of the compressed/not-compressed text of the packet
564     size_t checksum_idx = hash_mark_idx + 1; // The first character of the two hex checksum characters
565 
566     // Normally size_of_first_packet == m_bytes.size() but m_bytes may contain multiple packets.
567     // size_of_first_packet is the size of the initial packet which we'll replace with the decompressed
568     // version of, leaving the rest of m_bytes unmodified.
569     size_t size_of_first_packet = hash_mark_idx + 3;
570 
571     // Compressed packets ("$C") start with a base10 number which is the size of the uncompressed payload,
572     // then a : and then the compressed data.  e.g. $C1024:<binary>#00
573     // Update content_start and content_length to only include the <binary> part of the packet.
574 
575     uint64_t decompressed_bufsize = ULONG_MAX;
576     if (m_bytes[1] == 'C')
577     {
578         size_t i = content_start;
579         while (i < hash_mark_idx && isdigit(m_bytes[i]))
580             i++;
581         if (i < hash_mark_idx && m_bytes[i] == ':')
582         {
583             i++;
584             content_start = i;
585             content_length = hash_mark_idx - content_start;
586             std::string bufsize_str (m_bytes.data() + 2, i - 2 - 1);
587             errno = 0;
588             decompressed_bufsize = ::strtoul (bufsize_str.c_str(), NULL, 10);
589             if (errno != 0 || decompressed_bufsize == ULONG_MAX)
590             {
591                 m_bytes.erase (0, size_of_first_packet);
592                 return false;
593             }
594         }
595     }
596 
597     if (GetSendAcks ())
598     {
599         char packet_checksum_cstr[3];
600         packet_checksum_cstr[0] = m_bytes[checksum_idx];
601         packet_checksum_cstr[1] = m_bytes[checksum_idx + 1];
602         packet_checksum_cstr[2] = '\0';
603         long packet_checksum = strtol (packet_checksum_cstr, NULL, 16);
604 
605         long actual_checksum = CalculcateChecksum (m_bytes.data() + 1, hash_mark_idx - 1);
606         bool success = packet_checksum == actual_checksum;
607         if (!success)
608         {
609             if (log)
610                 log->Printf ("error: checksum mismatch: %.*s expected 0x%2.2x, got 0x%2.2x",
611                              (int)(pkt_size),
612                              m_bytes.c_str(),
613                              (uint8_t)packet_checksum,
614                              (uint8_t)actual_checksum);
615         }
616         // Send the ack or nack if needed
617         if (!success)
618         {
619             SendNack();
620             m_bytes.erase (0, size_of_first_packet);
621             return false;
622         }
623         else
624         {
625             SendAck();
626         }
627     }
628 
629     if (m_bytes[1] == 'N')
630     {
631         // This packet was not compressed -- delete the 'N' character at the
632         // start and the packet may be processed as-is.
633         m_bytes.erase(1, 1);
634         return true;
635     }
636 
637     // Reverse the gdb-remote binary escaping that was done to the compressed text to
638     // guard characters like '$', '#', '}', etc.
639     std::vector<uint8_t> unescaped_content;
640     unescaped_content.reserve (content_length);
641     size_t i = content_start;
642     while (i < hash_mark_idx)
643     {
644         if (m_bytes[i] == '}')
645         {
646             i++;
647             unescaped_content.push_back (m_bytes[i] ^ 0x20);
648         }
649         else
650         {
651             unescaped_content.push_back (m_bytes[i]);
652         }
653         i++;
654     }
655 
656     uint8_t *decompressed_buffer = nullptr;
657     size_t decompressed_bytes = 0;
658 
659     if (decompressed_bufsize != ULONG_MAX)
660     {
661         decompressed_buffer = (uint8_t *) malloc (decompressed_bufsize + 1);
662         if (decompressed_buffer == nullptr)
663         {
664             m_bytes.erase (0, size_of_first_packet);
665             return false;
666         }
667 
668     }
669 
670 #if defined (HAVE_LIBCOMPRESSION)
671     // libcompression is weak linked so check that compression_decode_buffer() is available
672     if (compression_decode_buffer != NULL &&
673         (m_compression_type == CompressionType::ZlibDeflate
674          || m_compression_type == CompressionType::LZFSE
675          || m_compression_type == CompressionType::LZ4))
676     {
677         compression_algorithm compression_type;
678         if (m_compression_type == CompressionType::ZlibDeflate)
679             compression_type = COMPRESSION_ZLIB;
680         else if (m_compression_type == CompressionType::LZFSE)
681             compression_type = COMPRESSION_LZFSE;
682         else if (m_compression_type == CompressionType::LZ4)
683             compression_type = COMPRESSION_LZ4_RAW;
684         else if (m_compression_type == CompressionType::LZMA)
685             compression_type = COMPRESSION_LZMA;
686 
687 
688         // If we have the expected size of the decompressed payload, we can allocate
689         // the right-sized buffer and do it.  If we don't have that information, we'll
690         // need to try decoding into a big buffer and if the buffer wasn't big enough,
691         // increase it and try again.
692 
693         if (decompressed_bufsize != ULONG_MAX && decompressed_buffer != nullptr)
694         {
695             decompressed_bytes = compression_decode_buffer (decompressed_buffer, decompressed_bufsize + 10 ,
696                                                         (uint8_t*) unescaped_content.data(),
697                                                         unescaped_content.size(),
698                                                         NULL,
699                                                         compression_type);
700         }
701     }
702 #endif
703 
704 #if defined (HAVE_LIBZ)
705     if (decompressed_bytes == 0
706         && decompressed_bufsize != ULONG_MAX
707         && decompressed_buffer != nullptr
708         && m_compression_type == CompressionType::ZlibDeflate)
709     {
710         z_stream stream;
711         memset (&stream, 0, sizeof (z_stream));
712         stream.next_in = (Bytef *) unescaped_content.data();
713         stream.avail_in = (uInt) unescaped_content.size();
714         stream.total_in = 0;
715         stream.next_out = (Bytef *) decompressed_buffer;
716         stream.avail_out = decompressed_bufsize;
717         stream.total_out = 0;
718         stream.zalloc = Z_NULL;
719         stream.zfree = Z_NULL;
720         stream.opaque = Z_NULL;
721 
722         if (inflateInit2 (&stream, -15) == Z_OK)
723         {
724             int status = inflate (&stream, Z_NO_FLUSH);
725             inflateEnd (&stream);
726             if (status == Z_STREAM_END)
727             {
728                 decompressed_bytes = stream.total_out;
729             }
730         }
731     }
732 #endif
733 
734     if (decompressed_bytes == 0 || decompressed_buffer == nullptr)
735     {
736         if (decompressed_buffer)
737             free (decompressed_buffer);
738         m_bytes.erase (0, size_of_first_packet);
739         return false;
740     }
741 
742     std::string new_packet;
743     new_packet.reserve (decompressed_bytes + 6);
744     new_packet.push_back (m_bytes[0]);
745     new_packet.append ((const char *) decompressed_buffer, decompressed_bytes);
746     new_packet.push_back ('#');
747     if (GetSendAcks ())
748     {
749         uint8_t decompressed_checksum = CalculcateChecksum ((const char *) decompressed_buffer, decompressed_bytes);
750         char decompressed_checksum_str[3];
751         snprintf (decompressed_checksum_str, 3, "%02x", decompressed_checksum);
752         new_packet.append (decompressed_checksum_str);
753     }
754     else
755     {
756         new_packet.push_back ('0');
757         new_packet.push_back ('0');
758     }
759 
760     m_bytes.replace (0, size_of_first_packet, new_packet.data(), new_packet.size());
761 
762     free (decompressed_buffer);
763     return true;
764 }
765 
766 GDBRemoteCommunication::PacketType
767 GDBRemoteCommunication::CheckForPacket (const uint8_t *src, size_t src_len, StringExtractorGDBRemote &packet)
768 {
769     // Put the packet data into the buffer in a thread safe fashion
770     std::lock_guard<std::recursive_mutex> guard(m_bytes_mutex);
771 
772     Log *log (ProcessGDBRemoteLog::GetLogIfAllCategoriesSet (GDBR_LOG_PACKETS));
773 
774     if (src && src_len > 0)
775     {
776         if (log && log->GetVerbose())
777         {
778             StreamString s;
779             log->Printf ("GDBRemoteCommunication::%s adding %u bytes: %.*s",
780                          __FUNCTION__,
781                          (uint32_t)src_len,
782                          (uint32_t)src_len,
783                          src);
784         }
785         m_bytes.append ((const char *)src, src_len);
786     }
787 
788     bool isNotifyPacket = false;
789 
790     // Parse up the packets into gdb remote packets
791     if (!m_bytes.empty())
792     {
793         // end_idx must be one past the last valid packet byte. Start
794         // it off with an invalid value that is the same as the current
795         // index.
796         size_t content_start = 0;
797         size_t content_length = 0;
798         size_t total_length = 0;
799         size_t checksum_idx = std::string::npos;
800 
801         // Size of packet before it is decompressed, for logging purposes
802         size_t original_packet_size = m_bytes.size();
803         if (CompressionIsEnabled())
804         {
805             if (DecompressPacket() == false)
806             {
807                 packet.Clear();
808                 return GDBRemoteCommunication::PacketType::Standard;
809             }
810         }
811 
812         switch (m_bytes[0])
813         {
814             case '+':       // Look for ack
815             case '-':       // Look for cancel
816             case '\x03':    // ^C to halt target
817                 content_length = total_length = 1;  // The command is one byte long...
818                 break;
819 
820             case '%': // Async notify packet
821                 isNotifyPacket = true;
822                 LLVM_FALLTHROUGH;
823 
824             case '$':
825                 // Look for a standard gdb packet?
826                 {
827                     size_t hash_pos = m_bytes.find('#');
828                     if (hash_pos != std::string::npos)
829                     {
830                         if (hash_pos + 2 < m_bytes.size())
831                         {
832                             checksum_idx = hash_pos + 1;
833                             // Skip the dollar sign
834                             content_start = 1;
835                             // Don't include the # in the content or the $ in the content length
836                             content_length = hash_pos - 1;
837 
838                             total_length = hash_pos + 3; // Skip the # and the two hex checksum bytes
839                         }
840                         else
841                         {
842                             // Checksum bytes aren't all here yet
843                             content_length = std::string::npos;
844                         }
845                     }
846                 }
847                 break;
848 
849             default:
850                 {
851                     // We have an unexpected byte and we need to flush all bad
852                     // data that is in m_bytes, so we need to find the first
853                     // byte that is a '+' (ACK), '-' (NACK), \x03 (CTRL+C interrupt),
854                     // or '$' character (start of packet header) or of course,
855                     // the end of the data in m_bytes...
856                     const size_t bytes_len = m_bytes.size();
857                     bool done = false;
858                     uint32_t idx;
859                     for (idx = 1; !done && idx < bytes_len; ++idx)
860                     {
861                         switch (m_bytes[idx])
862                         {
863                         case '+':
864                         case '-':
865                         case '\x03':
866                         case '%':
867                         case '$':
868                             done = true;
869                             break;
870 
871                         default:
872                             break;
873                         }
874                     }
875                     if (log)
876                         log->Printf ("GDBRemoteCommunication::%s tossing %u junk bytes: '%.*s'",
877                                      __FUNCTION__, idx - 1, idx - 1, m_bytes.c_str());
878                     m_bytes.erase(0, idx - 1);
879                 }
880                 break;
881         }
882 
883         if (content_length == std::string::npos)
884         {
885             packet.Clear();
886             return GDBRemoteCommunication::PacketType::Invalid;
887         }
888         else if (total_length > 0)
889         {
890 
891             // We have a valid packet...
892             assert (content_length <= m_bytes.size());
893             assert (total_length <= m_bytes.size());
894             assert (content_length <= total_length);
895             size_t content_end = content_start + content_length;
896 
897             bool success = true;
898             std::string &packet_str = packet.GetStringRef();
899             if (log)
900             {
901                 // If logging was just enabled and we have history, then dump out what
902                 // we have to the log so we get the historical context. The Dump() call that
903                 // logs all of the packet will set a boolean so that we don't dump this more
904                 // than once
905                 if (!m_history.DidDumpToLog ())
906                     m_history.Dump (log);
907 
908                 bool binary = false;
909                 // Only detect binary for packets that start with a '$' and have a '#CC' checksum
910                 if (m_bytes[0] == '$' && total_length > 4)
911                 {
912                     for (size_t i=0; !binary && i<total_length; ++i)
913                     {
914                         if (isprint (m_bytes[i]) == 0 && isspace (m_bytes[i]) == 0)
915                         {
916                             binary = true;
917                         }
918                     }
919                 }
920                 if (binary)
921                 {
922                     StreamString strm;
923                     // Packet header...
924                     if (CompressionIsEnabled())
925                         strm.Printf("<%4" PRIu64 ":%" PRIu64 "> read packet: %c", (uint64_t) original_packet_size, (uint64_t)total_length, m_bytes[0]);
926                     else
927                         strm.Printf("<%4" PRIu64 "> read packet: %c", (uint64_t)total_length, m_bytes[0]);
928                     for (size_t i=content_start; i<content_end; ++i)
929                     {
930                         // Remove binary escaped bytes when displaying the packet...
931                         const char ch = m_bytes[i];
932                         if (ch == 0x7d)
933                         {
934                             // 0x7d is the escape character.  The next character is to
935                             // be XOR'd with 0x20.
936                             const char escapee = m_bytes[++i] ^ 0x20;
937                             strm.Printf("%2.2x", escapee);
938                         }
939                         else
940                         {
941                             strm.Printf("%2.2x", (uint8_t)ch);
942                         }
943                     }
944                     // Packet footer...
945                     strm.Printf("%c%c%c", m_bytes[total_length-3], m_bytes[total_length-2], m_bytes[total_length-1]);
946                     log->PutCString(strm.GetString().c_str());
947                 }
948                 else
949                 {
950                     if (CompressionIsEnabled())
951                         log->Printf("<%4" PRIu64 ":%" PRIu64 "> read packet: %.*s", (uint64_t) original_packet_size, (uint64_t)total_length, (int)(total_length), m_bytes.c_str());
952                     else
953                         log->Printf("<%4" PRIu64 "> read packet: %.*s", (uint64_t)total_length, (int)(total_length), m_bytes.c_str());
954                 }
955             }
956 
957             m_history.AddPacket (m_bytes.c_str(), total_length, History::ePacketTypeRecv, total_length);
958 
959             // Clear packet_str in case there is some existing data in it.
960             packet_str.clear();
961             // Copy the packet from m_bytes to packet_str expanding the
962             // run-length encoding in the process.
963             // Reserve enough byte for the most common case (no RLE used)
964             packet_str.reserve(m_bytes.length());
965             for (std::string::const_iterator c = m_bytes.begin() + content_start; c != m_bytes.begin() + content_end; ++c)
966             {
967                 if (*c == '*')
968                 {
969                     // '*' indicates RLE. Next character will give us the
970                     // repeat count and previous character is what is to be
971                     // repeated.
972                     char char_to_repeat = packet_str.back();
973                     // Number of time the previous character is repeated
974                     int repeat_count = *++c + 3 - ' ';
975                     // We have the char_to_repeat and repeat_count. Now push
976                     // it in the packet.
977                     for (int i = 0; i < repeat_count; ++i)
978                         packet_str.push_back(char_to_repeat);
979                 }
980                 else if (*c == 0x7d)
981                 {
982                     // 0x7d is the escape character.  The next character is to
983                     // be XOR'd with 0x20.
984                     char escapee = *++c ^ 0x20;
985                     packet_str.push_back(escapee);
986                 }
987                 else
988                 {
989                     packet_str.push_back(*c);
990                 }
991             }
992 
993             if (m_bytes[0] == '$' || m_bytes[0] == '%')
994             {
995                 assert (checksum_idx < m_bytes.size());
996                 if (::isxdigit (m_bytes[checksum_idx+0]) ||
997                     ::isxdigit (m_bytes[checksum_idx+1]))
998                 {
999                     if (GetSendAcks ())
1000                     {
1001                         const char *packet_checksum_cstr = &m_bytes[checksum_idx];
1002                         char packet_checksum = strtol (packet_checksum_cstr, NULL, 16);
1003                         char actual_checksum = CalculcateChecksum (packet_str.c_str(), packet_str.size());
1004                         success = packet_checksum == actual_checksum;
1005                         if (!success)
1006                         {
1007                             if (log)
1008                                 log->Printf ("error: checksum mismatch: %.*s expected 0x%2.2x, got 0x%2.2x",
1009                                              (int)(total_length),
1010                                              m_bytes.c_str(),
1011                                              (uint8_t)packet_checksum,
1012                                              (uint8_t)actual_checksum);
1013                         }
1014                         // Send the ack or nack if needed
1015                         if (!success)
1016                             SendNack();
1017                         else
1018                             SendAck();
1019                     }
1020                 }
1021                 else
1022                 {
1023                     success = false;
1024                     if (log)
1025                         log->Printf ("error: invalid checksum in packet: '%s'\n", m_bytes.c_str());
1026                 }
1027             }
1028 
1029             m_bytes.erase(0, total_length);
1030             packet.SetFilePos(0);
1031 
1032             if (isNotifyPacket)
1033                 return GDBRemoteCommunication::PacketType::Notify;
1034             else
1035                 return GDBRemoteCommunication::PacketType::Standard;
1036         }
1037     }
1038     packet.Clear();
1039     return GDBRemoteCommunication::PacketType::Invalid;
1040 }
1041 
1042 Error
1043 GDBRemoteCommunication::StartListenThread (const char *hostname, uint16_t port)
1044 {
1045     Error error;
1046     if (m_listen_thread.IsJoinable())
1047     {
1048         error.SetErrorString("listen thread already running");
1049     }
1050     else
1051     {
1052         char listen_url[512];
1053         if (hostname && hostname[0])
1054             snprintf(listen_url, sizeof(listen_url), "listen://%s:%i", hostname, port);
1055         else
1056             snprintf(listen_url, sizeof(listen_url), "listen://%i", port);
1057         m_listen_url = listen_url;
1058         SetConnection(new ConnectionFileDescriptor());
1059         m_listen_thread = ThreadLauncher::LaunchThread(listen_url, GDBRemoteCommunication::ListenThread, this, &error);
1060     }
1061     return error;
1062 }
1063 
1064 bool
1065 GDBRemoteCommunication::JoinListenThread ()
1066 {
1067     if (m_listen_thread.IsJoinable())
1068         m_listen_thread.Join(nullptr);
1069     return true;
1070 }
1071 
1072 lldb::thread_result_t
1073 GDBRemoteCommunication::ListenThread (lldb::thread_arg_t arg)
1074 {
1075     GDBRemoteCommunication *comm = (GDBRemoteCommunication *)arg;
1076     Error error;
1077     ConnectionFileDescriptor *connection = (ConnectionFileDescriptor *)comm->GetConnection ();
1078 
1079     if (connection)
1080     {
1081         // Do the listen on another thread so we can continue on...
1082         if (connection->Connect(comm->m_listen_url.c_str(), &error) != eConnectionStatusSuccess)
1083             comm->SetConnection(NULL);
1084     }
1085     return NULL;
1086 }
1087 
1088 Error
1089 GDBRemoteCommunication::StartDebugserverProcess (const char *url,
1090                                                  Platform *platform,
1091                                                  ProcessLaunchInfo &launch_info,
1092                                                  uint16_t *port,
1093                                                  const Args& inferior_args)
1094 {
1095     Log *log (ProcessGDBRemoteLog::GetLogIfAllCategoriesSet (GDBR_LOG_PROCESS));
1096     if (log)
1097         log->Printf ("GDBRemoteCommunication::%s(url=%s, port=%" PRIu16 ")", __FUNCTION__, url ? url : "<empty>", port ? *port : uint16_t(0));
1098 
1099     Error error;
1100     // If we locate debugserver, keep that located version around
1101     static FileSpec g_debugserver_file_spec;
1102 
1103     char debugserver_path[PATH_MAX];
1104     FileSpec &debugserver_file_spec = launch_info.GetExecutableFile();
1105 
1106     // Always check to see if we have an environment override for the path
1107     // to the debugserver to use and use it if we do.
1108     const char *env_debugserver_path = getenv("LLDB_DEBUGSERVER_PATH");
1109     if (env_debugserver_path)
1110     {
1111         debugserver_file_spec.SetFile (env_debugserver_path, false);
1112         if (log)
1113             log->Printf ("GDBRemoteCommunication::%s() gdb-remote stub exe path set from environment variable: %s", __FUNCTION__, env_debugserver_path);
1114     }
1115     else
1116         debugserver_file_spec = g_debugserver_file_spec;
1117     bool debugserver_exists = debugserver_file_spec.Exists();
1118     if (!debugserver_exists)
1119     {
1120         // The debugserver binary is in the LLDB.framework/Resources
1121         // directory.
1122         if (HostInfo::GetLLDBPath(ePathTypeSupportExecutableDir, debugserver_file_spec))
1123         {
1124             debugserver_file_spec.AppendPathComponent (DEBUGSERVER_BASENAME);
1125             debugserver_exists = debugserver_file_spec.Exists();
1126             if (debugserver_exists)
1127             {
1128                 if (log)
1129                     log->Printf ("GDBRemoteCommunication::%s() found gdb-remote stub exe '%s'", __FUNCTION__, debugserver_file_spec.GetPath ().c_str ());
1130 
1131                 g_debugserver_file_spec = debugserver_file_spec;
1132             }
1133             else
1134             {
1135                 debugserver_file_spec = platform->LocateExecutable(DEBUGSERVER_BASENAME);
1136                 if (debugserver_file_spec)
1137                 {
1138                     // Platform::LocateExecutable() wouldn't return a path if it doesn't exist
1139                     debugserver_exists = true;
1140                 }
1141                 else
1142                 {
1143                     if (log)
1144                         log->Printf ("GDBRemoteCommunication::%s() could not find gdb-remote stub exe '%s'", __FUNCTION__, debugserver_file_spec.GetPath ().c_str ());
1145                 }
1146                 // Don't cache the platform specific GDB server binary as it could change
1147                 // from platform to platform
1148                 g_debugserver_file_spec.Clear();
1149             }
1150         }
1151     }
1152 
1153     if (debugserver_exists)
1154     {
1155         debugserver_file_spec.GetPath (debugserver_path, sizeof(debugserver_path));
1156 
1157         Args &debugserver_args = launch_info.GetArguments();
1158         debugserver_args.Clear();
1159         char arg_cstr[PATH_MAX];
1160 
1161         // Start args with "debugserver /file/path -r --"
1162         debugserver_args.AppendArgument(debugserver_path);
1163 
1164 #if !defined(__APPLE__)
1165         // First argument to lldb-server must be mode in which to run.
1166         debugserver_args.AppendArgument("gdbserver");
1167 #endif
1168 
1169         // If a url is supplied then use it
1170         if (url)
1171             debugserver_args.AppendArgument(url);
1172 
1173         // use native registers, not the GDB registers
1174         debugserver_args.AppendArgument("--native-regs");
1175 
1176         if (launch_info.GetLaunchInSeparateProcessGroup())
1177         {
1178             debugserver_args.AppendArgument("--setsid");
1179         }
1180 
1181         llvm::SmallString<PATH_MAX> named_pipe_path;
1182         // socket_pipe is used by debug server to communicate back either
1183         // TCP port or domain socket name which it listens on.
1184         // The second purpose of the pipe to serve as a synchronization point -
1185         // once data is written to the pipe, debug server is up and running.
1186         Pipe socket_pipe;
1187 
1188         // port is null when debug server should listen on domain socket -
1189         // we're not interested in port value but rather waiting for debug server
1190         // to become available.
1191         if ((port != nullptr && *port == 0) || port == nullptr)
1192         {
1193             if (url)
1194             {
1195                 // Create a temporary file to get the stdout/stderr and redirect the
1196                 // output of the command into this file. We will later read this file
1197                 // if all goes well and fill the data into "command_output_ptr"
1198 
1199 #if defined(__APPLE__)
1200                 // Binding to port zero, we need to figure out what port it ends up
1201                 // using using a named pipe...
1202                 error = socket_pipe.CreateWithUniqueName("debugserver-named-pipe", false, named_pipe_path);
1203                 if (error.Fail())
1204                 {
1205                     if (log)
1206                         log->Printf("GDBRemoteCommunication::%s() "
1207                                 "named pipe creation failed: %s",
1208                                 __FUNCTION__, error.AsCString());
1209                     return error;
1210                 }
1211                 debugserver_args.AppendArgument("--named-pipe");
1212                 debugserver_args.AppendArgument(named_pipe_path.c_str());
1213 #else
1214                 // Binding to port zero, we need to figure out what port it ends up
1215                 // using using an unnamed pipe...
1216                 error = socket_pipe.CreateNew(true);
1217                 if (error.Fail())
1218                 {
1219                     if (log)
1220                         log->Printf("GDBRemoteCommunication::%s() "
1221                                 "unnamed pipe creation failed: %s",
1222                                 __FUNCTION__, error.AsCString());
1223                     return error;
1224                 }
1225                 int write_fd = socket_pipe.GetWriteFileDescriptor();
1226                 debugserver_args.AppendArgument("--pipe");
1227                 debugserver_args.AppendArgument(std::to_string(write_fd).c_str());
1228                 launch_info.AppendCloseFileAction(socket_pipe.GetReadFileDescriptor());
1229 #endif
1230             }
1231             else
1232             {
1233                 // No host and port given, so lets listen on our end and make the debugserver
1234                 // connect to us..
1235                 error = StartListenThread ("127.0.0.1", 0);
1236                 if (error.Fail())
1237                 {
1238                     if (log)
1239                         log->Printf ("GDBRemoteCommunication::%s() unable to start listen thread: %s", __FUNCTION__, error.AsCString());
1240                     return error;
1241                 }
1242 
1243                 ConnectionFileDescriptor *connection = (ConnectionFileDescriptor *)GetConnection ();
1244                 // Wait for 10 seconds to resolve the bound port
1245                 *port = connection->GetListeningPort(10);
1246                 if (*port > 0)
1247                 {
1248                     char port_cstr[32];
1249                     snprintf(port_cstr, sizeof(port_cstr), "127.0.0.1:%i", *port);
1250                     // Send the host and port down that debugserver and specify an option
1251                     // so that it connects back to the port we are listening to in this process
1252                     debugserver_args.AppendArgument("--reverse-connect");
1253                     debugserver_args.AppendArgument(port_cstr);
1254                 }
1255                 else
1256                 {
1257                     error.SetErrorString ("failed to bind to port 0 on 127.0.0.1");
1258                     if (log)
1259                         log->Printf ("GDBRemoteCommunication::%s() failed: %s", __FUNCTION__, error.AsCString());
1260                     return error;
1261                 }
1262             }
1263         }
1264 
1265         const char *env_debugserver_log_file = getenv("LLDB_DEBUGSERVER_LOG_FILE");
1266         if (env_debugserver_log_file)
1267         {
1268             ::snprintf (arg_cstr, sizeof(arg_cstr), "--log-file=%s", env_debugserver_log_file);
1269             debugserver_args.AppendArgument(arg_cstr);
1270         }
1271 
1272 #if defined(__APPLE__)
1273         const char *env_debugserver_log_flags = getenv("LLDB_DEBUGSERVER_LOG_FLAGS");
1274         if (env_debugserver_log_flags)
1275         {
1276             ::snprintf (arg_cstr, sizeof(arg_cstr), "--log-flags=%s", env_debugserver_log_flags);
1277             debugserver_args.AppendArgument(arg_cstr);
1278         }
1279 #else
1280         const char *env_debugserver_log_channels = getenv("LLDB_SERVER_LOG_CHANNELS");
1281         if (env_debugserver_log_channels)
1282         {
1283             ::snprintf (arg_cstr, sizeof(arg_cstr), "--log-channels=%s", env_debugserver_log_channels);
1284             debugserver_args.AppendArgument(arg_cstr);
1285         }
1286 #endif
1287 
1288         // Add additional args, starting with LLDB_DEBUGSERVER_EXTRA_ARG_1 until an env var doesn't come back.
1289         uint32_t env_var_index = 1;
1290         bool has_env_var;
1291         do
1292         {
1293             char env_var_name[64];
1294             snprintf (env_var_name, sizeof (env_var_name), "LLDB_DEBUGSERVER_EXTRA_ARG_%" PRIu32, env_var_index++);
1295             const char *extra_arg = getenv(env_var_name);
1296             has_env_var = extra_arg != nullptr;
1297 
1298             if (has_env_var)
1299             {
1300                 debugserver_args.AppendArgument (extra_arg);
1301                 if (log)
1302                     log->Printf ("GDBRemoteCommunication::%s adding env var %s contents to stub command line (%s)", __FUNCTION__, env_var_name, extra_arg);
1303             }
1304         } while (has_env_var);
1305 
1306         if (inferior_args.GetArgumentCount() > 0)
1307         {
1308             debugserver_args.AppendArgument ("--");
1309             debugserver_args.AppendArguments (inferior_args);
1310         }
1311 
1312         // Copy the current environment to the gdbserver/debugserver instance
1313         StringList env;
1314         if (Host::GetEnvironment(env))
1315         {
1316             for (size_t i = 0; i < env.GetSize(); ++i)
1317                 launch_info.GetEnvironmentEntries().AppendArgument(env[i].c_str());
1318         }
1319 
1320         // Close STDIN, STDOUT and STDERR.
1321         launch_info.AppendCloseFileAction (STDIN_FILENO);
1322         launch_info.AppendCloseFileAction (STDOUT_FILENO);
1323         launch_info.AppendCloseFileAction (STDERR_FILENO);
1324 
1325         // Redirect STDIN, STDOUT and STDERR to "/dev/null".
1326         launch_info.AppendSuppressFileAction (STDIN_FILENO, true, false);
1327         launch_info.AppendSuppressFileAction (STDOUT_FILENO, false, true);
1328         launch_info.AppendSuppressFileAction (STDERR_FILENO, false, true);
1329 
1330         if (log)
1331         {
1332             StreamString string_stream;
1333             Platform *const platform = nullptr;
1334             launch_info.Dump(string_stream, platform);
1335             log->Printf("launch info for gdb-remote stub:\n%s", string_stream.GetString().c_str());
1336         }
1337         error = Host::LaunchProcess(launch_info);
1338 
1339         if (error.Success() &&
1340             launch_info.GetProcessID() != LLDB_INVALID_PROCESS_ID)
1341         {
1342             if (named_pipe_path.size() > 0)
1343             {
1344                 error = socket_pipe.OpenAsReader(named_pipe_path, false);
1345                 if (error.Fail())
1346                     if (log)
1347                         log->Printf("GDBRemoteCommunication::%s() "
1348                                 "failed to open named pipe %s for reading: %s",
1349                                 __FUNCTION__, named_pipe_path.c_str(), error.AsCString());
1350             }
1351 
1352             if (socket_pipe.CanWrite())
1353                 socket_pipe.CloseWriteFileDescriptor();
1354             if (socket_pipe.CanRead())
1355             {
1356                 char port_cstr[PATH_MAX] = {0};
1357                 port_cstr[0] = '\0';
1358                 size_t num_bytes = sizeof(port_cstr);
1359                 // Read port from pipe with 10 second timeout.
1360                 error = socket_pipe.ReadWithTimeout(port_cstr, num_bytes,
1361                         std::chrono::seconds{10}, num_bytes);
1362                 if (error.Success() && (port != nullptr))
1363                 {
1364                     assert(num_bytes > 0 && port_cstr[num_bytes-1] == '\0');
1365                     *port = StringConvert::ToUInt32(port_cstr, 0);
1366                     if (log)
1367                         log->Printf("GDBRemoteCommunication::%s() "
1368                                     "debugserver listens %u port",
1369                                     __FUNCTION__, *port);
1370                 }
1371                 else
1372                 {
1373                     if (log)
1374                         log->Printf("GDBRemoteCommunication::%s() "
1375                                 "failed to read a port value from pipe %s: %s",
1376                                 __FUNCTION__, named_pipe_path.c_str(), error.AsCString());
1377 
1378                 }
1379                 socket_pipe.Close();
1380             }
1381 
1382             if (named_pipe_path.size() > 0)
1383             {
1384                 const auto err = socket_pipe.Delete(named_pipe_path);
1385                 if (err.Fail())
1386                 {
1387                     if (log)
1388                         log->Printf ("GDBRemoteCommunication::%s failed to delete pipe %s: %s",
1389                                 __FUNCTION__, named_pipe_path.c_str(), err.AsCString());
1390                 }
1391             }
1392 
1393             // Make sure we actually connect with the debugserver...
1394             JoinListenThread();
1395         }
1396     }
1397     else
1398     {
1399         error.SetErrorStringWithFormat ("unable to locate " DEBUGSERVER_BASENAME );
1400     }
1401 
1402     if (error.Fail())
1403     {
1404         if (log)
1405             log->Printf ("GDBRemoteCommunication::%s() failed: %s", __FUNCTION__, error.AsCString());
1406     }
1407 
1408     return error;
1409 }
1410 
1411 void
1412 GDBRemoteCommunication::DumpHistory(Stream &strm)
1413 {
1414     m_history.Dump (strm);
1415 }
1416 
1417 GDBRemoteCommunication::ScopedTimeout::ScopedTimeout (GDBRemoteCommunication& gdb_comm,
1418                                                       uint32_t timeout) :
1419     m_gdb_comm (gdb_comm)
1420 {
1421     m_saved_timeout = m_gdb_comm.SetPacketTimeout (timeout);
1422 }
1423 
1424 GDBRemoteCommunication::ScopedTimeout::~ScopedTimeout ()
1425 {
1426     m_gdb_comm.SetPacketTimeout (m_saved_timeout);
1427 }
1428 
1429 // This function is called via the Communications class read thread when bytes become available
1430 // for this connection. This function will consume all incoming bytes and try to parse whole
1431 // packets as they become available. Full packets are placed in a queue, so that all packet
1432 // requests can simply pop from this queue. Async notification packets will be dispatched
1433 // immediately to the ProcessGDBRemote Async thread via an event.
1434 void GDBRemoteCommunication::AppendBytesToCache (const uint8_t * bytes, size_t len, bool broadcast, lldb::ConnectionStatus status)
1435 {
1436     StringExtractorGDBRemote packet;
1437 
1438     while (true)
1439     {
1440         PacketType type = CheckForPacket(bytes, len, packet);
1441 
1442         // scrub the data so we do not pass it back to CheckForPacket
1443         // on future passes of the loop
1444         bytes = nullptr;
1445         len = 0;
1446 
1447         // we may have received no packet so lets bail out
1448         if (type == PacketType::Invalid)
1449             break;
1450 
1451         if (type == PacketType::Standard)
1452         {
1453             // scope for the mutex
1454             {
1455                 // lock down the packet queue
1456                 std::lock_guard<std::mutex> guard(m_packet_queue_mutex);
1457                 // push a new packet into the queue
1458                 m_packet_queue.push(packet);
1459                 // Signal condition variable that we have a packet
1460                 m_condition_queue_not_empty.notify_one();
1461             }
1462         }
1463 
1464         if (type == PacketType::Notify)
1465         {
1466             // put this packet into an event
1467             const char *pdata = packet.GetStringRef().c_str();
1468 
1469             // as the communication class, we are a broadcaster and the
1470             // async thread is tuned to listen to us
1471             BroadcastEvent(
1472                 eBroadcastBitGdbReadThreadGotNotify,
1473                 new EventDataBytes(pdata));
1474         }
1475     }
1476 }
1477