xref: /llvm-project/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunication.cpp (revision b9c1b51e45b845debb76d8658edabca70ca56079)
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 #include "GDBRemoteCommunication.h"
11 
12 // C Includes
13 #include <limits.h>
14 #include <string.h>
15 #include <sys/stat.h>
16 
17 // C++ Includes
18 // Other libraries and framework includes
19 #include "lldb/Core/Log.h"
20 #include "lldb/Core/RegularExpression.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/Platform.h"
33 #include "lldb/Target/Process.h"
34 #include "llvm/ADT/SmallString.h"
35 #include "llvm/Support/ScopedPrinter.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(), m_curr_idx(0), m_total_packet_count(0),
60       m_dumped_to_log(false) {
61   m_packets.resize(size);
62 }
63 
64 GDBRemoteCommunication::History::~History() {}
65 
66 void GDBRemoteCommunication::History::AddPacket(char packet_char,
67                                                 PacketType type,
68                                                 uint32_t bytes_transmitted) {
69   const size_t size = m_packets.size();
70   if (size > 0) {
71     const uint32_t idx = GetNextIndex();
72     m_packets[idx].packet.assign(1, packet_char);
73     m_packets[idx].type = type;
74     m_packets[idx].bytes_transmitted = bytes_transmitted;
75     m_packets[idx].packet_idx = m_total_packet_count;
76     m_packets[idx].tid = Host::GetCurrentThreadID();
77   }
78 }
79 
80 void GDBRemoteCommunication::History::AddPacket(const std::string &src,
81                                                 uint32_t src_len,
82                                                 PacketType type,
83                                                 uint32_t bytes_transmitted) {
84   const size_t size = m_packets.size();
85   if (size > 0) {
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 GDBRemoteCommunication::History::Dump(Stream &strm) const {
96   const uint32_t size = GetNumPacketsInHistory();
97   const uint32_t first_idx = GetFirstSavedPacketIndex();
98   const uint32_t stop_idx = m_curr_idx + size;
99   for (uint32_t i = first_idx; i < stop_idx; ++i) {
100     const uint32_t idx = NormalizeIndex(i);
101     const Entry &entry = m_packets[idx];
102     if (entry.type == ePacketTypeInvalid || entry.packet.empty())
103       break;
104     strm.Printf("history[%u] tid=0x%4.4" PRIx64 " <%4u> %s packet: %s\n",
105                 entry.packet_idx, entry.tid, entry.bytes_transmitted,
106                 (entry.type == ePacketTypeSend) ? "send" : "read",
107                 entry.packet.c_str());
108   }
109 }
110 
111 void GDBRemoteCommunication::History::Dump(Log *log) const {
112   if (log && !m_dumped_to_log) {
113     m_dumped_to_log = true;
114     const uint32_t size = GetNumPacketsInHistory();
115     const uint32_t first_idx = GetFirstSavedPacketIndex();
116     const uint32_t stop_idx = m_curr_idx + size;
117     for (uint32_t i = first_idx; i < stop_idx; ++i) {
118       const uint32_t idx = NormalizeIndex(i);
119       const Entry &entry = m_packets[idx];
120       if (entry.type == ePacketTypeInvalid || entry.packet.empty())
121         break;
122       log->Printf("history[%u] tid=0x%4.4" PRIx64 " <%4u> %s packet: %s",
123                   entry.packet_idx, entry.tid, entry.bytes_transmitted,
124                   (entry.type == ePacketTypeSend) ? "send" : "read",
125                   entry.packet.c_str());
126     }
127   }
128 }
129 
130 //----------------------------------------------------------------------
131 // GDBRemoteCommunication constructor
132 //----------------------------------------------------------------------
133 GDBRemoteCommunication::GDBRemoteCommunication(const char *comm_name,
134                                                const char *listener_name)
135     : Communication(comm_name),
136 #ifdef LLDB_CONFIGURATION_DEBUG
137       m_packet_timeout(1000),
138 #else
139       m_packet_timeout(1),
140 #endif
141       m_echo_number(0), m_supports_qEcho(eLazyBoolCalculate), m_history(512),
142       m_send_acks(true), m_compression_type(CompressionType::None),
143       m_listen_url() {
144 }
145 
146 //----------------------------------------------------------------------
147 // Destructor
148 //----------------------------------------------------------------------
149 GDBRemoteCommunication::~GDBRemoteCommunication() {
150   if (IsConnected()) {
151     Disconnect();
152   }
153 
154   // Stop the communications read thread which is used to parse all
155   // incoming packets.  This function will block until the read
156   // thread returns.
157   if (m_read_thread_enabled)
158     StopReadThread();
159 }
160 
161 char GDBRemoteCommunication::CalculcateChecksum(llvm::StringRef payload) {
162   int checksum = 0;
163 
164   for (char c : payload)
165     checksum += c;
166 
167   return checksum & 255;
168 }
169 
170 size_t GDBRemoteCommunication::SendAck() {
171   Log *log(ProcessGDBRemoteLog::GetLogIfAllCategoriesSet(GDBR_LOG_PACKETS));
172   ConnectionStatus status = eConnectionStatusSuccess;
173   char ch = '+';
174   const size_t bytes_written = Write(&ch, 1, status, NULL);
175   if (log)
176     log->Printf("<%4" PRIu64 "> send packet: %c", (uint64_t)bytes_written, ch);
177   m_history.AddPacket(ch, History::ePacketTypeSend, bytes_written);
178   return bytes_written;
179 }
180 
181 size_t GDBRemoteCommunication::SendNack() {
182   Log *log(ProcessGDBRemoteLog::GetLogIfAllCategoriesSet(GDBR_LOG_PACKETS));
183   ConnectionStatus status = eConnectionStatusSuccess;
184   char ch = '-';
185   const size_t bytes_written = Write(&ch, 1, status, NULL);
186   if (log)
187     log->Printf("<%4" PRIu64 "> send packet: %c", (uint64_t)bytes_written, ch);
188   m_history.AddPacket(ch, History::ePacketTypeSend, bytes_written);
189   return bytes_written;
190 }
191 
192 GDBRemoteCommunication::PacketResult
193 GDBRemoteCommunication::SendPacketNoLock(llvm::StringRef payload) {
194   if (IsConnected()) {
195     StreamString packet(0, 4, eByteOrderBig);
196 
197     packet.PutChar('$');
198     packet.Write(payload.data(), payload.size());
199     packet.PutChar('#');
200     packet.PutHex8(CalculcateChecksum(payload));
201 
202     Log *log(ProcessGDBRemoteLog::GetLogIfAllCategoriesSet(GDBR_LOG_PACKETS));
203     ConnectionStatus status = eConnectionStatusSuccess;
204     const char *packet_data = packet.GetData();
205     const size_t packet_length = packet.GetSize();
206     size_t bytes_written = Write(packet_data, packet_length, status, NULL);
207     if (log) {
208       size_t binary_start_offset = 0;
209       if (strncmp(packet_data, "$vFile:pwrite:", strlen("$vFile:pwrite:")) ==
210           0) {
211         const char *first_comma = strchr(packet_data, ',');
212         if (first_comma) {
213           const char *second_comma = strchr(first_comma + 1, ',');
214           if (second_comma)
215             binary_start_offset = second_comma - packet_data + 1;
216         }
217       }
218 
219       // If logging was just enabled and we have history, then dump out what
220       // we have to the log so we get the historical context. The Dump() call
221       // that
222       // logs all of the packet will set a boolean so that we don't dump this
223       // more
224       // than once
225       if (!m_history.DidDumpToLog())
226         m_history.Dump(log);
227 
228       if (binary_start_offset) {
229         StreamString strm;
230         // Print non binary data header
231         strm.Printf("<%4" PRIu64 "> send packet: %.*s", (uint64_t)bytes_written,
232                     (int)binary_start_offset, packet_data);
233         const uint8_t *p;
234         // Print binary data exactly as sent
235         for (p = (const uint8_t *)packet_data + binary_start_offset; *p != '#';
236              ++p)
237           strm.Printf("\\x%2.2x", *p);
238         // Print the checksum
239         strm.Printf("%*s", (int)3, p);
240         log->PutCString(strm.GetString().c_str());
241       } else
242         log->Printf("<%4" PRIu64 "> send packet: %.*s", (uint64_t)bytes_written,
243                     (int)packet_length, packet_data);
244     }
245 
246     m_history.AddPacket(packet.GetString(), packet_length,
247                         History::ePacketTypeSend, bytes_written);
248 
249     if (bytes_written == packet_length) {
250       if (GetSendAcks())
251         return GetAck();
252       else
253         return PacketResult::Success;
254     } else {
255       if (log)
256         log->Printf("error: failed to send packet: %.*s", (int)packet_length,
257                     packet_data);
258     }
259   }
260   return PacketResult::ErrorSendFailed;
261 }
262 
263 GDBRemoteCommunication::PacketResult GDBRemoteCommunication::GetAck() {
264   StringExtractorGDBRemote packet;
265   PacketResult result =
266       ReadPacket(packet, GetPacketTimeoutInMicroSeconds(), false);
267   if (result == PacketResult::Success) {
268     if (packet.GetResponseType() ==
269         StringExtractorGDBRemote::ResponseType::eAck)
270       return PacketResult::Success;
271     else
272       return PacketResult::ErrorSendAck;
273   }
274   return result;
275 }
276 
277 GDBRemoteCommunication::PacketResult
278 GDBRemoteCommunication::ReadPacket(StringExtractorGDBRemote &response,
279                                    uint32_t timeout_usec,
280                                    bool sync_on_timeout) {
281   if (m_read_thread_enabled)
282     return PopPacketFromQueue(response, timeout_usec);
283   else
284     return WaitForPacketWithTimeoutMicroSecondsNoLock(response, timeout_usec,
285                                                       sync_on_timeout);
286 }
287 
288 // This function is called when a packet is requested.
289 // A whole packet is popped from the packet queue and returned to the caller.
290 // Packets are placed into this queue from the communication read thread.
291 // See GDBRemoteCommunication::AppendBytesToCache.
292 GDBRemoteCommunication::PacketResult
293 GDBRemoteCommunication::PopPacketFromQueue(StringExtractorGDBRemote &response,
294                                            uint32_t timeout_usec) {
295   auto until = std::chrono::system_clock::now() +
296                std::chrono::microseconds(timeout_usec);
297 
298   while (true) {
299     // scope for the mutex
300     {
301       // lock down the packet queue
302       std::unique_lock<std::mutex> lock(m_packet_queue_mutex);
303 
304       // Wait on condition variable.
305       if (m_packet_queue.size() == 0) {
306         std::cv_status result =
307             m_condition_queue_not_empty.wait_until(lock, until);
308         if (result == std::cv_status::timeout)
309           break;
310       }
311 
312       if (m_packet_queue.size() > 0) {
313         // get the front element of the queue
314         response = m_packet_queue.front();
315 
316         // remove the front element
317         m_packet_queue.pop();
318 
319         // we got a packet
320         return PacketResult::Success;
321       }
322     }
323 
324     // Disconnected
325     if (!IsConnected())
326       return PacketResult::ErrorDisconnected;
327 
328     // Loop while not timed out
329   }
330 
331   return PacketResult::ErrorReplyTimeout;
332 }
333 
334 GDBRemoteCommunication::PacketResult
335 GDBRemoteCommunication::WaitForPacketWithTimeoutMicroSecondsNoLock(
336     StringExtractorGDBRemote &packet, uint32_t timeout_usec,
337     bool sync_on_timeout) {
338   uint8_t buffer[8192];
339   Error error;
340 
341   Log *log(ProcessGDBRemoteLog::GetLogIfAllCategoriesSet(GDBR_LOG_PACKETS |
342                                                          GDBR_LOG_VERBOSE));
343 
344   // Check for a packet from our cache first without trying any reading...
345   if (CheckForPacket(NULL, 0, packet) != PacketType::Invalid)
346     return PacketResult::Success;
347 
348   bool timed_out = false;
349   bool disconnected = false;
350   while (IsConnected() && !timed_out) {
351     lldb::ConnectionStatus status = eConnectionStatusNoConnection;
352     size_t bytes_read =
353         Read(buffer, sizeof(buffer), timeout_usec, status, &error);
354 
355     if (log)
356       log->Printf("%s: Read (buffer, (sizeof(buffer), timeout_usec = 0x%x, "
357                   "status = %s, error = %s) => bytes_read = %" PRIu64,
358                   LLVM_PRETTY_FUNCTION, timeout_usec,
359                   Communication::ConnectionStatusAsCString(status),
360                   error.AsCString(), (uint64_t)bytes_read);
361 
362     if (bytes_read > 0) {
363       if (CheckForPacket(buffer, bytes_read, packet) != PacketType::Invalid)
364         return PacketResult::Success;
365     } else {
366       switch (status) {
367       case eConnectionStatusTimedOut:
368       case eConnectionStatusInterrupted:
369         if (sync_on_timeout) {
370           //------------------------------------------------------------------
371           /// Sync the remote GDB server and make sure we get a response that
372           /// corresponds to what we send.
373           ///
374           /// Sends a "qEcho" packet and makes sure it gets the exact packet
375           /// echoed back. If the qEcho packet isn't supported, we send a qC
376           /// packet and make sure we get a valid thread ID back. We use the
377           /// "qC" packet since its response if very unique: is responds with
378           /// "QC%x" where %x is the thread ID of the current thread. This
379           /// makes the response unique enough from other packet responses to
380           /// ensure we are back on track.
381           ///
382           /// This packet is needed after we time out sending a packet so we
383           /// can ensure that we are getting the response for the packet we
384           /// are sending. There are no sequence IDs in the GDB remote
385           /// protocol (there used to be, but they are not supported anymore)
386           /// so if you timeout sending packet "abc", you might then send
387           /// packet "cde" and get the response for the previous "abc" packet.
388           /// Many responses are "OK" or "" (unsupported) or "EXX" (error) so
389           /// many responses for packets can look like responses for other
390           /// packets. So if we timeout, we need to ensure that we can get
391           /// back on track. If we can't get back on track, we must
392           /// disconnect.
393           //------------------------------------------------------------------
394           bool sync_success = false;
395           bool got_actual_response = false;
396           // We timed out, we need to sync back up with the
397           char echo_packet[32];
398           int echo_packet_len = 0;
399           RegularExpression response_regex;
400 
401           if (m_supports_qEcho == eLazyBoolYes) {
402             echo_packet_len = ::snprintf(echo_packet, sizeof(echo_packet),
403                                          "qEcho:%u", ++m_echo_number);
404             std::string regex_str = "^";
405             regex_str += echo_packet;
406             regex_str += "$";
407             response_regex.Compile(regex_str.c_str());
408           } else {
409             echo_packet_len =
410                 ::snprintf(echo_packet, sizeof(echo_packet), "qC");
411             response_regex.Compile("^QC[0-9A-Fa-f]+$");
412           }
413 
414           PacketResult echo_packet_result =
415               SendPacketNoLock(llvm::StringRef(echo_packet, echo_packet_len));
416           if (echo_packet_result == PacketResult::Success) {
417             const uint32_t max_retries = 3;
418             uint32_t successful_responses = 0;
419             for (uint32_t i = 0; i < max_retries; ++i) {
420               StringExtractorGDBRemote echo_response;
421               echo_packet_result = WaitForPacketWithTimeoutMicroSecondsNoLock(
422                   echo_response, timeout_usec, false);
423               if (echo_packet_result == PacketResult::Success) {
424                 ++successful_responses;
425                 if (response_regex.Execute(
426                         echo_response.GetStringRef().c_str())) {
427                   sync_success = true;
428                   break;
429                 } else if (successful_responses == 1) {
430                   // We got something else back as the first successful
431                   // response, it probably is
432                   // the  response to the packet we actually wanted, so copy it
433                   // over if this
434                   // is the first success and continue to try to get the qEcho
435                   // response
436                   packet = echo_response;
437                   got_actual_response = true;
438                 }
439               } else if (echo_packet_result == PacketResult::ErrorReplyTimeout)
440                 continue; // Packet timed out, continue waiting for a response
441               else
442                 break; // Something else went wrong getting the packet back, we
443                        // failed and are done trying
444             }
445           }
446 
447           // We weren't able to sync back up with the server, we must abort
448           // otherwise
449           // all responses might not be from the right packets...
450           if (sync_success) {
451             // We timed out, but were able to recover
452             if (got_actual_response) {
453               // We initially timed out, but we did get a response that came in
454               // before the successful
455               // reply to our qEcho packet, so lets say everything is fine...
456               return PacketResult::Success;
457             }
458           } else {
459             disconnected = true;
460             Disconnect();
461           }
462         }
463         timed_out = true;
464         break;
465       case eConnectionStatusSuccess:
466         // printf ("status = success but error = %s\n",
467         // error.AsCString("<invalid>"));
468         break;
469 
470       case eConnectionStatusEndOfFile:
471       case eConnectionStatusNoConnection:
472       case eConnectionStatusLostConnection:
473       case eConnectionStatusError:
474         disconnected = true;
475         Disconnect();
476         break;
477       }
478     }
479   }
480   packet.Clear();
481   if (disconnected)
482     return PacketResult::ErrorDisconnected;
483   if (timed_out)
484     return PacketResult::ErrorReplyTimeout;
485   else
486     return PacketResult::ErrorReplyFailed;
487 }
488 
489 bool GDBRemoteCommunication::DecompressPacket() {
490   Log *log(ProcessGDBRemoteLog::GetLogIfAllCategoriesSet(GDBR_LOG_PACKETS));
491 
492   if (!CompressionIsEnabled())
493     return true;
494 
495   size_t pkt_size = m_bytes.size();
496 
497   // Smallest possible compressed packet is $N#00 - an uncompressed empty reply,
498   // most commonly indicating
499   // an unsupported packet.  Anything less than 5 characters, it's definitely
500   // not a compressed packet.
501   if (pkt_size < 5)
502     return true;
503 
504   if (m_bytes[0] != '$' && m_bytes[0] != '%')
505     return true;
506   if (m_bytes[1] != 'C' && m_bytes[1] != 'N')
507     return true;
508 
509   size_t hash_mark_idx = m_bytes.find('#');
510   if (hash_mark_idx == std::string::npos)
511     return true;
512   if (hash_mark_idx + 2 >= m_bytes.size())
513     return true;
514 
515   if (!::isxdigit(m_bytes[hash_mark_idx + 1]) ||
516       !::isxdigit(m_bytes[hash_mark_idx + 2]))
517     return true;
518 
519   size_t content_length =
520       pkt_size -
521       5; // not counting '$', 'C' | 'N', '#', & the two hex checksum chars
522   size_t content_start = 2; // The first character of the
523                             // compressed/not-compressed text of the packet
524   size_t checksum_idx =
525       hash_mark_idx +
526       1; // The first character of the two hex checksum characters
527 
528   // Normally size_of_first_packet == m_bytes.size() but m_bytes may contain
529   // multiple packets.
530   // size_of_first_packet is the size of the initial packet which we'll replace
531   // with the decompressed
532   // version of, leaving the rest of m_bytes unmodified.
533   size_t size_of_first_packet = hash_mark_idx + 3;
534 
535   // Compressed packets ("$C") start with a base10 number which is the size of
536   // the uncompressed payload,
537   // then a : and then the compressed data.  e.g. $C1024:<binary>#00
538   // Update content_start and content_length to only include the <binary> part
539   // of the packet.
540 
541   uint64_t decompressed_bufsize = ULONG_MAX;
542   if (m_bytes[1] == 'C') {
543     size_t i = content_start;
544     while (i < hash_mark_idx && isdigit(m_bytes[i]))
545       i++;
546     if (i < hash_mark_idx && m_bytes[i] == ':') {
547       i++;
548       content_start = i;
549       content_length = hash_mark_idx - content_start;
550       std::string bufsize_str(m_bytes.data() + 2, i - 2 - 1);
551       errno = 0;
552       decompressed_bufsize = ::strtoul(bufsize_str.c_str(), NULL, 10);
553       if (errno != 0 || decompressed_bufsize == ULONG_MAX) {
554         m_bytes.erase(0, size_of_first_packet);
555         return false;
556       }
557     }
558   }
559 
560   if (GetSendAcks()) {
561     char packet_checksum_cstr[3];
562     packet_checksum_cstr[0] = m_bytes[checksum_idx];
563     packet_checksum_cstr[1] = m_bytes[checksum_idx + 1];
564     packet_checksum_cstr[2] = '\0';
565     long packet_checksum = strtol(packet_checksum_cstr, NULL, 16);
566 
567     long actual_checksum = CalculcateChecksum(
568         llvm::StringRef(m_bytes).substr(1, hash_mark_idx - 1));
569     bool success = packet_checksum == actual_checksum;
570     if (!success) {
571       if (log)
572         log->Printf(
573             "error: checksum mismatch: %.*s expected 0x%2.2x, got 0x%2.2x",
574             (int)(pkt_size), m_bytes.c_str(), (uint8_t)packet_checksum,
575             (uint8_t)actual_checksum);
576     }
577     // Send the ack or nack if needed
578     if (!success) {
579       SendNack();
580       m_bytes.erase(0, size_of_first_packet);
581       return false;
582     } else {
583       SendAck();
584     }
585   }
586 
587   if (m_bytes[1] == 'N') {
588     // This packet was not compressed -- delete the 'N' character at the
589     // start and the packet may be processed as-is.
590     m_bytes.erase(1, 1);
591     return true;
592   }
593 
594   // Reverse the gdb-remote binary escaping that was done to the compressed text
595   // to
596   // guard characters like '$', '#', '}', etc.
597   std::vector<uint8_t> unescaped_content;
598   unescaped_content.reserve(content_length);
599   size_t i = content_start;
600   while (i < hash_mark_idx) {
601     if (m_bytes[i] == '}') {
602       i++;
603       unescaped_content.push_back(m_bytes[i] ^ 0x20);
604     } else {
605       unescaped_content.push_back(m_bytes[i]);
606     }
607     i++;
608   }
609 
610   uint8_t *decompressed_buffer = nullptr;
611   size_t decompressed_bytes = 0;
612 
613   if (decompressed_bufsize != ULONG_MAX) {
614     decompressed_buffer = (uint8_t *)malloc(decompressed_bufsize + 1);
615     if (decompressed_buffer == nullptr) {
616       m_bytes.erase(0, size_of_first_packet);
617       return false;
618     }
619   }
620 
621 #if defined(HAVE_LIBCOMPRESSION)
622   // libcompression is weak linked so check that compression_decode_buffer() is
623   // available
624   if (compression_decode_buffer != NULL &&
625       (m_compression_type == CompressionType::ZlibDeflate ||
626        m_compression_type == CompressionType::LZFSE ||
627        m_compression_type == CompressionType::LZ4)) {
628     compression_algorithm compression_type;
629     if (m_compression_type == CompressionType::ZlibDeflate)
630       compression_type = COMPRESSION_ZLIB;
631     else if (m_compression_type == CompressionType::LZFSE)
632       compression_type = COMPRESSION_LZFSE;
633     else if (m_compression_type == CompressionType::LZ4)
634       compression_type = COMPRESSION_LZ4_RAW;
635     else if (m_compression_type == CompressionType::LZMA)
636       compression_type = COMPRESSION_LZMA;
637 
638     // If we have the expected size of the decompressed payload, we can allocate
639     // the right-sized buffer and do it.  If we don't have that information,
640     // we'll
641     // need to try decoding into a big buffer and if the buffer wasn't big
642     // enough,
643     // increase it and try again.
644 
645     if (decompressed_bufsize != ULONG_MAX && decompressed_buffer != nullptr) {
646       decompressed_bytes = compression_decode_buffer(
647           decompressed_buffer, decompressed_bufsize + 10,
648           (uint8_t *)unescaped_content.data(), unescaped_content.size(), NULL,
649           compression_type);
650     }
651   }
652 #endif
653 
654 #if defined(HAVE_LIBZ)
655   if (decompressed_bytes == 0 && decompressed_bufsize != ULONG_MAX &&
656       decompressed_buffer != nullptr &&
657       m_compression_type == CompressionType::ZlibDeflate) {
658     z_stream stream;
659     memset(&stream, 0, sizeof(z_stream));
660     stream.next_in = (Bytef *)unescaped_content.data();
661     stream.avail_in = (uInt)unescaped_content.size();
662     stream.total_in = 0;
663     stream.next_out = (Bytef *)decompressed_buffer;
664     stream.avail_out = decompressed_bufsize;
665     stream.total_out = 0;
666     stream.zalloc = Z_NULL;
667     stream.zfree = Z_NULL;
668     stream.opaque = Z_NULL;
669 
670     if (inflateInit2(&stream, -15) == Z_OK) {
671       int status = inflate(&stream, Z_NO_FLUSH);
672       inflateEnd(&stream);
673       if (status == Z_STREAM_END) {
674         decompressed_bytes = stream.total_out;
675       }
676     }
677   }
678 #endif
679 
680   if (decompressed_bytes == 0 || decompressed_buffer == nullptr) {
681     if (decompressed_buffer)
682       free(decompressed_buffer);
683     m_bytes.erase(0, size_of_first_packet);
684     return false;
685   }
686 
687   std::string new_packet;
688   new_packet.reserve(decompressed_bytes + 6);
689   new_packet.push_back(m_bytes[0]);
690   new_packet.append((const char *)decompressed_buffer, decompressed_bytes);
691   new_packet.push_back('#');
692   if (GetSendAcks()) {
693     uint8_t decompressed_checksum = CalculcateChecksum(
694         llvm::StringRef((const char *)decompressed_buffer, decompressed_bytes));
695     char decompressed_checksum_str[3];
696     snprintf(decompressed_checksum_str, 3, "%02x", decompressed_checksum);
697     new_packet.append(decompressed_checksum_str);
698   } else {
699     new_packet.push_back('0');
700     new_packet.push_back('0');
701   }
702 
703   m_bytes.replace(0, size_of_first_packet, new_packet.data(),
704                   new_packet.size());
705 
706   free(decompressed_buffer);
707   return true;
708 }
709 
710 GDBRemoteCommunication::PacketType
711 GDBRemoteCommunication::CheckForPacket(const uint8_t *src, size_t src_len,
712                                        StringExtractorGDBRemote &packet) {
713   // Put the packet data into the buffer in a thread safe fashion
714   std::lock_guard<std::recursive_mutex> guard(m_bytes_mutex);
715 
716   Log *log(ProcessGDBRemoteLog::GetLogIfAllCategoriesSet(GDBR_LOG_PACKETS));
717 
718   if (src && src_len > 0) {
719     if (log && log->GetVerbose()) {
720       StreamString s;
721       log->Printf("GDBRemoteCommunication::%s adding %u bytes: %.*s",
722                   __FUNCTION__, (uint32_t)src_len, (uint32_t)src_len, src);
723     }
724     m_bytes.append((const char *)src, src_len);
725   }
726 
727   bool isNotifyPacket = false;
728 
729   // Parse up the packets into gdb remote packets
730   if (!m_bytes.empty()) {
731     // end_idx must be one past the last valid packet byte. Start
732     // it off with an invalid value that is the same as the current
733     // index.
734     size_t content_start = 0;
735     size_t content_length = 0;
736     size_t total_length = 0;
737     size_t checksum_idx = std::string::npos;
738 
739     // Size of packet before it is decompressed, for logging purposes
740     size_t original_packet_size = m_bytes.size();
741     if (CompressionIsEnabled()) {
742       if (DecompressPacket() == false) {
743         packet.Clear();
744         return GDBRemoteCommunication::PacketType::Standard;
745       }
746     }
747 
748     switch (m_bytes[0]) {
749     case '+':                            // Look for ack
750     case '-':                            // Look for cancel
751     case '\x03':                         // ^C to halt target
752       content_length = total_length = 1; // The command is one byte long...
753       break;
754 
755     case '%': // Async notify packet
756       isNotifyPacket = true;
757       LLVM_FALLTHROUGH;
758 
759     case '$':
760       // Look for a standard gdb packet?
761       {
762         size_t hash_pos = m_bytes.find('#');
763         if (hash_pos != std::string::npos) {
764           if (hash_pos + 2 < m_bytes.size()) {
765             checksum_idx = hash_pos + 1;
766             // Skip the dollar sign
767             content_start = 1;
768             // Don't include the # in the content or the $ in the content length
769             content_length = hash_pos - 1;
770 
771             total_length =
772                 hash_pos + 3; // Skip the # and the two hex checksum bytes
773           } else {
774             // Checksum bytes aren't all here yet
775             content_length = std::string::npos;
776           }
777         }
778       }
779       break;
780 
781     default: {
782       // We have an unexpected byte and we need to flush all bad
783       // data that is in m_bytes, so we need to find the first
784       // byte that is a '+' (ACK), '-' (NACK), \x03 (CTRL+C interrupt),
785       // or '$' character (start of packet header) or of course,
786       // the end of the data in m_bytes...
787       const size_t bytes_len = m_bytes.size();
788       bool done = false;
789       uint32_t idx;
790       for (idx = 1; !done && idx < bytes_len; ++idx) {
791         switch (m_bytes[idx]) {
792         case '+':
793         case '-':
794         case '\x03':
795         case '%':
796         case '$':
797           done = true;
798           break;
799 
800         default:
801           break;
802         }
803       }
804       if (log)
805         log->Printf("GDBRemoteCommunication::%s tossing %u junk bytes: '%.*s'",
806                     __FUNCTION__, idx - 1, idx - 1, m_bytes.c_str());
807       m_bytes.erase(0, idx - 1);
808     } break;
809     }
810 
811     if (content_length == std::string::npos) {
812       packet.Clear();
813       return GDBRemoteCommunication::PacketType::Invalid;
814     } else if (total_length > 0) {
815 
816       // We have a valid packet...
817       assert(content_length <= m_bytes.size());
818       assert(total_length <= m_bytes.size());
819       assert(content_length <= total_length);
820       size_t content_end = content_start + content_length;
821 
822       bool success = true;
823       std::string &packet_str = packet.GetStringRef();
824       if (log) {
825         // If logging was just enabled and we have history, then dump out what
826         // we have to the log so we get the historical context. The Dump() call
827         // that
828         // logs all of the packet will set a boolean so that we don't dump this
829         // more
830         // than once
831         if (!m_history.DidDumpToLog())
832           m_history.Dump(log);
833 
834         bool binary = false;
835         // Only detect binary for packets that start with a '$' and have a '#CC'
836         // checksum
837         if (m_bytes[0] == '$' && total_length > 4) {
838           for (size_t i = 0; !binary && i < total_length; ++i) {
839             if (isprint(m_bytes[i]) == 0 && isspace(m_bytes[i]) == 0) {
840               binary = true;
841             }
842           }
843         }
844         if (binary) {
845           StreamString strm;
846           // Packet header...
847           if (CompressionIsEnabled())
848             strm.Printf("<%4" PRIu64 ":%" PRIu64 "> read packet: %c",
849                         (uint64_t)original_packet_size, (uint64_t)total_length,
850                         m_bytes[0]);
851           else
852             strm.Printf("<%4" PRIu64 "> read packet: %c",
853                         (uint64_t)total_length, m_bytes[0]);
854           for (size_t i = content_start; i < content_end; ++i) {
855             // Remove binary escaped bytes when displaying the packet...
856             const char ch = m_bytes[i];
857             if (ch == 0x7d) {
858               // 0x7d is the escape character.  The next character is to
859               // be XOR'd with 0x20.
860               const char escapee = m_bytes[++i] ^ 0x20;
861               strm.Printf("%2.2x", escapee);
862             } else {
863               strm.Printf("%2.2x", (uint8_t)ch);
864             }
865           }
866           // Packet footer...
867           strm.Printf("%c%c%c", m_bytes[total_length - 3],
868                       m_bytes[total_length - 2], m_bytes[total_length - 1]);
869           log->PutCString(strm.GetString().c_str());
870         } else {
871           if (CompressionIsEnabled())
872             log->Printf("<%4" PRIu64 ":%" PRIu64 "> read packet: %.*s",
873                         (uint64_t)original_packet_size, (uint64_t)total_length,
874                         (int)(total_length), m_bytes.c_str());
875           else
876             log->Printf("<%4" PRIu64 "> read packet: %.*s",
877                         (uint64_t)total_length, (int)(total_length),
878                         m_bytes.c_str());
879         }
880       }
881 
882       m_history.AddPacket(m_bytes.c_str(), total_length,
883                           History::ePacketTypeRecv, total_length);
884 
885       // Clear packet_str in case there is some existing data in it.
886       packet_str.clear();
887       // Copy the packet from m_bytes to packet_str expanding the
888       // run-length encoding in the process.
889       // Reserve enough byte for the most common case (no RLE used)
890       packet_str.reserve(m_bytes.length());
891       for (std::string::const_iterator c = m_bytes.begin() + content_start;
892            c != m_bytes.begin() + content_end; ++c) {
893         if (*c == '*') {
894           // '*' indicates RLE. Next character will give us the
895           // repeat count and previous character is what is to be
896           // repeated.
897           char char_to_repeat = packet_str.back();
898           // Number of time the previous character is repeated
899           int repeat_count = *++c + 3 - ' ';
900           // We have the char_to_repeat and repeat_count. Now push
901           // it in the packet.
902           for (int i = 0; i < repeat_count; ++i)
903             packet_str.push_back(char_to_repeat);
904         } else if (*c == 0x7d) {
905           // 0x7d is the escape character.  The next character is to
906           // be XOR'd with 0x20.
907           char escapee = *++c ^ 0x20;
908           packet_str.push_back(escapee);
909         } else {
910           packet_str.push_back(*c);
911         }
912       }
913 
914       if (m_bytes[0] == '$' || m_bytes[0] == '%') {
915         assert(checksum_idx < m_bytes.size());
916         if (::isxdigit(m_bytes[checksum_idx + 0]) ||
917             ::isxdigit(m_bytes[checksum_idx + 1])) {
918           if (GetSendAcks()) {
919             const char *packet_checksum_cstr = &m_bytes[checksum_idx];
920             char packet_checksum = strtol(packet_checksum_cstr, NULL, 16);
921             char actual_checksum = CalculcateChecksum(packet_str);
922             success = packet_checksum == actual_checksum;
923             if (!success) {
924               if (log)
925                 log->Printf("error: checksum mismatch: %.*s expected 0x%2.2x, "
926                             "got 0x%2.2x",
927                             (int)(total_length), m_bytes.c_str(),
928                             (uint8_t)packet_checksum, (uint8_t)actual_checksum);
929             }
930             // Send the ack or nack if needed
931             if (!success)
932               SendNack();
933             else
934               SendAck();
935           }
936         } else {
937           success = false;
938           if (log)
939             log->Printf("error: invalid checksum in packet: '%s'\n",
940                         m_bytes.c_str());
941         }
942       }
943 
944       m_bytes.erase(0, total_length);
945       packet.SetFilePos(0);
946 
947       if (isNotifyPacket)
948         return GDBRemoteCommunication::PacketType::Notify;
949       else
950         return GDBRemoteCommunication::PacketType::Standard;
951     }
952   }
953   packet.Clear();
954   return GDBRemoteCommunication::PacketType::Invalid;
955 }
956 
957 Error GDBRemoteCommunication::StartListenThread(const char *hostname,
958                                                 uint16_t port) {
959   Error error;
960   if (m_listen_thread.IsJoinable()) {
961     error.SetErrorString("listen thread already running");
962   } else {
963     char listen_url[512];
964     if (hostname && hostname[0])
965       snprintf(listen_url, sizeof(listen_url), "listen://%s:%i", hostname,
966                port);
967     else
968       snprintf(listen_url, sizeof(listen_url), "listen://%i", port);
969     m_listen_url = listen_url;
970     SetConnection(new ConnectionFileDescriptor());
971     m_listen_thread = ThreadLauncher::LaunchThread(
972         listen_url, GDBRemoteCommunication::ListenThread, this, &error);
973   }
974   return error;
975 }
976 
977 bool GDBRemoteCommunication::JoinListenThread() {
978   if (m_listen_thread.IsJoinable())
979     m_listen_thread.Join(nullptr);
980   return true;
981 }
982 
983 lldb::thread_result_t
984 GDBRemoteCommunication::ListenThread(lldb::thread_arg_t arg) {
985   GDBRemoteCommunication *comm = (GDBRemoteCommunication *)arg;
986   Error error;
987   ConnectionFileDescriptor *connection =
988       (ConnectionFileDescriptor *)comm->GetConnection();
989 
990   if (connection) {
991     // Do the listen on another thread so we can continue on...
992     if (connection->Connect(comm->m_listen_url.c_str(), &error) !=
993         eConnectionStatusSuccess)
994       comm->SetConnection(NULL);
995   }
996   return NULL;
997 }
998 
999 Error GDBRemoteCommunication::StartDebugserverProcess(
1000     const char *url, Platform *platform, ProcessLaunchInfo &launch_info,
1001     uint16_t *port, const Args *inferior_args, int pass_comm_fd) {
1002   Log *log(ProcessGDBRemoteLog::GetLogIfAllCategoriesSet(GDBR_LOG_PROCESS));
1003   if (log)
1004     log->Printf("GDBRemoteCommunication::%s(url=%s, port=%" PRIu16 ")",
1005                 __FUNCTION__, url ? url : "<empty>",
1006                 port ? *port : uint16_t(0));
1007 
1008   Error error;
1009   // If we locate debugserver, keep that located version around
1010   static FileSpec g_debugserver_file_spec;
1011 
1012   char debugserver_path[PATH_MAX];
1013   FileSpec &debugserver_file_spec = launch_info.GetExecutableFile();
1014 
1015   // Always check to see if we have an environment override for the path
1016   // to the debugserver to use and use it if we do.
1017   const char *env_debugserver_path = getenv("LLDB_DEBUGSERVER_PATH");
1018   if (env_debugserver_path) {
1019     debugserver_file_spec.SetFile(env_debugserver_path, false);
1020     if (log)
1021       log->Printf("GDBRemoteCommunication::%s() gdb-remote stub exe path set "
1022                   "from environment variable: %s",
1023                   __FUNCTION__, env_debugserver_path);
1024   } else
1025     debugserver_file_spec = g_debugserver_file_spec;
1026   bool debugserver_exists = debugserver_file_spec.Exists();
1027   if (!debugserver_exists) {
1028     // The debugserver binary is in the LLDB.framework/Resources
1029     // directory.
1030     if (HostInfo::GetLLDBPath(ePathTypeSupportExecutableDir,
1031                               debugserver_file_spec)) {
1032       debugserver_file_spec.AppendPathComponent(DEBUGSERVER_BASENAME);
1033       debugserver_exists = debugserver_file_spec.Exists();
1034       if (debugserver_exists) {
1035         if (log)
1036           log->Printf(
1037               "GDBRemoteCommunication::%s() found gdb-remote stub exe '%s'",
1038               __FUNCTION__, debugserver_file_spec.GetPath().c_str());
1039 
1040         g_debugserver_file_spec = debugserver_file_spec;
1041       } else {
1042         debugserver_file_spec =
1043             platform->LocateExecutable(DEBUGSERVER_BASENAME);
1044         if (debugserver_file_spec) {
1045           // Platform::LocateExecutable() wouldn't return a path if it doesn't
1046           // exist
1047           debugserver_exists = true;
1048         } else {
1049           if (log)
1050             log->Printf("GDBRemoteCommunication::%s() could not find "
1051                         "gdb-remote stub exe '%s'",
1052                         __FUNCTION__, debugserver_file_spec.GetPath().c_str());
1053         }
1054         // Don't cache the platform specific GDB server binary as it could
1055         // change
1056         // from platform to platform
1057         g_debugserver_file_spec.Clear();
1058       }
1059     }
1060   }
1061 
1062   if (debugserver_exists) {
1063     debugserver_file_spec.GetPath(debugserver_path, sizeof(debugserver_path));
1064 
1065     Args &debugserver_args = launch_info.GetArguments();
1066     debugserver_args.Clear();
1067     char arg_cstr[PATH_MAX];
1068 
1069     // Start args with "debugserver /file/path -r --"
1070     debugserver_args.AppendArgument(debugserver_path);
1071 
1072 #if !defined(__APPLE__)
1073     // First argument to lldb-server must be mode in which to run.
1074     debugserver_args.AppendArgument("gdbserver");
1075 #endif
1076 
1077     // If a url is supplied then use it
1078     if (url)
1079       debugserver_args.AppendArgument(url);
1080 
1081     if (pass_comm_fd >= 0) {
1082       StreamString fd_arg;
1083       fd_arg.Printf("--fd=%i", pass_comm_fd);
1084       debugserver_args.AppendArgument(fd_arg.GetData());
1085       // Send "pass_comm_fd" down to the inferior so it can use it to
1086       // communicate back with this process
1087       launch_info.AppendDuplicateFileAction(pass_comm_fd, pass_comm_fd);
1088     }
1089 
1090     // use native registers, not the GDB registers
1091     debugserver_args.AppendArgument("--native-regs");
1092 
1093     if (launch_info.GetLaunchInSeparateProcessGroup()) {
1094       debugserver_args.AppendArgument("--setsid");
1095     }
1096 
1097     llvm::SmallString<PATH_MAX> named_pipe_path;
1098     // socket_pipe is used by debug server to communicate back either
1099     // TCP port or domain socket name which it listens on.
1100     // The second purpose of the pipe to serve as a synchronization point -
1101     // once data is written to the pipe, debug server is up and running.
1102     Pipe socket_pipe;
1103 
1104     // port is null when debug server should listen on domain socket -
1105     // we're not interested in port value but rather waiting for debug server
1106     // to become available.
1107     if (pass_comm_fd == -1 &&
1108         ((port != nullptr && *port == 0) || port == nullptr)) {
1109       if (url) {
1110 // Create a temporary file to get the stdout/stderr and redirect the
1111 // output of the command into this file. We will later read this file
1112 // if all goes well and fill the data into "command_output_ptr"
1113 
1114 #if defined(__APPLE__)
1115         // Binding to port zero, we need to figure out what port it ends up
1116         // using using a named pipe...
1117         error = socket_pipe.CreateWithUniqueName("debugserver-named-pipe",
1118                                                  false, named_pipe_path);
1119         if (error.Fail()) {
1120           if (log)
1121             log->Printf("GDBRemoteCommunication::%s() "
1122                         "named pipe creation failed: %s",
1123                         __FUNCTION__, error.AsCString());
1124           return error;
1125         }
1126         debugserver_args.AppendArgument("--named-pipe");
1127         debugserver_args.AppendArgument(named_pipe_path.c_str());
1128 #else
1129         // Binding to port zero, we need to figure out what port it ends up
1130         // using using an unnamed pipe...
1131         error = socket_pipe.CreateNew(true);
1132         if (error.Fail()) {
1133           if (log)
1134             log->Printf("GDBRemoteCommunication::%s() "
1135                         "unnamed pipe creation failed: %s",
1136                         __FUNCTION__, error.AsCString());
1137           return error;
1138         }
1139         int write_fd = socket_pipe.GetWriteFileDescriptor();
1140         debugserver_args.AppendArgument("--pipe");
1141         debugserver_args.AppendArgument(llvm::to_string(write_fd).c_str());
1142         launch_info.AppendCloseFileAction(socket_pipe.GetReadFileDescriptor());
1143 #endif
1144       } else {
1145         // No host and port given, so lets listen on our end and make the
1146         // debugserver
1147         // connect to us..
1148         error = StartListenThread("127.0.0.1", 0);
1149         if (error.Fail()) {
1150           if (log)
1151             log->Printf("GDBRemoteCommunication::%s() unable to start listen "
1152                         "thread: %s",
1153                         __FUNCTION__, error.AsCString());
1154           return error;
1155         }
1156 
1157         ConnectionFileDescriptor *connection =
1158             (ConnectionFileDescriptor *)GetConnection();
1159         // Wait for 10 seconds to resolve the bound port
1160         uint16_t port_ = connection->GetListeningPort(10);
1161         if (port_ > 0) {
1162           char port_cstr[32];
1163           snprintf(port_cstr, sizeof(port_cstr), "127.0.0.1:%i", port_);
1164           // Send the host and port down that debugserver and specify an option
1165           // so that it connects back to the port we are listening to in this
1166           // process
1167           debugserver_args.AppendArgument("--reverse-connect");
1168           debugserver_args.AppendArgument(port_cstr);
1169           if (port)
1170             *port = port_;
1171         } else {
1172           error.SetErrorString("failed to bind to port 0 on 127.0.0.1");
1173           if (log)
1174             log->Printf("GDBRemoteCommunication::%s() failed: %s", __FUNCTION__,
1175                         error.AsCString());
1176           return error;
1177         }
1178       }
1179     }
1180 
1181     const char *env_debugserver_log_file = getenv("LLDB_DEBUGSERVER_LOG_FILE");
1182     if (env_debugserver_log_file) {
1183       ::snprintf(arg_cstr, sizeof(arg_cstr), "--log-file=%s",
1184                  env_debugserver_log_file);
1185       debugserver_args.AppendArgument(arg_cstr);
1186     }
1187 
1188 #if defined(__APPLE__)
1189     const char *env_debugserver_log_flags =
1190         getenv("LLDB_DEBUGSERVER_LOG_FLAGS");
1191     if (env_debugserver_log_flags) {
1192       ::snprintf(arg_cstr, sizeof(arg_cstr), "--log-flags=%s",
1193                  env_debugserver_log_flags);
1194       debugserver_args.AppendArgument(arg_cstr);
1195     }
1196 #else
1197     const char *env_debugserver_log_channels =
1198         getenv("LLDB_SERVER_LOG_CHANNELS");
1199     if (env_debugserver_log_channels) {
1200       ::snprintf(arg_cstr, sizeof(arg_cstr), "--log-channels=%s",
1201                  env_debugserver_log_channels);
1202       debugserver_args.AppendArgument(arg_cstr);
1203     }
1204 #endif
1205 
1206     // Add additional args, starting with LLDB_DEBUGSERVER_EXTRA_ARG_1 until an
1207     // env var doesn't come back.
1208     uint32_t env_var_index = 1;
1209     bool has_env_var;
1210     do {
1211       char env_var_name[64];
1212       snprintf(env_var_name, sizeof(env_var_name),
1213                "LLDB_DEBUGSERVER_EXTRA_ARG_%" PRIu32, env_var_index++);
1214       const char *extra_arg = getenv(env_var_name);
1215       has_env_var = extra_arg != nullptr;
1216 
1217       if (has_env_var) {
1218         debugserver_args.AppendArgument(extra_arg);
1219         if (log)
1220           log->Printf("GDBRemoteCommunication::%s adding env var %s contents "
1221                       "to stub command line (%s)",
1222                       __FUNCTION__, env_var_name, extra_arg);
1223       }
1224     } while (has_env_var);
1225 
1226     if (inferior_args && inferior_args->GetArgumentCount() > 0) {
1227       debugserver_args.AppendArgument("--");
1228       debugserver_args.AppendArguments(*inferior_args);
1229     }
1230 
1231     // Copy the current environment to the gdbserver/debugserver instance
1232     StringList env;
1233     if (Host::GetEnvironment(env)) {
1234       for (size_t i = 0; i < env.GetSize(); ++i)
1235         launch_info.GetEnvironmentEntries().AppendArgument(env[i].c_str());
1236     }
1237 
1238     // Close STDIN, STDOUT and STDERR.
1239     launch_info.AppendCloseFileAction(STDIN_FILENO);
1240     launch_info.AppendCloseFileAction(STDOUT_FILENO);
1241     launch_info.AppendCloseFileAction(STDERR_FILENO);
1242 
1243     // Redirect STDIN, STDOUT and STDERR to "/dev/null".
1244     launch_info.AppendSuppressFileAction(STDIN_FILENO, true, false);
1245     launch_info.AppendSuppressFileAction(STDOUT_FILENO, false, true);
1246     launch_info.AppendSuppressFileAction(STDERR_FILENO, false, true);
1247 
1248     if (log) {
1249       StreamString string_stream;
1250       Platform *const platform = nullptr;
1251       launch_info.Dump(string_stream, platform);
1252       log->Printf("launch info for gdb-remote stub:\n%s",
1253                   string_stream.GetString().c_str());
1254     }
1255     error = Host::LaunchProcess(launch_info);
1256 
1257     if (error.Success() &&
1258         (launch_info.GetProcessID() != LLDB_INVALID_PROCESS_ID) &&
1259         pass_comm_fd == -1) {
1260       if (named_pipe_path.size() > 0) {
1261         error = socket_pipe.OpenAsReader(named_pipe_path, false);
1262         if (error.Fail())
1263           if (log)
1264             log->Printf("GDBRemoteCommunication::%s() "
1265                         "failed to open named pipe %s for reading: %s",
1266                         __FUNCTION__, named_pipe_path.c_str(),
1267                         error.AsCString());
1268       }
1269 
1270       if (socket_pipe.CanWrite())
1271         socket_pipe.CloseWriteFileDescriptor();
1272       if (socket_pipe.CanRead()) {
1273         char port_cstr[PATH_MAX] = {0};
1274         port_cstr[0] = '\0';
1275         size_t num_bytes = sizeof(port_cstr);
1276         // Read port from pipe with 10 second timeout.
1277         error = socket_pipe.ReadWithTimeout(
1278             port_cstr, num_bytes, std::chrono::seconds{10}, num_bytes);
1279         if (error.Success() && (port != nullptr)) {
1280           assert(num_bytes > 0 && port_cstr[num_bytes - 1] == '\0');
1281           *port = StringConvert::ToUInt32(port_cstr, 0);
1282           if (log)
1283             log->Printf("GDBRemoteCommunication::%s() "
1284                         "debugserver listens %u port",
1285                         __FUNCTION__, *port);
1286         } else {
1287           if (log)
1288             log->Printf("GDBRemoteCommunication::%s() "
1289                         "failed to read a port value from pipe %s: %s",
1290                         __FUNCTION__, named_pipe_path.c_str(),
1291                         error.AsCString());
1292         }
1293         socket_pipe.Close();
1294       }
1295 
1296       if (named_pipe_path.size() > 0) {
1297         const auto err = socket_pipe.Delete(named_pipe_path);
1298         if (err.Fail()) {
1299           if (log)
1300             log->Printf(
1301                 "GDBRemoteCommunication::%s failed to delete pipe %s: %s",
1302                 __FUNCTION__, named_pipe_path.c_str(), err.AsCString());
1303         }
1304       }
1305 
1306       // Make sure we actually connect with the debugserver...
1307       JoinListenThread();
1308     }
1309   } else {
1310     error.SetErrorStringWithFormat("unable to locate " DEBUGSERVER_BASENAME);
1311   }
1312 
1313   if (error.Fail()) {
1314     if (log)
1315       log->Printf("GDBRemoteCommunication::%s() failed: %s", __FUNCTION__,
1316                   error.AsCString());
1317   }
1318 
1319   return error;
1320 }
1321 
1322 void GDBRemoteCommunication::DumpHistory(Stream &strm) { m_history.Dump(strm); }
1323 
1324 GDBRemoteCommunication::ScopedTimeout::ScopedTimeout(
1325     GDBRemoteCommunication &gdb_comm, uint32_t timeout)
1326     : m_gdb_comm(gdb_comm) {
1327   m_saved_timeout = m_gdb_comm.SetPacketTimeout(timeout);
1328 }
1329 
1330 GDBRemoteCommunication::ScopedTimeout::~ScopedTimeout() {
1331   m_gdb_comm.SetPacketTimeout(m_saved_timeout);
1332 }
1333 
1334 // This function is called via the Communications class read thread when bytes
1335 // become available
1336 // for this connection. This function will consume all incoming bytes and try to
1337 // parse whole
1338 // packets as they become available. Full packets are placed in a queue, so that
1339 // all packet
1340 // requests can simply pop from this queue. Async notification packets will be
1341 // dispatched
1342 // immediately to the ProcessGDBRemote Async thread via an event.
1343 void GDBRemoteCommunication::AppendBytesToCache(const uint8_t *bytes,
1344                                                 size_t len, bool broadcast,
1345                                                 lldb::ConnectionStatus status) {
1346   StringExtractorGDBRemote packet;
1347 
1348   while (true) {
1349     PacketType type = CheckForPacket(bytes, len, packet);
1350 
1351     // scrub the data so we do not pass it back to CheckForPacket
1352     // on future passes of the loop
1353     bytes = nullptr;
1354     len = 0;
1355 
1356     // we may have received no packet so lets bail out
1357     if (type == PacketType::Invalid)
1358       break;
1359 
1360     if (type == PacketType::Standard) {
1361       // scope for the mutex
1362       {
1363         // lock down the packet queue
1364         std::lock_guard<std::mutex> guard(m_packet_queue_mutex);
1365         // push a new packet into the queue
1366         m_packet_queue.push(packet);
1367         // Signal condition variable that we have a packet
1368         m_condition_queue_not_empty.notify_one();
1369       }
1370     }
1371 
1372     if (type == PacketType::Notify) {
1373       // put this packet into an event
1374       const char *pdata = packet.GetStringRef().c_str();
1375 
1376       // as the communication class, we are a broadcaster and the
1377       // async thread is tuned to listen to us
1378       BroadcastEvent(eBroadcastBitGdbReadThreadGotNotify,
1379                      new EventDataBytes(pdata));
1380     }
1381   }
1382 }
1383