1 //===-- GDBRemoteCommunication.h --------------------------------*- 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 #ifndef liblldb_GDBRemoteCommunication_h_
11 #define liblldb_GDBRemoteCommunication_h_
12 
13 #include "GDBRemoteCommunicationHistory.h"
14 
15 #include <condition_variable>
16 #include <mutex>
17 #include <queue>
18 #include <string>
19 #include <vector>
20 
21 #include "lldb/Core/Communication.h"
22 #include "lldb/Host/HostThread.h"
23 #include "lldb/Utility/Args.h"
24 #include "lldb/Utility/Listener.h"
25 #include "lldb/Utility/Predicate.h"
26 #include "lldb/Utility/StringExtractorGDBRemote.h"
27 #include "lldb/lldb-public.h"
28 
29 namespace lldb_private {
30 namespace process_gdb_remote {
31 
32 typedef enum {
33   eStoppointInvalid = -1,
34   eBreakpointSoftware = 0,
35   eBreakpointHardware,
36   eWatchpointWrite,
37   eWatchpointRead,
38   eWatchpointReadWrite
39 } GDBStoppointType;
40 
41 enum class CompressionType {
42   None = 0,    // no compression
43   ZlibDeflate, // zlib's deflate compression scheme, requires zlib or Apple's
44                // libcompression
45   LZFSE,       // an Apple compression scheme, requires Apple's libcompression
46   LZ4, // lz compression - called "lz4 raw" in libcompression terms, compat with
47        // https://code.google.com/p/lz4/
48   LZMA, // Lempel–Ziv–Markov chain algorithm
49 };
50 
51 class ProcessGDBRemote;
52 
53 class GDBRemoteCommunication : public Communication {
54 public:
55   enum {
56     eBroadcastBitRunPacketSent = kLoUserBroadcastBit,
57     eBroadcastBitGdbReadThreadGotNotify =
58         kLoUserBroadcastBit << 1 // Sent when we received a notify packet.
59   };
60 
61   enum class PacketType { Invalid = 0, Standard, Notify };
62 
63   enum class PacketResult {
64     Success = 0,        // Success
65     ErrorSendFailed,    // Status sending the packet
66     ErrorSendAck,       // Didn't get an ack back after sending a packet
67     ErrorReplyFailed,   // Status getting the reply
68     ErrorReplyTimeout,  // Timed out waiting for reply
69     ErrorReplyInvalid,  // Got a reply but it wasn't valid for the packet that
70                         // was sent
71     ErrorReplyAck,      // Sending reply ack failed
72     ErrorDisconnected,  // We were disconnected
73     ErrorNoSequenceLock // We couldn't get the sequence lock for a multi-packet
74                         // request
75   };
76 
77   // Class to change the timeout for a given scope and restore it to the
78   // original value when the
79   // created ScopedTimeout object got out of scope
80   class ScopedTimeout {
81   public:
82     ScopedTimeout(GDBRemoteCommunication &gdb_comm,
83                   std::chrono::seconds timeout);
84     ~ScopedTimeout();
85 
86   private:
87     GDBRemoteCommunication &m_gdb_comm;
88     std::chrono::seconds m_saved_timeout;
89     // Don't ever reduce the timeout for a packet, only increase it. If the
90     // requested timeout if less than the current timeout, we don't set it
91     // and won't need to restore it.
92     bool m_timeout_modified;
93   };
94 
95   GDBRemoteCommunication(const char *comm_name, const char *listener_name);
96 
97   ~GDBRemoteCommunication() override;
98 
99   PacketResult GetAck();
100 
101   size_t SendAck();
102 
103   size_t SendNack();
104 
105   char CalculcateChecksum(llvm::StringRef payload);
106 
107   PacketType CheckForPacket(const uint8_t *src, size_t src_len,
108                             StringExtractorGDBRemote &packet);
109 
GetSendAcks()110   bool GetSendAcks() { return m_send_acks; }
111 
112   //------------------------------------------------------------------
113   // Set the global packet timeout.
114   //
115   // For clients, this is the timeout that gets used when sending
116   // packets and waiting for responses. For servers, this is used when waiting
117   // for ACKs.
118   //------------------------------------------------------------------
SetPacketTimeout(std::chrono::seconds packet_timeout)119   std::chrono::seconds SetPacketTimeout(std::chrono::seconds packet_timeout) {
120     const auto old_packet_timeout = m_packet_timeout;
121     m_packet_timeout = packet_timeout;
122     return old_packet_timeout;
123   }
124 
GetPacketTimeout()125   std::chrono::seconds GetPacketTimeout() const { return m_packet_timeout; }
126 
127   //------------------------------------------------------------------
128   // Start a debugserver instance on the current host using the
129   // supplied connection URL.
130   //------------------------------------------------------------------
131   Status StartDebugserverProcess(
132       const char *url,
133       Platform *platform, // If non nullptr, then check with the platform for
134                           // the GDB server binary if it can't be located
135       ProcessLaunchInfo &launch_info, uint16_t *port, const Args *inferior_args,
136       int pass_comm_fd); // Communication file descriptor to pass during
137                          // fork/exec to avoid having to connect/accept
138 
139   void DumpHistory(Stream &strm);
140   void SetHistoryStream(llvm::raw_ostream *strm);
141 
142   static llvm::Error ConnectLocally(GDBRemoteCommunication &client,
143                                     GDBRemoteCommunication &server);
144 
145 protected:
146   std::chrono::seconds m_packet_timeout;
147   uint32_t m_echo_number;
148   LazyBool m_supports_qEcho;
149   GDBRemoteCommunicationHistory m_history;
150   bool m_send_acks;
151   bool m_is_platform; // Set to true if this class represents a platform,
152                       // false if this class represents a debug session for
153                       // a single process
154 
155   CompressionType m_compression_type;
156 
157   PacketResult SendPacketNoLock(llvm::StringRef payload);
158   PacketResult SendRawPacketNoLock(llvm::StringRef payload,
159                                    bool skip_ack = false);
160 
161   PacketResult ReadPacket(StringExtractorGDBRemote &response,
162                           Timeout<std::micro> timeout, bool sync_on_timeout);
163 
164   PacketResult ReadPacketWithOutputSupport(
165       StringExtractorGDBRemote &response, Timeout<std::micro> timeout,
166       bool sync_on_timeout,
167       llvm::function_ref<void(llvm::StringRef)> output_callback);
168 
169   // Pop a packet from the queue in a thread safe manner
170   PacketResult PopPacketFromQueue(StringExtractorGDBRemote &response,
171                                   Timeout<std::micro> timeout);
172 
173   PacketResult WaitForPacketNoLock(StringExtractorGDBRemote &response,
174                                    Timeout<std::micro> timeout,
175                                    bool sync_on_timeout);
176 
CompressionIsEnabled()177   bool CompressionIsEnabled() {
178     return m_compression_type != CompressionType::None;
179   }
180 
181   // If compression is enabled, decompress the packet in m_bytes and update
182   // m_bytes with the uncompressed version.
183   // Returns 'true' packet was decompressed and m_bytes is the now-decompressed
184   // text.
185   // Returns 'false' if unable to decompress or if the checksum was invalid.
186   //
187   // NB: Once the packet has been decompressed, checksum cannot be computed
188   // based
189   // on m_bytes.  The checksum was for the compressed packet.
190   bool DecompressPacket();
191 
192   Status StartListenThread(const char *hostname = "127.0.0.1",
193                            uint16_t port = 0);
194 
195   bool JoinListenThread();
196 
197   static lldb::thread_result_t ListenThread(lldb::thread_arg_t arg);
198 
199   // GDB-Remote read thread
200   //  . this thread constantly tries to read from the communication
201   //    class and stores all packets received in a queue.  The usual
202   //    threads read requests simply pop packets off the queue in the
203   //    usual order.
204   //    This setup allows us to intercept and handle async packets, such
205   //    as the notify packet.
206 
207   // This method is defined as part of communication.h
208   // when the read thread gets any bytes it will pass them on to this function
209   void AppendBytesToCache(const uint8_t *bytes, size_t len, bool broadcast,
210                           lldb::ConnectionStatus status) override;
211 
212 private:
213   std::queue<StringExtractorGDBRemote> m_packet_queue; // The packet queue
214   std::mutex m_packet_queue_mutex; // Mutex for accessing queue
215   std::condition_variable
216       m_condition_queue_not_empty; // Condition variable to wait for packets
217 
218   HostThread m_listen_thread;
219   std::string m_listen_url;
220 
221   CompressionType m_decompression_scratch_type;
222   void *m_decompression_scratch;
223 
224   DISALLOW_COPY_AND_ASSIGN(GDBRemoteCommunication);
225 };
226 
227 } // namespace process_gdb_remote
228 } // namespace lldb_private
229 
230 namespace llvm {
231 template <>
232 struct format_provider<
233     lldb_private::process_gdb_remote::GDBRemoteCommunication::PacketResult> {
234   static void format(const lldb_private::process_gdb_remote::
235                          GDBRemoteCommunication::PacketResult &state,
236                      raw_ostream &Stream, StringRef Style);
237 };
238 } // namespace llvm
239 
240 #endif // liblldb_GDBRemoteCommunication_h_
241