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1 // Copyright 2020 the V8 project authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4 
5 #ifndef V8_DEBUG_WASM_GDB_SERVER_PACKET_H_
6 #define V8_DEBUG_WASM_GDB_SERVER_PACKET_H_
7 
8 #include <string>
9 
10 #include "src/base/macros.h"
11 
12 namespace v8 {
13 namespace internal {
14 namespace wasm {
15 namespace gdb_server {
16 
17 class V8_EXPORT_PRIVATE Packet {
18  public:
19   Packet();
20 
21   // Empty the vector and reset the read/write pointers.
22   void Clear();
23 
24   // Reset the read pointer, allowing the packet to be re-read.
25   void Rewind();
26 
27   // Return true of the read pointer has reached the write pointer.
28   bool EndOfPacket() const;
29 
30   // Store a single raw 8 bit value
31   void AddRawChar(char ch);
32 
33   // Store a block of data as hex pairs per byte
34   void AddBlock(const void* ptr, uint32_t len);
35 
36   // Store a byte as a 2 chars block.
37   void AddWord8(uint8_t val);
38 
39   // Store a number up to 64 bits, formatted as a big-endian hex string with
40   // preceeding zeros removed.  Since zeros can be removed, the width of this
41   // number is unknown, and the number is always followed by a NULL or a
42   // separator (non hex digit).
43   void AddNumberSep(uint64_t val, char sep);
44 
45   // Add a raw string.
46   void AddString(const char* str);
47 
48   // Add a string stored as a stream of ASCII hex digit pairs.  It is safe
49   // to use any non-null character in this stream.  If this does not terminate
50   // the packet, there should be a separator (non hex digit) immediately
51   // following.
52   void AddHexString(const char* str);
53 
54   // Retrieve a single character if available
55   bool GetRawChar(char* ch);
56 
57   // Retrieve "len" ASCII character pairs.
58   bool GetBlock(void* ptr, uint32_t len);
59 
60   // Retrieve a 8, 16, 32, or 64 bit word as pairs of hex digits.  These
61   // functions will always consume bits/4 characters from the stream.
62   bool GetWord8(uint8_t* val);
63 
64   // Retrieve a number (formatted as a big-endian hex string) and a separator.
65   // If 'sep' is null, the separator is consumed but thrown away.
66   bool GetNumberSep(uint64_t* val, char* sep);
67 
68   // Get a string from the stream
69   bool GetString(std::string* str);
70   bool GetHexString(std::string* str);
71 
72   // Return a pointer to the entire packet payload
73   const char* GetPayload() const;
74   size_t GetPayloadSize() const;
75 
76   // Returns true and the sequence number, or false if it is unset.
77   bool GetSequence(int32_t* seq) const;
78 
79   // Parses sequence number in package data and moves read pointer past it.
80   void ParseSequence();
81 
82   // Set the sequence number.
83   void SetSequence(int32_t seq);
84 
85   enum class ErrDef { None = 0, BadFormat = 1, BadArgs = 2, Failed = 3 };
86   void SetError(ErrDef);
87 
88   // Returns the full content of a GDB-remote packet, in the format:
89   //    $payload#checksum
90   // where the two-digit checksum is computed as the modulo 256 sum of all
91   // characters between the leading ‘$’ and the trailing ‘#’.
92   std::string GetPacketData() const;
93 
94  private:
95   int32_t seq_;
96   std::string data_;
97   size_t read_index_;
98 };
99 
100 }  // namespace gdb_server
101 }  // namespace wasm
102 }  // namespace internal
103 }  // namespace v8
104 
105 #endif  // V8_DEBUG_WASM_GDB_SERVER_PACKET_H_
106