gdb/python/lib/gdb/dap/io.py

   1 # Copyright 2022 Free Software Foundation, Inc.
   2
   3 # This program is free software; you can redistribute it and/or modify
   4 # it under the terms of the GNU General Public License as published by
   5 # the Free Software Foundation; either version 3 of the License, or
   6 # (at your option) any later version.
   7 #
   8 # This program is distributed in the hope that it will be useful,
   9 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  10 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11 # GNU General Public License for more details.
  12 #
  13 # You should have received a copy of the GNU General Public License
  14 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
  15
  16 import json
  17
  18 from .startup import start_thread, send_gdb
  19
  20
  21 def read_json(stream):
  22     """Read a JSON-RPC message from STREAM.
  23     The decoded object is returned."""
  24     # First read and parse the header.
  25     content_length = None
  26     while True:
  27         line = stream.readline()
  28         line = line.strip()
  29         if line == b"":
  30             break
  31         if line.startswith(b"Content-Length:"):
  32             line = line[15:].strip()
  33             content_length = int(line)
  34     data = bytes()
  35     while len(data) < content_length:
  36         new_data = stream.read(content_length - len(data))
  37         data += new_data
  38     result = json.loads(data)
  39     return result
  40
  41
  42 def start_json_writer(stream, queue):
  43     """Start the JSON writer thread.
  44     It will read objects from QUEUE and write them to STREAM,
  45     following the JSON-RPC protocol."""
  46
  47     def _json_writer():
  48         seq = 1
  49         while True:
  50             obj = queue.get()
  51             if obj is None:
  52                 # This is an exit request.  The stream is already
  53                 # flushed, so all that's left to do is request an
  54                 # exit.
  55                 send_gdb("quit")
  56                 break
  57             obj["seq"] = seq
  58             seq = seq + 1
  59             encoded = json.dumps(obj)
  60             body_bytes = encoded.encode("utf-8")
  61             header = f"Content-Length: {len(body_bytes)}\r\n\r\n"
  62             header_bytes = header.encode("ASCII")
  63             stream.write(header_bytes)
  64             stream.write(body_bytes)
  65             stream.flush()
  66
  67     start_thread("JSON writer", _json_writer)