Re: [PATCH] Initial implementation of Debugger Adapter Protocol

[Tom de Vries <tdevries@suse.de>]

On 9/1/22 18:30, Tom Tromey via Gdb-patches wrote:
> +def read_json(stream):
> +    """Read a JSON-RPC message from STREAM.
> +    The decoded object is returned."""
> +    # First read and parse the header.
> +    content_length = None
> +    while True:
> +        line = stream.readline()
> +        line = line.strip()
> +        if line == b"":
> +            break
> +        if line.startswith(b"Content-Length:"):
> +            line = line[15:].strip()
> +            content_length = int(line)
> +    data = bytes()
> +    while len(data) < content_length:
> +        new_data = stream.read(content_length - len(data))
> +        data += new_data
> +    result = json.loads(data)
> +    return result

Hi,

In case you haven't seen it, on IRC someone mentioned:
...
[10:53] <john3> does -i dap already something usable?  I get a python 
exception on startup: /usr/local/share/gdb/python/gdb/dap/io.py    while 
len(data) < content_length:  "TypeError: '<' not supported between 
instances of 'int' and 'NoneType'\n
...

I didn't manage to reproduce this, but looking at the code I think it's 
possible that this could be triggered, and that this would fix it:
...
diff --git a/gdb/python/lib/gdb/dap/io.py b/gdb/python/lib/gdb/dap/io.py
index 656ac08b4ec..1d561f07665 100644
--- a/gdb/python/lib/gdb/dap/io.py
+++ b/gdb/python/lib/gdb/dap/io.py
@@ -22,7 +22,7 @@ def read_json(stream):
      """Read a JSON-RPC message from STREAM.
      The decoded object is returned."""
      # First read and parse the header.
-    content_length = None
+    content_length = 0
      while True:
          line = stream.readline()
          line = line.strip()
...

Thanks,
- Tom