On 25/04/2021 22:26, Jason Molenda wrote:
I was looking at lldb-platform and I noticed I implemented the A packet in it,
and I was worried I might have the same radix error as lldb in there, but this
code I wrote made me laugh:
const char *p = pkt.c_str() + 1; // skip the 'A'
std::vector packet_contents =
get_fields_from_delimited_string (p, ',');
std::vector inferior_arguments;
std::string executable_filename;
if (packet_contents.size() % 3 != 0)
{
log_error ("A packet received with fields that are not a multiple of 3:
%s\n", pkt.c_str());
}
unsigned long tuples = packet_contents.size() / 3;
for (int i = 0; i < tuples; i++)
{
std::string length_of_argument_str = packet_contents[i * 3];
std::string argument_number_str = packet_contents[(i * 3) + 1];
std::string argument = decode_asciihex (packet_contents[(i * 3) +
2].c_str());
int len_of_argument;
if (ascii_to_i (length_of_argument_str, 16, len_of_argument) == false)
log_error ("Unable to parse length-of-argument field of A packet: %s in
full packet %s\n",
length_of_argument_str.c_str(), pkt.c_str());
int argument_number;
if (ascii_to_i (argument_number_str, 16, argument_number) == false)
log_error ("Unable to parse argument-number field of A packet: %s in
full packet %s\n",
argument_number_str.c_str(), pkt.c_str());
if (argument_number == 0)
{
executable_filename = argument;
}
inferior_arguments.push_back (argument);
}
These A packet fields give you the name of the binary and the arguments to pass
on the cmdline. My guess is at some point in the past the arguments were not
asciihex encoded, so you genuinely needed to know the length of each argument.
But now, of course, and you could write a perfectly fine client that mostly
ignores argnum and arglen altogether.
That's quite clever, actually. I like it. :)
I wrote a fix for the A packet for debugserver using a 'a-packet-base16'
feature in qSupported to activate it, and tested it by hand, works correctly.
If we're all agreed that this is how we'll request/indicate these protocol
fixes, I can put up a phab etc and get this started.
I think that's fine, though possible changing the servers to just ignore
the length fields, like you did above, might be even better, as then
they will work fine regardless of which client they are talking to. They
still should advertise their non-brokenness so that the client can form
the right packet, but this will be just a formality to satisfy protocol
purists (or pickier servers), and not make a functional difference.
pl
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