The fidlcat
tool allows you to monitor and debug FIDL connections to trace individual FIDL messages sent and received by your component. Similar to the Fuchsia debugger (zxdb
), fidlcat
connects to a running debug_agent
component on the target device and monitors running processes.
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Setting up the monitoring session requires the following high-level steps:
debug_agent
component on the target device.fidlcat
client and connect to the target device.The simplest method to start a FIDL debug session is to use the ffx debug fidl
command, which does all of these in the context of your local Fuchsia build. However, these steps can also be performed manually if you need to configure them separately.
Below is an example fidlcat
message for a FIDL protocol request. The trace output contains helpful information for each translation, including:
echo-client.cm 256109:256122 zx_channel_read(handle:handle: e4c7c57f, options:uint32: 0, num_bytes:uint32: 48, num_handles:uint32: 0) -> ZX_OK received response fidl.examples.echo/Echo.EchoString = { response: string = "hello world!" }
Note: For complete details on fidlcat
usage and options, see Monitor and debug your FIDL calls.