Re: [RFC PATCH 4/4] trace-cruncher: Example script for uprobes high level API

[Yordan Karadzhov <y.karadz@gmail.com>]

On 31.03.22 г. 12:55 ч., Tzvetomir Stoyanov (VMware) wrote:
> Proposed example illustrates how to use uprobes high level API to trace
> all functions for user program. It can be attached to already running
> program, or run the program and trace its execution.
> 
> Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
> ---
>   examples/user_trace.py | 41 +++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 41 insertions(+)
>   create mode 100755 examples/user_trace.py
> 
> diff --git a/examples/user_trace.py b/examples/user_trace.py
> new file mode 100755
> index 0000000..0d3adcd
> --- /dev/null
> +++ b/examples/user_trace.py
> @@ -0,0 +1,41 @@
> +#!/usr/bin/env python3
> +
> +"""
> +SPDX-License-Identifier: CC-BY-4.0
> +
> +Copyright 2022 VMware Inc, Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
> +"""
> +
> +import sys
> +
> +import tracecruncher.ftracepy as ft
> +
> +if __name__ == "__main__":
> +    if len(sys.argv) < 2:
> +        print('Usage: ', sys.argv[0], ' [PROCESS]')
> +        sys.exit(1)
> +
> +    # Create new Ftrace instance to work in. The tracing in this new instance
> +    # is not going to be enabled yet.
> +    inst = ft.create_instance(tracing_on=False)
> +
> +    # Create a user tracing context for given process, exclude the libraries
> +    if sys.argv[1].isdigit():
> +        utrace = ft.user_trace(pid=int(sys.argv[1]), follow_libs=False)
> +    else:
> +        utrace = ft.user_trace(name=sys.argv[1], follow_libs=False)
> +
> +    # Trace execution of all available functions in the given process
> +    utrace.add_function(fname = "*")
> +
> +    # Add trace points on functions return as well
> +    utrace.add_ret_function(fname = "*")
> +
> +    # Start tracing in an instance
> +    utrace.start(instance = inst)
> +
> +    # Read the trace buffer during the trace until ctrl-c is pressed
> +    ft.read_trace(instance=inst)
> +
> +    # Disable the tracing
> +    utrace.stop(instance = inst)

The "stop" must be performed by the 'destroy' method of utrace object.
And 'destroy' must be called automatically at exit.

Thanks!
Yordan