Re: [PATCH v3] Introduce remote_target_is_gdbserver

[Doug Evans <xdje42@gmail.com>]

Simon Marchi <simon.marchi@ericsson.com> writes:
> This patch introduces a function in gdbserver-support.exp to find out
> whether the current target is GDBserver.
>
> The code was inspired from gdb.trace/qtor.exp, so it replaces the code
> there by a call to the new function.
>
> New in v3:
> - Remove useless "pass" in remote_target_is_gdbserver.
> - Coding style in qtro.exp (braces in condition).
> - Changelog entry about qtro.exp.
>
> gdb/testsuite/ChangeLog:
>
> 	* gdb.trace/qtro.exp: Replace gdbserver detection code by...
> 	* lib/gdbserver-support.exp (remote_target_is_gdbserver): New
> 	function.
> ---
>  gdb/testsuite/gdb.trace/qtro.exp        | 14 +-------------
>  gdb/testsuite/lib/gdbserver-support.exp | 18 ++++++++++++++++++
>  2 files changed, 19 insertions(+), 13 deletions(-)
>
> diff --git a/gdb/testsuite/gdb.trace/qtro.exp b/gdb/testsuite/gdb.trace/qtro.exp
> index 22b5051..700c157 100644
> --- a/gdb/testsuite/gdb.trace/qtro.exp
> +++ b/gdb/testsuite/gdb.trace/qtro.exp
> @@ -98,19 +98,7 @@ if { $traceframe_info_supported == -1 } {
>  }
>  
>  # Check whether we're testing with our own GDBserver.
> -set is_gdbserver -1
> -set test "probe for GDBserver"
> -gdb_test_multiple "monitor help" $test {
> -    -re "The following monitor commands are supported.*debug-hw-points.*remote-debug.*GDBserver.*$gdb_prompt $" {
> -	set is_gdbserver 1
> -	pass $test
> -    }
> -    -re "$gdb_prompt $" {
> -	set is_gdbserver 0
> -	pass $test
> -    }
> -}
> -if { $is_gdbserver == -1 } {
> +if { ![remote_target_is_gdbserver] } {
>      return -1
>  }
>  
> diff --git a/gdb/testsuite/lib/gdbserver-support.exp b/gdb/testsuite/lib/gdbserver-support.exp
> index 026a937..423c729 100644
> --- a/gdb/testsuite/lib/gdbserver-support.exp
> +++ b/gdb/testsuite/lib/gdbserver-support.exp
> @@ -436,3 +436,21 @@ proc mi_gdbserver_start_multi { } {
>  
>      return [mi_gdb_target_cmd $gdbserver_protocol $gdbserver_gdbport]
>  }
> +
> +# Return true if the current remote target is an instance of gdbserver.
> +
> +proc remote_target_is_gdbserver { } {
> +    global gdb_prompt
> +
> +    set is_gdbserver 0
> +    set test "Probing for GDBserver"
> +
> +    gdb_test_multiple "monitor help" $test {
> +	-re "The following monitor commands are supported.*Quit GDBserver.*$gdb_prompt $" {
> +		set is_gdbserver 1
> +	}
> +	-re "$gdb_prompt $" {
> +	}
> +    }
> +    return $is_gdbserver
> +}

Hi.

The original code allowed for a -1 value of is_gdbserver
to handle the case of "can't tell" (e.g. for a timeout or
whatever, IIUC).
While IWBN to not complicate the API of
remote_target_is_gdbserver by requiring the caller
to have to handle this, maybe it'd be best if the caller
did have to watch for -1 and not just assume "not gdbserver":
maybe a different test will want to handle all three cases
(can't-tell, no, or yes).
E.g., initialize is_gdbserver to -1, and watch for a -1 value
before returning.

proc remote_target_is_gdbserver { } {
    global gdb_prompt

    set is_gdbserver -1
    set test "Probing for GDBserver"

    gdb_test_multiple "monitor help" $test {
	-re "The following monitor commands are supported.*Quit GDBserver.*$gdb_prompt $" {
	    set is_gdbserver 1
	}
	-re "$gdb_prompt $" {
	    set is_gdbserver 0
	}
    }
    if { $is_gdbserver == -1 } {
	verbose -log "can't tell if using gdbserver or not" # or whatever
	set $is_gdbserver 0  # <<<< this part I'm not sure about
    }
    return $is_gdbserver

Also, I see an earlier version of the patch first
did a check for [is_remote_target] before calling
target_is_gdbserver, and the new version of the
patch changes that to just calling remote_target_is_gdbserver.
Since the function remote_target_is_gdbserver can
be used regardless of whether the target is remote,
let's remove "remote_" from the name.
ie., go back to target_is_gdbserver.

Hmmm, another thought.
Since this requires an exchange with the target,
IWBN to cache the result.
There's support for doing this in the harness,
grep for gdb_caching_proc.