2:14 a.m.
On 2023/05/30 14:09, Hsin-Yi Wang wrote:
On Tue, May 30, 2023 at 10:31 AM HAGIO KAZUHITO(萩尾 一仁)
<k-hagio-ab(a)nec.com> wrote:
>
> On 2023/05/28 5:17, Hsin-Yi Wang wrote:
>> hi crash-utility community,
>>
>> When stdin is not a TTY, but all the other flags remain the same,
>> prompt ("crash> ") won't be displayed. An example use case is,
the
>> stdin of crash is replaced by a piped fd connected to another process.
>>
>> In process_command_line(), it checks if pc->flags does NOT have any of
>> the flag: READLINE|SILENT|CMDLINE_IFILE|RCHOME_IFILE|RCLOCAL_IFILE, a
>> prompt should be printed.
>>
>> But in setup_environment(), pc->flags is set to have READLINE flag[2],
>> the above check will not be true at all.
>>
>> Should READLINE be set for all cases in setup_environment()?
>> - If true, should the check in process_command_line() look for TTY
>> instead of READLINE? Since if pc->flags has TTY, [2] won't be true and
>> the prompt will be printed later in TTY's case[3].
>> - If false, where should be a proper place and conditions to set READLINE?
>>
>> Or is the current behavior intended? I may not fully understand the
>> design logic. Any explanations are appreciated.
>
> I don't know the full history of crash, but my impression of the flag is
> that probably it's an ancient code and almost meaningless now, but the
> current behavior is intended.
>
> What you want to do is displaying the prompt and command without a tty?
Interact with crash through another process that piped stdin/stdout
with crash to do additional input/output processing, so the filemode
won't work.
Ah, got it. So the prompt can be used as a delimiter or something? It
might be useful.
> This is also my imagination, but probably they wanted only command
> output like this without the prompt and command:
>
> # echo sys | crash -s
> KERNEL: /usr/lib/debug/lib/modules/4.18.0-305.el8.x86_64/vmlinux
> DUMPFILE: /proc/kcore
> CPUS: 16
> DATE: Tue May 30 11:15:41 JST 2023
> UPTIME: 19 days, 23:23:48
> LOAD AVERAGE: 0.18, 0.12, 0.09
> TASKS: 555
> NODENAME: r110j-1
> RELEASE: 4.18.0-305.el8.x86_64
> VERSION: #1 SMP Thu Apr 29 08:54:30 EDT 2021
> MACHINE: x86_64 (3400 Mhz)
> MEMORY: 63.9 GB
> #
But I wonder if the current behavior is intended, wouldn't [1] never
be run because of [2]?
[1]
https://github.com/crash-utility/crash/blob/05a3a328fcd8920e49926b6d1c9c8...
[2]
https://github.com/crash-utility/crash/blob/8246dce99dd23457e8c7a3fe9609c...
Right, I guessed that it ultimately became so after changes, although it
should have got removed. But maybe not.
Another not necessarily related data point is, I compared the gdb tool
and it will also give the prompt if no tty presented.
>
> Because if they wanted the prompt and command, it would be easily done
> like this...
>
> --- a/cmdline.c
> +++ b/cmdline.c
> @@ -139,6 +139,7 @@ process_command_line(void)
> } else {
> if (fgets(pc->command_line, BUFSIZE-1, stdin) == NULL)
> clean_exit(1);
> + fprintf(fp, "%s%s", pc->prompt, pc->command_line);
> clean_line(pc->command_line);
> strcpy(pc->orig_line, pc->command_line);
> }
Yeah, maybe print this before the fgets with fflush()? similar to [1],
or does the following make sense?
diff --git a/cmdline.c b/cmdline.c
index ded6551..181800a 100644
--- a/cmdline.c
+++ b/cmdline.c
@@ -65,7 +65,7 @@ process_command_line(void)
BZERO(pc->command_line, BUFSIZE);
if (!(pc->flags &
- (READLINE|SILENT|CMDLINE_IFILE|RCHOME_IFILE|RCLOCAL_IFILE)))
+ (TTY|SILENT|CMDLINE_IFILE|RCHOME_IFILE|RCLOCAL_IFILE)))
fprintf(fp, "%s", pc->prompt);
fflush(fp);
It does not print the input command line only with this, I would like to
also print it if we print the prompt. How about this?
--- a/cmdline.c
+++ b/cmdline.c
@@ -65,7 +65,7 @@ process_command_line(void)
BZERO(pc->command_line, BUFSIZE);
if (!(pc->flags &
- (READLINE|SILENT|CMDLINE_IFILE|RCHOME_IFILE|RCLOCAL_IFILE)))
+ (TTY|SILENT|CMDLINE_IFILE|RCHOME_IFILE|RCLOCAL_IFILE)))
fprintf(fp, "%s", pc->prompt);
fflush(fp);
@@ -139,6 +139,11 @@ process_command_line(void)
} else {
if (fgets(pc->command_line, BUFSIZE-1, stdin) == NULL)
clean_exit(1);
+
+ if (!(pc->flags & SILENT)) {
+ fprintf(fp, "%s", pc->command_line);
+ fflush(fp);
+ }
clean_line(pc->command_line);
strcpy(pc->orig_line, pc->command_line);
}
This looks consistent with the other types of crash session.
And we can still get only a command output with -s option.
# echo sys | crash -s
Thanks,
Kazu
>
>>
>> If you want the prompt and command with pre-generated crash commands,
>> you can use "crash -i" option. How about this?
>
> Filemode is not ideal if we want to pipe crash with another process
> that users interact with, since we will have to load vmlinux and
> dumpfile every time.
>
> But if this still looks like working as intended, I will close this issue.
>
> Thanks for your reply.
>
>>
>> # echo sys > cmd
>> # crash -i cmd
>>
>> Thanks,
>> Kazu
>>
>>>
>>> Thanks!
>>>
>>> [1]
https://github.com/crash-utility/crash/blob/05a3a328fcd8920e49926b6d1c9c8...
>>> [2]
https://github.com/crash-utility/crash/blob/8246dce99dd23457e8c7a3fe9609c...
>>> [3]
https://github.com/crash-utility/crash/blob/05a3a328fcd8920e49926b6d1c9c8...
>>>
>>> --
>>> Crash-utility mailing list
>>> Crash-utility(a)redhat.com
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>>> Contribution Guidelines: https://github.com/crash-utility/crash/wiki