Re: [Crash-utility] [PATCH] Output prompt when stdin is not a TTY.
On Wed, May 31, 2023 at 10:54 AM HAGIO KAZUHITO(萩尾 一仁)
<k-hagio-ab(a)nec.com> wrote:
On 2023/05/31 3:13, Hsin-Yi Wang wrote:
> When stdin is not a TTY, prompt ("crash> ") won't be displayed. If
> another process interact with crash with piped stdin/stdout, it will not
> get the prompt as a delimiter.
>
> Compared to other debugger like gdb, crash seems intended to give a
> prompt in this case in the beginning of process_command_line(). It
> checks if pc->flags does NOT have any of
> READLINE|SILENT|CMDLINE_IFILE|RCHOME_IFILE|RCLOCAL_IFILE, a
> prompt should be printed. The check will never be true since READLINE is
> set in setup_environment() unconditionally. It makes more sense to
> change the READLINE flag in the check to TTY instead.
>
> Additionally, when stdin is not TTY, repeat the command line from user
> after prompt, which can give more context.
>
> The prompt and command line can be opt out by using the silent (-s) flag.
>
> Signed-off-by: Hsin-Yi Wang <hsinyi(a)chromium.org>
Thanks, but I found a case that prints two prompts, after a fatal error:
# cat ~/.crashrc
sys config <<-- any command that fails with error(FATAL)
sys
# echo quit | crash
...
2 crash> sys config
sys: kernel_config_data does not exist in this kernel
1 crash> 2 crash> sys
KERNEL: /usr/lib/debug/lib/modules/4.18.0-305.el8.x86_64/vmlinux
...
where the crash has this:
--- a/cmdline.c
+++ b/cmdline.c
@@ -66,7 +66,7 @@ process_command_line(void)
if (!(pc->flags &
(TTY|SILENT|CMDLINE_IFILE|RCHOME_IFILE|RCLOCAL_IFILE)))
- fprintf(fp, "%s", pc->prompt);
+ fprintf(fp, "1 %s", pc->prompt);
fflush(fp);
/*
@@ -1487,7 +1487,7 @@ exec_input_file(void)
continue;
if (!(pc->flags & SILENT)) {
- fprintf(fp, "%s%s", pc->prompt, buf);
+ fprintf(fp, "2 %s%s", pc->prompt, buf);
I don't think we need to print a prompt again here. It can be used as
a delimiter when all the previous output are done and waiting for user
input. If we print the prompt again. what it will read:
crash 8.0.3++
1 crash>
// suppose stdin has cmd1 after here.
2 crash> cmd1
cmd1_output
1 crash>
// supposes stdin has cmd2 after here.
2 crash> cmd2
cmd2_output
Without the 2nd prompt:
crash 8.0.3++
1 crash>
// suppose stdin has cmd1 after here.
cmd1
cmd1_output
1 crash>
// suppose stdin has cmd2 after here.
cmd2
cmd2_output
fflush(fp);
}
Can we avoid this?
Thanks,
Kazu
> ---
> v1:
> - The original discussion:
https://listman.redhat.com/archives/crash-utility/2023-May/010710.html
> - Kazu: provide the idea to print the command line as well.
> ---
> cmdline.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/cmdline.c b/cmdline.c
> index ded6551..9821d86 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);
>
> @@ -139,6 +139,10 @@ 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);
> }