sys/shell: native: stop RIOT when the shell reads EOF

[benpicco]

Contribution description

Currently when the shell receives EOF on native, sending EOF
(ctrl + D) closes the stdin file descriptor, leading to all
consecutive reads to also return EOF.

The result is that shell_run_forever() will re-start the shell
forever in a loop, filling up the terminal with

> > > > > > > > > > > > > > > > > > > > > > …

until the user hits ctrl + C.

This is annoying.

Instead, cleanly shutdown RIOT when receiving EOF on native, which
should match the expected behaviour of most users.

Testing procedure

Run any native example.
Press ctrl + D.

Issues/PRs references

[kaspar030]

How about CONFIG_SHELL_SHUTDOWN_ON_EOF?

[benpicco]

Sure can change it - I just wanted to be consistent with SHELL_NO_ECHO and SHELL_NO_PROMPT

[kaspar030]

Sure can change it - I just wanted to be consistent with SHELL_NO_ECHO and SHELL_NO_PROMPT

ok, consistency is good. edit I mean, ok to leave as is.

[aabadie]

There is #10788 which is also related to this (it seems, I haven't checked in details) but it provides a different approach.

[benpicco]

@aabadie #10788 is for making the shell on the target exit on ctrl-d.
On native this is already turned into closing of stdin by the C library/the kernel, so the shell never sees the raw EOT.

[fjmolinas]

BTW I don't get the same result, My shell doesn't exit but there is not loop either it just keeps printing the prompt the amount of time CNTRL+D is pressed:

RIOT native interrupts/signals initialized.
LED_RED_OFF
LED_GREEN_ON
RIOT native board initialized.
RIOT native hardware initialization complete.

main(): This is RIOT! (Version: 2020.07-devel-108-gcac35-HEAD)
test_shell.
> > > > > 

> heelp
heelp
shell: command not found: heelp
> 

[fjmolinas]

Tested the PR rebased on master. Please rebase!

• master:

main(): This is RIOT! (Version: 2020.07-devel-1415-gae95e-HEAD)
test_shell.
> > > > > 

> 

> 

> > > > 

> 

• pr

LED_GREEN_ON
RIOT native board initialized.
RIOT native hardware initialization complete.

main(): This is RIOT! (Version: 2020.04-devel-1867-g2992d9-pr-13675)
test_shell.
> 
native: exiting
make: Leaving directory '/home/francisco/workspace/RIOT/tests/shell'

[benpicco]

On a second thought, how about we do

diff --git a/sys/include/shell.h b/sys/include/shell.h
index 234fe80b35..1045325dfb 100644
--- a/sys/include/shell.h
+++ b/sys/include/shell.h
@@ -21,6 +21,7 @@
 #define SHELL_H
 
 #include <stdint.h>
+#include "periph/pm.h"
 
 #include "kernel_defines.h"
 
@@ -97,7 +98,12 @@ static inline void shell_run_forever(const shell_command_t *commands,
 static inline void shell_run(const shell_command_t *commands,
                              char *line_buf, int len)
 {
+#ifdef CPU_NATIVE
+    shell_run_once(commands, line_buf, len);
+    pm_off();
+#else
     shell_run_forever(commands, line_buf, len);
+#endif
 }
 
 #ifdef __cplusplus

alternative solution proposed

[fjmolinas]

I'm unable to reproduce the described behaviour locally but @aabadie gets the same behviour. Not sure where the difference comes from, but I'm OK with this temporary fix. The proper fix IMO would be to not have native shell running in cookmode.

@benpicco feel free to squash when you add the comment.

[fjmolinas]

@benpicco the commit you reverted is still present!

[benpicco]

Good catch, dropped it.

[fjmolinas]

ACK.