cmd: exit: Exit functionality broken

* cmd: exit: Exit functionality broken
@ 2022-12-13 12:24 Max van den Biggelaar
  2022-12-13 15:41 ` Hector Palacios
  0 siblings, 1 reply; 4+ messages in thread
From: Max van den Biggelaar @ 2022-12-13 12:24 UTC (permalink / raw)
  To: u-boot, marex; +Cc: Martijn de Gouw

Hi,

I have a question regarding the U-Boot exit command. We are currently using mainline U-Boot 2022.04 version to provide our embedded systems with a bootloader image. To start our firmware via U-Boot environment, we use a bootscript to start our firmware. However, when we tried to exit a bootscript with the exit command, the bootscript was never exited.

After debugging to investigate the problem, we found this commit (https://github.com/u-boot/u-boot/commit/8c4e3b79bd0bb76eea16869e9666e19047c0d005) in mainline U-Boot:
cmd: exit: Fix return value

In case exit is called in a script without parameter, the command
returns -2 ; in case exit is called with a numerical parameter,
the command returns -2 and lower. This leads to the following problem:
=> setenv foo 'echo bar ; exit 1' ; run foo ; echo $?
bar
0
=> setenv foo 'echo bar ; exit 0' ; run foo ; echo $?
bar
0
=> setenv foo 'echo bar ; exit -2' ; run foo ; echo $?
bar
0
That is, no matter what the 'exit' command argument is, the return
value is always 0 and so it is not possible to use script return
value in subsequent tests.

Fix this and simplify the exit command such that if exit is called with
no argument, the command returns 0, just like 'true' in cmd/test.c. In
case the command is called with any argument that is positive integer,
the argument is set as return value.
=> setenv foo 'echo bar ; exit 1' ; run foo ; echo $?
bar
1
=> setenv foo 'echo bar ; exit 0' ; run foo ; echo $?
bar
0
=> setenv foo 'echo bar ; exit -2' ; run foo ; echo $?
bar
0

Note that this does change ABI established in 2004 , although it is
unclear whether that ABI was originally OK or not.

Fixes: c26e454<https://github.com/u-boot/u-boot/commit/c26e454dfc6650428854fa2db3b1ed7f19e0ba0e>
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
Cc: Tom Rini <trini@konsulko.com>

This commit does solve the problem of returning the correct value given to the exit command, but this breaks the following source code in common/cli_hush.c:
https://github.com/u-boot/u-boot/blob/master/common/cli_hush.c#L3207

In the previous versions of U-Boot, such as 2020.04, the exit command returned -2, which was expected of the exit command API. However, after the patch above to fix the return value, -2 was never returned and the functionality to exit a bootscript or mainline U-Boot shell is not supported anymore. Thus, by the patch above the return value is fixed, but the functionality of the exit command is broken.

My question is if the functionality of this patch is fully tested/qualified to push in mainline U-Boot source code? And if so, is the functionality of the exit command also going to be fixed so that in future U-Boot source code releases bootscripts can be exited with this command?

Thank you in advance for the response.

Met vriendelijke groet / Kind regards,

Max van den Biggelaar
Designer

Mobile  +31 62 57 28 396
Phone   +31 40 26 76 200
Address         Science Park Eindhoven 5501
5692 EM SON, The Netherlands

www.prodrive-technologies.com<http://www.prodrive-technologies.com>

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