cmd: exit: Exit functionality broken

[Max van den Biggelaar]

Hi Hector and Marek,

Thanks for your reply. I am glad that there is already a thread open for this problem. As reverting the commit seems to be the best way to resolve this problem, we will take the same approach in our forked U-Boot mainline source code.

I am looking forward to the solution in mainline U-Boot. Thanks for your support.

Met vriendelijke groet / Kind regards,

Max van den Biggelaar
Designer

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________________________________
From: Marek Vasut <marex at denx.de>
Sent: Tuesday, December 13, 2022 5:06 PM
To: Hector Palacios <hector.palacios at digi.com>; Max van den Biggelaar <max.van.den.biggelaar at prodrive-technologies.com>; u-boot at lists.denx.de <u-boot at lists.denx.de>
Cc: Martijn de Gouw <martijn.de.gouw at prodrive-technologies.com>
Subject: Re: cmd: exit: Exit functionality broken

On 12/13/22 16:41, Hector Palacios wrote:
> Hi Max,
>
> On 12/13/22 13:24, Max van den Biggelaar wrote:
>> 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://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fu-boot%2Fu-boot%2Fcommit%2F8c4e3b79bd0bb76eea16869e9666e19047c0d005&data=05%7C01%7Cmax.van.den.biggelaar%40prodrive-technologies.com%7Cdc9f555b4f9047280cb508dadd23f512%7C612607c95af74e7f8976faf1ae77be60%7C0%7C0%7C638065443753164173%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=nhHtOiLzPhWV0VXIQhXS5mvefORmuierzfOV%2B69o10A%3D&reserved=0) 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://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fu-boot%2Fu-boot%2Fcommit%2Fc26e454dfc6650428854fa2db3b1ed7f19e0ba0e&data=05%7C01%7Cmax.van.den.biggelaar%40prodrive-technologies.com%7Cdc9f555b4f9047280cb508dadd23f512%7C612607c95af74e7f8976faf1ae77be60%7C0%7C0%7C638065443753164173%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=WPDkviE3%2Bw%2BVOb4AQ34byFp99Ovi18fTGR%2F8C4t0SHo%3D&reserved=0>
>> Signed-off-by: Marek Vasut <marex at denx.de>
>> Cc: Pantelis Antoniou <pantelis.antoniou at konsulko.com>
>> Cc: Tom Rini <trini at 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://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fu-boot%2Fu-boot%2Fblob%2Fmaster%2Fcommon%2Fcli_hush.c%23L3207&data=05%7C01%7Cmax.van.den.biggelaar%40prodrive-technologies.com%7Cdc9f555b4f9047280cb508dadd23f512%7C612607c95af74e7f8976faf1ae77be60%7C0%7C0%7C638065443753164173%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=iZMaTL7J477g9JKwiI0%2BmLurEmNzcl4rhTEoF0WPlNs%3D&reserved=0
>>
>> 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?
>
> I believe Marek's commit must be reverted as having 'exit' return a code
> other than 0 (success) or 1 (error) was never part of U-Boot. I don't
> know if reverting may break newer scripts, but now many scripts are
> broken because 'exit' does not currently work.
>
> Anyway, Marek wanted to give it a second thought. See
> https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.mail-archive.com%2Fu-boot%2540lists.denx.de%2Fmsg456830.html&data=05%7C01%7Cmax.van.den.biggelaar%40prodrive-technologies.com%7Cdc9f555b4f9047280cb508dadd23f512%7C612607c95af74e7f8976faf1ae77be60%7C0%7C0%7C638065443753164173%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=t1obkYm9Zye5BSsip8PVkwYwMdPj8kt0h5LBieJajNc%3D&reserved=0

Right, reverting the aforementioned commit breaks exit return value
handling. Special-casing 'exit' in shell with strcmp is not the right
approach, the exit behavior clearly needs closer look. I just haven't
had time to do that yet and reply to Hector.