[PATCH] shell script error management in ash (set of 6 patches)

[Harald van Dijk]

Hi,

In bash, the ERR trap is documented as triggering in under the exact 
same conditions that 'set -e' would cause the shell to abort. This is 
not what you have implemented, you have implemented it as triggering 
whenever a simple command returns non-zero. Consider:

   trap "echo ERR" ERR
   (:) >/access-denied

With bash, this prints:

   bash: line 2: /access-denied: Permission denied
   ERR

With your patches, this prints:

   ash: can't create /access-denied: Permission denied

That is, the ERR action is not executed when it should be. The command 
that failed here is not a simple command.

Consider:

   trap "echo ERR" ERR
   false || true

With bash, this prints nothing. With your patches, this prints ERR. That 
is, the ERR action is executed when it should not be. The command that 
failed here is one that had its exit status tested.

On 14/08/2021 17:14, Roberto A. Foglietta wrote:
> Hi all,
> 
>   I will send the whole six patches developed in these days with the 
> test suite in a tarball.
> 
> busybox-1.33.1-1of6-add-trap-ERR-to-ash.patch
> busybox-1.33.1-2of6-trap-ERR-fix-global-LINENO.patch
> busybox-1.33.1-3of6-set-E-error-trace-added.patch
> busybox-1.33.1-4of6-global-FUNCNAME.patch
> busybox-1.33.1-5of6-multiline-trap-LINENO-bugfix.patch
> busybox-1.33.1-6of6-when-FUNCNAME-is-null-bugfix.patch
> 
>   The whole set enanches the shell script management in ash (compatible 
> with bash)
> 
>   Best regards,
> -- 
> Roberto A. Foglietta
> +39.349.33.30.697
> 
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