Re: [Qemu-devel] [PATCH v5 8/9] qemu-binfmt-conf.sh: add option --clear

[Laurent Vivier]

On 11/03/2019 21:23, Unai Martinez-Corral wrote:
> This is a partial implementation.
> 
> Allows to remove a single or a list of already registered binfmt
> interpreters. Valid values are those in qemu_target_list.
> If TARGETS is empty, all the existing 'qemu-*' interpreters are
> removed.
> 
> This is partial because 'debian' and 'systemd' configurations are not
> supported. The script will exit with error 'option clear not
> implemented for this mode yet'.
> 
> Removal is done by printing '-1' as explained at:
> https://www.kernel.org/doc/Documentation/admin-guide/binfmt-misc.rst
> 
> Signed-off-by: Unai Martinez-Corral <address@hidden>
> ---
>  scripts/qemu-binfmt-conf.sh | 39 +++++++++++++++++++++++++++++++++++--
>  1 file changed, 37 insertions(+), 2 deletions(-)
> 
> diff --git a/scripts/qemu-binfmt-conf.sh b/scripts/qemu-binfmt-conf.sh
> index 2be9867727..382bdaabfe 100755
> --- a/scripts/qemu-binfmt-conf.sh
> +++ b/scripts/qemu-binfmt-conf.sh
> @@ -197,7 +197,7 @@ Options and associated environment variables:
> 
>  Argument             Env-variable     Description
>  TARGETS              QEMU_TARGETS     A single arch name or a list of them 
> (see all names below);
> -                                      if empty, configure all known targets;
> +                                      if empty, configure/clear all known 
> targets;
>                                        if 'NONE', no interpreter is 
> configured.
>  -h|--help                             display this usage
>  -Q|--path PATH       QEMU_PATH        set path to qemu interpreter(s)
> @@ -206,6 +206,8 @@ TARGETS              QEMU_TARGETS     A single arch name 
> or a list of them (see
>                                        uses are cloned from the open file.
>  -c|--credential      QEMU_CREDENTIAL  (yes) credential and security tokens 
> are calculated according
>                                        to the binary to interpret
> +-r|--clear           QEMU_CLEAR       (yes) remove registered interpreters 
> for target TARGETS;
> +                                      then exit.
>  -e|--exportdir PATH  DEBIANDIR        define where to write configuration 
> files
>                       SYSTEMDDIR
>  -s|--systemd                          don't write into /proc, generate 
> file(s) for
> @@ -218,6 +220,7 @@ QEMU_PATH=$QEMU_PATH
>  QEMU_SUFFIX=$QEMU_SUFFIX
>  QEMU_PERSISTENT=$QEMU_PERSISTENT
>  QEMU_CREDENTIAL=$QEMU_CREDENTIAL
> +QEMU_CLEAR=$QEMU_CLEAR
> 
>  To import templates with update-binfmts, use :
> 
> @@ -344,8 +347,28 @@ qemu_set_binfmts() {
>      done
>  }
> 
> +qemu_clear_notimplemented() {
> +    echo "ERROR: option clear not implemented for this mode yet" 1>&2
> +    usage
> +    exit 1
> +}
> +
> +qemu_clear_interpreter() {
> +    names='qemu-*'
> +    if [ $# -ne 0 ] ; then
> +        qemu_check_target_list $1
> +        unset names pre
> +        for t in $checked_target_list ; do
> +            names="${names}${pre}qemu-$t"
> +            pre=' -o -name '
> +        done
> +    fi
> +    find /proc/sys/fs/binfmt_misc/ -type f -name "$names" -exec sh -c 
> 'printf %s -1 > {}' \;

You don't need to use "find".

put the printf in the loop with the full path
/proc/sys/fs/binfmt_mist/qemu-$t.

For the ALL case, use the list of the known interpreters, or if you want
to remove them all, use the "status" file that does that.

Thanks,
Laurent