Re: [OE-core] [PATCH v6 6/7] utils: Add cmdline_shebang_wrapper util.

[Jacob Kroon <jacob.kroon@gmail.com>]

On 6/19/22 21:20, Paulo Neves wrote:
> Useful to work around shebang relocation issues, where
> shebangs are too long or have arguments in them, thus preventing them
> from using the /usr/bin/env shebang.
> ---
>   .../wrapper/cmdline-shebang-wrapper-test.bb   | 21 ++++++++++++
>   .../recipes-test/wrapper/files/test.awk       |  2 ++
>   meta/classes/utils.bbclass                    | 34 +++++++++++++++++++
>   meta/lib/oeqa/selftest/cases/wrapper.py       | 11 ++++++
>   4 files changed, 68 insertions(+)
>   create mode 100644 meta-selftest/recipes-test/wrapper/cmdline-shebang-wrapper-test.bb
>   create mode 100644 meta-selftest/recipes-test/wrapper/files/test.awk
>   create mode 100644 meta/lib/oeqa/selftest/cases/wrapper.py
> 
> diff --git a/meta-selftest/recipes-test/wrapper/cmdline-shebang-wrapper-test.bb b/meta-selftest/recipes-test/wrapper/cmdline-shebang-wrapper-test.bb
> new file mode 100644
> index 0000000000..c4126a41fc
> --- /dev/null
> +++ b/meta-selftest/recipes-test/wrapper/cmdline-shebang-wrapper-test.bb
> @@ -0,0 +1,21 @@
> +SUMMARY = "Check that create_cmdline_shebang works"
> +LICENSE = "MIT"
> +LIC_FILES_CHKSUM = "file://${COREBASE}/meta/COPYING.MIT;md5=3da9cfbcb788c80a0384361b4de20420"
> +INHIBIT_DEFAULT_DEPS = "1"
> +
> +SRC_URI += "file://test.awk"
> +
> +EXCLUDE_FROM_WORLD = "1"
> +do_install() {
> +    install -d ${D}${bindir}
> +    install -m 0755 ${WORKDIR}/test.awk ${D}${bindir}/test
> +    sed -i -e 's|@AWK_BIN@|${bindir}/awk|g' ${D}${bindir}/test
> +    create_cmdline_shebang_wrapper ${D}${bindir}/test
> +    if [ $(${D}${bindir}/test) != "Don't Panic!" ]; then
> +        bbfatal "Wrapper is broken"
> +    else
> +        bbnote "Wrapper is good"
> +    fi
> +}
> +
> +BBCLASSEXTEND = "native"
> diff --git a/meta-selftest/recipes-test/wrapper/files/test.awk b/meta-selftest/recipes-test/wrapper/files/test.awk
> new file mode 100644
> index 0000000000..91429197b1
> --- /dev/null
> +++ b/meta-selftest/recipes-test/wrapper/files/test.awk
> @@ -0,0 +1,2 @@
> +#! @AWK_BIN@ -f
> +BEGIN { print "Don't Panic!" }
> diff --git a/meta/classes/utils.bbclass b/meta/classes/utils.bbclass
> index b4eb3d38ab..b58c22771f 100644
> --- a/meta/classes/utils.bbclass
> +++ b/meta/classes/utils.bbclass
> @@ -184,6 +184,40 @@ END
>   	chmod +x $cmd
>   }
>   
> +create_cmdline_shebang_wrapper () {
> +	# Create a wrapper script where commandline options are needed
> +	#
> +	# These are useful to work around shebang relocation issues, where shebangs are too
> +	# long or have arguments in them, thus preventing them from using the /usr/bin/env
> +	# shebang
> +	#
> +	# Usage: create_cmdline_wrapper FILENAME <extra-options>
> +
> +	cmd=$1
> +	shift
> +
> +	echo "Generating wrapper script for $cmd"
> +
> +	# Strip #! and get remaining interpreter + arg
> +	argument="$(sed -ne 's/^#! *//p;q' $cmd)"
> +	# strip the shebang from the real script as we do not want it to be usable anyway
> +	tail -n +2 $cmd > $cmd.real
> +	cmdname=$(basename $cmd)
> +	dirname=$(dirname $cmd)
> +	cmdoptions=$@
> +	if [ "${base_prefix}" != "" ]; then
> +		relpath=`python3 -c "import os; print(os.path.relpath('${D}${base_prefix}', '$dirname'))"`
> +		cmdoptions=`echo $@ | sed -e "s:${base_prefix}:\\$realdir/$relpath:g"`
> +	fi
> +	cat <<END >$cmd
> +#!/usr/bin/env bash
> +realpath=\`readlink -fn \$0\`
> +realdir=\`dirname \$realpath\`
> +exec -a \$realdir/$cmdname $argument \$realdir/$cmdname.real $cmdoptions "\$@"
> +END
> +	chmod +x $cmd
> +}
> +

Maybe this has already been raised before, but the wrapper above does a 
couple of addtitional forks, which could be avoided if we use a python 
wrapper script instead.

Jacob

>   create_wrapper () {
>   	# Create a wrapper script where extra environment variables are needed
>   	#
> diff --git a/meta/lib/oeqa/selftest/cases/wrapper.py b/meta/lib/oeqa/selftest/cases/wrapper.py
> new file mode 100644
> index 0000000000..6de63310c0
> --- /dev/null
> +++ b/meta/lib/oeqa/selftest/cases/wrapper.py
> @@ -0,0 +1,11 @@
> +from oeqa.selftest.case import OESelftestTestCase
> +from oeqa.utils.commands import bitbake
> +
> +class WrapperTests(OESelftestTestCase):
> +    def test_shebang_wrapper(self):
> +        """
> +        Summary:   Build a recipe which will fail if the cmdline_shebang_wrapper function is defective.
> +        Expected:  Exit status to be 0.
> +        Author:    Paulo Neves <ptsneves@gmail.com>
> +        """
> +        res = bitbake("cmdline-shebang-wrapper-test -c install", ignore_status=False)
> 
> 
> 
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