#! /bin/bash

#

# This script is called during external module building to create dependencies

# both upon the RHEL kernel, and on additional external modules. Symbols that

# cannot be reconciled against those provided by the kernel are assumed to be

# provided by an external module and "ksym" replaces th regular "kernel" dep.

IFS=$'\n'

# Extract all of the symbols provided by this module.

all_provides() {

    for module in "$@"; do

        tmpfile=""

        if [ "x${module%.ko}" = "x${module}" ]; then

            tmpfile=$(mktemp -t ${0##*/}.XXXXXX.ko)

            proc_bin=

            case "${module##*.}" in

            zst)

                    proc_bin=zstd

                    ;;

            xz)

                    proc_bin=xz

                    ;;

            bz2)

                    proc_bin=bzip2

                    ;;

            gz)

                    proc_bin=gzip

                    ;;

            esac

            [ -n "$proc_bin" ] || continue

            "$proc_bin" -d -c - < "$module" > "$tmpfile" || continue

            module="$tmpfile"

        fi

        if [[ -n $(nm "$module" | sed -r -ne 's:^0*([0-9a-f]+) A __crc_(.+):0x\1 \2:p') ]]; then

            nm "$module" \

            | sed -r -ne 's:^0*([0-9a-f]+) A __crc_(.+):0x\1 \2:p' \

            | awk --non-decimal-data '{printf("%s:0x%08x\n", $2, $1)}'

        else

            ELFRODATA=$(readelf -R .rodata "$module" | awk '/0x/{printf $2$3$4$5}')

            if [[ -n $(readelf -h "$module" | grep "little endian") ]]; then

                RODATA=$(echo $ELFRODATA | sed 's/\(..\)\(..\)\(..\)\(..\)/\4\3\2\1/g')

            else

                RODATA=$ELFRODATA

            fi

            # Commit binutils-2_33~1385[1] has changed (and binutils-2_35~1768[2]

            # has not reverted it) the calculated type for symbols in read-write

            # .rodata section from 'R' to 'D', since, apparently, many kernel

            # modules have it indeed read-write.

            #

            # [1] https://sourceware.org/git/?p=binutils-gdb.git;a=commitdiff;h=a288c270991d

            # [2] https://sourceware.org/git/?p=binutils-gdb.git;a=commitdiff;h=49d9fd42acef

            for sym in $(nm "$module" | sed -r -ne 's:^0*([0-9a-f]+) [DR] __crc_(.+):0x\1 \2:p'); do

                echo $sym $RODATA

            done \

            | awk --non-decimal-data '{printf("%s:0x%08s\n", $2, substr($3,($1*2)+1,8))}'

        fi

        [ -z "$tmpfile" ] || rm -f -- "$tmpfile"

    done \

    | LC_ALL=C sort -k1,1 -u

}

# Extract all of the requirements of this module.

all_requires() {

    for module in "$@"; do

        set -- $(/sbin/modinfo -F vermagic "$module" | sed -e 's: .*::' -e q)

        /sbin/modprobe --dump-modversions "$module" \

        | awk --non-decimal-data '

            BEGIN { FS = "\t" ; OFS = "\t" }

            {printf("%s:0x%08x\n", $2, $1)}' \

        | sed -r -e 's:$:\t'"$1"':'

    done \

    | LC_ALL=C sort -k1,1 -u

}

# Filter out requirements fulfilled by the module itself.

mod_requires() {

    LC_ALL=C join -t $'\t' -j 1 -v 1 \

        <(all_requires "$@") \

        <(all_provides "$@") \

    | LC_ALL=C sort -k1,1 -u

}

if ! [ -e /sbin/modinfo -a -e /sbin/modprobe ]; then

    cat > /dev/null

    exit 0

fi

check_kabi() {

    arch=$(uname -m)

    kabi_file="/lib/modules/kabi-current/kabi_stablelist_$arch"

    # If not installed, output a warning and return (continue)

    if [ ! -f "$kabi_file" ]; then

        echo "" >&2

        echo "********************************************************************************" >&2

        echo "*********************** KERNEL ABI COMPATIBILITY WARNING ***********************" >&2

        echo "********************************************************************************" >&2

        echo "The kernel ABI reference files (provided by "kabi-stablelists") were not found." >&2

        echo "No compatibility check was performed. Please install the kABI reference files" >&2

        echo "and rebuild if you would like to verify compatibility with kernel ABI." >&2

        echo "" >&2

        return

    fi

    unset non_kabi

    for symbol in "$@"; do

        if ! egrep "^[[:space:]]$symbol\$" $kabi_file >/dev/null; then

            non_kabi=("${non_kabi[@]}" "$symbol")

        fi

    done

    if [ ${#non_kabi[@]} -gt 0 ]; then

        echo "" >&2

        echo "********************************************************************************" >&2

        echo "*********************** KERNEL ABI COMPATIBILITY WARNING ***********************" >&2

        echo "********************************************************************************" >&2

        echo "The following kernel symbols are not guaranteed to remain compatible with" >&2

        echo "future kernel updates to this RHEL release:" >&2

        echo "" >&2

        for symbol in "${non_kabi[@]}"; do

            printf "\t$symbol\n" >&2

        done

        echo "" >&2

        echo "Red Hat recommends that you consider using only official kernel ABI symbols" >&2

        echo "where possible. Requests for additions to the kernel ABI can be filed with" >&2

        echo "your partner or customer representative (component: driver-update-program)." >&2

        echo "" >&2

    fi

}

modules=($(grep -E '/lib/modules/.+\.ko(\.gz|\.bz2|\.xz|\.zst)?$') "$@")

if [ ${#modules[@]} -gt 0 ]; then

    kernel=$(/sbin/modinfo -F vermagic "${modules[0]}" | sed -e 's: .*::' -e q)

    # get all that kernel provides

    symvers=$(mktemp -t ${0##*/}.XXXXX)

    cat /usr/src/kernels/$kernel/Module.symvers | awk '

        BEGIN { FS = "\t" ; OFS = "\t" }

        { print $2 ":" $1 }

    ' \

    | sed -r -e 's:$:\t'"$kernel"':' \

    | LC_ALL=C sort -k1,1 -u > $symvers

    # Symbols matching with the kernel get a "kernel" dependency

    mod_req=$(mktemp -t mod_req.XXXXX)

    mod_requires "${modules[@]}" > "$mod_req"

    LC_ALL=C join -t $'\t' -j 1 $symvers "$mod_req" | LC_ALL=C sort -u \

    | awk 'BEGIN { FS = "[\t:]" ; OFS = "\t" } { print "kernel(" $1 ") = " $2 }'

    # Symbols from elsewhere get a "ksym" dependency

    LC_ALL=C join -t $'\t' -j 1 -v 2 $symvers "$mod_req" | LC_ALL=C sort -u \

    | awk 'BEGIN { FS = "[\t:]" ; OFS = "\t" } { print "ksym(" $1 ") = " $2 }'

    # Check kABI if the kabi-stablelists package is installed

    # Do this last so we can try to output this error at the end

    kabi_check_symbols=($(LC_ALL=C join -t $'\t' -j 1 $symvers "$mod_req" | LC_ALL=C sort -u \

    | awk 'BEGIN { FS = "[\t:]" ; OFS = "\t" } { print $1 }'))

    check_kabi "${kabi_check_symbols[@]}"

fi