#! /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'
export LC_ALL=C

# Prevent elfutils from trying to download debuginfos
unset DEBUGINFOD_URLS


# 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

        # awk script return code:
        #   0 - absolute __crc_* symbols have been found, output has been
        #       generated;
        #   23 - a non-absolute __crc_* symbold has been found;
        #   42 - no __crc_* symbols have been found.
        nm "$module" \
        | awk \
           -v 'dep_pfx='"$dep_pfx" \
           --non-decimal-data \
           'BEGIN { exit_code = 42 }
           match($0, /^([0-9a-f]+) (.) __crc_(.+)/, a) {
               if (a[2] == "A") {
                   printf("%s(%s) = 0x%08x\n", dep_pfx, a[3], strtonum("0x" a[1]));
                   exit_code = 0;
               } else {
                   exit_code = 23;
                   exit;
               }
           }
           END { exit exit_code }'

        [ 23 = "$?" ] && {
            kmod_elf_hdr="$(readelf -h "$module")"
            [ "x$kmod_elf_hdr" = "x${kmod_elf_hdr%Data:*little endian*}" ]
            revbytes="$?"

            objdump -t "$module" \
            | awk \
              -v 'dep_pfx='"$dep_pfx" \
              -v 'module='"$module" \
              -v 'revbytes='"$revbytes" \
              --non-decimal-data \
              'function readsect(name,   a, t) {
                  a = "";
                  while (("readelf -R \"" name "\" \"" module "\"" | getline t) > 0) {
                      if (match(t, /^  0x[0-9a-f]{8}/))
                          a = a substr(t, 14, 8) substr(t, 23, 8) substr(t, 32, 8) substr(t, 41, 8);
                  }
                  if (revbytes) { a = gensub(/(..)(..)(..)(..)/, "\\4\\3\\2\\1", "g", a); }
                  sectdata[name] = a;
              }

              match($0, /^([0-9a-f]+) [gl]...... (.*)	[0-9a-f]+ __crc_(.*)$/, a) {
                  if (!(a[2] in sectdata)) { readsect(a[2]) }
                  printf("%s(%s) = 0x%08s\n", dep_pfx, a[3], substr(sectdata[a[2]], (strtonum("0x" a[1]) * 2) + 1, 8))
              }'
        }

        [ -z "$tmpfile" ] || rm -f -- "$tmpfile"
    done \
    | 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 \
    | sort -k1,1 -u
}

# Filter out requirements fulfilled by the module itself.
mod_requires() {
    join -t $'\t' -j 1 -v 1 \
        <(all_requires "$@") \
        <(all_provides "$@") \
    | 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"':' \
    | 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"
    join -t $'\t' -j 1 $symvers "$mod_req" | sort -u \
    | awk 'BEGIN { FS = "[\t:]" ; OFS = "\t" } { print "kernel(" $1 ") = " $2 }'

    # Symbols from elsewhere get a "ksym" dependency
    join -t $'\t' -j 1 -v 2 $symvers "$mod_req" | 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=($(join -t $'\t' -j 1 $symvers "$mod_req" | sort -u \
    | awk 'BEGIN { FS = "[\t:]" ; OFS = "\t" } { print $1 }'))
    check_kabi "${kabi_check_symbols[@]}"
fi