support/scripts/check-host-rpath

#!/usr/bin/env bash

# This script scans $(HOST_DIR)/{bin,sbin} for all ELF files, and checks
# they have an RPATH to $(HOST_DIR)/lib if they need libraries from
# there.

# Override the user's locale so we are sure we can parse the output of
# readelf(1) and file(1)
export LC_ALL=C

main() {
    local pkg="${1}"
    local hostdir="${2}"
    local perpackagedir="${3}"
    local file ret

    # Remove duplicate and trailing '/' for proper match
    hostdir="$( sed -r -e 's:/+:/:g; s:/$::;' <<<"${hostdir}" )"

    ret=0
    while read file; do
        is_elf "${file}" || continue
        elf_needs_rpath "${file}" "${hostdir}" || continue
        check_elf_has_rpath "${file}" "${hostdir}" "${perpackagedir}" && continue
        if [ ${ret} -eq 0 ]; then
            ret=1
            printf "***\n"
            printf "*** ERROR: package %s installs executables without proper RPATH:\n" "${pkg}"
        fi
        printf "***   %s\n" "${file}"
    done < <( find "${hostdir}"/{bin,sbin} -type f 2>/dev/null )

    return ${ret}
}

is_elf() {
    local f="${1}"

    readelf -l "${f}" 2>/dev/null \
    |grep -E 'Requesting program interpreter:' >/dev/null 2>&1
}

# This function tells whether a given ELF executable (first argument)
# needs a RPATH pointing to the host library directory or not. It
# needs such an RPATH if at least of the libraries used by the ELF
# executable is available in the host library directory. This function
# returns 0 when a RPATH is needed, 1 otherwise.
#
# With per-package directory support, ${hostdir} will point to the
# current package per-package host directory, and this is where this
# function will check if the libraries needed by the executable are
# located (or not). In practice, the ELF executable RPATH may point to
# another package per-package host directory, but that is fine because
# if such an executable is within the current package per-package host
# directory, its libraries will also have been copied into the current
# package per-package host directory.
elf_needs_rpath() {
    local file="${1}"
    local hostdir="${2}"
    local lib

    while read lib; do
        [ -e "${hostdir}/lib/${lib}" ] && return 0
    done < <( readelf -d "${file}" 2>/dev/null                             \
              |sed -r -e '/^.* \(NEEDED\) .*Shared library: \[(.+)\]$/!d;' \
                     -e 's//\1/;'                                          \
            )

    return 1
}

# This function checks whether at least one of the RPATH of the given
# ELF executable (first argument) properly points to the host library
# directory (second argument), either through an absolute RPATH or a
# relative RPATH. In the context of per-package directory support,
# ${hostdir} (second argument) points to the current package host
# directory. However, it is perfectly valid for an ELF binary to have
# a RPATH pointing to another package per-package host directory,
# which is why such RPATH is also accepted (the per-package directory
# gets passed as third argument). Having a RPATH pointing to the host
# directory will make sure the ELF executable will find at runtime the
# shared libraries it depends on. This function returns 0 when a
# proper RPATH was found, or 1 otherwise.
check_elf_has_rpath() {
    local file="${1}"
    local hostdir="${2}"
    local perpackagedir="${3}"
    local rpath dir

    while read rpath; do
        for dir in ${rpath//:/ }; do
            # Remove duplicate and trailing '/' for proper match
            dir="$( sed -r -e 's:/+:/:g; s:/$::;' <<<"${dir}" )"
            [ "${dir}" = "${hostdir}/lib" ] && return 0
            [ "${dir}" = "\$ORIGIN/../lib" ] && return 0
            # This check is done even for builds where
            # BR2_PER_PACKAGE_DIRECTORIES is disabled. In this case,
            # PER_PACKAGE_DIR and therefore ${perpackagedir} points to
            # a non-existent directory, and this check will always be
            # false.
            [[ ${dir} =~ "${perpackagedir}/"[^/]+/host/lib ]] && return 0
        done
    done < <( readelf -d "${file}" 2>/dev/null                                  \
              |sed -r -e '/.* \(R(UN)?PATH\) +Library r(un)?path: \[(.+)\]$/!d' \
                      -e 's//\3/;'                                              \
            )

    return 1
}

main "${@}"