testdiff2/deploy/linux-fixup-rpaths.bash

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#!/usr/bin/env bash
#
# Premise:
# Shared libraries (Qt, airmap, etc) on Linux are built without knowing where
# they will be installed to; they assume they will be installed to the system.
#
# QGC does not install to the system. Instead it copies them to `Qt/libs`. The
# libraries need to have their rpath set correctly to ensure that the built
# application and its libraries are found at runtime. Without this step then the
# libraries won't be found. You might not notice it if you have the libraries
# installed in your system. A lot of systems will have the Qt libs installed,
# but they might be a different version. It "might" work, it might cause subtle
# bugs, or it might not work at all.
#
# It's possible there's no current rpath for a particular library. It's also
# possible that the library has other dependencies in its existing rpath. So
# updating the rpath is non-trivial and it's a real shame that qmake doesn't
# do this for us.
#
# To patch the libraries `readelf` and `patchelf` tools are used.
#
# If the libraries' rpath isn't set correctly then LD_LIBRARY_PATH would need
# to be used, like such:
# LD_LIBRARY_PATH=./Qt/libs ./QGroundControl
#
# -e: stop on error
# -u: undefined variable use is an error
# -o pipefail: if any part of a pipeline fails, then the whole pipeline fails.
set -euo pipefail
# To set these arguments, set them as an environment variable. For example:
# SEARCHDIR=/opt/qgc-deploy/Qt RPATHDIR=/opt/qgc-deploy/Qt/libs ./linux-post-link.sh
: "${SEARCHDIR:=./Qt}"
: "${RPATHDIR:="${SEARCHDIR}/libs"}"
# find:
# type f (files)
# that end with '.so'
# or that end with '.so.5'
# and are executable
# silence stderr (find will complain if it doesn't have permission to traverse)
find "${SEARCHDIR}" \
-type f \
-iname '*.so' \
-o -iname '*.so.5' \
-executable \
2>/dev/null |
while IFS='' read -r library; do
# readelf is expensive, so keep track of updates with a timestamp file
if [ ! -e "$library.stamp" ] || [ "$library" -nt "$library.stamp" ]; then
# Get the library's current RPATH (RUNPATH)
# Example output of `readelf -d ./build/build-qgroundcontrol-Desktop_Qt_5_15_2_GCC_64bit-Debug/staging/QGroundControl`:
# 0x000000000000001d (RUNPATH) Library runpath: [$ORIGIN/Qt/libs:/home/kbennett/storage/Qt/5.15.2/gcc_64/lib]
#
# It's possible there's no current rpath for a particular library, so turn
# off pipefail to avoid grep causing it to die.
# If you find a better way to do this, please fix.
set +o pipefail
current_rpath="$(
# read the library, parsing its header
# search for the RUNPATH field
# filter out the human-readable text to leave only the RUNPATH value
readelf -d "${library}" |
grep -P '^ 0x[0-9a-f]+ +\(RUNPATH\) ' |
sed -r 's/^ 0x[0-9a-f]+ +\(RUNPATH\) +Library runpath: \[(.*)\]$/\1/g'
)"
set -o pipefail
# Get the directory containing the library
library_dir="$(dirname "${library}")"
# Get the relative path from the library's directory to the Qt/libs directory.
our_rpath="$(realpath --relative-to "${library_dir}" "${RPATHDIR}")"
# Calculate a new rpath with our library's rpath prefixed.
# Note: '$ORIGIN' must not be expanded by the shell!
# shellcheck disable=SC2016
new_rpath='$ORIGIN/'"${our_rpath}"
# If the library already had an rpath, then prefix ours to it.
if [ -n "${current_rpath}" ]; then
new_rpath="${new_rpath}:${current_rpath}"
fi
# patch the library's rpath
patchelf --set-rpath "${new_rpath}" "${library}"
touch "$library.stamp"
fi
done