Initial release for automated binary releases for amd64 and aach64 targets

Automatically builds amd64 and aach64 target through gitlab workflow.
Also allows for local cross-compilation through `cross` tool

Co-authored-by: Frédéric Druppel <Frederic.druppel@icloud.com>

contrib/cross-compile/Dockerfile.aarch64

@@ -0,0 +1,18 @@
+FROM ghcr.io/cross-rs/aarch64-unknown-linux-gnu:main
+
+RUN dpkg --add-architecture arm64 && \
+    apt-get update && \
+    apt-get install -y --no-install-recommends \
+        cmake git g++ && \
+    rm -rf /var/lib/apt/lists/*
+
+RUN git clone https://github.com/pothosware/SoapySDR.git --branch soapy-sdr-0.8.1 && \
+    cd SoapySDR && \
+    mkdir build && cd build && \
+    cmake .. \
+        -DCMAKE_INSTALL_PREFIX=/usr \
+        -DCMAKE_INSTALL_LIBDIR=lib/aarch64-linux-gnu \
+        -DCMAKE_TOOLCHAIN_FILE=/opt/toolchain.cmake && \
+    make -j"$(nproc)" && \
+    make install && \
+    cd / && rm -rf SoapySDR

contrib/cross-compile/setup_cross_compile.sh

@@ -0,0 +1,194 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# setup_cross_compile.sh
+#
+# Installs:
+# - Docker Engine / docker.io
+# - docker group membership for the invoking user
+# - Rust `cross`
+# - Adds cargo bin directory to $PATH
+#
+# Assumptions:
+# - Rust + cargo + rustup are already installed
+#
+# Usage:
+#   ./setup_cross_compile.sh
+#
+# Notes:
+# - Must not be run as root.
+# - Group membership changes require a new login session.
+# - Path change needs new shell.
+
+require_cmd() {
+  if ! command -v "$1" >/dev/null 2>&1; then
+    echo "[-] error: required command not found: $1" >&2
+    exit 1
+  fi
+}
+
+ensure_not_root() {
+  if [[ "${EUID}" -eq 0 ]]; then
+    echo "[-] error: do not run this script as root" >&2
+    echo "    Run it as your normal user. The script will use sudo when needed." >&2
+    exit 1
+  fi
+}
+
+confirm_plan() {
+  cat <<'EOF'
+[i] This script will perform the following actions:
+
+    1. Install Docker via apt if it is not already installed.
+    2. Enable and start the Docker service.
+    3. Add your user to the docker group if needed.
+    4. Install the Rust `cross` tool if it is not already installed.
+    5. Ensure $HOME/.cargo/bin is added to your PATH in ~/.bashrc if needed.
+
+    This script may call sudo for system changes.
+    It must be run as a normal user, not as root.
+
+Proceed? [y/N]
+EOF
+
+  read -r reply
+  case "${reply}" in
+    y|Y|yes|YES)
+      ;;
+    *)
+      echo "[i] Aborted."
+      exit 0
+      ;;
+  esac
+}
+
+need_root() {
+  if [[ "${EUID}" -ne 0 ]]; then
+    require_cmd sudo
+    sudo "$@"
+  else
+    "$@"
+  fi
+}
+
+detect_user() {
+  if [[ -n "${SUDO_USER:-}" && "${SUDO_USER}" != "root" ]]; then
+    printf '%s\n' "${SUDO_USER}"
+  else
+    id -un
+  fi
+}
+
+user_home() {
+  local target_user
+  target_user="$(detect_user)"
+  getent passwd "${target_user}" | cut -d: -f6
+}
+
+install_docker_debian() {
+  if command -v docker >/dev/null 2>&1; then
+    echo "[+] docker already installed"
+    return
+  fi
+
+  echo "[i] installing docker"
+  need_root apt-get update
+  need_root apt-get install -y docker.io
+  need_root systemctl enable --now docker
+}
+
+ensure_docker_group_membership() {
+  local target_user
+  target_user="$(detect_user)"
+
+  if id -nG "${target_user}" | tr ' ' '\n' | grep -qx docker; then
+    echo "[+] user '${target_user}' is already in docker group"
+    return
+  fi
+
+  echo "[i] adding user '${target_user}' to docker group"
+  need_root usermod -aG docker "${target_user}"
+
+  cat <<EOF
+
+[+] docker group membership was updated for user '${target_user}'.
+You must log out and log back in before you can proceed.
+EOF
+}
+
+install_cross() {
+  require_cmd cargo
+  require_cmd rustup
+
+  if command -v cross >/dev/null 2>&1; then
+    echo "[+] cross already installed: $(command -v cross)"
+    return
+  fi
+
+  echo "[i] installing cross"
+  cargo install cross --locked
+}
+
+ensure_cargo_bin_in_bashrc_if_needed() {
+  local target_user home_dir bashrc cargo_bin line
+  target_user="$(detect_user)"
+  home_dir="$(user_home)"
+  bashrc="${home_dir}/.bashrc"
+  cargo_bin="${home_dir}/.cargo/bin"
+  line='export PATH="$HOME/.cargo/bin:$PATH"'
+
+  if command -v cross >/dev/null 2>&1; then
+    echo "[+] cross is already available in PATH: $(command -v cross)"
+    return
+  fi
+
+  echo "[!] cross is installed but not currently available in PATH"
+
+  mkdir -p "${cargo_bin}"
+
+  if [[ ! -f "${bashrc}" ]]; then
+    touch "${bashrc}"
+    chown "${target_user}:${target_user}" "${bashrc}" 2>/dev/null || true
+  fi
+
+  if ! grep -Fqx "${line}" "${bashrc}"; then
+    printf '\n%s\n' "${line}" >> "${bashrc}"
+    chown "${target_user}:${target_user}" "${bashrc}" 2>/dev/null || true
+    echo "[+] added Cargo bin directory to ${bashrc}"
+  else
+    echo "[+] Cargo bin PATH line already present in ${bashrc}"
+  fi
+
+  cat <<EOF
+
+[i] PATH was updated in ${bashrc}, but the current shell will not pick it up automatically.
+    Log out and log back in, then verify:
+      command -v cross
+      cross --version
+EOF
+}
+
+main() {
+  confirm_plan
+  ensure_not_root
+  require_cmd apt-get
+  require_cmd getent
+
+  install_docker_debian
+  ensure_docker_group_membership
+  install_cross
+  ensure_cargo_bin_in_bashrc_if_needed
+
+  cat <<'EOF'
+
+[+] Setup complete.
+    Verify these two commands work:
+      docker --version
+      cross --version
+
+    Then run cross compilation:
+      cross build --release --target aarch64-unknown-linux-gnu
+EOF
+}
+
+main "$@"