shellcheck: use --source-path if supported

... so that we get equivalent scan results as if we scanned all scripts
at once.

py/plugins/shellcheck.py

@@ -57,6 +57,9 @@ def handle_args(self, parser, args, props):
         dirs_to_scan = csmock.common.util.dirs_to_scan_by_args(
             parser, args, props, "shellcheck")
 
+        # append "/*" to each directory in dirs_to_scan (to scan pkg-specific dirs)
+        dirs_to_scan = " ".join([dir + "/*" for dir in dirs_to_scan.split()])
+
         props.install_pkgs += ["ShellCheck"]
         cmd = f"SC_RESULTS_DIR={SHELLCHECK_CAP_DIR} {RUN_SHELLCHECK_SH} {dirs_to_scan}"
         props.post_build_chroot_cmds += [cmd]

scripts/run-shellcheck.sh

@@ -36,6 +36,23 @@ if shellcheck --help 2>/dev/null | grep external-sources > /dev/null; then
     SC_OPTS="${SC_OPTS} --external-sources"
 fi
 
+# check whether shellcheck supports --source-path
+if shellcheck --help 2>/dev/null | grep source-path > /dev/null; then
+    sp=
+    for dir in "$@"; do
+        # search path works only for directories
+        test -d "$dir" || continue
+
+        # spaces cannot be safely put to SC_OPTS because it is not an array
+        [[ "$dir" != *" "* ]] || continue
+
+        sp="${sp}:${dir}"
+    done
+    if test -n "$sp"; then
+        SC_OPTS="${SC_OPTS} --source-path=${sp#:}"
+    fi
+fi
+
 # implementation of the script that filters shell scripts
 filter_shell_scripts() {
     for i in "$@"; do