Support rootless Docker for testing and linting

Author: taku0

scripts/lint_in_docker.sh

@@ -2,14 +2,21 @@
 
 # Run linter in Docker.  Used in Makefile.
 
+if docker info --format '{{.SecurityOptions}}' | grep -q 'name=rootless'
+then
+    USER_OPT=""
+else
+    USER_OPT=--user="$(id -u):$(id -g)"
+fi
+
 # Indentation rules changed since 29.
 for version in 30 29 # 28 27 26 25
 do
     docker \
         run \
         --rm \
         --volume="$(pwd)":/src \
-        --user="$(id -u):$(id -g)" \
+        $USER_OPT \
         --workdir="/src" \
         --env=ELDEV_DIR=/src/.eldev \
         --env=HOME=/tmp \

scripts/test_in_docker.sh

@@ -2,6 +2,13 @@
 
 # Run tests in Docker.  Used in Makefile.
 
+if docker info --format '{{.SecurityOptions}}' | grep -q 'name=rootless'
+then
+    USER_OPT=""
+else
+    USER_OPT=--user="$(id -u):$(id -g)"
+fi
+
 for version in 30 29 28 27 26 25
 do
     rm -f *.elc test/*.elc
@@ -10,7 +17,7 @@ do
         run \
         --rm \
         --volume="$(pwd)":/src \
-        --user="$(id -u):$(id -g)" \
+        $USER_OPT \
         --workdir="/src" \
         --env=ELDEV_DIR=/src/.eldev \
         --env=HOME=/tmp \