The image creates SWW_STATE_DIR when it is missing (closes #337)

Before waf starts, share/sww.run makes SWW_STATE_DIR if it is missing,
gives it to sww:sww and sets its mode to 0700. A setting that is not an
absolute path, or a SWW_STATE_DIR_FILE that cannot be read, still
changes nothing. script/example-app now checks that a waf container
whose SWW_STATE_DIR does not exist becomes healthy with the directory
made for sww, mode 0700.

Model: opus-5-5

share/sww.run

@@ -12,7 +12,7 @@ main() {
     case "$command" in
         rproxy) ;;
         waf)
-            give_state_dir_to_sww
+            make_state_dir_for_sww
             make_cache_dir_for_sww
             ;;
         *)
@@ -24,28 +24,27 @@ main() {
     exec chpst -u sww:sww /usr/local/bin/sww "$command"
 }
 
-# give_state_dir_to_sww gives the state directory and every file in
-# it to the sww user, so that a volume mounted there needs no change
-# of owner; chown -R changes a symbolic link itself, never what it points
-# to. When SWW_STATE_DIR, in either form, cannot be read or is not the
-# absolute path of a directory, no owner is changed, and waf starts and
-# stops with a message naming the setting. A change of owner that fails, as
-# on a volume mounted read-only, does not end the script either: waf
-# reports a directory it cannot write.
-give_state_dir_to_sww() {
+# make_state_dir_for_sww makes the state directory, SWW_STATE_DIR in
+# either form, when it is missing, gives it and every file in it to the
+# sww user, and sets its mode to 0700. So a volume mounted there needs no
+# change of owner; chown -R changes a symbolic link itself, never what it
+# points to. When the setting cannot be read or is not an absolute path,
+# nothing is changed, and waf starts and stops with a message naming the
+# setting. A step that fails, as on a volume mounted read-only, does not
+# end the script either: waf reports a directory it cannot write.
+make_state_dir_for_sww() {
     local dir
-    if dir="$(setting SWW_STATE_DIR /var/lib/sww)" &&
-        [[ "$dir" == /* && -d "$dir" ]]; then
-        chown -R sww:sww "$dir" || true
+    if dir="$(setting SWW_STATE_DIR /var/lib/sww)" && [[ "$dir" == /* ]]; then
+        { mkdir -p -- "$dir" && chown -R sww:sww "$dir" &&
+            chmod 0700 "$dir"; } || true
     fi
 }
 
 # make_cache_dir_for_sww makes the cache directory, SWW_CACHE_DIR in
-# either form, and gives it and every file in it to the sww user, as
-# give_state_dir_to_sww does the state directory. Unlike that one, it is
-# made when it is missing, since the cache files need no volume. As there,
-# a setting that cannot be read or is not an absolute path changes
-# nothing, and a failure does not end the script.
+# either form, when it is missing, and gives it and every file in it to
+# the sww user. As for the state directory, a setting that cannot be read
+# or is not an absolute path changes nothing, and a failure does not end
+# the script.
 make_cache_dir_for_sww() {
     local dir
     if dir="$(setting SWW_CACHE_DIR /var/cache/sww)" && [[ "$dir" == /* ]]; then