tmpfiles: enforce ordering when executing lines

Always create files first, and then adjust their ACLs, xattrs, file
attributes, never the opposite. Previously the order was not
deterministic, thus possibly first adjusting ACLs/xattrs/file
attributes before actually creating the items.

src/tmpfiles/tmpfiles.c

@@ -76,20 +76,20 @@ typedef enum ItemType {
         COPY_FILES = 'C',
 
         /* These ones take globs */
+        WRITE_FILE = 'w',
         SET_XATTR = 't',
         RECURSIVE_SET_XATTR = 'T',
         SET_ACL = 'a',
         RECURSIVE_SET_ACL = 'A',
-        WRITE_FILE = 'w',
+        SET_ATTRIBUTE = 'h',
+        RECURSIVE_SET_ATTRIBUTE = 'H',
         IGNORE_PATH = 'x',
         IGNORE_DIRECTORY_PATH = 'X',
         REMOVE_PATH = 'r',
         RECURSIVE_REMOVE_PATH = 'R',
-        ADJUST_MODE = 'm', /* legacy, 'z' is identical to this */
         RELABEL_PATH = 'z',
         RECURSIVE_RELABEL_PATH = 'Z',
-        SET_ATTRIBUTE = 'h',
-        RECURSIVE_SET_ATTRIBUTE = 'H',
+        ADJUST_MODE = 'm', /* legacy, 'z' is identical to this */
 } ItemType;
 
 typedef struct Item {
@@ -1610,6 +1610,31 @@ static void item_array_free(ItemArray *a) {
         free(a);
 }
 
+static int item_compare(const void *a, const void *b) {
+        const Item *x = a, *y = b;
+
+        /* Make sure that the ownership taking item is put first, so
+         * that we first create the node, and then can adjust it */
+
+        if (takes_ownership(x->type) && !takes_ownership(y->type))
+                return -1;
+        if (!takes_ownership(x->type) && takes_ownership(y->type))
+                return 1;
+
+        return (int) x->type - (int) y->type;
+}
+
+static void item_array_sort(ItemArray *a) {
+
+        /* Sort an item array, to enforce stable ordering in which we
+         * apply things. */
+
+        if (a->count <= 1)
+                return;
+
+        qsort(a->items, a->count, sizeof(Item), item_compare);
+}
+
 static bool item_compatible(Item *a, Item *b) {
         assert(a);
         assert(b);
@@ -1944,6 +1969,8 @@ static int parse_line(const char *fname, unsigned line, const char *buffer) {
                 return log_oom();
 
         memcpy(existing->items + existing->count++, &i, sizeof(i));
+        item_array_sort(existing);
+
         zero(i);
         return 0;
 }
@@ -2183,13 +2210,17 @@ int main(int argc, char *argv[]) {
                 }
         }
 
-        HASHMAP_FOREACH(a, globs, iterator) {
+        /* The non-globbing ones usually create things, hence we apply
+         * them first */
+        HASHMAP_FOREACH(a, items, iterator) {
                 k = process_item_array(a);
                 if (k < 0 && r == 0)
                         r = k;
         }
 
-        HASHMAP_FOREACH(a, items, iterator) {
+        /* The globbing ones usually alter things, hence we apply them
+         * second. */
+        HASHMAP_FOREACH(a, globs, iterator) {
                 k = process_item_array(a);
                 if (k < 0 && r == 0)
                         r = k;