bftw: Fix to_close list corruption with !BFS_USE_UNWRAPDIR

It's possible for pincount to drop to zero, then get incremented and
drop back to zero again.  If this happens, we shouldn't add it to the
to_close list twice.

This should fix the intermittent hang on the macOS CI.

Fixes: 815798e1eea7fc8dacd5acab40202ec4d251d517

diff --git a/src/bftw.c b/src/bftw.c
index c0bff75bb979b4096cc03c94a9bb75ef9e6aacf9..1995e125ea92309e256a666f71a31987114bd6c3 100644 (file)
--- a/src/bftw.c
+++ b/src/bftw.c
@@ -546,6 +546,17 @@ static int bftw_state_init(struct bftw_state *state, const struct bftw_args *arg
        return 0;
 }
 
+/** Unpin a directory, and possibly queue it for unwrapping. */
+static void bftw_unpin_dir(struct bftw_state *state, struct bftw_file *file, bool force) {
+       bftw_cache_unpin(&state->cache, file);
+
+       if (file->dir && (force || file->pincount == 0)) {
+               if (!SLIST_ATTACHED(&state->to_close, file)) {
+                       SLIST_APPEND(&state->to_close, file);
+               }
+       }
+}
+
 /** Pop a response from the I/O queue. */
 static int bftw_ioq_pop(struct bftw_state *state, bool block) {
        struct ioq *ioq = state->ioq;
@@ -582,10 +593,7 @@ static int bftw_ioq_pop(struct bftw_state *state, bool block) {
                ++cache->capacity;
                parent = file->parent;
                if (parent) {
-                       bftw_cache_unpin(cache, parent);
-                       if (parent->pincount == 0 && parent->dir) {
-                               SLIST_APPEND(&state->to_close, parent);
-                       }
+                       bftw_unpin_dir(state, parent, false);
                }
 
                dir = ent->opendir.dir;
@@ -1285,8 +1293,7 @@ static int bftw_gc(struct bftw_state *state, enum bftw_gc_flags flags) {
 
        struct bftw_file *file = state->file;
        if (file && file->dir) {
-               bftw_cache_unpin(&state->cache, file);
-               SLIST_APPEND(&state->to_close, file);
+               bftw_unpin_dir(state, file, true);
        }
        state->dir = NULL;
        state->de = NULL;