Fix fd/inode leak

If do_readdir() calls do_lookup(), but the latter fails, we still have
to return any entries that we already stored in the readdir buffer to
avoid leaking inodes.

do_lookup() may fail if e.g. we reach the file descriptor limit.

diff --git a/example/passthrough_ll.c b/example/passthrough_ll.c
index eadad3a0a3c8324c70531aab1b50066b99001648..5364b978f953ab2f07872d2895fad20e1ee58bc8 100644 (file)
--- a/example/passthrough_ll.c
+++ b/example/passthrough_ll.c
@@ -666,22 +666,23 @@ static void lo_do_readdir(fuse_req_t req, fuse_ino_t ino, size_t size,
        struct lo_dirp *d = lo_dirp(fi);
        char *buf;
        char *p;
-       size_t rem;
+       size_t rem = size;
        int err;
 
        (void) ino;
 
        buf = calloc(1, size);
-       if (!buf)
-               return (void) fuse_reply_err(req, ENOMEM);
+       if (!buf) {
+               err = ENOMEM;
+               goto error;
+       }
+       p = buf;
 
        if (offset != d->offset) {
                seekdir(d->dp, offset);
                d->entry = NULL;
                d->offset = offset;
        }
-       p = buf;
-       rem = size;
        while (1) {
                size_t entsize;
                off_t nextoff;
@@ -691,11 +692,12 @@ static void lo_do_readdir(fuse_req_t req, fuse_ino_t ino, size_t size,
                        errno = 0;
                        d->entry = readdir(d->dp);
                        if (!d->entry) {
-                               if (errno && rem == size) {
+                               if (errno) {  // Error
                                        err = errno;
                                        goto error;
+                               } else {  // End of stream
+                                       break; 
                                }
-                               break;
                        }
                }
                nextoff = d->entry->d_off;
@@ -738,13 +740,17 @@ static void lo_do_readdir(fuse_req_t req, fuse_ino_t ino, size_t size,
                d->offset = nextoff;
        }
 
-       fuse_reply_buf(req, buf, size - rem);
-       free(buf);
-       return;
-
+    err = 0;
 error:
-       free(buf);
-       fuse_reply_err(req, err);
+    // If there's an error, we can only signal it if we haven't stored
+    // any entries yet - otherwise we'd end up with wrong lookup
+    // counts for the entries that are already in the buffer. So we
+    // return what we've collected until that point.
+    if (err && rem == size)
+           fuse_reply_err(req, err);
+    else
+           fuse_reply_buf(req, buf, size - rem);
+    free(buf);
 }
 
 static void lo_readdir(fuse_req_t req, fuse_ino_t ino, size_t size,