# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1645123283 -3600
# Node ID b8f26cc013ed441de6ad022daebd065cbfcb3717
# Parent  8145967ef0123ba1c2475f3fd07da4811a1ea6b1
Introduced empty directory testing.

diff -r 8145967ef012 -r b8f26cc013ed libfsserver/include/fsserver/ext2_file_opener.h
--- a/libfsserver/include/fsserver/ext2_file_opener.h	Thu Feb 17 00:37:13 2022 +0100
+++ b/libfsserver/include/fsserver/ext2_file_opener.h	Thu Feb 17 19:41:23 2022 +0100
@@ -44,6 +44,8 @@
 
     virtual bool accessing_file(flags_t flags, fileid_t fileid);
 
+    virtual bool directory_is_empty(fileid_t fileid);
+
 public:
     explicit Ext2FileOpener(ResourceRegistry *registry, Ext2FileOperations *ops, user_t user)
     : OpenerResource(registry), _ops(ops), _user(user)
diff -r 8145967ef012 -r b8f26cc013ed libfsserver/include/fsserver/ext2_file_operations.h
--- a/libfsserver/include/fsserver/ext2_file_operations.h	Thu Feb 17 00:37:13 2022 +0100
+++ b/libfsserver/include/fsserver/ext2_file_operations.h	Thu Feb 17 19:41:23 2022 +0100
@@ -61,6 +61,8 @@
 
     bool can_access(user_t user, flags_t flags, ext2_ino_t ino);
 
+    bool directory_is_empty(ext2_ino_t ino);
+
     bool is_directory(ext2_ino_t ino_file);
 
     bool is_file(ext2_ino_t ino_file);
diff -r 8145967ef012 -r b8f26cc013ed libfsserver/include/fsserver/file_opening.h
--- a/libfsserver/include/fsserver/file_opening.h	Thu Feb 17 00:37:13 2022 +0100
+++ b/libfsserver/include/fsserver/file_opening.h	Thu Feb 17 19:41:23 2022 +0100
@@ -35,6 +35,8 @@
 
     virtual bool accessing_file(flags_t flags, fileid_t fileid) = 0;
 
+    virtual bool directory_is_empty(fileid_t fileid) = 0;
+
     virtual long get_fileid(const char *path, flags_t flags, fileid_t *fileid) = 0;
 
     virtual long get_parent(const char *path, fileid_t *fileid);
diff -r 8145967ef012 -r b8f26cc013ed libfsserver/include/fsserver/host_file_opener.h
--- a/libfsserver/include/fsserver/host_file_opener.h	Thu Feb 17 00:37:13 2022 +0100
+++ b/libfsserver/include/fsserver/host_file_opener.h	Thu Feb 17 19:41:23 2022 +0100
@@ -58,6 +58,8 @@
 
     virtual bool accessing_file(flags_t flags, fileid_t fileid);
 
+    virtual bool directory_is_empty(fileid_t fileid);
+
 public:
     explicit HostFileOpener(ResourceRegistry *registry)
     : OpenerResource(registry)
diff -r 8145967ef012 -r b8f26cc013ed libfsserver/include/fsserver/test_file_opener.h
--- a/libfsserver/include/fsserver/test_file_opener.h	Thu Feb 17 00:37:13 2022 +0100
+++ b/libfsserver/include/fsserver/test_file_opener.h	Thu Feb 17 19:41:23 2022 +0100
@@ -38,6 +38,8 @@
 
     virtual bool accessing_file(flags_t flags, fileid_t fileid);
 
+    virtual bool directory_is_empty(fileid_t fileid);
+
 public:
     explicit TestFileOpener(ResourceRegistry *registry, offset_t file_size=0);
 
diff -r 8145967ef012 -r b8f26cc013ed libfsserver/lib/files/ext2_file_opener.cc
--- a/libfsserver/lib/files/ext2_file_opener.cc	Thu Feb 17 00:37:13 2022 +0100
+++ b/libfsserver/lib/files/ext2_file_opener.cc	Thu Feb 17 19:41:23 2022 +0100
@@ -52,6 +52,13 @@
     return _ops->is_file((ext2_ino_t) fileid);
 }
 
+/* Test if a directory is empty. */
+
+bool Ext2FileOpener::directory_is_empty(fileid_t fileid)
+{
+    return _ops->directory_is_empty(fileid);
+}
+
 /* Return a file identifier for the given 'path'. */
 
 long Ext2FileOpener::get_fileid(const char *path, flags_t flags, fileid_t *fileid)
diff -r 8145967ef012 -r b8f26cc013ed libfsserver/lib/files/ext2_file_operations.cc
--- a/libfsserver/lib/files/ext2_file_operations.cc	Thu Feb 17 00:37:13 2022 +0100
+++ b/libfsserver/lib/files/ext2_file_operations.cc	Thu Feb 17 19:41:23 2022 +0100
@@ -44,6 +44,17 @@
         return access_can_read(user, &inode);
 }
 
+/* Assert that a directory is empty. */
+
+bool Ext2FileOperations::directory_is_empty(ext2_ino_t ino)
+{
+    std::lock_guard<std::mutex> guard(_lock);
+
+    return !image_dir_empty_by_inode(_fs, ino);
+}
+
+/* Test for a directory. */
+
 bool Ext2FileOperations::is_directory(ext2_ino_t ino_file)
 {
     std::lock_guard<std::mutex> guard(_lock);
@@ -51,6 +62,8 @@
     return _image_isdir(_fs, ino_file);
 }
 
+/* Test for a file. */
+
 bool Ext2FileOperations::is_file(ext2_ino_t ino_file)
 {
     std::lock_guard<std::mutex> guard(_lock);
diff -r 8145967ef012 -r b8f26cc013ed libfsserver/lib/files/host_file_opener.cc
--- a/libfsserver/lib/files/host_file_opener.cc	Thu Feb 17 00:37:13 2022 +0100
+++ b/libfsserver/lib/files/host_file_opener.cc	Thu Feb 17 19:41:23 2022 +0100
@@ -19,7 +19,9 @@
  * Boston, MA  02110-1301, USA
  */
 
+#include <dirent.h>
 #include <stdio.h>
+#include <string.h>
 #include <sys/stat.h>
 #include <unistd.h>
 
@@ -69,6 +71,34 @@
     return (st.st_mode & S_IFREG) ? true : false;
 }
 
+/* Test if a directory is empty. */
+
+bool HostFileOpener::directory_is_empty(fileid_t fileid)
+{
+    const char *path = _get_path(fileid);
+
+    if (path == NULL)
+        return false;
+
+    DIR *dir = opendir(path);
+    struct dirent *entry;
+
+    if (dir == NULL)
+        return false;
+
+    while ((entry = readdir(dir)) != NULL)
+    {
+        if (strcmp(entry->d_name, ".") && strcmp(entry->d_name, ".."))
+        {
+            closedir(dir);
+            return false;
+        }
+    }
+
+    closedir(dir);
+    return true;
+}
+
 /* Return a file identifier for the given 'path'. */
 
 long HostFileOpener::get_fileid(const char *path, flags_t flags, fileid_t *fileid)
diff -r 8145967ef012 -r b8f26cc013ed libfsserver/lib/files/test_file_opener.cc
--- a/libfsserver/lib/files/test_file_opener.cc	Thu Feb 17 00:37:13 2022 +0100
+++ b/libfsserver/lib/files/test_file_opener.cc	Thu Feb 17 19:41:23 2022 +0100
@@ -47,6 +47,14 @@
     return true;
 }
 
+/* Test if a directory is empty. */
+
+bool TestFileOpener::directory_is_empty(fileid_t fileid)
+{
+    (void) fileid;
+    return false;
+}
+
 /* Return a file identifier for the given 'path'. */
 
 long TestFileOpener::get_fileid(const char *path, flags_t flags, fileid_t *fileid)
diff -r 8145967ef012 -r b8f26cc013ed libfsserver/lib/generic/resource_registry.cc
--- a/libfsserver/lib/generic/resource_registry.cc	Thu Feb 17 00:37:13 2022 +0100
+++ b/libfsserver/lib/generic/resource_registry.cc	Thu Feb 17 19:41:23 2022 +0100
@@ -207,6 +207,12 @@
     if (err)
         return err;
 
+    /* Test for an empty directory.
+       NOTE: A descriptive error should be communicated. */
+
+    if (opening->accessing_directory(0, fileid) && !opening->directory_is_empty(fileid))
+        return -L4_EIO;
+
     /* Unlink the object regardless of whether it will be removed. */
 
     err = opening->unlink_object(parent_fileid, fileid);