eio/fallback: avoid emitting monitor events if the backend is pending deletion

emitting events if the delete_me flag is set may result in events being emitted
for an already-freed monitor, resulting in both invalid memory access and a
deadlock later on if eio_shutdown has been called at this point

this causes the monitoring thread to check the status of the backend during the
block where the main loop and thread are in sync, avoiding any data races which
could occur when checking the flag at another time, and also avoiding accessing
the internals of the Ecore_Thread which could also have been deallocated during
shutdown

fix T7086

Differential Revision: https://phab.enlightenment.org/D6449

1 files changed, 22 insertions, 10 deletions

diff --git a/src/lib/eio/eio_monitor_poll.c b/src/lib/eio/eio_monitor_poll.c
index 2133b3fe45..c7f208092c 100644
--- a/src/lib/eio/eio_monitor_poll.c
+++ b/src/lib/eio/eio_monitor_poll.c
@@ -66,6 +66,7 @@ _eio_monitor_fallback_heavy_cb(void *data, Ecore_Thread *thread)
    Eina_Stat *est;
    Eina_File_Direct_Info *info;
    _eio_stat_t st;
+   Eina_Bool deleted = EINA_FALSE;
    /* FIXME : copy ecore_file_monitor_poll here */
 
    if (!backend->initialised)
@@ -81,7 +82,9 @@ _eio_monitor_fallback_heavy_cb(void *data, Ecore_Thread *thread)
         if (backend->initialised && !backend->destroyed)
           {
              ecore_thread_main_loop_begin();
-             _eio_monitor_send(backend->parent, backend->parent->path, EIO_MONITOR_SELF_DELETED);
+             deleted = backend->delete_me;
+             if (!deleted)
+               _eio_monitor_send(backend->parent, backend->parent->path, EIO_MONITOR_SELF_DELETED);
              ecore_thread_main_loop_end();
              backend->destroyed = EINA_TRUE;
           }
@@ -132,8 +135,11 @@ _eio_monitor_fallback_heavy_cb(void *data, Ecore_Thread *thread)
           /* regular file: eina_file_direct_ls will return NULL */
           event = EIO_MONITOR_FILE_MODIFIED;
         ecore_thread_main_loop_begin();
-        _eio_monitor_send(backend->parent, backend->parent->path, event);
+        deleted = backend->delete_me;
+        if (!deleted)
+          _eio_monitor_send(backend->parent, backend->parent->path, event);
         ecore_thread_main_loop_end();
+        if (deleted) return;
      }
 
    it = eina_file_direct_ls(backend->parent->path);
@@ -164,10 +170,12 @@ _eio_monitor_fallback_heavy_cb(void *data, Ecore_Thread *thread)
                {
                   /* New file or new directory added */
                   ecore_thread_main_loop_begin();
-                  _eio_monitor_send(backend->parent, info->path,
-                                    info->type != EINA_FILE_DIR ? EIO_MONITOR_FILE_CREATED : EIO_MONITOR_DIRECTORY_CREATED);
+                  deleted = backend->delete_me;
+                  if (!deleted)
+                    _eio_monitor_send(backend->parent, info->path,
+                                      info->type != EINA_FILE_DIR ? EIO_MONITOR_FILE_CREATED : EIO_MONITOR_DIRECTORY_CREATED);
                   ecore_thread_main_loop_end();
-
+                  if (deleted) break;
                   cmp = malloc(sizeof (Eio_Monitor_Stat));
                   memcpy(cmp, &buffer, sizeof (Eina_Stat));
 
@@ -177,18 +185,20 @@ _eio_monitor_fallback_heavy_cb(void *data, Ecore_Thread *thread)
                {
                   /* file has been modified */
                   ecore_thread_main_loop_begin();
-                  _eio_monitor_send(backend->parent, info->path,
-                                    info->type != EINA_FILE_DIR ? EIO_MONITOR_FILE_MODIFIED : EIO_MONITOR_DIRECTORY_MODIFIED);
+                  deleted = backend->delete_me;
+                  if (!deleted)
+                    _eio_monitor_send(backend->parent, info->path,
+                                      info->type != EINA_FILE_DIR ? EIO_MONITOR_FILE_MODIFIED : EIO_MONITOR_DIRECTORY_MODIFIED);
                   ecore_thread_main_loop_end();
-
+                  if (deleted) break;
                   memcpy(cmp, &buffer, sizeof (Eina_Stat));
                }
           }
 
         cmp->version = backend->version;
-        if (ecore_thread_check(thread)) goto out;
+        if (ecore_thread_check(thread)) break;
      }
- out:
+
    if (it) eina_iterator_free(it);
 
    if (backend->initialised && !ecore_thread_check(thread))
@@ -206,6 +216,8 @@ _eio_monitor_fallback_heavy_cb(void *data, Ecore_Thread *thread)
 
              if (cmp->version != backend->version)
                {
+                  deleted = backend->delete_me;
+                  if (deleted) break;
                   _eio_monitor_send(backend->parent, tuple->key,
                                     eio_file_is_dir(&cmp->buffer) ? EIO_MONITOR_DIRECTORY_DELETED : EIO_MONITOR_FILE_DELETED);
                   eina_array_push(arr, tuple->key);