inotify-util: drop to use pointer outside of the buffer

Hopefully fixes many Coverity issues.

src/basic/inotify-util.c

@@ -4,6 +4,43 @@
 #include "inotify-util.h"
 #include "stat-util.h"
 
+bool inotify_event_next(
+                union inotify_event_buffer *buffer,
+                size_t size,
+                struct inotify_event **iterator,
+                int log_level) {
+
+        struct inotify_event *e;
+        size_t offset = 0;
+
+        assert(buffer);
+        assert(iterator);
+
+        if (*iterator) {
+                assert((uint8_t*) *iterator >= buffer->raw);
+                offset = (uint8_t*) *iterator - buffer->raw;
+                offset += offsetof(struct inotify_event, name) + (*iterator)->len;
+        }
+
+        if (size == offset)
+                return false; /* reached end of list */
+
+        if (size < offset ||
+            size - offset < offsetof(struct inotify_event, name)) {
+                log_full(log_level, "Received invalid inotify event, ignoring.");
+                return false;
+        }
+
+        e = CAST_ALIGN_PTR(struct inotify_event, buffer->raw + offset);
+        if (size - offset - offsetof(struct inotify_event, name) < e->len) {
+                log_full(log_level, "Received invalid inotify event, ignoring.");
+                return false;
+        }
+
+        *iterator = e;
+        return true;
+}
+
 int inotify_add_watch_fd(int fd, int what, uint32_t mask) {
         int wd, r;