From 13b3c916f306ab97877c5331cc9a15a6296616f7 Mon Sep 17 00:00:00 2001
From: Ivan Grokhotkov <ivan@espressif.com>
Date: Mon, 7 Nov 2016 14:26:21 +0800
Subject: [PATCH] vfs: check error code returned by FS driver open function

Fixes https://github.com/espressif/esp-idf/issues/78
---
 components/vfs/vfs.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/components/vfs/vfs.c b/components/vfs/vfs.c
index bf26968ff7..b60c60a818 100644
--- a/components/vfs/vfs.c
+++ b/components/vfs/vfs.c
@@ -151,6 +151,10 @@ int esp_vfs_open(struct _reent *r, const char * path, int flags, int mode)
     const char* path_within_vfs = translate_path(vfs, path);
     int ret;
     CHECK_AND_CALL(ret, r, vfs, open, path_within_vfs, flags, mode);
+    if (ret < 0) {
+        return ret;
+    }
+    assert(ret >= vfs->vfs.fd_offset);
     return ret - vfs->vfs.fd_offset + (vfs->offset << VFS_INDEX_S);
 }