From ff213006623982582dc3be5f125ec33b01eb4d59 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Yan=20Facai=20=28=E9=A2=9C=E5=8F=91=E6=89=8D=29?=
 <facai.yan@gmail.com>
Date: Wed, 6 Sep 2017 13:44:10 +0800
Subject: [PATCH] BLD: precheck patch

---
 tensorflow/workspace.bzl | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/tensorflow/workspace.bzl b/tensorflow/workspace.bzl
index 176719fabb4..80f1b0a9596 100644
--- a/tensorflow/workspace.bzl
+++ b/tensorflow/workspace.bzl
@@ -99,6 +99,9 @@ def _execute_and_check_ret_code(repo_ctx, cmd_and_args):
 # Apply a patch_file to the repository root directory
 # Runs 'patch -p1'
 def _apply_patch(repo_ctx, patch_file):
+  if not repo_ctx.which("patch"):
+    fail("patch command is not found, please install it")
+
   cmd = [
       "patch", "-p1", "-d", repo_ctx.path("."), "-i", repo_ctx.path(patch_file)
   ]