bug#24046: [PATCH] vc-git: prevent execution of git stash in error cases

[Alexander Kuleshov <kuleshovmail@gmail.com>]

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Here is simple patch which adds two additional checks to the vc-git-stash-show
function to check that correct stash name is passed and actually repo
has stashes.

Thank you

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From f9fc64560dcf892826eddca535c0c869d2922041 Mon Sep 17 00:00:00 2001
From: Alexander Kuleshov <kuleshovmail@gmail.com>
Date: Thu, 21 Jul 2016 18:42:48 +0600
Subject: [PATCH] vc-git: prevent execution of git stash in error cases

* lisp/vc/vc-git.el (vc-git-stash-show): prevent execution if stash
name is empty or a repo hasn't stashes.
---
 lisp/vc/vc-git.el | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/lisp/vc/vc-git.el b/lisp/vc/vc-git.el
index e6fe019..940738d 100644
--- a/lisp/vc/vc-git.el
+++ b/lisp/vc/vc-git.el
@@ -1348,12 +1348,16 @@ vc-git-stash
 (defun vc-git-stash-show (name)
   "Show the contents of stash NAME."
   (interactive "sStash name: ")
-  (vc-setup-buffer "*vc-git-stash*")
-  (vc-git-command "*vc-git-stash*" 'async nil "stash" "show" "-p" name)
-  (set-buffer "*vc-git-stash*")
-  (diff-mode)
-  (setq buffer-read-only t)
-  (pop-to-buffer (current-buffer)))
+  (if (string= name "")
+      (error "stash name can't be empty string."))
+  (if (eq (vc-git-stash-list) nil)
+      (error "There are no stashes.")
+    (vc-setup-buffer "*vc-git-stash*")
+    (vc-git-command "*vc-git-stash*" 'async nil "stash" "show" "-p" name)
+    (set-buffer "*vc-git-stash*")
+    (diff-mode)
+    (setq buffer-read-only t)
+    (pop-to-buffer (current-buffer))))
 
 (defun vc-git-stash-apply (name)
   "Apply stash NAME."
-- 
2.8.0.rc3.1353.gea9bdc0