From 663c5d129a8f400cc6eb8ab7b91772d6e578152d Mon Sep 17 00:00:00 2001
From: Werner Koch <wk@gnupg.org>
Date: Thu, 14 Jan 2016 20:45:33 +0100
Subject: [PATCH] w32: Fix deadlock introduced by keybox_file_rename.

* g10/keyring.c (keyring_lock) [W32]: Flush the close cache before
locking.
* kbx/keybox-init.c (keybox_lock) [W32]: Close the file before
locking.

Signed-off-by: Werner Koch <wk@gnupg.org>
---
 g10/keyring.c     | 21 +++++++++++++++++----
 kbx/keybox-init.c | 44 ++++++++++++++++++++++++++++++--------------
 2 files changed, 47 insertions(+), 18 deletions(-)

diff --git a/g10/keyring.c b/g10/keyring.c
index 7ae50a392..ca9a69874 100644
--- a/g10/keyring.c
+++ b/g10/keyring.c
@@ -328,8 +328,20 @@ keyring_lock (KEYRING_HANDLE hd, int yes)
             if (!keyring_is_writable(kr))
                 continue;
             if (kr->is_locked)
-                ;
-            else if (dotlock_take (kr->lockhd, -1) ) {
+                continue;
+
+#ifdef HAVE_W32_SYSTEM
+            /* Under Windows we need to CloseHandle the file before we
+             * try to lock it.  This is because another process might
+             * have taken the lock and is using keybox_file_rename to
+             * rename the base file.  How if our dotlock_take below is
+             * waiting for the lock but we have the base file still
+             * open, keybox_file_rename will never succeed as we are
+             * in a deadlock.  */
+            iobuf_ioctl (NULL, IOBUF_IOCTL_INVALIDATE_CACHE, 0,
+                         (char*)kr->fname);
+#endif /*HAVE_W32_SYSTEM*/
+            if (dotlock_take (kr->lockhd, -1) ) {
                 log_info ("can't lock '%s'\n", kr->fname );
                 rc = GPG_ERR_GENERAL;
             }
@@ -343,8 +355,9 @@ keyring_lock (KEYRING_HANDLE hd, int yes)
             if (!keyring_is_writable(kr))
                 continue;
             if (!kr->is_locked)
-                ;
-            else if (dotlock_release (kr->lockhd))
+                continue;
+
+            if (dotlock_release (kr->lockhd))
                 log_info ("can't unlock '%s'\n", kr->fname );
             else
                 kr->is_locked = 0;
diff --git a/kbx/keybox-init.c b/kbx/keybox-init.c
index 01d29f0f6..3b53cd5ec 100644
--- a/kbx/keybox-init.c
+++ b/kbx/keybox-init.c
@@ -286,27 +286,43 @@ keybox_lock (KEYBOX_HANDLE hd, int yes)
 
   if (yes) /* Take the lock.  */
     {
-      if (kb->is_locked)
-        ;
-      else if (dotlock_take (kb->lockhd, -1))
+      if (!kb->is_locked)
         {
-          err = gpg_error_from_syserror ();
-          log_info ("can't lock '%s'\n", kb->fname );
+#ifdef HAVE_W32_SYSTEM
+            /* Under Windows we need to close the file before we try
+             * to lock it.  This is because another process might have
+             * taken the lock and is using keybox_file_rename to
+             * rename the base file.  How if our dotlock_take below is
+             * waiting for the lock but we have the base file still
+             * open, keybox_file_rename will never succeed as we are
+             * in a deadlock.  */
+          if (hd->fp)
+            {
+              fclose (hd->fp);
+              hd->fp = NULL;
+            }
+#endif /*HAVE_W32_SYSTEM*/
+          if (dotlock_take (kb->lockhd, -1))
+            {
+              err = gpg_error_from_syserror ();
+              log_info ("can't lock '%s'\n", kb->fname );
+            }
+          else
+            kb->is_locked = 1;
         }
-      else
-        kb->is_locked = 1;
     }
   else /* Release the lock.  */
     {
-      if (!kb->is_locked)
-        ;
-      else if (dotlock_release (kb->lockhd))
+      if (kb->is_locked)
         {
-          err = gpg_error_from_syserror ();
-          log_info ("can't unlock '%s'\n", kb->fname );
+          if (dotlock_release (kb->lockhd))
+            {
+              err = gpg_error_from_syserror ();
+              log_info ("can't unlock '%s'\n", kb->fname );
+            }
+          else
+            kb->is_locked = 0;
         }
-      else
-        kb->is_locked = 0;
    }
 
   return err;