From cc9568cd59b2d3944d34c601e7c8cf9ea462a245 Mon Sep 17 00:00:00 2001
From: Werner Koch <wk@gnupg.org>
Date: Tue, 9 Jan 2024 10:09:36 +0100
Subject: [PATCH] common,w32: Remove duplicated backslashes when setting the
 homedir.

* common/homedir.c (copy_dir_with_fixup) [W32]: Fold double
backslashes.
--

This is in general no problem but when we hash or compare the directory
to test whether tit is the standard home directory, we may use a
different socket file and thus a second instance of a daemon.

GnuPG-bug-id: 6833
---
 NEWS             |  5 ++++-
 common/homedir.c | 26 +++++++++++++++++++++++++-
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/NEWS b/NEWS
index 2b7be9ca2..0bc848a15 100644
--- a/NEWS
+++ b/NEWS
@@ -1,6 +1,9 @@
-Noteworthy changes in version 2.2.42 (unreleased)
+Noteworthy changes in version 2.2.43 (unreleased)
 -------------------------------------------------
 
+  * dirmngr: Avoid starting a second instance on Windows via GPGME
+    based launching.  [T6833]
+
 
 Noteworthy changes in version 2.2.42 (2023-11-28)
 -------------------------------------------------
diff --git a/common/homedir.c b/common/homedir.c
index 9788c22f1..fb2640d67 100644
--- a/common/homedir.c
+++ b/common/homedir.c
@@ -176,7 +176,8 @@ static char *
 copy_dir_with_fixup (const char *newdir)
 {
   char *result = NULL;
-  char *p;
+  char *p, *p0;
+  const char *s;
 
   if (!*newdir)
     return NULL;
@@ -208,6 +209,29 @@ copy_dir_with_fixup (const char *newdir)
         *p-- = 0;
     }
 
+  /* Hack to mitigate badly doubled backslashes.  */
+  s = result? result : newdir;
+  if (s[0] == '\\' && s[1] == '\\' && s[2] != '\\')
+    {
+      /* UNC (\\Servername\file) or Long UNC (\\?\Servername\file)
+       * Does not seem to be double quoted.  */
+    }
+  else if (strstr (s, "\\\\"))
+    {
+      /* Double quotes detected.  Fold them into one because that is
+       * what what Windows does.  This way we get a unique hash
+       * regardless of the number of doubled backslashes. */
+      if (!result)
+        result = xstrdup (newdir);
+      for (p0=p=result; *p; p++)
+        {
+          *p0++ = *p;
+          while (*p == '\\' && p[1] == '\\')
+            p++;
+        }
+      *p0 = 0;
+    }
+
 #else /*!HAVE_W32_SYSTEM*/
 
   if (newdir[strlen (newdir)-1] == '/')