Fix the value of default-directory upon startup on MS-Windows

* src/w32.c (w32_get_current_directory): New function.
(GetCachedVolumeInformation, init_environment): Use it.
(w32_init_current_directory): New function.
* src/w32.h (w32_init_current_directory): Add prototype.
* src/emacs.c (main) [WINDOWSNT]: Use w32_init_current_directory
to get the accurate value of cwd.  This is needed to record
the correct directory in emacs_wd, which is now initialized
way earlier in the startup process, when init_environment was
not yet called.  For details, see the problems reported in
http://lists.gnu.org/archive/html/emacs-devel/2018-12/msg00068.html.
Reported by Angelo Graziosi <angelo.g0@libero.it>.

3 files changed, 43 insertions, 35 deletions

diff --git a/src/emacs.c b/src/emacs.c
index acb4959bfea..eddd729f0a4 100644
--- a/src/emacs.c
+++ b/src/emacs.c
@@ -736,6 +736,8 @@ main (int argc, char **argv)
   /* Initialize the codepage for file names, needed to decode
      non-ASCII file names during startup.  */
   w32_init_file_name_codepage ();
+  /* Initialize the startup directory, needed for emacs_wd below.  */
+  w32_init_current_directory ();
 #endif
   w32_init_main_thread ();
 #endif
@@ -816,6 +818,10 @@ main (int argc, char **argv)
           exit (1);
         }
       original_pwd = emacs_wd;
+#ifdef WINDOWSNT
+      /* Reinitialize Emacs's notion of the startup directory.  */
+      w32_init_current_directory ();
+#endif
       emacs_wd = emacs_get_current_dir_name ();
     }
 
diff --git a/src/w32.c b/src/w32.c
index 26cfae7a6af..dc8bed582c0 100644
--- a/src/w32.c
+++ b/src/w32.c
@@ -1771,7 +1771,40 @@ filename_from_ansi (const char *fn_in, char *fn_out)
 /* The directory where we started, in UTF-8. */
 static char startup_dir[MAX_UTF8_PATH];
 
-/* Get the current working directory.  */
+/* Get the current working directory.  The caller must arrange for CWD
+   to be allocated with enough space to hold a 260-char directory name
+   in UTF-8.  IOW, the space should be at least MAX_UTF8_PATH bytes.  */
+static void
+w32_get_current_directory (char *cwd)
+{
+  /* FIXME: Do we need to resolve possible symlinks in startup_dir?
+     Does it matter anywhere in Emacs?  */
+  if (w32_unicode_filenames)
+    {
+      wchar_t wstartup_dir[MAX_PATH];
+
+      if (!GetCurrentDirectoryW (MAX_PATH, wstartup_dir))
+        emacs_abort ();
+      filename_from_utf16 (wstartup_dir, cwd);
+    }
+  else
+    {
+      char astartup_dir[MAX_PATH];
+
+      if (!GetCurrentDirectoryA (MAX_PATH, astartup_dir))
+        emacs_abort ();
+      filename_from_ansi (astartup_dir, cwd);
+    }
+}
+
+/* For external callers.  Used by 'main' in emacs.c.  */
+void
+w32_init_current_directory (void)
+{
+  w32_get_current_directory (startup_dir);
+}
+
+/* Return the original directory where Emacs started.  */
 char *
 getcwd (char *dir, int dirsize)
 {
@@ -2997,24 +3030,7 @@ init_environment (char ** argv)
   }
 
   /* Remember the initial working directory for getcwd.  */
-  /* FIXME: Do we need to resolve possible symlinks in startup_dir?
-     Does it matter anywhere in Emacs?  */
-  if (w32_unicode_filenames)
-    {
-      wchar_t wstartup_dir[MAX_PATH];
-
-      if (!GetCurrentDirectoryW (MAX_PATH, wstartup_dir))
-        emacs_abort ();
-      filename_from_utf16 (wstartup_dir, startup_dir);
-    }
-  else
-    {
-      char astartup_dir[MAX_PATH];
-
-      if (!GetCurrentDirectoryA (MAX_PATH, astartup_dir))
-        emacs_abort ();
-      filename_from_ansi (astartup_dir, startup_dir);
-    }
+  w32_get_current_directory (startup_dir);
 
   {
     static char modname[MAX_PATH];
@@ -3198,22 +3214,7 @@ GetCachedVolumeInformation (char * root_dir)
   /* NULL for root_dir means use root from current directory.  */
   if (root_dir == NULL)
     {
-      if (w32_unicode_filenames)
-        {
-          wchar_t curdirw[MAX_PATH];
-
-          if (GetCurrentDirectoryW (MAX_PATH, curdirw) == 0)
-            return NULL;
-          filename_from_utf16 (curdirw, default_root);
-        }
-      else
-        {
-          char curdira[MAX_PATH];
-
-          if (GetCurrentDirectoryA (MAX_PATH, curdira) == 0)
-            return NULL;
-          filename_from_ansi (curdira, default_root);
-        }
+      w32_get_current_directory (default_root);
       parse_root (default_root, (const char **)&root_dir);
       *root_dir = 0;
       root_dir = default_root;
diff --git a/src/w32.h b/src/w32.h
index 42b3d98245f..5054b400c5b 100644
--- a/src/w32.h
+++ b/src/w32.h
@@ -201,6 +201,7 @@ extern int  codepage_for_filenames (CPINFO *);
 extern Lisp_Object ansi_encode_filename (Lisp_Object);
 extern int  w32_copy_file (const char *, const char *, int, int, int);
 extern int  w32_accessible_directory_p (const char *, ptrdiff_t);
+extern void w32_init_current_directory (void);
 
 extern BOOL init_winsock (int load_now);
 extern void srandom (int);