Fix resolution of symlinks during dumping

* src/comp.c (Fcomp_el_to_eln_rel_filename): Don't use
'file-truename', as it is only available once files.el is loaded,
which doesn't work during dumping, until loadup loads files.el.
Instead, use 'realpath'.  (Bug#48578)
* src/w32.c (realpath): New function.
* src/w32.h (realpath): Add prototype.

* nt/mingw-cfg.site (ac_cv_func_realpath)
(gl_cv_func_realpath_works): Define to "yes", as this function is
now implemented in w32.c.

1 files changed, 39 insertions, 0 deletions

diff --git a/src/w32.c b/src/w32.c
index 26cc28f877c..968b4bbe489 100644
--- a/src/w32.c
+++ b/src/w32.c
@@ -10587,6 +10587,45 @@ w32_my_exename (void)
   return exename;
 }
 
+/* Emulate Posix 'realpath'.  This is needed in
+   comp-el-to-eln-rel-filename.  */
+char *
+realpath (const char *file_name, char *resolved_name)
+{
+  char *tgt = chase_symlinks (file_name);
+  char target[MAX_UTF8_PATH];
+
+  if (tgt == file_name)
+    {
+      /* If FILE_NAME is not a symlink, chase_symlinks returns its
+	 argument, possibly not in canonical absolute form.  Make sure
+	 we return a canonical file name.  */
+      if (w32_unicode_filenames)
+	{
+	  wchar_t file_w[MAX_PATH], tgt_w[MAX_PATH];
+
+	  filename_to_utf16 (file_name, file_w);
+	  if (GetFullPathNameW (file_w, MAX_PATH, tgt_w, NULL) == 0)
+	    return NULL;
+	  filename_from_utf16 (tgt_w, target);
+	}
+      else
+	{
+	  char file_a[MAX_PATH], tgt_a[MAX_PATH];
+
+	  filename_to_ansi (file_name, file_a);
+	  if (GetFullPathNameA (file_a, MAX_PATH, tgt_a, NULL) == 0)
+	    return NULL;
+	  filename_from_ansi (tgt_a, target);
+	}
+      tgt = target;
+    }
+
+  if (resolved_name)
+    return strcpy (resolved_name, tgt);
+  return xstrdup (tgt);
+}
+
 /*
 	globals_of_w32 is used to initialize those global variables that
 	must always be initialized on startup even when the global variable