Support symlinks on latest versions of MS-Windows.

 src/w32.c: Include winioctl.h and aclapi.h.
 (is_symlink, chase_symlinks, enable_privilege, restore_privilege)
 (revert_to_self): Forward declarations of static functions.
 <static BOOL g_b_init_get_security_info>:
 <g_b_init_create_symbolic_link>: New static flags.
 (globals_of_w32): Initialize them to zero.
 (GetSecurityInfo_Proc, CreateSymbolicLink_Proc): New typedefs.
 (map_w32_filename): Improve commentary.  Simplify switch.
 (SYMBOLIC_LINK_FLAG_DIRECTORY): Define if not defined in system
 headers (most versions of MinGW w32api don't).
 (get_security_info, create_symbolic_link)
 (get_file_security_desc_by_handle, is_symlink, chase_symlinks):
 New functions.
 (sys_access, sys_chmod): Call 'chase_symlinks' to resolve symlinks
 in the argument file name.
 (sys_access): Call unc_volume_file_attributes only if
 GetFileAttributes fails with network-related error codes.
 (sys_rename): Diagnose renaming of a symlink when the user doesn't
 have the required privileges.
 (get_file_security_desc_by_name): Renamed from
 get_file_security_desc.
 (stat_worker): New function, with most of the guts of 'stat', and
 with addition of handling of symlinks and support for 'lstat'.  If
 possible, get file's attributes and security information by
 handle, not by name.  Produce S_IFLNK bit for symlinks, when
 called from 'lstat'.
 (stat, lstat): New functions, call 'stat_worker'.
 (symlink, readlink, careadlinkat): Rewritten to create and resolve
 symlinks when the underlying filesystem supports them.

 lib/src/ntlib.c (lstat): New function, calls 'stat'.

 nt/inc/sys/stat.h (S_IFLNK): Define.
 (S_ISLNK): A non-trivial definition.
 (lstat): Prototype instead of a macro that redirects to 'stat'.

 lisp/files.el (file-truename): Don't skip symlink-chasing part on
 windows-nt.  Incorporate the resolution of 8+3 short aliases on
 Windows into the loop that recursively chases symlinks.  Compare
 directory and its parent case-insensitively on MS-Windows and
 MS-DOS.

 etc/NEWS: Announce the symlink support on MS-Windows.

2 files changed, 20 insertions, 28 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 4bd509ce277..d36cc4574fa 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,11 @@
+2012-08-03  Eli Zaretskii  <eliz@gnu.org>
+
+        * files.el (file-truename): Don't skip symlink-chasing part on
+        windows-nt.  Incorporate the resolution of 8+3 short aliases on
+        Windows into the loop that recursively chases symlinks.  Compare
+        directory and its parent case-insensitively on MS-Windows and
+        MS-DOS.
+
 2012-08-03  Chong Yidong  <cyd@gnu.org>
 
         * menu-bar.el (menu-bar-tools-menu): Remove PCL-CVS.
diff --git a/lisp/files.el b/lisp/files.el
index 7fc7ccc8553..0c895669542 100644
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -1079,9 +1079,7 @@ containing it, until no links are left at any level.
              (delq (rassq 'ange-ftp-completion-hook-function tem) tem)))))
     (or prev-dirs (setq prev-dirs (list nil)))
 
-    ;; andrewi@harlequin.co.uk - none of the following code (except for
-    ;; invoking the file-name handler) currently applies on Windows
-    ;; (ie. there are no native symlinks), but there is an issue with
+    ;; andrewi@harlequin.co.uk - on Windows, there is an issue with
     ;; case differences being ignored by the OS, and short "8.3 DOS"
     ;; name aliases existing for all files.  (The short names are not
     ;; reported by directory-files, but can be used to refer to files.)
@@ -1091,31 +1089,15 @@ containing it, until no links are left at any level.
     ;; it is stored on disk (expanding short name aliases with the full
     ;; name in the process).
     (if (eq system-type 'windows-nt)
-      (let ((handler (find-file-name-handler filename 'file-truename)))
-        ;; For file name that has a special handler, call handler.
-        ;; This is so that ange-ftp can save time by doing a no-op.
-        (if handler
-            (setq filename (funcall handler 'file-truename filename))
-          ;; If filename contains a wildcard, newname will be the old name.
-          (unless (string-match "[[*?]" filename)
-            ;; If filename exists, use the long name.  If it doesn't exist,
-            ;; drill down until we find a directory that exists, and use
-            ;; the long name of that, with the extra non-existent path
-            ;; components concatenated.
-            (let ((longname (w32-long-file-name filename))
-                  missing rest)
-              (if longname
-                  (setq filename longname)
-                ;; Include the preceding directory separator in the missing
-                ;; part so subsequent recursion on the rest works.
-                (setq missing (concat "/" (file-name-nondirectory filename)))
-                (let ((length (length missing)))
-                  (setq rest
-                        (if (> length (length filename))
-                            ""
-                          (substring filename 0 (- length)))))
-                (setq filename (concat (file-truename rest) missing))))))
-        (setq done t)))
+        (unless (string-match "[[*?]" filename)
+          ;; If filename exists, use its long name.  If it doesn't
+          ;; exist, the recursion below on the directory of filename
+          ;; will drill down until we find a directory that exists,
+          ;; and use the long name of that, with the extra
+          ;; non-existent path components concatenated.
+          (let ((longname (w32-long-file-name filename)))
+            (if longname
+                (setq filename longname)))))
 
     ;; If this file directly leads to a link, process that iteratively
     ;; so that we don't use lots of stack.
@@ -1135,6 +1117,8 @@ containing it, until no links are left at any level.
             (setq dirfile (directory-file-name dir))
             ;; If these are equal, we have the (or a) root directory.
             (or (string= dir dirfile)
+                (and (memq system-type '(windows-nt ms-dos cygwin))
+                     (eq (compare-strings dir 0 nil dirfile 0 nil t) t))
                 ;; If this is the same dir we last got the truename for,
                 ;; save time--don't recalculate.
                 (if (assoc dir (car prev-dirs))