* external.cc (sync_wincwd): Remove.

(cygwin_internal): Drop CW_SYNC_WINCWD case.
	* globals.cc (ro_u_pipedir): New R/O unicode string.
	* ntdll.h (RtlSetCurrentDirectory_U): Declare.
	* path.cc (cwdstuff::set): Improve comments.  Drop setting Win32 CWD to
	\\?\PIPE\ on init.  Keep Win32 CWD in sync, if possible.  Set to
	\\?\PIPE\ otherwise.
	* include/cygwin/version.h (CYGWIN_VERSION_API_MINOR): Revert to 230.
	* include/sys/cygwin.h (cygwin_getinfo_types): Remove CW_SYNC_WINCWD.

winsup/cygwin/ChangeLog

@@ -1,3 +1,15 @@
+2010-08-27  Corinna Vinschen  <corinna@vinschen.de>
+
+	* external.cc (sync_wincwd): Remove.
+	(cygwin_internal): Drop CW_SYNC_WINCWD case.
+	* globals.cc (ro_u_pipedir): New R/O unicode string.
+	* ntdll.h (RtlSetCurrentDirectory_U): Declare.
+	* path.cc (cwdstuff::set): Improve comments.  Drop setting Win32 CWD to
+	\\?\PIPE\ on init.  Keep Win32 CWD in sync, if possible.  Set to
+	\\?\PIPE\ otherwise.
+	* include/cygwin/version.h (CYGWIN_VERSION_API_MINOR): Revert to 230.
+	* include/sys/cygwin.h (cygwin_getinfo_types): Remove CW_SYNC_WINCWD.
+
 2010-08-27  Corinna Vinschen  <corinna@vinschen.de>
 
 	* fhandler_proc.cc (format_proc_partitions): Improve comment.

winsup/cygwin/external.cc

@@ -162,29 +162,6 @@ sync_winenv ()
   free (envblock);
 }
 
-/* Synchronize Win32 CWD with Cygwin CWD.  Return -1 and set errno if
-   setting the Win32 CWD fails. */
-static unsigned long
-sync_wincwd ()
-{
-  unsigned long ret = (unsigned long) -1;
-  /* Lock cwd.  We're accessing it directly here. */
-  cygheap->cwd.cwd_lock.acquire ();
-  /* First check if the path can work at all.  Fortunately we already have
-     an error code in the cwd, which was stored there for the sake of
-     spawn_guts. */
-  if (cygheap->cwd.get_error ())
-    set_errno (cygheap->cwd.get_error ());
-  /* Of course, SetCurrentDirectoryW still can fail, for instance, if the
-     CWD has been removed or renamed in the meantime. */
-  else if (!SetCurrentDirectoryW (cygheap->cwd.win32.Buffer))
-    __seterrno ();
-  else
-    ret = 0;
-  cygheap->cwd.cwd_lock.release ();
-  return ret;
-}
-
 /*
  * Cygwin-specific wrapper for win32 ExitProcess and TerminateProcess.
  * It ensures that the correct exit code, derived from the specified
@@ -537,9 +514,6 @@ cygwin_internal (cygwin_getinfo_types t, ...)
 	  res = (uintptr_t) strerror (err);
 	}
 	break;
-      case CW_SYNC_WINCWD:
-	res = sync_wincwd ();
-	break;
 
       default:
 	set_errno (ENOSYS);

winsup/cygwin/globals.cc

@@ -109,6 +109,7 @@ UNICODE_STRING _RDATA ro_u_udf = _ROU (L"UDF");
 UNICODE_STRING _RDATA ro_u_unixfs = _ROU (L"UNIXFS");
 UNICODE_STRING _RDATA ro_u_nwfs = _ROU (L"NWFS");
 UNICODE_STRING _RDATA ro_u_volume = _ROU (L"\\??\\Volume{");
+UNICODE_STRING _RDATA ro_u_pipedir = _ROU (L"\\\\?\\PIPE\\");
 #undef _ROU
 
 /* Cygwin properties are meant to be readonly data placed in the DLL, but

winsup/cygwin/include/cygwin/version.h

@@ -390,13 +390,12 @@ details. */
       228: CW_STRERROR added.
       229: Add mkostemp, mkostemps.
       230: Add CLOCK_MONOTONIC.
-      231: CW_SYNC_WINCWD.
      */
 
      /* Note that we forgot to bump the api for ualarm, strtoll, strtoull */
 
 #define CYGWIN_VERSION_API_MAJOR 0
-#define CYGWIN_VERSION_API_MINOR 231
+#define CYGWIN_VERSION_API_MINOR 230
 
      /* There is also a compatibity version number associated with the
 	shared memory regions.  It is incremented when incompatible

winsup/cygwin/include/sys/cygwin.h

@@ -149,8 +149,7 @@ typedef enum
     CW_INT_SETLOCALE,
     CW_CVT_MNT_OPTS,
     CW_LST_MNT_OPTS,
-    CW_STRERROR,
+    CW_STRERROR
-    CW_SYNC_WINCWD
   } cygwin_getinfo_types;
 
 /* Token type for CW_SET_EXTERNAL_TOKEN */

winsup/cygwin/ntdll.h

@@ -1005,6 +1005,7 @@ extern "C"
 					BOOLEAN);
   VOID NTAPI RtlReleasePebLock ();
   VOID NTAPI RtlSecondsSince1970ToTime (ULONG, PLARGE_INTEGER);
+  NTSTATUS NTAPI RtlSetCurrentDirectory_U (PUNICODE_STRING);
   BOOLEAN NTAPI RtlSetCurrentTransaction (HANDLE);
   NTSTATUS NTAPI RtlUnicodeStringToAnsiString (PANSI_STRING, PUNICODE_STRING,
 					       BOOLEAN);

winsup/cygwin/path.cc

@@ -3286,36 +3286,48 @@ cwdstuff::init ()
 int
 cwdstuff::set (path_conv *nat_cwd, const char *posix_cwd)
 {
+  NTSTATUS status;
   UNICODE_STRING upath;
   bool virtual_path = false;
   bool unc_path = false;
   bool inaccessible_path = false;
 
-  /* Here are the problems with using SetCurrentDirectory:
+  /* Here are the problems with using SetCurrentDirectory.  Just skip this
+     comment if you don't like whining.
      
      - SetCurrentDirectory only supports paths of up to MAX_PATH - 1 chars,
        including a trailing backslash.  That's an absolute restriction, even
        in the UNICODE API.
 
-     - SetCurrentDirectory fails for directories with strict
+     - SetCurrentDirectory fails for directories with strict permissions even
-       permissions even for processes with the SE_BACKUP_NAME
+       for processes with the SE_BACKUP_NAME privilege enabled.  The reason
-       privilege enabled.  The reason is apparently that
+       is apparently that SetCurrentDirectory calls NtOpenFile without the
-       SetCurrentDirectory calls NtOpenFile without the
        FILE_OPEN_FOR_BACKUP_INTENT flag set.
 
      - SetCurrentDirectory does not support case-sensitivity.
 
-     - Unlinking a cwd fails because SetCurrentDirectory seems to
+     - Unlinking a cwd fails because SetCurrentDirectory seems to open
-       open directories so that deleting the directory is disallowed.
+       directories so that deleting the directory is disallowed.
 
      - SetCurrentDirectory can naturally not work on virtual Cygwin paths
        like /proc or /cygdrive.
 
-     Therefore, we do without SetCurrentDirectory and handle the CWD all
+     Unfortunately, even though we have access to the Win32 process parameter
-     by ourselves.  To avoid surprising behaviour in the Win32 API which
+     block, we can't just replace the directory handle.  Starting with Vista,
-     would stem from the fact that the Win32 CWD is different from the
+     the handle is used elsewhere, and just replacing the handle in the process
-     POSIX CWD, we move the Win32 CWD to an invalid directory in which
+     parameter block shows quite surprising results.
-     typical relative Win32 path handling fails.  */
+     FIXME: If we ever find a *safe* way to replace the directory handle in
+     the process parameter block, we're back in business.
+
+     Nevertheless, doing entirely without SetCurrentDirectory is not really
+     feasible, because it breaks too many mixed applications using the Win32
+     API.
+
+     Therefore we handle the CWD all by ourselves and just keep the Win32
+     CWD in sync.  However, to avoid surprising behaviour in the Win32 API
+     when we are in a CWD which is inaccessible as Win32 CWD, we set the
+     Win32 CWD to a "weird" directory in which all relative filesystem-related
+     calls fail. */
 
   cwd_lock.acquire ();
 
@@ -3332,7 +3344,6 @@ cwdstuff::set (path_conv *nat_cwd, const char *posix_cwd)
   HANDLE h = NULL;
   if (!virtual_path)
     {
-      NTSTATUS status;
       IO_STATUS_BLOCK io;
       OBJECT_ATTRIBUTES attr;
 
@@ -3351,7 +3362,9 @@ cwdstuff::set (path_conv *nat_cwd, const char *posix_cwd)
 			nat_cwd->objcaseinsensitive () | OBJ_INHERIT,
 			NULL, NULL);
       /* First try without FILE_OPEN_FOR_BACKUP_INTENT, to find out if the
-         directory is valid for Win32 apps. */
+         directory is valid for Win32 apps.  And, no, we can't just call
+	 SetCurrentDirectory here, since that would potentially break
+	 case-sensitivity. */
       status = NtOpenFile (&h, SYNCHRONIZE | FILE_TRAVERSE, &attr, &io,
 			   FILE_SHARE_VALID_FLAGS,
 			   FILE_DIRECTORY_FILE
@@ -3397,15 +3410,6 @@ cwdstuff::set (path_conv *nat_cwd, const char *posix_cwd)
 	unc_path = true;
 
       posix_cwd = NULL;
-
-      /* When inited move the actual Win32 CWD out of the way, as explained
-	 above.  Surprisingly, the PIPE filesystem seems to be usable as CWD
-	 on all Windows systems. */
-      if (!SetCurrentDirectoryW (L"\\\\?\\PIPE\\"))
-	system_printf (
-"WARNING: Couldn't set Win32 CWD to //?/PIPE (error %E).  This will\n"
-"probably not affect normal POSIX path operations.  However, please report\n"
-"this problem to the mailing list mailto:cygwin@cygwin.com.  Thank you.");
     }
   else
     {
@@ -3468,6 +3472,15 @@ cwdstuff::set (path_conv *nat_cwd, const char *posix_cwd)
       else
 	error = 0;
     }
+  /* Keep the Win32 CWD in sync.  Don't check for error, other than for
+     strace output.  Try to keep overhead low. */
+  if (nat_cwd)
+    {
+      status = RtlSetCurrentDirectory_U (error ? &ro_u_pipedir : &win32);
+      if (!NT_SUCCESS (status))
+	debug_printf ("RtlSetCurrentDirectory_U(%S) failed, %p",
+		      error ? &ro_u_pipedir : &win32, status);
+    }
 
   /* Eventually, create POSIX path if it's not set on entry. */
   tmp_pathbuf tp;