* syscalls.cc (rename): Use volume serial numbers stored in path_conv

	rather than fetching them here for the "same file" test.  Change
	comment to reflect this.

1 files changed, 7 insertions, 15 deletions

diff --git a/winsup/cygwin/syscalls.cc b/winsup/cygwin/syscalls.cc
index 7da929efa..b323da203 100644
--- a/winsup/cygwin/syscalls.cc
+++ b/winsup/cygwin/syscalls.cc
@@ -1740,12 +1740,14 @@ rename (const char *oldpath, const char *newpath)
   /* SUSv3: If the old argument and the new argument resolve to the same
      existing file, rename() shall return successfully and perform no
      other action.
-     The test tries to be as quick as possible.  First it tests if oldpath
-     has more than 1 hardlink, then it opens newpath and tests for identical
-     file ids.  If so, it tests for identical volume serial numbers,  If so,
-     oldpath and newpath refer to the same file. */
+     The test tries to be as quick as possible.  First it tests for identical
+     volume serial numbers because that information is available anyway.
+     Then it tests if oldpath has more than 1 hardlink, then it opens newpath
+     and tests for identical file ids.  If so, oldpath and newpath refer to
+     the same file. */
   if ((removepc || dstpc->exists ())
       && !oldpc.isdir ()
+      && dstpc->fs_serial_number () == oldpc.fs_serial_number ()
       && NT_SUCCESS (NtQueryInformationFile (fh, &io, &ofsi, sizeof ofsi,
 					     FileStandardInformation))
       && ofsi.NumberOfLinks > 1
@@ -1756,23 +1758,13 @@ rename (const char *oldpath, const char *newpath)
 		     | ((removepc ?: dstpc)->is_rep_symlink ()
 			? FILE_OPEN_REPARSE_POINT : 0))))
     {
-      static const size_t vsiz = sizeof (FILE_FS_VOLUME_INFORMATION)
-				 + 32 * sizeof (WCHAR);
       FILE_INTERNAL_INFORMATION ofii, nfii;
-      PFILE_FS_VOLUME_INFORMATION opffvi, npffvi;
 
       if (NT_SUCCESS (NtQueryInformationFile (fh, &io, &ofii, sizeof ofii,
 					      FileInternalInformation))
 	  && NT_SUCCESS (NtQueryInformationFile (nfh, &io, &nfii, sizeof nfii,
 						 FileInternalInformation))
-	  && ofii.FileId.QuadPart == nfii.FileId.QuadPart
-	  && (opffvi = (PFILE_FS_VOLUME_INFORMATION) alloca (vsiz))
-	  && (npffvi = (PFILE_FS_VOLUME_INFORMATION) alloca (vsiz))
-	  && NT_SUCCESS (NtQueryVolumeInformationFile (fh, &io, opffvi, vsiz,
-						    FileFsVolumeInformation))
-	  && NT_SUCCESS (NtQueryVolumeInformationFile (nfh, &io, npffvi, vsiz,
-						    FileFsVolumeInformation))
-	  && opffvi->VolumeSerialNumber == npffvi->VolumeSerialNumber)
+	  && ofii.FileId.QuadPart == nfii.FileId.QuadPart)
 	{
 	  debug_printf ("%s and %s are the same file", oldpath, newpath);
 	  NtClose (nfh);