ENH: Move RenameFile to cmSystemTools

This moves the cmGeneratedFileStream::RenameFile method implementation
into cmSystemTools.  It works only within a single filesystem volume,
but is atomic when the operating system permits.

Source/cmGeneratedFileStream.cxx

@@ -18,14 +18,6 @@
 
 #include "cmSystemTools.h"
 
-// Includes needed for implementation of RenameFile.  This is not in
-// system tools because it is not implemented robustly enough to move
-// files across directories.
-#ifdef _WIN32
-# include <windows.h>
-# include <sys/stat.h>
-#endif
-
 #if defined(CMAKE_BUILD_WITH_CMAKE)
 # include <cm_zlib.h>
 #endif
@@ -254,51 +246,7 @@ int cmGeneratedFileStreamBase::CompressFile(const char*, const char*)
 int cmGeneratedFileStreamBase::RenameFile(const char* oldname,
                                           const char* newname)
 {
-#ifdef _WIN32
+  return cmSystemTools::RenameFile(oldname, newname);
-  /* On Windows the move functions will not replace existing files.
-     Check if the destination exists.  */
-  struct stat newFile;
-  if(stat(newname, &newFile) == 0)
-    {
-    /* The destination exists.  We have to replace it carefully.  The
-       MoveFileEx function does what we need but is not available on
-       Win9x.  */
-    OSVERSIONINFO osv;
-    DWORD attrs;
-
-    /* Make sure the destination is not read only.  */
-    attrs = GetFileAttributes(newname);
-    if(attrs & FILE_ATTRIBUTE_READONLY)
-      {
-      SetFileAttributes(newname, attrs & ~FILE_ATTRIBUTE_READONLY);
-      }
-
-    /* Check the windows version number.  */
-    osv.dwOSVersionInfoSize = sizeof(osv);
-    GetVersionEx(&osv);
-    if(osv.dwPlatformId == VER_PLATFORM_WIN32_WINDOWS)
-      {
-      /* This is Win9x.  There is no MoveFileEx implementation.  We
-         cannot quite rename the file atomically.  Just delete the
-         destination and then move the file.  */
-      DeleteFile(newname);
-      return MoveFile(oldname, newname);
-      }
-    else
-      {
-      /* This is not Win9x.  Use the MoveFileEx implementation.  */
-      return MoveFileEx(oldname, newname, MOVEFILE_REPLACE_EXISTING);
-      }
-    }
-  else
-    {
-    /* The destination does not exist.  Just move the file.  */
-    return MoveFile(oldname, newname);
-    }
-#else
-  /* On UNIX we have an OS-provided call to do this atomically.  */
-  return rename(oldname, newname) == 0;
-#endif
 }
 
 //----------------------------------------------------------------------------

Source/cmSystemTools.cxx

@@ -1108,6 +1108,56 @@ bool cmSystemTools::CopyFileIfDifferent(const char* source,
   return Superclass::CopyFileIfDifferent(source, destination);
 }
 
+//----------------------------------------------------------------------------
+bool cmSystemTools::RenameFile(const char* oldname, const char* newname)
+{
+#ifdef _WIN32
+  /* On Windows the move functions will not replace existing files.
+     Check if the destination exists.  */
+  struct stat newFile;
+  if(stat(newname, &newFile) == 0)
+    {
+    /* The destination exists.  We have to replace it carefully.  The
+       MoveFileEx function does what we need but is not available on
+       Win9x.  */
+    OSVERSIONINFO osv;
+    DWORD attrs;
+
+    /* Make sure the destination is not read only.  */
+    attrs = GetFileAttributes(newname);
+    if(attrs & FILE_ATTRIBUTE_READONLY)
+      {
+      SetFileAttributes(newname, attrs & ~FILE_ATTRIBUTE_READONLY);
+      }
+
+    /* Check the windows version number.  */
+    osv.dwOSVersionInfoSize = sizeof(osv);
+    GetVersionEx(&osv);
+    if(osv.dwPlatformId == VER_PLATFORM_WIN32_WINDOWS)
+      {
+      /* This is Win9x.  There is no MoveFileEx implementation.  We
+         cannot quite rename the file atomically.  Just delete the
+         destination and then move the file.  */
+      DeleteFile(newname);
+      return MoveFile(oldname, newname);
+      }
+    else
+      {
+      /* This is not Win9x.  Use the MoveFileEx implementation.  */
+      return MoveFileEx(oldname, newname, MOVEFILE_REPLACE_EXISTING);
+      }
+    }
+  else
+    {
+    /* The destination does not exist.  Just move the file.  */
+    return MoveFile(oldname, newname);
+    }
+#else
+  /* On UNIX we have an OS-provided call to do this atomically.  */
+  return rename(oldname, newname) == 0;
+#endif
+}
+
 bool cmSystemTools::ComputeFileMD5(const char* source, char* md5out)
 {
 #if defined(CMAKE_BUILD_WITH_CMAKE)

Source/cmSystemTools.h

@@ -166,6 +166,10 @@ public:
   static bool CopyFileIfDifferent(const char* source, 
     const char* destination);
 
+  /** Rename a file or directory within a single disk volume (atomic
+      if possible).  */
+  static bool RenameFile(const char* oldname, const char* newname);
+
   ///! Compute the md5sum of a file
   static bool ComputeFileMD5(const char* source, char* md5out);