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.

1 files changed, 50 insertions, 0 deletions

diff --git a/Source/cmSystemTools.cxx b/Source/cmSystemTools.cxx
index 84ed729..4fb9afa 100644
--- a/Source/cmSystemTools.cxx
+++ b/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)