The tempnam() function creates a temporary file with 0600 permissions, regardless of the umask. This requires that every dumpFile() call is followed by a chmod() to 'fix' the permissions. I would assume that the function does this for me, since other filesystem operations (eg: copy and touch) also create files with the default file permissions.

I found this issue that relates to this issue, and deprecated the argument in which you could set the permissions in the dumpFile() call. So, without being able to use the argument, I would prefer it if the created file has the right permissions. If not, the documentation for this function should specify this clearly, I think.