On Wed, Jan 11, 2012 at 12:35 PM, Charles Pritchard <ch...@visc.us> wrote: > On 1/11/2012 12:27 PM, Eric U wrote: >> >> On Wed, Jan 11, 2012 at 12:22 PM, Charles Pritchard<ch...@jumis.com> >> wrote: >>> >>> On 1/11/2012 9:00 AM, Glenn Maynard wrote: >>>> >>>> >>>> This isn't properly specced anywhere and may be impossible to implement >>>> perfectly, but previous discussions indicated that Chrome, at least, >>>> wanted >>>> File objects loaded from input elements to only represent access for the >>>> file as it is when the user opened it. That is, the File is immutable >>>> (like >>>> a Blob), and if the underlying OS file changes (thus making the original >>>> data no longer available), attempting to read the File would fail. >>>> (This >>>> was in the context of storing File in structured clone persistent >>>> storage, >>>> like IndexedDB.) >>>> >>> Mozilla seems to only take a snapshot when the user opens the file. >>> Chrome >>> goes in the other direction, and does so intentionally with FileEntry. >>> I'd prefer everyone follow Chrome. >> >> We do so with FileEntry, in the sandbox, because it's intended to be a >> much more powerful API than File, and the security aspects of it are >> much simpler. When the user drags a File into the browser, it's much >> less clear that they intend to give the web app persistent access to >> that File, including all future changes until the page is closed. I >> don't think we'd rush to make that change to the spec. And if our >> implementation isn't snapshotting currently, that's a bug. > > > In my reading of the spec, UAs explicitly instructed not to implement a > snapshot.
If so that's a bug in the spec. File and Blob objects are intended to contain constant data. For a file object returned from <input type=file> I would expect the implementation to make all reads fail if the data changes on disk. I know we don't do this in Firefox right now, but I consider that a bug. / Jonas