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Web browsers should preserve the file system Last-Modified time of downloaded files

From: Brolin Empey <brolin@brolin.be>
Date: Fri, 04 Nov 2011 16:18:51 -0700
Message-ID: <4EB472DB.6060605@brolin.be>
To: www-tag@w3.org
CC: Tim Berners-Lee <timbl@w3.org>, Amy van der Hiel <amy@w3.org>

I have already contacted timbl and amy (in CC above) about this subject 
because I wanted timblís personal opinion, but timbl referred me to this 

Most GUI Web browsers (maybe most Web browsers, including non-GUI ones?) 
do not preserve the file system last modified time of downloaded files: 
  even if the HTTP server sends the Last-Modified response header, the 
Web browser does not set the last modified time (mtime) field of the 
downloaded file in the local file system to the Last-Modified time 
served with the file.  This behaviour effectively *changes* the last 
modified time of the downloaded file even if the file has not actually 
been modified.

The Web browser should preserve the file system last modified time by 
default because this time cannot easily be recovered after it is discarded.

I believe implementing this basic file copy functionality should be 
prioritised above advanced features such as WebGL and Typed Arrays [1]:

current releases of both Mozilla Firefox [2] and Google Chrome [3] can 
run Quake II [4] [5] and boot and run a Linux v2.6.20 kernel and BusyBox 
userland on an x86 computer emulated in JavaScript [6] without requiring 
any extensions or plug-ins but still cannot even preserve the file 
system last modified time of a downloaded file without an optional 
extension (for Mozilla only, not Google Chrome).

Mozilla Firefox >= v5.0 can preserve the file system last modified time 
if the optional Preserve Download Modification Timestamp (PDMTS) 
extension is installed:


This extension probably would not have been created if I had not acted 
to fix Mozilla:


I used to believe my priorities in life were inverted, but my priority 
inversion seems to have been outdone by the developers of major GUI Web 

I do not want to start Yet Anotherô debate over the last modified time 
preservation behaviour but, if necessary, I can fully support my 
argument, as I have already done elsewhere multiple times.

I want the W3C to convince the developers of (at least major GUI) Web 
browsers to finally fix this bug by preserving the file system last 
modified time of downloaded files by default.  The behaviour could be a 
policy with an easily discoverable GUI to change it because I know some 
confused users will resist change by wanting the broken behaviour.

At the least, I want Mozilla to include PDMTS in the base installation 
of both Firefox and SeaMonkey with file system last modified time 
preservation enabled by default.

Thank you,
Brolin Empey

[1] <http://www.khronos.org/registry/typedarray/specs/latest/>
[2] Tested with v5.0 on Windows 7 Professional Service Pack 1 IA-32
[3] Tested v15 on on Windows 7 Professional Service Pack 1 IA-32
[4] <http://code.google.com/p/quake2-gwt-port/>
[5] <http://playwebgl.com/games/quake-2-webgl/
[6] <http://bellard.org/jslinux/>
Received on Saturday, 5 November 2011 07:23:31 UTC

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