PHP escapeshellarg function, UTF8 and locales

2011-06-14 23:09

The PHP escapeshellarg function depends on your current locale. I think it’s bad, but PHP developers made this choice. If like me your default locale is ‘C’ you lose all UTF8 characters.

They suggest you to call something like setlocale(LC_CTYPE, "en_US.UTF-8"). It doesn’t work if the en_US.utf8 locale is not installed on your system. Of course maybe you have the fr_FR.utf8, or de_DE.utf8, but you will have to try all of them until you find one utf8 matching locale. And if there is not, you’re screwed. It’s also bad if you want code that runs everywhere.

Simply use that:

$escapedArg = "'".str_replace("'", "'\\''", $arg)."'";

It will do the same as the escapeshellarg function: replace yourstringthat'slong by

'yourstringthat'\''slong'

as described in the escapeshellarg manual (and I also looked into the PHP source code to be sure).

See also:

2011-06-14 23:09 · Tags: , ,

Preload web content using link prefetch or javascript

2010-10-30 16:50

For the Bizou php gallery, I looked for different ways of preloading next image in “view” mode (example).

With Firefox it’s very simple. Just use the following element and the browser will preload your contents.
Contents are preloaded in background, once the whole current page is loaded.

 [html]
<link rel="prefetch" href="/images/nextimage.jpg" />

Problem: only Firefox supports this currently.
Note: a ticket is opened about this in the Chromium project.

For other browsers, use some Javascript triggered by the window.onload event:

 [javascript]
<script type="text/javascript">
window.onload = function() {
    // for images
    var im = new Image();
    im.src = '/images/nextimage.jpg';
    // and for other content
    var req = new XMLHttpRequest();
    req.open('GET', 'nextpage.php', false);
    req.send(null);
};
</script>

Beware of HTTP cache headers sent by the server to the browser.
To preload correctly PHP pages, make your script send an Expires header:

header('Expires: '.gmdate('D, d M Y H:i:s \G\M\T', time() + 3600));

Then, for a simple browser detection from your PHP script:

<?php if (strpos($_SERVER['HTTP_USER_AGENT'], 'Firefox') !== false) { ?>
<link rel="prefetch" href="nextpage.php" />

<?php } else { ?>
<script type="text/javascript">
window.onload = function() {
    var req = new XMLHttpRequest();
    req.open('GET', 'nextpage.php', false);
    req.send(null);
};
</script>
<?php } ?>

Links :

2010-10-30 16:50 · Tags: , , , , ,