文件上传拒绝动画 GIF（使用 PHP/Zend 框架）答案

【问题标题】：File Upload Deny Animated GIFs (using PHP/Zend Framework)文件上传拒绝动画 GIF（使用 PHP/Zend 框架）
【发布时间】：2010-07-29 11:01:11
【问题描述】：

我想我可能希望用户能够上传静态 GIF，但不能上传动画。说化身，因为他们可能看起来......不专业和分散注意力。 PHP 或 Zend 框架中是否有一种方法可以验证文件上传？

【问题讨论】：

标签： php validation zend-framework file-upload

【解决方案1】：

您可以使用gd 库来保存您的图像。对于 gif 类型的文件，如果动画，则仅保存 gif 文件中的第一帧。有关如何使用它的更多信息，请参阅imagegif 函数。

【讨论】：

【解决方案2】：

形成PHP: imagecreatefromgif - Manual：

I wrote two alternate versions of ZeBadger's is_ani() function, for determining if a gif file is animated

Original:
http://us.php.net/manual/en/function.imagecreatefromgif.php#59787

The first alternative version is just as memory intensive as the original, and more CPU intensive, but far simpler:

<?php
function is_ani($filename) {
    return (bool)preg_match('#(\x00\x21\xF9\x04.{4}\x00\x2C.*){2,}#s', file_get_contents($filename));
}
?>

The second alternative is about as CPU intensive as the original function, but uses less memory (and may also result in less disk activity)

<?php
function is_ani($filename) {
    if(!($fh = @fopen($filename, 'rb')))
        return false;
    $count = 0;
    //an animated gif contains multiple "frames", with each frame having a
    //header made up of:
    // * a static 4-byte sequence (\x00\x21\xF9\x04)
    // * 4 variable bytes
    // * a static 2-byte sequence (\x00\x2C)

    // We read through the file til we reach the end of the file, or we've found
    // at least 2 frame headers
    while(!feof($fh) && $count < 2)
        $chunk = fread($fh, 1024 * 100); //read 100kb at a time
        $count += preg_match_all('#\x00\x21\xF9\x04.{4}\x00\x2C#s', $chunk, $matches);

    fclose($fh);
    return $count > 1;
}
?>

【讨论】：