getimagesize（）在有效的图像引用上失败

Question

我正在尝试确定图像的元数据。此代码适用于我遇到的每个有效图像引用，直到现在。这是我正在使用的代码：

<?php

$url = "http://206.196.103.100/Vendor%20Images/ADI36462.jpg";

try {
    list($content, $img_info) = captureImageData($url);
    print("Success!!\n");
    var_dump($img_info);
} catch (Exception $e) {
    print("Failure!!\n" . (string)$e);
}

function captureImageData($filepath) {
    print('"' . $filepath . '" detected as a remote file' . "\n");
    $local_file = '/tmp/img_' . uniqid();
    try {
        // harvest the data into a temp file
        $cmd = 'wget -O "' . $local_file . '" "' . $filepath . '"';
        print('Running cmd: ' . $cmd . "\n");
        `$cmd`;
    } catch (Exception $e) {
        // output the wget headers
        unlink($local_file);
        throw new Exception('Unable to read file: '.$filepath);
    }

    $content = file_get_contents($local_file);
    if ($content === false) {
        unlink($local_file);
        throw new Exception('Unable to read file: '.$filepath);
    }

    $img_info = getimagesize($local_file);
    if ($img_info === false) {
        unlink($local_file);
        throw new Exception('File "' . $filepath . '" did not return an image');
    }

    unlink($local_file);

    return array($content, $img_info);
}

在进入getimagesize（）调用之前，所有内容都处理得很好，并返回false。这种情况是不是原因，还是我应该做其他检查？