composer_fixer.php

<?php

$content = file_get_contents(__DIR__ . '/composer.json');

printf(
    "    \"hash\": \"%s\",\n    \"content-hash\": \"%s\",\n",
    md5($content),
    getContentHash($content)
);

function getContentHash($composerFileContents)
{
    $content = json_decode($composerFileContents, true);

    $relevantKeys = array(
        'name',
        'version',
        'require',
        'require-dev',
        'conflict',
        'replace',
        'provide',
        'minimum-stability',
        'prefer-stable',
        'repositories',
        'extra',
    );

    $relevantContent = array();

    foreach (array_intersect($relevantKeys, array_keys($content)) as $key) {
        $relevantContent[$key] = $content[$key];
    }
    if (isset($content['config']['platform'])) {
        $relevantContent['config']['platform'] = $content['config']['platform'];
    }

    ksort($relevantContent);

    return md5(json_encode($relevantContent));
}