Fix mime-type of existing S3 files

composer.json

{
    "require": {
        "aws/aws-sdk-php": "*"
    }
}

fix_mimetypes.php

<?php
use Aws\S3\S3Client;
use Guzzle\Service\Resource\Model;

ini_set('error_reporting', E_ALL);
require_once __DIR__.'/vendor/autoload.php';

class MimeFixer
{
  protected $unknown_exts = array();

  protected $checked_count = 0;
  protected $changed_count = 0;

  public function __construct()
  {
    $this->client = S3Client::factory(array(
          'profile' => 's3_mimefixer'
    ));
  }

  public function fixMimes($bucket)
  {
    foreach ($this->getS3FileIterator($bucket) as $s3Object) {
      if ($s3Object['Size'] > 0) {
        $this->checked_count++;
        $this->fixMime($bucket, $s3Object);
      }
    }

    print "Checked ".$this->checked_count." files".PHP_EOL;
    print "Updated ".$this->changed_count." files".PHP_EOL;

    print_r("Unknown file extensions:");
    print_r($this->unknown_exts);
  }

  protected function getS3FileIterator($bucket)
  {
    return $this->client->getIterator('ListObjects', array('Bucket' => $bucket));
  }

  protected function fixMime($bucket, $s3Object)
  {
    $metadata = $this->client->headObject(array('Bucket' => $bucket, 'Key' => $s3Object['Key']));
    $new_mime = $this->getMimeForObjectName($s3Object['Key']);

    if ($new_mime AND ($metadata['ContentType'] !== $new_mime)) {
     $this->setNewMimeType($bucket, $s3Object, $metadata, $new_mime);
    } else {
      print "✓ Matching or unknown content type for ".$s3Object['Key'].' ('.$metadata['ContentType'].')'.PHP_EOL;
    }
  }

  protected function getMimeForObjectName($key)
  {
    $ext = pathinfo($key, PATHINFO_EXTENSION);
    switch ($ext) {
      case 'jpg':
        return 'image/jpeg';

      case 'htm':
      case 'html':
        return 'text/html';

      case 'm4a':
        return 'audio/mp4';

      case 'mp3':
        return 'audio/mpeg';

      case 'mp4':
        return 'video/mp4';

      case 'flv':
        return 'video/flv';

      case 'png':
        return 'image/png';

      case 'xml':
        return 'application/xml';

      default:
        $this->unknown_exts[$ext][] = $key;
        return NULL;
    }
  }

  protected function setNewMimeType($bucket, $s3Object, Model $metadata, $new_mime)
  {
    $this->changed_count++;
    $key = $s3Object['Key'];
    print "! Setting $key from ".$metadata['ContentType'].' to '.$new_mime.PHP_EOL;

    $request = array(
        'ACL'               => 'public-read',
        'Bucket'            => $bucket,
        'Key'               => $key,
        'CopySource'        => urlencode($bucket.'/'.$key),
        'CacheControl'      => $metadata->get('CacheControl'),
        'ContentType'       => $new_mime,
        'Metadata'          => $metadata->get('Metadata'),
        'MetadataDirective' => 'REPLACE',
    );
    $response = $this->client->copyObject($request);
  }

}

$fixer = new MimeFixer();
$fixer->fixMimes($argv[1]);