<?php
namespace Aws\S3\Crypto;
use \Aws\Crypto\MetadataStrategyInterface;
use \Aws\Crypto\MetadataEnvelope;
use \Aws\S3\S3Client;
/**
* Stores and reads encryption MetadataEnvelope information in a file on Amazon
* S3.
*
* A file with the contents of a MetadataEnvelope will be created or read from
* alongside the base file on Amazon S3. The provided client will be used for
* reading or writing this object. A specified suffix (default of '.instruction'
* will be applied to each of the operations involved with the instruction file.
*
* If there is a failure after an instruction file has been uploaded, it will
* not be automatically deleted.
*/
class InstructionFileMetadataStrategy implements MetadataStrategyInterface
{
const DEFAULT_FILE_SUFFIX = '.instruction';
private $client;
private $suffix;
/**
* @param S3Client $client Client for use in uploading the instruction file.
* @param string|null $suffix Optional override suffix for instruction file
* object keys.
*/
public function __construct(S3Client $client, $suffix = null)
{
$this->suffix = empty($suffix)
? self::DEFAULT_FILE_SUFFIX
: $suffix;
$this->client = $client;
}
/**
* Places the information in the MetadataEnvelope to a location on S3.
*
* @param MetadataEnvelope $envelope Encryption data to save according to
* the strategy.
* @param array $args Starting arguments for PutObject, used for saving
* extra the instruction file.
*
* @return array Updated arguments for PutObject.
*/
public function save(MetadataEnvelope $envelope, array $args)
{
$this->client->putObject([
'Bucket' => $args['Bucket'],
'Key' => $args['Key'] . $this->suffix,
'Body' => json_encode($envelope)
]);
return $args;
}
/**
* Uses the strategy's client to retrieve the instruction file from S3 and generates
* a MetadataEnvelope from its contents.
*
* @param array $args Arguments from Command and Result that contains
* S3 Object information, relevant headers, and command
* configuration.
*
* @return MetadataEnvelope
*/
public function load(array $args)
{
$result = $this->client->getObject([
'Bucket' => $args['Bucket'],
'Key' => $args['Key'] . $this->suffix
]);
$metadataHeaders = json_decode($result['Body'], true);
$envelope = new MetadataEnvelope();
$constantValues = MetadataEnvelope::getConstantValues();
foreach ($constantValues as $constant) {
if (!empty($metadataHeaders[$constant])) {
$envelope[$constant] = $metadataHeaders[$constant];
}
}
return $envelope;
}
}