Checksums

Checksum retrieval was added in 3.7

Flysystem can resolve checksums for files. Some filesystems provide native checksum generation capabilities. As a fallback, the Filesystem class can generate a polyfill checksum. In some cases, an Etag pseudo-checksum is provided.

The following adapters provide checksums:

• AWS S3 (etag)
• Async AWS S3 (etag)
• Google Cloud Storage (md5, crc32c, etag)
• Azure (md5)

By default, these implementations will return the first checksum type listed above. If native checksum generation is not available, the filesystem will compute a checksum by (stream) reading the file and computing a hash. If the chosen algorithm is not supported by your adapter, the fallback mechanism will be used to produce the checksum.

You can use the hash_algos function to see which algorithms are supported for your PHP version.

Usage

Checksums can be retrieved using the checksum method.

$checksum = $filesystem->checksum('path/to/file.txt'); // etag or md5

// you can specify the algo during the method call too
$checksum = $filesystem->checksum('path/to/file.txt', ['checksum_algo' => 'sha1']);

Specifying a default checksum type

You can specify the default checksum type by configuring the Filesystem class.

use League\Flysystem\Filesystem;

$filesystem = new Filesystem(
    $adapter,
    ['checksum_algo' => 'sha256']
);


$checksum = $filesystem->checksum('path/to/file.txt'); // always sha256