Stream FTP upload in chunks with PHP?

Question

Is it possible to stream an FTP upload with PHP? I have files I need to upload to another server, and I can only access that server through FTP. Unfortunately, I can't up the timeout time on this server. Is it at all possible to do this?

Basically, if there is a way to write part of a file, and then append the next part (and repeat) instead of uploading the whole thing at once, that'd save me. However, my Googling hasn't provided me with an answer.

Is this achievable?

Answer 1

The easiest way to append a chunk to the end of a remote file is to use file_put_contents with FILE_APPEND flag:

file_put_contents('ftp://username:pa‌​ssword@hostname/path/to/file', $chunk, FILE_APPEND);

If it does not work, it's probably because you do not have URL wrappers enabled in PHP.

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If you need a greater control over the writing (transfer mode, passive mode, etc), or you cannot use the file_put_contents, use the ftp_fput with a handle to the php://temp (or the php://memory) stream:

$conn_id = ftp_connect('hostname');

ftp_login($conn_id, 'username', 'password');
ftp_pasv($conn_id, true);

$h = fopen('php://temp', 'r+');
fwrite($h, $chunk);
rewind($h);

// prevent ftp_fput from seeking local "file" ($h)
ftp_set_option($conn_id, FTP_AUTOSEEK, false);

$remote_path = '/path/to/file';
$size = ftp_size($conn_id, $remote_path);
$r = ftp_fput($conn_id, $remote_path, $h, FTP_BINARY, $size);

fclose($h);
ftp_close($conn_id);

(add error handling)

Answer 2

OK then... This might be what you're looking for. Are you familiar with curl?

CURL can support appending for FTP:

curl_setopt($ch, CURLOPT_FTPAPPEND, TRUE ); // APPEND FLAG

The other option is to use ftp:// / ftps:// streams, since PHP 5 they allow appending. See ftp://; ftps:// Docs. Might be easier to access.