getLines.php

<?php // works on single-file non-ZIp64 zip files compressed with deflate (AKA a common case), licensed MIT

function getLinesFromZippedCSVfromURL(string $url) : \Generator
{
    $stream = fopen($url, 'rb');

    fread($stream, 4 + 2 + 2 + 2 + 2 + 2 + 4); // skip up to compressed size

    // bindec() was doing weird things, hence converting through hex first
    // sttrev() to match endian-ness to expectations; zip file values are little-endian
    $compressedSize = hexdec(bin2hex(strrev(fread($stream, 4)))); // compressed size
    fread($stream, 4); // uncompressed size; we don't need this

    $filenameLength = hexdec(bin2hex(strrev(fread($stream, 2))));
    $extraLength = hexdec(bin2hex(strrev(fread($stream, 2))));

    fread($stream, $filenameLength); // filename
    if ($extraLength) {
        fread($stream, $extraLength);
    }

    // We're past headers now; let's get some data!

    $inflate = inflate_init(ZLIB_ENCODING_RAW);

    $uncompressedBuffer = '';
    for ($offset = 0, $chunkSize = 256; $offset < $compressedSize; $offset += $chunkSize) {
        if ($offset + $chunkSize > $compressedSize) {
            $chunkSize = $compressedSize - $offset;
        }

        $uncompressedBuffer .= inflate_add($inflate, fread($stream, $chunkSize));
        while (strpos($uncompressedBuffer, "\n") !== false) {
            [$line, $uncompressedBuffer] = explode("\n", $uncompressedBuffer, 2);
            yield str_getcsv($line);
        }
    }
}