Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Reader/Slk.php
public function canRead($pFilename)
    {
        // Check if file exists
        try {
            $this->openFile($pFilename);
        } catch (Exception $e) {
            return false;
        }

        // Read sample data (first 2 KB will do)
        $data = fread($this->fileHandle, 2048);

        // Count delimiters in file
        $delimiterCount = substr_count($data, ';');
        $hasDelimiter = $delimiterCount > 0;

        // Analyze first line looking for ID; signature
        $lines = explode("\n", $data);
        $hasId = substr($lines[0], 0, 4) === 'ID;P';

        fclose($this->fileHandle);

        return $hasDelimiter && $hasId;
    }
public function canRead($pFilename)
    {
        // Check if file exists
        try {
            $this->openFile($pFilename);
        } catch (Exception $e) {
            return false;
        }

        // Read sample data (first 2 KB will do)
        $data = fread($this->fileHandle, 2048);

        // Count delimiters in file
        $delimiterCount = substr_count($data, ';');
        $hasDelimiter = $delimiterCount > 0;

        // Analyze first line looking for ID; signature
        $lines = explode("\n", $data);
        $hasId = substr($lines[0], 0, 4) === 'ID;P';

        fclose($this->fileHandle);

        return $hasDelimiter && $hasId;
    }
Validate that the current file is a SYLK file.

@param string $pFilename

@return bool