Datei-Uploads verarbeiten

Datei-Uploads in PHP – Überblick

HTML-Upload-Formular

<!-- Single file -->
<form method="POST" action="upload.php"
      enctype="multipart/form-data">
    <input type="file" name="document">
    <button>Upload</button>
</form>

<!-- Multiple files -->
<form method="POST" enctype="multipart/form-data">
    <input type="file" name="photos[]" multiple>
    <button>Upload All</button>
</form>

Struktur von $_FILES

<?php
$file = $_FILES['document'];

echo $file['name'];      // original name: report.pdf
echo $file['type'];      // browser-reported MIME: application/pdf
echo $file['tmp_name'];  // server temp path: /tmp/phpXXXXXX
echo $file['error'];     // error code: 0 = UPLOAD_ERR_OK
echo $file['size'];      // file size in bytes

Upload-Fehlercodes

<?php
$errorMessages = [
    UPLOAD_ERR_INI_SIZE   => 'Exceeds upload_max_filesize in php.ini',
    UPLOAD_ERR_FORM_SIZE  => 'Exceeds MAX_FILE_SIZE in form',
    UPLOAD_ERR_PARTIAL    => 'Only partially uploaded',
    UPLOAD_ERR_NO_FILE    => 'No file uploaded',
    UPLOAD_ERR_NO_TMP_DIR => 'Missing temp folder',
    UPLOAD_ERR_CANT_WRITE => 'Failed to write to disk',
    UPLOAD_ERR_EXTENSION  => 'PHP extension stopped upload',
];

$err = $_FILES['doc']['error'];
if ($err !== UPLOAD_ERR_OK) {
    die($errorMessages[$err] ?? 'Unknown error');
}

Dateityp sicher validieren

<?php
$tmp  = $_FILES['image']['tmp_name'];
$allowed = ['image/jpeg', 'image/png', 'image/webp'];

// Check real MIME type from file content
$realMime = mime_content_type($tmp);

if (!in_array($realMime, $allowed)) {
    die('Invalid file type: ' . $realMime);
}

Dateigröße validieren

<?php
$maxBytes = 5 * 1024 * 1024;  // 5MB
$size     = $_FILES['video']['size'];

if ($size > $maxBytes) {
    $mb = round($size / 1024 / 1024, 2);
    die("File too large: {$mb}MB (max 5MB)");
}

is_uploaded_file und move_uploaded_file

<?php
$tmp  = $_FILES['photo']['tmp_name'];
$dest = '/var/www/uploads/' . basename($_FILES['photo']['name']);

if (!is_uploaded_file($tmp)) {
    die('Not an uploaded file — possible attack');
}

if (!move_uploaded_file($tmp, $dest)) {
    die('Failed to move uploaded file');
}

echo 'Upload saved to: ' . $dest;

Sichere Dateinamen erzeugen

<?php
$originalName = $_FILES['doc']['name'];
$ext          = strtolower(pathinfo($originalName, PATHINFO_EXTENSION));

$allowedExts = ['jpg', 'jpeg', 'png', 'pdf'];
if (!in_array($ext, $allowedExts)) {
    die('File type not allowed');
}

$safeName = bin2hex(random_bytes(16)) . '.' . $ext;
$dest     = '/var/www/uploads/' . $safeName;

move_uploaded_file($_FILES['doc']['tmp_name'], $dest);

Mehrere Datei-Uploads verarbeiten

<?php
$files = $_FILES['photos'];
$count = count($files['name']);

for ($i = 0; $i < $count; $i++) {
    if ($files['error'][$i] !== UPLOAD_ERR_OK) continue;
    
    $tmp  = $files['tmp_name'][$i];
    $ext  = pathinfo($files['name'][$i], PATHINFO_EXTENSION);
    $dest = '/uploads/' . uniqid() . '.' . strtolower($ext);
    
    move_uploaded_file($tmp, $dest);
    echo "Saved: $dest" . PHP_EOL;
}

Upload-Einstellungen in php.ini

Bilder nach dem Upload skalieren

<?php
function resizeImage(string $src, string $dst, int $maxW): void {
    [$w, $h, $type] = getimagesize($src);
    $ratio   = $maxW / $w;
    $newH    = (int) ($h * $ratio);
    $srcImg  = imagecreatefromjpeg($src);
    $dstImg  = imagecreatetruecolor($maxW, $newH);
    imagecopyresampled($dstImg, $srcImg, 0,0,0,0, $maxW, $newH, $w, $h);
    imagejpeg($dstImg, $dst, 90);
    imagedestroy($srcImg);
    imagedestroy($dstImg);
}

Schnelltest

Zusammenfassung: Datei-Uploads