Handle File Upload Size Limits in Web Applications

Configure file upload limits at multiple levels:

Step 1: PHP Configuration (php.ini)

; Maximum allowed size for uploaded files
upload_max_filesize = 50M

; Maximum size of POST data
post_max_size = 50M

; Maximum execution time for scripts
max_execution_time = 300

; Maximum input time
max_input_time = 300

; Memory limit
memory_limit = 256M

Step 2: Web Server Configuration

For Apache (.htaccess)

# Increase upload limits
php_value upload_max_filesize 50M
php_value post_max_size 50M
php_value max_execution_time 300
php_value max_input_time 300

For Nginx

server {
    # Maximum allowed size of client request body
    client_max_body_size 50M;

    # Timeout for reading client request body
    client_body_timeout 300s;
}

Step 3: Application-Level Handling

<?php
// Check upload errors
if ($_FILES['upload']['error'] !== UPLOAD_ERR_OK) {
    switch ($_FILES['upload']['error']) {
        case UPLOAD_ERR_INI_SIZE:
            $error = 'File exceeds upload_max_filesize directive';
            break;
        case UPLOAD_ERR_FORM_SIZE:
            $error = 'File exceeds MAX_FILE_SIZE directive';
            break;
        case UPLOAD_ERR_PARTIAL:
            $error = 'File was only partially uploaded';
            break;
        case UPLOAD_ERR_NO_FILE:
            $error = 'No file was uploaded';
            break;
        default:
            $error = 'Unknown upload error';
            break;
    }
    throw new Exception($error);
}

// Validate file size
$maxSize = 50 * 1024 * 1024; // 50MB in bytes
if ($_FILES['upload']['size'] > $maxSize) {
    throw new Exception('File size exceeds limit');
}

// Validate file type
$allowedTypes = ['image/jpeg', 'image/png', 'application/pdf'];
if (!in_array($_FILES['upload']['type'], $allowedTypes)) {
    throw new Exception('File type not allowed');
}
?>

Step 4: Frontend Progress Indication

// Show upload progress
function uploadFile(file) {
    const formData = new FormData();
    formData.append('upload', file);

    fetch('/upload.php', {
        method: 'POST',
        body: formData
    })
    .then(response => response.json())
    .then(data => {
        console.log('Upload successful:', data);
    })
    .catch(error => {
        console.error('Upload failed:', error);
    });
}