How to Get File Information with pathinfo()

Table Of Contents

• Working Solution
• Behind the Scenes

Working Solution

<?php

// Basic pathinfo usage
$filepath = '/var/www/html/uploads/document.pdf';
$info = pathinfo($filepath);

print_r($info);
/* Output:
Array (
    [dirname] => /var/www/html/uploads
    [basename] => document.pdf
    [extension] => pdf
    [filename] => document
)
*/

// Get specific components
$directory = pathinfo($filepath, PATHINFO_DIRNAME);     // '/var/www/html/uploads'
$filename = pathinfo($filepath, PATHINFO_FILENAME);     // 'document'
$extension = pathinfo($filepath, PATHINFO_EXTENSION);   // 'pdf'
$basename = pathinfo($filepath, PATHINFO_BASENAME);     // 'document.pdf'

// File upload validation
function validateUploadedFile(string $originalName): array {
    $info = pathinfo($originalName);
    
    $allowedExtensions = ['jpg', 'jpeg', 'png', 'gif', 'pdf', 'doc', 'docx'];
    $maxFilenameLength = 100;
    
    $validation = [
        'valid' => true,
        'errors' => []
    ];
    
    // Check extension
    if (!isset($info['extension']) || !in_array(strtolower($info['extension']), $allowedExtensions)) {
        $validation['valid'] = false;
        $validation['errors'][] = 'Invalid file extension';
    }
    
    // Check filename length
    if (strlen($info['filename']) > $maxFilenameLength) {
        $validation['valid'] = false;
        $validation['errors'][] = 'Filename too long';
    }
    
    // Check for dangerous characters
    if (preg_match('/[^a-zA-Z0-9._-]/', $info['filename'])) {
        $validation['valid'] = false;
        $validation['errors'][] = 'Filename contains invalid characters';
    }
    
    return $validation;
}

// Generate unique filename while preserving extension
function generateUniqueFilename(string $originalPath, string $targetDirectory): string {
    $info = pathinfo($originalPath);
    $extension = isset($info['extension']) ? '.' . $info['extension'] : '';
    $basename = $info['filename'];
    
    $counter = 1;
    $newFilename = $basename . $extension;
    
    while (file_exists($targetDirectory . '/' . $newFilename)) {
        $newFilename = $basename . '_' . $counter . $extension;
        $counter++;
    }
    
    return $newFilename;
}

// File organization by extension
function organizeFilesByType(array $filePaths): array {
    $organized = [
        'images' => [],
        'documents' => [],
        'archives' => [],
        'other' => []
    ];
    
    $imageExts = ['jpg', 'jpeg', 'png', 'gif', 'webp', 'svg'];
    $docExts = ['pdf', 'doc', 'docx', 'txt', 'rtf', 'odt'];
    $archiveExts = ['zip', 'rar', '7z', 'tar', 'gz'];
    
    foreach ($filePaths as $filepath) {
        $extension = strtolower(pathinfo($filepath, PATHINFO_EXTENSION));
        
        if (in_array($extension, $imageExts)) {
            $organized['images'][] = $filepath;
        } elseif (in_array($extension, $docExts)) {
            $organized['documents'][] = $filepath;
        } elseif (in_array($extension, $archiveExts)) {
            $organized['archives'][] = $filepath;
        } else {
            $organized['other'][] = $filepath;
        }
    }
    
    return $organized;
}

// Safe filename sanitization
function sanitizeFilename(string $filename): string {
    $info = pathinfo($filename);
    $extension = isset($info['extension']) ? '.' . $info['extension'] : '';
    
    // Remove directory path (security measure)
    $cleanName = $info['filename'];
    
    // Replace dangerous characters
    $cleanName = preg_replace('/[^a-zA-Z0-9._-]/', '_', $cleanName);
    
    // Remove multiple consecutive underscores
    $cleanName = preg_replace('/_+/', '_', $cleanName);
    
    // Trim underscores from start/end
    $cleanName = trim($cleanName, '_');
    
    // Ensure we have a name
    if (empty($cleanName)) {
        $cleanName = 'file_' . time();
    }
    
    return $cleanName . $extension;
}

// Create backup filename
function createBackupFilename(string $originalPath): string {
    $info = pathinfo($originalPath);
    $timestamp = date('Y-m-d_H-i-s');
    
    $backupName = $info['filename'] . '_backup_' . $timestamp;
    if (isset($info['extension'])) {
        $backupName .= '.' . $info['extension'];
    }
    
    return $info['dirname'] . '/' . $backupName;
}

// Usage examples
$uploadedFile = $_FILES['document']['name'] ?? 'test-file.pdf';

// Validate uploaded file
$validation = validateUploadedFile($uploadedFile);
if ($validation['valid']) {
    echo "File is valid\n";
} else {
    echo "Errors: " . implode(', ', $validation['errors']) . "\n";
}

// Generate unique filename
$uniqueName = generateUniqueFilename($uploadedFile, '/uploads');
echo "Unique filename: $uniqueName\n";

// Organize files
$files = [
    '/docs/report.pdf',
    '/images/photo.jpg',
    '/data/archive.zip',
    '/misc/readme.txt'
];
$organized = organizeFilesByType($files);
print_r($organized);

// Sanitize filename
$unsafeFilename = '../../../etc/passwd.txt';
$safeFilename = sanitizeFilename($unsafeFilename);
echo "Safe filename: $safeFilename\n"; // 'passwd.txt'

// Create backup
$backupPath = createBackupFilename('/config/settings.json');
echo "Backup path: $backupPath\n";

Behind the Scenes

pathinfo() breaks down file paths into manageable components:

1. Path Parsing: Separates directory, filename, and extension
2. Cross-Platform: Works on Windows, Linux, and macOS paths
3. Safe Extraction: Handles edge cases like files without extensions
4. Component Access: Get specific parts without manual string manipulation

Available Components:

• PATHINFO_DIRNAME - Directory path
• PATHINFO_BASENAME - Full filename with extension
• PATHINFO_EXTENSION - File extension only
• PATHINFO_FILENAME - Filename without extension

Essential for file uploads, path manipulation, and file organization tasks where you need to work with specific parts of file paths.