sanitize_file_name( string $filename )

Sanitizes a filename, replacing whitespace with dashes.


Description Description

Removes special characters that are illegal in filenames on certain operating systems and special characters requiring special escaping to manipulate at the command line. Replaces spaces and consecutive dashes with a single dash. Trims period, dash and underscore from beginning and end of filename. It is not guaranteed that this function will return a filename that is allowed to be uploaded.


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Parameters Parameters

$filename

(string) (Required) The filename to be sanitized.


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Return Return

(string) The sanitized filename.


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More Information More Information

The special characters are passed through the sanitize_file_name_chars filter before removing them from the file name, allowing plugins to change which characters are considered invalid. After sanitize_file_name() has done its work, it passes the sanitized file name through the sanitize_file_name filter.



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Source Source

File: wp-includes/formatting.php

function sanitize_file_name( $filename ) {
	$filename_raw  = $filename;
	$special_chars = array( '?', '[', ']', '/', '\\', '=', '<', '>', ':', ';', ',', "'", '"', '&', '$', '#', '*', '(', ')', '|', '~', '`', '!', '{', '}', '%', '+', chr( 0 ) );
	/**
	 * Filters the list of characters to remove from a filename.
	 *
	 * @since 2.8.0
	 *
	 * @param string[] $special_chars Array of characters to remove.
	 * @param string   $filename_raw  The original filename to be sanitized.
	 */
	$special_chars = apply_filters( 'sanitize_file_name_chars', $special_chars, $filename_raw );
	$filename      = preg_replace( "#\x{00a0}#siu", ' ', $filename );
	$filename      = str_replace( $special_chars, '', $filename );
	$filename      = str_replace( array( '%20', '+' ), '-', $filename );
	$filename      = preg_replace( '/[\r\n\t -]+/', '-', $filename );
	$filename      = trim( $filename, '.-_' );

	if ( false === strpos( $filename, '.' ) ) {
		$mime_types = wp_get_mime_types();
		$filetype   = wp_check_filetype( 'test.' . $filename, $mime_types );
		if ( $filetype['ext'] === $filename ) {
			$filename = 'unnamed-file.' . $filetype['ext'];
		}
	}

	// Split the filename into a base and extension[s].
	$parts = explode( '.', $filename );

	// Return if only one extension.
	if ( count( $parts ) <= 2 ) {
		/**
		 * Filters a sanitized filename string.
		 *
		 * @since 2.8.0
		 *
		 * @param string $filename     Sanitized filename.
		 * @param string $filename_raw The filename prior to sanitization.
		 */
		return apply_filters( 'sanitize_file_name', $filename, $filename_raw );
	}

	// Process multiple extensions.
	$filename  = array_shift( $parts );
	$extension = array_pop( $parts );
	$mimes     = get_allowed_mime_types();

	/*
	 * Loop over any intermediate extensions. Postfix them with a trailing underscore
	 * if they are a 2 - 5 character long alpha string not in the extension whitelist.
	 */
	foreach ( (array) $parts as $part ) {
		$filename .= '.' . $part;

		if ( preg_match( '/^[a-zA-Z]{2,5}\d?$/', $part ) ) {
			$allowed = false;
			foreach ( $mimes as $ext_preg => $mime_match ) {
				$ext_preg = '!^(' . $ext_preg . ')$!i';
				if ( preg_match( $ext_preg, $part ) ) {
					$allowed = true;
					break;
				}
			}
			if ( ! $allowed ) {
				$filename .= '_';
			}
		}
	}
	$filename .= '.' . $extension;
	/** This filter is documented in wp-includes/formatting.php */
	return apply_filters( 'sanitize_file_name', $filename, $filename_raw );
}

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Changelog Changelog

Changelog
Version Description
2.1.0 Introduced.

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