sanitize_file_name( string $filename ): string

Description

Compatibility

Present in every tracked release (6.7.7 to 7.1.0), and compiles on PHP 7.4 through 8.6-dev.

Parameters

$filenamestring

The filename to be sanitized.

Return value

string

The sanitized filename.

Performance profile

How much work a call to sanitize_file_name() does, and what it touches: the algorithmic scaling, the Zend instruction count per call across PHP versions, the hooks it hands control to, and the core code that calls it. Measured from the compiled opcodes, not a stopwatch, so every number is identical on any machine running the same PHP version, and every function in core is ranked by cost.

Cost class

Light

Touches nothing outside its own arguments.

Scaling

Scales with input

The body loops, so the work grows with what you pass in.

Instructions

50–101

Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 125.

Plugin surface

2 hooks

Third-party callbacks on 'sanitize_file_name_chars', 'sanitize_file_name' run inside this call, and their cost is not bounded by anything here.

Called by

5

5 places in core call this, so the cost is paid more often than your own code shows.

What it touches

• hookthird-party callbacksapply_filters()called directly

Further down the call graph this can also reach option, cache, serialize, query and transient. Those are the worst case, several calls deep and usually down an error path, not what a normal call pays.

What one call costs · 8 distinct outcomes

One number would be a lie: the work depends on which branch runs. These are every distinct cost sanitize_file_name() can have, taken from its control-flow graph on PHP 8.5.

Hooks and filters fired · 3

3 hooks fire while sanitize_file_name() runs, in this order:

1. 1
   apply_filters( sanitize_file_name_chars )filterline 2069 (+34 into the body)

   Filters the list of characters to remove from a filename.

2. 2
   apply_filters( sanitize_file_name )filterline 2091 (+56 into the body)

   Filters a sanitized filename string.

3. 3
   apply_filters( sanitize_file_name )filterline 2131 (+96 into the body)

   Filters a sanitized filename string.

Uses · 9

• remove_accents()Converts all accent characters to ASCII characters.
• wp_is_valid_utf8()Determines if a given byte string represents a valid UTF-8 encoding.
• sanitize_title_with_dashes()Sanitizes a title, replacing whitespace and a few other characters with dashes.
• _wp_can_use_pcre_u()Returns whether PCRE/u (PCRE_UTF8 modifier) is available for use.
• apply_filters()Calls the callback functions that have been added to a filter hook.
• str_contains()Polyfill for `str_contains()` function added in PHP 8.0.
• wp_get_mime_types()Retrieves the list of mime types and file extensions.
• wp_check_filetype()Retrieves the file type from the file name.
• get_allowed_mime_types()Retrieves the list of allowed mime types and file extensions.

Used by · 5

• File_Upload_Upgrader::__construct()Construct the upgrader for a form.
• download_url()Downloads a URL to a local temporary file using the WordPress HTTP API.
• wp_copy_parent_attachment_properties()Copy parent attachment properties to newly cropped image.
• wp_unique_filename()Gets a filename that is sanitized and unique for the given directory.
• wp_xmlrpc_server::mw_newMediaObject()Uploads a file, following your settings.

Source code

View on Trac ↗View on GitHub ↗

2035function sanitize_file_name( $filename ) {2036	$filename_raw = $filename;2037	$filename     = remove_accents( $filename );2038 2039	$special_chars = array( '?', '[', ']', '/', '\\', '=', '<', '>', ':', ';', ',', "'", '"', '&', '$', '#', '*', '(', ')', '|', '~', '`', '!', '{', '}', '%', '+', '’', '«', '»', '”', '“', chr( 0 ) );2040 2041	if ( ! wp_is_valid_utf8( $filename ) ) {2042		$_ext     = pathinfo( $filename, PATHINFO_EXTENSION );2043		$_name    = pathinfo( $filename, PATHINFO_FILENAME );2044		$filename = sanitize_title_with_dashes( $_name ) . '.' . $_ext;2045	}2046 2047	if ( _wp_can_use_pcre_u() ) {2048		/**2049		 * Replace all whitespace characters with a basic space (U+0020).2050		 *2051		 * The “Zs” in the pattern selects characters in the `Space_Separator`2052		 * category, which is what Unicode considers space characters.2053		 *2054		 * @see https://www.unicode.org/reports/tr44/#General_Category_Values2055		 * @see https://www.unicode.org/versions/Unicode16.0.0/core-spec/chapter-6/#G175482056		 * @see https://www.php.net/manual/en/regexp.reference.unicode.php2057		 */2058		$filename = preg_replace( '#\p{Zs}#siu', ' ', $filename );2059	}2060 2061	/**2062	 * Filters the list of characters to remove from a filename.2063	 *2064	 * @since 2.8.02065	 *2066	 * @param string[] $special_chars Array of characters to remove.2067	 * @param string   $filename_raw  The original filename to be sanitized.2068	 */2069	$special_chars = apply_filters( 'sanitize_file_name_chars', $special_chars, $filename_raw );2070 2071	$filename = str_replace( $special_chars, '', $filename );2072	$filename = str_replace( array( '%20', '+' ), '-', $filename );2073	$filename = preg_replace( '/\.{2,}/', '.', $filename );2074	$filename = preg_replace( '/[\r\n\t -]+/', '-', $filename );2075	$filename = trim( $filename, '.-_' );2076 2077	if ( ! str_contains( $filename, '.' ) ) {2078		$mime_types = wp_get_mime_types();2079		$filetype   = wp_check_filetype( 'test.' . $filename, $mime_types );2080		if ( $filetype['ext'] === $filename ) {2081			$filename = 'unnamed-file.' . $filetype['ext'];2082		}2083	}2084 2085	// Split the filename into a base and extension[s].2086	$parts = explode( '.', $filename );2087 2088	// Return if only one extension.2089	if ( count( $parts ) <= 2 ) {2090		/** This filter is documented in wp-includes/formatting.php */2091		return apply_filters( 'sanitize_file_name', $filename, $filename_raw );2092	}2093 2094	// Process multiple extensions.2095	$filename  = array_shift( $parts );2096	$extension = array_pop( $parts );2097	$mimes     = get_allowed_mime_types();2098 2099	/*2100	 * Loop over any intermediate extensions. Postfix them with a trailing underscore2101	 * if they are a 2 - 5 character long alpha string not in the allowed extension list.2102	 */2103	foreach ( (array) $parts as $part ) {2104		$filename .= '.' . $part;2105 2106		if ( preg_match( '/^[a-zA-Z]{2,5}\d?$/', $part ) ) {2107			$allowed = false;2108			foreach ( $mimes as $ext_preg => $mime_match ) {2109				$ext_preg = '!^(' . $ext_preg . ')$!i';2110				if ( preg_match( $ext_preg, $part ) ) {2111					$allowed = true;2112					break;2113				}2114			}

Changelog

Introduced in 2.1.0. Unchanged from 6.7.7 through 7.1.0.

1. 6.7.7
2. 6.8.8
3. 6.9.7
4. 7.0.4
5. 7.1.0

Signature, return type and hooks compared across 5 parsed releases.

About this page

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