Add wp_join_paths and wp_canonicalize_path functions

composer.json

@@ -29,6 +29,7 @@
     },
     "files": [
       "src/WordPress/Blueprints/functions.php",
+      "src/WordPress/Filesystem/functions.php",
       "src/WordPress/Streams/stream_str_replace.php"
     ]
   },

src/WordPress/Filesystem/functions.php

@@ -0,0 +1,41 @@
+<?php
+
+function wp_join_paths() {
+	$paths = array();
+	foreach ( func_get_args() as $arg ) {
+		if ( $arg !== '' ) {
+			$paths[] = $arg;
+		}
+	}
+	$path = implode( '/', $paths );
+
+	return preg_replace( '#/+#', '/', $path );
+}
+
+function wp_canonicalize_path( $path ) {
+	// Convert to absolute path
+	if ( ! str_starts_with( $path, '/' ) ) {
+		$path = '/' . $path;
+	}
+
+	// Resolve . and ..
+	$parts      = explode( '/', $path );
+	$normalized = array();
+	foreach ( $parts as $part ) {
+		if ( $part === '.' || $part === '' ) {
+			continue;
+		}
+		if ( $part === '..' ) {
+			array_pop( $normalized );
+			continue;
+		}
+		$normalized[] = $part;
+	}
+
+	// Reconstruct path
+	$result = '/' . implode( '/', $normalized );
+	if ( $result === '/.' ) {
+		$result = '/';
+	}
+	return $result === '' ? '/' : $result;
+}