diff --git a/src/os/file.php b/src/os/file.php
new file mode 100644
index 0000000..e42749b
--- /dev/null
+++ b/src/os/file.php
@@ -0,0 +1,57 @@
+<?php
+namespace nur\sery\os;
+
+use nur\sery\os\file\FileReader;
+use nur\sery\os\file\FileWriter;
+use nur\sery\os\file\SharedFile;
+use nur\sery\os\file\TmpfileWriter;
+
+/**
+ * Class file: outils pour gérer les fichiers
+ */
+class file {
+  static function reader($input, ?callable $func=null): FileReader {
+    $reader = new FileReader($input);
+    if ($func !== null) {
+      try {
+        $func($reader);
+      } finally {
+        $reader->close();
+      }
+    }
+  }
+  
+  static function writer($output, ?callable $func=null): FileWriter {
+    $writer = new FileWriter($output);
+    if ($func !== null) {
+      try {
+        $func($writer);
+      } finally {
+        $writer->close();
+      }
+    }
+  }
+  
+  static function tmpwriter($destdir=null, ?callable $func=null): TmpfileWriter {
+    $tmpwriter = new TmpfileWriter($destdir);
+    if ($func !== null) {
+      try {
+        $func($tmpwriter);
+      } finally {
+        $tmpwriter->close();
+      }
+    }
+  }
+
+  static function shared($file, ?callable $func=null): SharedFile {
+    $shared  = new SharedFile($file);
+    if ($func !== null) {
+      try {
+        $func($shared);
+      } finally {
+        $shared ->close();
+      }
+    }
+  }
+
+}
diff --git a/src/os/path.php b/src/os/path.php
index a15b47a..0a11003 100644
--- a/src/os/path.php
+++ b/src/os/path.php
@@ -18,8 +18,9 @@ class path {
    * - retourner la valeur null inchangée
    * - retourner '.' pour un chemin vide
    */
-  static final function normalize(?string $path): ?string {
-    if ($path === null) return null;
+  static final function normalize($path): ?string {
+    if ($path === null || $path === false) return null;
+    $path = strval($path);
     if ($path !== "") {
       if (substr($path, 0, 2) == "~/") {
         $path = sh::homedir().substr($path, 1);
@@ -53,15 +54,9 @@ class path {
     return $path !== ""? $path: ".";
   }
 
-  /** Comme normalize() mais retourner inchangée la valeur false */
-  static final function with($path) {
-    if ($path === null || $path === false) return $path;
-    else return self::normalize(strval($path));
-  }
-
   /** obtenir le chemin absolu normalisé correspondant à $path */
-  static final function abspath($path, ?string $cwd=null) {
-    if ($path === null || $path === false) return $path;
+  static final function abspath($path, ?string $cwd=null): ?string {
+    if ($path === null || $path === false) return null;
     $path = strval($path);
     if (substr($path, 0, 1) !== "/") {
       if ($cwd === null) $cwd = getcwd();
@@ -125,14 +120,12 @@ class path {
    * @throws IOException si le chemin n'existe pas ou si une autre erreur se
    * produit
    */
-  static final function realpath($path) {
-    if ($path === null || $path === false) return $path;
+  static final function realpath($path): ?string {
+    if ($path === null || $path === false) return null;
     $path = strval($path);
-    $realpath = realpath($path);
-    if ($realpath === false) throw IOException::last_error();
-    return $realpath;
+    return IOException::ensure_value(realpath($path));
   }
-  
+
   /**
    * obtenir le chemin parent de $path
    *
@@ -141,13 +134,14 @@ class path {
    * dirname("filename") === ".";
    */
   static final function dirname($path): ?string {
-    if ($path === null || $path === false) return $path;
+    if ($path === null || $path === false) return null;
     else return dirname(strval($path));
   }
 
   /** obtenir le nom du fichier sans son chemin */
   static final function filename($path): ?string {
-    if ($path === null || $path === false) return $path;
+    if ($path === null || $path === false) return null;
+    $path = strval($path);
     $index = strrpos($path, "/");
     if ($index !== false) $path = substr($path, $index + 1);
     return $path;
@@ -155,7 +149,7 @@ class path {
 
   /** obtenir le nom de base du fichier (sans son chemin et sans l'extension) */
   static final function basename($path): ?string {
-    if ($path === null || $path === false) return $path;
+    if ($path === null || $path === false) return null;
     $basename = self::filename($path);
     $index = strrpos($basename, ".");
     if ($index !== false) $basename = substr($basename, 0, $index);
@@ -164,7 +158,7 @@ class path {
 
   /** obtenir l'extension du fichier. l'extension est retournée avec le '.' */
   static final function ext($path): ?string {
-    if ($path === null || $path === false) return $path;
+    if ($path === null || $path === false) return null;
     $ext = self::filename($path);
     $index = strrpos($ext, ".");
     if ($index === false) $ext = "";
@@ -174,8 +168,9 @@ class path {
 
   /** découper le chemin entre sa partie "répertoire" et "fichier" */
   static final function split($path): array {
-    if ($path === null || $path === false) return [$path, $path];
+    if ($path === null || $path === false) return [null, null];
     elseif ($path === "") return ["", ""];
+    $path = strval($path);
     $index = strrpos($path, "/");
     if ($index !== false) {
       if ($index == 0) $dir = "/";