Make Icinga\Util\File an object

Was a class with just one static function beforehand and is now a fully
object oriented alternative for how files and pipes can be handled.
PHP warnings emitted by fopen, fwrite, fread and chmod are catched
and thrown as exceptions.

library/Icinga/Util/File.php

@@ -1,16 +1,164 @@
 <?php
-// @codeCoverageIgnoreStart
 // {{{ICINGA_LICENSE_HEADER}}}
 // {{{ICINGA_LICENSE_HEADER}}}
 
 namespace Icinga\Util;
 
+use Exception;
+use Icinga\Exception\ProgrammingError;
+
+/**
+ * File
+ *
+ * A class to ease opening files and reading/writing to them.
+ */
 class File
 {
-    public static function create($filename, $mode = 0664)
+    /**
+     * The location of the file
+     *
+     * @var string
+     */
+    protected $path;
+
+    /**
+     * The file resource
+     *
+     * @var resource
+     */
+    protected $handle;
+
+    /**
+     * The file access mode to set
+     *
+     * Gets set/updated after the file has been closed.
+     *
+     * @var int
+     */
+    protected $accessMode;
+
+    /**
+     * Open a file
+     *
+     * @param   string  $path       The location of the file
+     * @param   int     $openMode   The open mode to use
+     */
+    protected function __construct($path, $openMode)
     {
-        fclose(fopen($filename, 'a'));
-        chmod($filename, $mode);
+        $this->setupErrorHandler();
+        $this->handle = fopen($path, $openMode);
+        $this->resetErrorHandler();
+    }
+
+    /**
+     * Open a file
+     *
+     * @param   string  $path       The location of the file
+     * @param   int     $openMode   The open mode to use
+     *
+     * @return  File
+     */
+    public static function open($path, $openMode = 'r')
+    {
+        return new static($path, $openMode);
+    }
+
+    /**
+     * Read contents of file
+     *
+     * @param   int|null    $length     Read up to $length bytes or until EOF if null
+     *
+     * @return  string
+     */
+    public function read($length = null)
+    {
+        $this->setupErrorHandler();
+        $content = stream_get_contents($this->handle, $length !== null ? $length : -1);
+        $this->resetErrorHandler();
+        return $content;
+    }
+
+    /**
+     * Write contents to file
+     *
+     * @param   string  $bytes      The contents to write
+     *
+     * @return  self
+     */
+    public function write($bytes)
+    {
+        $this->setupErrorHandler();
+
+        $written = 0;
+        while ($bytes) {
+            $justWritten = fwrite($this->handle, $bytes);
+
+            if ($justWritten === 0) {
+                throw new Exception('Failed to write to open file.');
+            }
+
+            $bytes = substr($bytes, $justWritten);
+            $written += $justWritten;
+        }
+
+        $this->resetErrorHandler();
+        return $this;
+    }
+
+    /**
+     * Change access mode of file
+     *
+     * Note that the access mode cannot be changed until the file is still open.
+     *
+     * @param   int     $accessMode     The access mode to set
+     *
+     * @return  self
+     */
+    public function chmod($accessMode)
+    {
+        $this->accessMode = $accessMode;
+        return $this;
+    }
+
+    /**
+     * Close the file
+     *
+     * @throws  ProgrammingError    In case the file is already closed or its resource became invalid
+     */
+    public function close()
+    {
+        if (!is_resource($this->handle)) {
+            throw new ProgrammingError('Tried to close an invalid file resource or an already closed file');
+        }
+
+        fclose($this->handle);
+
+        if ($this->accessMode !== null) {
+            $this->setupErrorHandler();
+            chmod($this->path, $this->accessMode);
+            $this->resetErrorHandler();
+        }
+    }
+
+    /**
+     * Setup an error handler that throws an exception for every emitted E_WARNING
+     */
+    protected function setupErrorHandler()
+    {
+        set_error_handler(
+            function ($errno, $errstr) {
+                restore_error_handler(); // Should we call resetErrorHandler() here? (Requires it to be public)
+                throw new Exception($errstr);
+            },
+            E_WARNING
+        );
+    }
+
+    /**
+     * Reset the error handler to the system default
+     */
+    protected function resetErrorHandler()
+    {
+        restore_error_handler();
     }
 }
-// @codeCoverageIgnoreEnd