Improved sysfs file access code

lib/GpioPin.php

@@ -19,6 +19,8 @@
 
 namespace NoccyLabs\Gpio;
 
+use NoccyLabs\Gpio\Exception\HardwareException;
+
 use NoccyLabs\Sansi\Charset as CS;
 
 /**
@@ -41,10 +43,13 @@ class GpioPin
     protected $handler;
 
     protected $label;
+    
+    protected $gpio;
 
-    public function __construct($pin)
+    public function __construct($pin, Gpio $gpio)
     {
         $this->pin = (int)$pin;
+        $this->gpio = $gpio;
         $this->export();
         $this->fd = fopen("/sys/class/gpio/gpio{$pin}/value", "rb");
     }
@@ -80,13 +85,24 @@ class GpioPin
     {
         return $this->value;
     }
-    
+
+    /**
+     * Set a descriptive label for the pin, used for debugging and troubleshooting.
+     *
+     * @param string $label
+     * @return NoccyLabs\Gpio\GpioPin 
+     */    
     public function setLabel($label)
     {
         $this->label = (string)$label;
         return $this;
     }
     
+    /**
+     * Get the assigned label for this pin.
+     *
+     * @return string The label
+     */    
     public function getLabel()
     {
         return $this->label;
@@ -94,9 +110,9 @@ class GpioPin
     
     public function export()
     {
-        @file_put_contents("/sys/class/gpio/export", $this->pin);
+        $this->sysfsWrite(null, "export", $this->pin);
         if (!file_exists("/sys/class/gpio/gpio{$this->pin}")) {
-            throw new \Exception();
+            throw new HardwareException("Unable to export pin {$this->pin}");
         }
         return $this;
     }
@@ -107,23 +123,54 @@ class GpioPin
         return $this;
     }
     
+    public function sysfsWrite($pin, $file, $value)
+    {
+        if ($pin) {
+            $path = "/sys/class/gpio/gpio{$pin}/{$file}";
+        } else {
+            $path = "/sys/class/gpio/{$file}";
+        }
+        if (!is_writable($path)) {
+            throw new HardwareException("Sysfs file {$path} not writable");
+        }
+        $f = fopen($path,"w+");
+        if (!is_resource($f)) {
+            throw new HardwareException("Unable to write to sysfs file {$path}");
+        }
+        fwrite($f,$value);
+        fclose($f);
+    }
+    
+    public function sysfsRead($pin, $file)
+    {
+        $path = "/sys/class/gpio/gpio{$pin}/{$file}";
+        $f = fopen($path,"r");
+        if (!is_resource($f)) {
+            throw new HardwareException("Unable to read from sysfs file {$path}");
+        }
+        $ret = fgets($f);
+        fclose($f);
+        return $ret;
+    }
+    
     public function setEdge($edge)
     {
         if (!in_array($edge, array("rising", "falling", "both", "none"))) {
             throw new \Exception;
         }
         $this->edge = $edge;
-        @file_put_contents("/sys/class/gpio/gpio{$this->pin}/edge", $edge);
+        $this->sysfsWrite($this->pin, "edge", $edge);
         return $this;
     }
     
     public function getEdge()
     {
-        return $this->edge;
+        return $this->sysfsRead($this->pin, "edge");
     }
     
     public function setHandler(callable $handler=null)
     {
+        $this->gpio->setInterruptHandler($this->pin, $this->fd);
         return $this;
     }