Check for valid file descriptor after opening, before writing data into it

1 files changed, 24 insertions, 29 deletions

diff --git a/lights.c b/lights.c
index f0c1cb5..c387faf 100755
--- a/lights.c
+++ b/lights.c
@@ -5,20 +5,22 @@
 #include <hardware/lights.h>
 #include <hardware/hardware.h>
 
-
 #define BACKLIGHT "/sys/class/backlight/aml-bl/brightness"
+
 static int set_light_backlight(struct light_device_t* dev,
         struct light_state_t const* state)
 {
-    int nwr, ret, fd;
+    int nwr, ret = -1, fd;
     char value[20];
     int light_level;
     light_level =state->color&0xff;
     
     fd = open(BACKLIGHT, O_RDWR);
-    nwr = sprintf(value, "%d\n", light_level);
-    ret = write(fd, value, nwr);
-    close(fd);
+    if (fd > 0) {
+        nwr = sprintf(value, "%d\n", light_level);
+        ret = write(fd, value, nwr);
+        close(fd);
+    }
 
     return ret;
 }
@@ -27,44 +29,37 @@ static int open_lights(const struct hw_module_t* module, char const* name,
         struct hw_device_t** device)
 {
     int res = -EINVAL;
-    int (*set_light)(struct light_device_t* dev,
-            struct light_state_t const* state);
 
     if (strcmp(LIGHT_ID_BACKLIGHT, name) == 0) {
-    struct light_device_t *dev = malloc(sizeof(struct light_device_t));
-    if (!dev) {
-        return res;
-    }
-                
-    set_light = set_light_backlight;
-    
-    memset(dev, 0, sizeof(*dev));
-    dev->common.tag = HARDWARE_DEVICE_TAG;
-    dev->common.version = 0;
-    dev->common.module = (struct hw_module_t*)module;
-    dev->common.close = NULL;
-    dev->set_light = set_light;
+        struct light_device_t *dev = malloc(sizeof(struct light_device_t));
+        if (!dev) {
+            return res;
+        }
+
+        memset(dev, 0, sizeof(*dev));
+        dev->common.tag = HARDWARE_DEVICE_TAG;
+        dev->common.version = 0;
+        dev->common.module = (struct hw_module_t*)module;
+        dev->common.close = NULL;
+        dev->set_light = set_light_backlight;
 
-    *device = (struct hw_device_t*)dev;
-    res = 0;
+        *device = (struct hw_device_t*)dev;
+        res = 0;
     }
+
     return res;
 }
 
-
-
-
 static struct hw_module_methods_t lights_module_methods = {
     .open =  open_lights,
 };
+
 const struct hw_module_t HAL_MODULE_INFO_SYM = {
     .tag = HARDWARE_MODULE_TAG,
     .version_major = 1,
     .version_minor = 0,
     .id = LIGHTS_HARDWARE_MODULE_ID,
-    .name = "lights Module",
-    .author = "",
+    .name = "Backlight",
+    .author = "Amlogic",
     .methods = &lights_module_methods,
 };
-
-