AP_HAL_Linux: VideoIn: follow coding style and minor fixes

- No need to if/else if just returning
 - Sort includes
 - Fix missing space in log message
 - When closing the fd, set it to -1. It's better to later fail the
   operation than to operate on another random file descriptor
 - Add some spaces to improve readability
 - Use pragma once
 - Do not initialize members to zero, it's already the behavior for our
   custom allocator

libraries/AP_HAL_Linux/VideoIn.cpp

@@ -21,22 +21,21 @@
 #if CONFIG_HAL_BOARD_SUBTYPE == HAL_BOARD_SUBTYPE_LINUX_BEBOP
 #include "VideoIn.h"
 
-#include <stdio.h>
-#include <string.h>
-#include <fcntl.h>
-#include <unistd.h>
-#include <stdlib.h>
 #include <errno.h>
-#include <sched.h>
-#include <time.h>
+#include <fcntl.h>
+#include <linux/videodev2.h>
 #include <pthread.h>
+#include <sched.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
 #include <sys/ioctl.h>
 #include <sys/mman.h>
 #include <sys/select.h>
 #include <sys/stat.h>
 #include <sys/time.h>
-
-#include <linux/videodev2.h>
+#include <time.h>
+#include <unistd.h>
 
 extern const AP_HAL::HAL& hal;
 
@@ -52,11 +51,7 @@ bool VideoIn::get_frame(Frame &frame)
         _streaming = true;
     }
 
-    if (_dequeue_frame(frame)) {
-        return true;
-    } else {
-        return false;
-    }
+    return _dequeue_frame(frame);
 }
 
 void VideoIn::put_frame(Frame &frame)
@@ -88,9 +83,10 @@ bool VideoIn::open_device(const char *device_path, uint32_t memtype)
     }
 
     if (!(cap.capabilities & V4L2_CAP_VIDEO_CAPTURE)) {
-        hal.console->printf("Error opening device %s: is not a video capture"
-                            "device\n", device_path);
+        hal.console->printf("Error opening device %s: is not a video capture device\n",
+                            device_path);
         close(_fd);
+        _fd = -1;
         return false;
     }
 
@@ -112,8 +108,7 @@ bool VideoIn::allocate_buffers(uint32_t nbufs)
 
     ret = ioctl(_fd, VIDIOC_REQBUFS, &rb);
     if (ret < 0) {
-        printf("Unable to request buffers: %s (%d).\n", strerror(errno),
-        errno);
+        printf("Unable to request buffers: %s (%d).\n", strerror(errno), errno);
         return ret;
     }
 
@@ -249,6 +244,7 @@ void VideoIn::_queue_buffer(int index)
 {
     int ret;
     struct v4l2_buffer buf;
+
     memset(&buf, 0, sizeof buf);
     buf.index = index;
     buf.type = V4L2_CAP_VIDEO_CAPTURE;
@@ -257,6 +253,7 @@ void VideoIn::_queue_buffer(int index)
     if (_memtype == V4L2_MEMORY_USERPTR) {
         buf.m.userptr = (unsigned long) _buffers[index].mem;
     }
+
     ret = ioctl(_fd, VIDIOC_QBUF, &buf);
     if (ret < 0) {
         hal.console->printf("Unable to queue buffer : %s (%d).\n",

libraries/AP_HAL_Linux/VideoIn.h

@@ -12,8 +12,7 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
-#ifndef __VIDEOIN_H__
-#define __VIDEOIN_H__
+#pragma once
 
 #include "AP_HAL_Linux.h"
 #include <linux/videodev2.h>
@@ -31,9 +30,9 @@ public:
     class Frame {
     friend class VideoIn;
     public:
-        uint32_t timestamp = 0;
-        uint32_t sequence = 0;
-        void *data = NULL;
+        uint32_t timestamp;
+        uint32_t sequence;
+        void *data;
     private:
         uint32_t buf_index;
     };
@@ -56,14 +55,13 @@ private:
     bool _dequeue_frame(Frame &frame);
     uint32_t _timeval_to_us(struct timeval& tv);
     int _fd = -1;
-    struct buffer *_buffers = NULL;
-    unsigned int _nbufs = 0;
-    bool _streaming = false;
-    uint32_t _width = 0;
-    uint32_t _height = 0;
-    uint32_t _format = 0;
-    uint32_t _bytesperline = 0;
-    uint32_t _sizeimage = 0;
+    struct buffer *_buffers;
+    unsigned int _nbufs;
+    bool _streaming;
+    uint32_t _width;
+    uint32_t _height;
+    uint32_t _format;
+    uint32_t _bytesperline;
+    uint32_t _sizeimage;
     uint32_t _memtype = V4L2_MEMORY_MMAP;
 };
-#endif