raspicam: Check system is running legacy camera stack

If the system is obviously configured for libcamera (for example) by
dint of /dev/video0 being given over to "unicam", complain and abort
immediately. In all other circumstances maintain previous behaviour.

Signed-off-by: David Plowman <[email protected]>

host_applications/linux/apps/raspicam/RaspiHelpers.c

@@ -33,6 +33,9 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include <unistd.h>
 #include <stdint.h>
 
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <linux/videodev2.h>
 
 #include "interface/vcos/vcos.h"
 #include "interface/mmal/mmal.h"
@@ -294,3 +297,25 @@ uint64_t get_microseconds64()
 
    return us;
 }
+
+
+/*
+ * If we are configured to use /dev/video0 as unicam (e.g. for libcamera) then
+ * these legacy camera apps can't work. Fail immediately with an obvious message.
+ */
+void check_camera_stack()
+{
+	int fd = open("/dev/video0", O_RDWR, 0);
+	if (fd < 0)
+		return;
+
+	struct v4l2_capability caps;
+	int ret = ioctl(fd, VIDIOC_QUERYCAP, &caps);
+	close(fd);
+
+	if (ret < 0 || strcmp((char *)caps.driver, "unicam"))
+		return;
+
+	fprintf(stderr, "ERROR: the system should be configured for the legacy camera stack\n");
+	exit(-1);
+}

host_applications/linux/apps/raspicam/RaspiHelpers.h

@@ -39,5 +39,6 @@ void default_signal_handler(int signal_number);
 int mmal_status_to_int(MMAL_STATUS_T status);
 void print_app_details(FILE *fd);
 uint64_t get_microseconds64();
+void check_camera_stack();
 
 #endif

host_applications/linux/apps/raspicam/RaspiStill.c

@@ -1647,6 +1647,8 @@ int main(int argc, const char **argv)
    MMAL_PORT_T *encoder_input_port = NULL;
    MMAL_PORT_T *encoder_output_port = NULL;
 
+   check_camera_stack();
+
    bcm_host_init();
 
    // Register our application with the logging system

host_applications/linux/apps/raspicam/RaspiStillYUV.c

@@ -1066,6 +1066,8 @@ int main(int argc, const char **argv)
    MMAL_PORT_T *preview_input_port = NULL;
    FILE *output_file = NULL;
 
+   check_camera_stack();
+
    bcm_host_init();
 
    // Register our application with the logging system

host_applications/linux/apps/raspicam/RaspiVid.c

@@ -2408,6 +2408,8 @@ int main(int argc, const char **argv)
    MMAL_PORT_T *splitter_output_port = NULL;
    MMAL_PORT_T *splitter_preview_port = NULL;
 
+   check_camera_stack();
+
    bcm_host_init();
 
    // Register our application with the logging system

host_applications/linux/apps/raspicam/RaspiVidYUV.c

@@ -1239,6 +1239,8 @@ int main(int argc, const char **argv)
    MMAL_PORT_T *camera_still_port = NULL;
    MMAL_PORT_T *preview_input_port = NULL;
 
+   check_camera_stack();
+
    bcm_host_init();
 
    // Register our application with the logging system