mmal: Allow /dev/vchiq to be opened initialised prior to mmal_vc_init

This avoids an issue with Chromium sandbox

interface/mmal/vc/mmal_vc_api.h

@@ -145,7 +145,12 @@ typedef enum
    MMAL_STATS_INVALID = 0x7fffffff
 } MMAL_STATS_RESULT_T;
 
+/* If opening dev_vchiq outside mmal/vchiq this is the file path and mode */
+#define MMAL_DEV_VCHIQ_PATH "/dev/vchiq"
+#define MMAL_DEV_VCHIQ_MODE O_RDWR
+
 MMAL_STATUS_T mmal_vc_init(void);
+MMAL_STATUS_T mmal_vc_init_fd(int dev_vchiq_fd);
 void mmal_vc_deinit(void);
 
 MMAL_STATUS_T mmal_vc_use(void);

interface/mmal/vc/mmal_vc_client.c

@@ -693,7 +693,7 @@ MMAL_STATUS_T mmal_vc_release(void)
    return status;
 }
 
-MMAL_STATUS_T mmal_vc_init(void)
+MMAL_STATUS_T mmal_vc_init_fd(int dev_vchiq_fd)
 {
    VCHIQ_SERVICE_PARAMS_T vchiq_params;
    MMAL_BOOL_T vchiq_initialised = 0, waitpool_initialised = 0;
@@ -717,7 +717,7 @@ MMAL_STATUS_T mmal_vc_init(void)
    vcos_log_register("mmalipc", VCOS_LOG_CATEGORY);
 
    /* Initialise a VCHIQ instance */
-   vchiq_status = vchiq_initialise(&mmal_vchiq_instance);
+   vchiq_status = vchiq_initialise_fd(&mmal_vchiq_instance, dev_vchiq_fd);
    if (vchiq_status != VCHIQ_SUCCESS)
    {
       LOG_ERROR("failed to initialise vchiq");
@@ -792,6 +792,11 @@ MMAL_STATUS_T mmal_vc_init(void)
    return status;
 }
 
+MMAL_STATUS_T mmal_vc_init(void)
+{
+   return mmal_vc_init_fd(-1);
+}
+
 void mmal_vc_deinit(void)
 {
    int count;

interface/vchiq_arm/vchiq_if.h

@@ -132,6 +132,7 @@ typedef void (*VCHIQ_REMOTE_USE_CALLBACK_T)(void* cb_arg);
 
 
 extern VCHIQ_STATUS_T vchiq_initialise(VCHIQ_INSTANCE_T *pinstance);
+extern VCHIQ_STATUS_T vchiq_initialise_fd(VCHIQ_INSTANCE_T *pinstance, int dev_vchiq_fd);
 extern VCHIQ_STATUS_T vchiq_shutdown(VCHIQ_INSTANCE_T instance);
 extern VCHIQ_STATUS_T vchiq_connect(VCHIQ_INSTANCE_T instance);
 extern VCHIQ_STATUS_T vchiq_add_service(VCHIQ_INSTANCE_T instance,

interface/vchiq_arm/vchiq_lib.c

@@ -85,7 +85,7 @@ vcos_static_assert(IS_POWER_2(VCHIQ_MAX_INSTANCE_SERVICES));
 
 /* Local utility functions */
 static VCHIQ_INSTANCE_T
-vchiq_lib_init(void);
+vchiq_lib_init(const int dev_vchiq_fd);
 
 static void *completion_thread(void *);
 
@@ -137,12 +137,18 @@ find_service_by_handle(VCHIQ_SERVICE_HANDLE_T handle)
  * VCHIQ API
  */
 
+// If dev_vchiq_fd == -1 then /dev/vchiq will be opened by this fn (as normal)
+//
+// Otherwise the given fd will be used.  N.B. in this case the fd is duped
+// so the caller will probably want to close whatever fd was passed once
+// this call has returned.  This slightly odd behaviour makes shutdown and
+// error cases much simpler.
 VCHIQ_STATUS_T
-vchiq_initialise(VCHIQ_INSTANCE_T *pinstance)
+vchiq_initialise_fd(VCHIQ_INSTANCE_T *pinstance, int dev_vchiq_fd)
 {
    VCHIQ_INSTANCE_T instance;
 
-   instance = vchiq_lib_init();
+   instance = vchiq_lib_init(dev_vchiq_fd);
 
    vcos_log_trace( "%s: returning instance handle %p", __func__, instance );
 
@@ -151,6 +157,12 @@ vchiq_initialise(VCHIQ_INSTANCE_T *pinstance)
    return (instance != NULL) ? VCHIQ_SUCCESS : VCHIQ_ERROR;
 }
 
+VCHIQ_STATUS_T
+vchiq_initialise(VCHIQ_INSTANCE_T *pinstance)
+{
+   vchiq_initialise_fd(pinstance, -1);
+}
+
 VCHIQ_STATUS_T
 vchiq_shutdown(VCHIQ_INSTANCE_T instance)
 {
@@ -1083,7 +1095,7 @@ vchi_initialise( VCHI_INSTANCE_T *instance_handle )
 {
    VCHIQ_INSTANCE_T instance;
 
-   instance = vchiq_lib_init();
+   instance = vchiq_lib_init(-1);
 
    vcos_log_trace( "%s: returning instance handle %p", __func__, instance );
 
@@ -1405,7 +1417,7 @@ VCHIQ_STATUS_T vchiq_dump_phys_mem( VCHIQ_SERVICE_HANDLE_T handle,
  */
 
 static VCHIQ_INSTANCE_T
-vchiq_lib_init(void)
+vchiq_lib_init(const int dev_vchiq_fd)
 {
    static int mutex_initialised = 0;
    static VCOS_MUTEX_T vchiq_lib_mutex;
@@ -1427,7 +1439,9 @@ vchiq_lib_init(void)
 
    if (instance->initialised == 0)
    {
-      instance->fd = open("/dev/vchiq", O_RDWR);
+      instance->fd = dev_vchiq_fd == -1 ?
+         open("/dev/vchiq", O_RDWR) :
+         dup(dev_vchiq_fd);
       if (instance->fd >= 0)
       {
          VCHIQ_GET_CONFIG_T args;