int uORB::Manager::node_open
(
Flavor f,
const struct orb_metadata *meta,
const void *data,
bool advertiser,
int *instance,
int priority
)
{
char path[orb_maxpath];
int fd, ret;
/*
* If meta is null, the object was not defined, i.e. it is not
* known to the system. We can't advertise/subscribe such a thing.
*/
if (nullptr == meta) {
errno = ENOENT;
return ERROR;
}
/*
* Advertiser must publish an initial value.
*/
if (advertiser && (data == nullptr)) {
errno = EINVAL;
return ERROR;
}
/*
* Generate the path to the node and try to open it.
*/
ret = uORB::Utils::node_mkpath(path, f, meta, instance);
if (ret != OK) {
errno = -ret;
return ERROR;
}
/* open the path as either the advertiser or the subscriber */
fd = open(path, (advertiser) ? O_WRONLY : O_RDONLY);
/* if we want to advertise and the node existed, we have to re-try again */
if ((fd >= 0) && (instance != nullptr) && (advertiser)) {
/* close the fd, we want a new one */
close(fd);
/* the node_advertise call will automatically go for the next free entry */
fd = -1;
}
/* we may need to advertise the node... */
if (fd < 0) {
/* try to create the node */
ret = node_advertise(meta, instance, priority);
if (ret == OK) {
/* update the path, as it might have been updated during the node_advertise call */
ret = uORB::Utils::node_mkpath(path, f, meta, instance);
if (ret != OK) {
errno = -ret;
return ERROR;
}
}
/* on success, try the open again */
if (ret == OK) {
fd = open(path, (advertiser) ? O_WRONLY : O_RDONLY);
}
}
if (fd < 0) {
errno = EIO;
return ERROR;
}
/* everything has been OK, we can return the handle now */
return fd;
}
int uORB::Manager::node_open(const struct orb_metadata *meta, const void *data, bool advertiser, int *instance,
int priority)
{
char path[orb_maxpath];
int fd = -1, ret;
/*
* If meta is null, the object was not defined, i.e. it is not
* known to the system. We can't advertise/subscribe such a thing.
*/
if (nullptr == meta) {
errno = ENOENT;
return PX4_ERROR;
}
/*
* Advertiser must publish an initial value.
*/
if (advertiser && (data == nullptr)) {
errno = EINVAL;
return PX4_ERROR;
}
/* if we have an instance and are an advertiser, we will generate a new node and set the instance,
* so we do not need to open here */
if (!instance || !advertiser) {
/*
* Generate the path to the node and try to open it.
*/
ret = uORB::Utils::node_mkpath(path, meta, instance);
if (ret != OK) {
errno = -ret;
return PX4_ERROR;
}
/* open the path as either the advertiser or the subscriber */
fd = px4_open(path, advertiser ? PX4_F_WRONLY : PX4_F_RDONLY);
} else {
*instance = 0;
}
/* we may need to advertise the node... */
if (fd < 0) {
/* try to create the node */
ret = node_advertise(meta, instance, priority);
if (ret == PX4_OK) {
/* update the path, as it might have been updated during the node_advertise call */
ret = uORB::Utils::node_mkpath(path, meta, instance);
if (ret != PX4_OK) {
errno = -ret;
return PX4_ERROR;
}
}
/* on success, try the open again */
if (ret == PX4_OK) {
fd = px4_open(path, (advertiser) ? PX4_F_WRONLY : PX4_F_RDONLY);
}
}
/*
else if (advertiser) {
* We have a valid fd and are an advertiser.
* This can happen if the topic is already subscribed/published, and orb_advertise() is called,
* where instance==nullptr.
* We would need to set the priority here (via px4_ioctl(fd, ...) and a new IOCTL), but orb_advertise()
* uses ORB_PRIO_DEFAULT, and a subscriber also creates the node with ORB_PRIO_DEFAULT. So we don't need
* to do anything here.
}
*/
if (fd < 0) {
errno = EIO;
return PX4_ERROR;
}
/* everything has been OK, we can return the handle now */
return fd;
}
