EXAMPLES
Create a consumer, attach it to a given provider, gain read access and read first sector.
void
some_function(struct g_geom *mygeom, struct g_provider *pp)
{
struct g_consumer *cp;
void *ptr;
int error;
g_topology_assert();
/* Create new consumer on ’mygeom’ geom. */
cp = g_new_consumer(mygeom);
/* Attach newly created consumer to given provider. */
if (g_attach(cp, pp) != 0) {
g_destroy_consumer(cp);
return;
}
/* Open provider for reading through our consumer. */
error = g_access(cp, 1, 0, 0);
if (error != 0) {
printf("Cannot access provider: %s\n", error);
g_detach(cp);
g_destroy_consumer(cp);
return;
}
/*
* Don’t hold topology lock while reading.
*/
g_topology_unlock();
ptr = g_read_data(cp, 0, pp->sectorsize, &error);
if (ptr == NULL)
printf("Error while reading: %d\n", error);
/*
* Do something useful with data.
*/
g_topology_lock();
/* Disconnect from provider (release access count). */
g_access(cp, -1, 0, 0);
/* Detach from provider. */
g_detach(cp);
/* Destroy consumer. */
g_destroy_consumer(cp);
}
ERRORS
Possible errors:
