minix/servers/ds/store.c

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2005-10-20 22:29:52 +02:00
/* Implementation of the Data Store. */
#include "inc.h"
/* Allocate space for the data store. */
PRIVATE struct data_store ds_store[NR_DS_KEYS];
PRIVATE int nr_in_use;
PRIVATE _PROTOTYPE(int find_key, (int key, struct data_store **dsp));
PRIVATE _PROTOTYPE(int set_owner, (struct data_store *dsp, void *auth_ptr));
PRIVATE _PROTOTYPE(int is_authorized, (struct data_store *dsp, void *auth_ptr));
PRIVATE int set_owner(dsp, ap)
struct data_store *dsp; /* data store structure */
void *ap; /* authorization pointer */
{
/* Authorize the caller. */
return(TRUE);
}
PRIVATE int is_authorized(dsp, ap)
struct data_store *dsp; /* data store structure */
void *ap; /* authorization pointer */
{
/* Authorize the caller. */
return(TRUE);
}
PRIVATE int find_key(key, dsp)
int key; /* key to look up */
struct data_store **dsp; /* store pointer here */
{
register int i;
*dsp = NULL;
for (i=0; i<NR_DS_KEYS; i++) {
if ((ds_store[i].ds_flags & DS_IN_USE) && ds_store[i].ds_key == key) {
*dsp = &ds_store[i];
return(TRUE); /* report success */
}
}
return(FALSE); /* report not found */
}
PUBLIC int do_publish(m_ptr)
message *m_ptr; /* request message */
{
struct data_store *dsp;
/* Store (key,value)-pair. First see if key already exists. If so,
* check if the caller is allowed to overwrite the value. Otherwise
* find a new slot and store the new value.
*/
if (find_key(m_ptr->DS_KEY, &dsp)) { /* look up key */
if (! is_authorized(dsp,m_ptr->DS_AUTH)) { /* check if owner */
return(EPERM);
}
}
else { /* find a new slot */
if (nr_in_use >= NR_DS_KEYS) {
return(EAGAIN); /* store is full */
} else {
dsp = &ds_store[nr_in_use]; /* new slot found */
dsp->ds_key = m_ptr->DS_KEY;
if (! set_owner(dsp,m_ptr->DS_AUTH)) { /* associate owner */
return(EINVAL);
}
dsp->ds_nr_subs = 0; /* nr of subscribers */
dsp->ds_flags = DS_IN_USE; /* initialize slot */
nr_in_use ++;
}
}
/* At this point we have a data store pointer and know the caller is
* authorize to write to it. Set all fields as requested.
*/
dsp->ds_val_l1 = m_ptr->DS_VAL_L1; /* store all data */
dsp->ds_val_l2 = m_ptr->DS_VAL_L2;
/* If the data is public. Check if there are any subscribers to this key.
* If so, notify all subscribers so that they can retrieve the data, if
* they're still interested.
*/
if ((dsp->ds_flags & DS_PUBLIC) && dsp->ds_nr_subs > 0) {
/* Subscriptions are not yet implemented. */
}
return(OK);
}
PUBLIC int do_retrieve(m_ptr)
message *m_ptr; /* request message */
{
struct data_store *dsp;
/* Retrieve data. Look up the key in the data store. Return an error if it
* is not found. If this data is private, only the owner may retrieve it.
*/
if (find_key(m_ptr->DS_KEY, &dsp)) { /* look up key */
/* If the data is not public, the caller must be authorized. */
if (! dsp->ds_flags & DS_PUBLIC) { /* check if private */
if (! is_authorized(dsp,m_ptr->DS_AUTH)) { /* authorize call */
return(EPERM); /* not allowed */
}
}
/* Data is public or the caller is authorized to retrieve it. */
printf("DS retrieves data: key %d (found %d), l1 %u, l2 %u\n",
m_ptr->DS_KEY, dsp->ds_key, dsp->ds_val_l1, dsp->ds_val_l2);
m_ptr->DS_VAL_L1 = dsp->ds_val_l1; /* return value */
m_ptr->DS_VAL_L2 = dsp->ds_val_l2; /* return value */
return(OK); /* report success */
}
return(ESRCH); /* key not found */
}
PUBLIC int do_subscribe(m_ptr)
message *m_ptr; /* request message */
{
/* Subscribe to a key of interest. Only existing and public keys can be
* subscribed to. All updates to the key will cause a notification message
* to be sent to the subscribed. On success, directly return a copy of the
* data for the given key.
*/
return(ENOSYS);
}
/*===========================================================================*
* do_getsysinfo *
*===========================================================================*/
PUBLIC int do_getsysinfo(m_ptr)
message *m_ptr;
{
vir_bytes src_addr, dst_addr;
int dst_proc;
size_t len;
int s;
switch(m_ptr->m1_i1) {
case SI_DATA_STORE:
src_addr = (vir_bytes) ds_store;
len = sizeof(struct data_store) * NR_DS_KEYS;
break;
default:
return(EINVAL);
}
dst_proc = m_ptr->m_source;
dst_addr = (vir_bytes) m_ptr->m1_p1;
if (OK != (s=sys_datacopy(SELF, src_addr, dst_proc, dst_addr, len)))
return(s);
return(OK);
}