int db_schema_verify(DB_txn *const txn) {
char const magic[] = "DBDB schema layer v1";
size_t const len = sizeof(magic)-1;
DB_val key[1];
DB_VAL_STORAGE(key, DB_VARINT_MAX*2);
db_bind_uint64(key, DBSchema);
db_bind_uint64(key, 0);
DB_val val[1];
DB_cursor *cur;
int rc = db_txn_cursor(txn, &cur);
if(rc < 0) return rc;
rc = db_cursor_first(cur, NULL, NULL, +1);
if(rc < 0 && DB_NOTFOUND != rc) return rc;
// If the database is completely empty
// we can assume it's ours to play with
if(DB_NOTFOUND == rc) {
*val = (DB_val){ len, (char *)magic };
rc = db_put(txn, key, val, 0);
if(rc < 0) return rc;
return 0;
}
rc = db_get(txn, key, val);
if(DB_NOTFOUND == rc) return DB_VERSION_MISMATCH;
if(rc < 0) return rc;
if(len != val->size) return DB_VERSION_MISMATCH;
if(0 != memcmp(val->data, magic, len)) return DB_VERSION_MISMATCH;
return 0;
}
uint64_t db_next_id(dbid_t const table, DB_txn *const txn) {
DB_cursor *cur = NULL;
if(db_txn_cursor(txn, &cur) < 0) return 0;
DB_range range[1];
DB_RANGE_STORAGE(range, DB_VARINT_MAX);
db_bind_uint64(range->min, table+0);
db_bind_uint64(range->max, table+1);
DB_val prev[1];
int rc = db_cursor_firstr(cur, range, prev, NULL, -1);
if(DB_NOTFOUND == rc) return 1;
if(rc < 0) return 0;
uint64_t const t = db_read_uint64(prev);
assert(table == t);
return db_read_uint64(prev)+1;
}
int SLNSessionCopyLastSubmissionURIs(SLNSessionRef const session, str_t *const outFileURI, str_t *const outMetaURI) {
DB_env *db = NULL;
DB_txn *txn = NULL;
int rc = SLNSessionDBOpen(session, SLN_RDWR, &db);
if(rc < 0) goto cleanup;
rc = db_txn_begin(db, NULL, DB_RDONLY, &txn);
if(rc < 0) goto cleanup;
if(outFileURI) {
DB_val key[1], val[1];
DB_VAL_STORAGE(key, DB_VARINT_MAX*2);
db_bind_uint64(key, SLNLastFileURIBySessionID);
db_bind_uint64(key, session->sessionID);
DB_VAL_STORAGE_VERIFY(key);
rc = db_get(txn, key, val);
if(rc >= 0) {
strarg_t const URI = db_read_string(val, txn);
strlcpy(outFileURI, URI, SLN_URI_MAX);
} else if(DB_NOTFOUND == rc) {
outFileURI[0] = '\0';
rc = 0;
} else {
goto cleanup;
}
}
if(outMetaURI) {
DB_val key[1], val[1];
DB_VAL_STORAGE(key, DB_VARINT_MAX*2);
db_bind_uint64(key, SLNLastMetaURIBySessionID);
db_bind_uint64(key, session->sessionID);
DB_VAL_STORAGE_VERIFY(key);
rc = db_get(txn, key, val);
if(rc >= 0) {
strarg_t const URI = db_read_string(val, txn);
strlcpy(outMetaURI, URI, SLN_URI_MAX);
} else if(DB_NOTFOUND == rc) {
outMetaURI[0] = '\0';
rc = 0;
} else {
goto cleanup;
}
}
cleanup:
db_txn_abort(txn); txn = NULL;
SLNSessionDBClose(session, &db);
return rc;
}
