@@ -249,14 +249,17 @@ static int nbd_handle_reply_err(QIOChannel *ioc, nbd_opt_reply *reply,
return result;
}
-static int nbd_receive_list(QIOChannel *ioc, char **name, Error **errp)
+/* Return -1 if unrecoverable error occurs, 0 if NBD_OPT_LIST is
+ * unsupported, 1 if iteration is done, 2 to keep looking, and 3 if
+ * this entry matches @want. */
+static int nbd_receive_list(QIOChannel *ioc, const char *want, Error **errp)
{
nbd_opt_reply reply;
uint32_t len;
uint32_t namelen;
+ char name[NBD_MAX_NAME_SIZE + 1];
int error;
- *name = NULL;
if (nbd_receive_option_reply(ioc, NBD_OPT_LIST, &reply, errp) < 0) {
return -1;
}
@@ -272,105 +275,102 @@ static int nbd_receive_list(QIOChannel *ioc, char **name, Error **errp)
nbd_send_opt_abort(ioc);
return -1;
}
- } else if (reply.type == NBD_REP_SERVER) {
- if (len < sizeof(namelen) || len > NBD_MAX_BUFFER_SIZE) {
- error_setg(errp, "incorrect option length %"PRIu32, len);
- nbd_send_opt_abort(ioc);
- return -1;
- }
- if (read_sync(ioc, &namelen, sizeof(namelen)) != sizeof(namelen)) {
- error_setg(errp, "failed to read option name length");
- nbd_send_opt_abort(ioc);
- return -1;
- }
- namelen = be32_to_cpu(namelen);
- len -= sizeof(namelen);
- if (len < namelen) {
- error_setg(errp, "incorrect option name length");
- nbd_send_opt_abort(ioc);
- return -1;
- }
- if (namelen > NBD_MAX_NAME_SIZE) {
- error_setg(errp, "export name length too long %" PRIu32, namelen);
- nbd_send_opt_abort(ioc);
- return -1;
- }
-
- *name = g_new0(char, namelen + 1);
- if (read_sync(ioc, *name, namelen) != namelen) {
- error_setg(errp, "failed to read export name");
- g_free(*name);
- *name = NULL;
- nbd_send_opt_abort(ioc);
- return -1;
- }
- (*name)[namelen] = '\0';
- len -= namelen;
- if (drop_sync(ioc, len) != len) {
- error_setg(errp, "failed to read export description");
- g_free(*name);
- *name = NULL;
- nbd_send_opt_abort(ioc);
- return -1;
- }
- } else {
+ return 1;
+ } else if (reply.type != NBD_REP_SERVER) {
error_setg(errp, "Unexpected reply type %" PRIx32 " expected %x",
reply.type, NBD_REP_SERVER);
nbd_send_opt_abort(ioc);
return -1;
}
- return 1;
+
+ if (len < sizeof(namelen) || len > NBD_MAX_BUFFER_SIZE) {
+ error_setg(errp, "incorrect option length %"PRIu32, len);
+ nbd_send_opt_abort(ioc);
+ return -1;
+ }
+ if (read_sync(ioc, &namelen, sizeof(namelen)) != sizeof(namelen)) {
+ error_setg(errp, "failed to read option name length");
+ nbd_send_opt_abort(ioc);
+ return -1;
+ }
+ namelen = be32_to_cpu(namelen);
+ len -= sizeof(namelen);
+ if (len < namelen) {
+ error_setg(errp, "incorrect option name length");
+ nbd_send_opt_abort(ioc);
+ return -1;
+ }
+ if (namelen != strlen(want)) {
+ if (drop_sync(ioc, len) != len) {
+ error_setg(errp, "failed to skip export name with wrong length");
+ nbd_send_opt_abort(ioc);
+ return -1;
+ }
+ return 2;
+ }
+
+ assert(namelen < sizeof(name));
+ if (read_sync(ioc, name, namelen) != namelen) {
+ error_setg(errp, "failed to read export name");
+ nbd_send_opt_abort(ioc);
+ return -1;
+ }
+ name[namelen] = '\0';
+ len -= namelen;
+ if (drop_sync(ioc, len) != len) {
+ error_setg(errp, "failed to read export description");
+ nbd_send_opt_abort(ioc);
+ return -1;
+ }
+ return strcmp(name, want) == 0 ? 3 : 2;
}
+/* Return -1 on failure, 0 if wantname is an available export. */
static int nbd_receive_query_exports(QIOChannel *ioc,
const char *wantname,
Error **errp)
{
bool foundExport = false;
- TRACE("Querying export list");
+ TRACE("Querying export list for '%s'", wantname);
if (nbd_send_option_request(ioc, NBD_OPT_LIST, 0, NULL, errp) < 0) {
return -1;
}
TRACE("Reading available export names");
while (1) {
- char *name = NULL;
- int ret = nbd_receive_list(ioc, &name, errp);
+ int ret = nbd_receive_list(ioc, wantname, errp);
- if (ret < 0) {
- g_free(name);
- name = NULL;
+ switch (ret) {
+ default:
+ /* Server gave unexpected reply */
+ assert(ret < 0);
return -1;
- }
- if (ret == 0) {
+ case 0:
/* Server doesn't support export listing, so
* we will just assume an export with our
* wanted name exists */
- foundExport = true;
- break;
- }
- if (name == NULL) {
- TRACE("End of export name list");
+ return 0;
+ case 1:
+ /* Done iterating. */
+ if (!foundExport) {
+ error_setg(errp, "No export with name '%s' available",
+ wantname);
+ nbd_send_opt_abort(ioc);
+ return -1;
+ }
+ return 0;
+ case 2:
+ /* Wasn't this one, keep going. */
break;
- }
- if (g_str_equal(name, wantname)) {
+ case 3:
+ /* Found a match, but must finish parsing reply. */
+ TRACE("Found desired export name '%s'", wantname);
foundExport = true;
- TRACE("Found desired export name '%s'", name);
- } else {
- TRACE("Ignored export name '%s'", name);
+ break;
}
- g_free(name);
- }
-
- if (!foundExport) {
- error_setg(errp, "No export with name '%s' available", wantname);
- nbd_send_opt_abort(ioc);
- return -1;
}
-
- return 0;
}
static QIOChannel *nbd_receive_starttls(QIOChannel *ioc,
Since we know that the maximum name we are willing to accept is small enough to stack-allocate, rework the iteration over NBD_OPT_LIST responses to reuse a stack buffer rather than allocating every time. Furthermore, we don't even have to allocate if we know the server's length doesn't match what we are searching for. Signed-off-by: Eric Blake <eblake@redhat.com> --- v4: rebase v3: tweak commit message --- nbd/client.c | 144 +++++++++++++++++++++++++++++------------------------------ 1 file changed, 72 insertions(+), 72 deletions(-)