Set a maximum message time allowed for a block of MsgSends
#include <qvm/utils.h>
int qvm_msgblock_start(const vdev_t *vdp, unsigned mult)
Use this function when you are communicating with an untrusted server and you don't know how many MsgSends there will be. Wrap your messages with qvm_msgblock_start() and qvm_msgblock_stop() calls to make sure that you don't block if a server doesn't reply within the prescribed time.
To set the maximum message time allowed for a single MsgSend, call qvm_msgblock_oneshot().
To configure default timeouts, use the qvm set option's message-block-timeout and vdev-message-block-timeout options (see the set section in the "VM Configuration Reference" chapter in the User's Guide).
EOK if successful; otherwise an errno value.