enhancementhelp wanted
描述
When downloaded from the network on sync, a txhashset archive should be handled with more care than we do now, as it could be forged to mess things up in all sorts of ways. We should fence this off in a different process until the validation code is completely happy with what we were provided. Something like chroot, that limits the hard drive visibility of the forked process would also be great but may be hard to achieve across platforms.