MAX_SNAPSHOT_VMNAME is a macro used to set the size of a character
buffer that stores a filename or the path to a file. I suggest
renaming this macro to MAX_SNAPSHOT_FILENAME instead.

Since MAX_SNAPSHOT_FILENAME is used to store a filename, NAME_MAX is
probably a better value. I thought about PATH_MAX, as it may be more
appropriate, but I chose the more conservative value of the two, so
NAME_MAX.