[Libvir] [for discussion only] virDomainBlockPeek preliminary implementation

The attached patch (for discussion only) adds a virDomainBlockPeek call, allowing callers to peek into the block devices of domains. +/** + * virDomainBlockPeek: + * @dom: pointer to the domain object + * @path: path to the block device + * @offset: offset within block device + * @size: size to read + * @buffer: return buffer (must be at least size bytes) + * + * This function allows you to read the contents of a domain's + * disk device. + * + * Typical uses for this are to determine if the domain has + * written a Master Boot Record (indicating that the domain + * has completed installation), or to try to work out the state + * of the domain's filesystems. + * + * (Note that in the local case you might try to open the + * block device or file directly, but that won't work in the + * remote case, nor if you don't have sufficient permission. + * Hence the need for this call). + * + * 'path' must be a device or file corresponding to the domain. + * In other words it must be the precise string returned in + * a <disk><source dev='...'/></disk> from + * virDomainGetXMLDesc. + * + * 'offset' and 'size' represent an area which must lie entirely + * within the device or file. 'size' may be 0 to test if the + * call would succeed. + * + * 'buffer' is the return buffer and must be at least 'size' bytes. + * + * Returns: 0 in case of success or -1 in case of failure. + */ +int +virDomainBlockPeek (virDomainPtr dom, + const char *path, + long long offset /* really 64 bits */, + size_t size, + void *buffer) The patch doesn't include: - remote - qemu - Xen < 3.0.3 inactive domains I will add these if I get favourable feedback. Rich. -- Emerging Technologies, Red Hat - http://et.redhat.com/~rjones/ Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SL4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 03798903