On 09/25/2013 12:01 PM, Jeff Cody wrote:
> It is from UML, right? Is there an official spec that is still around
> (most of the links I have found suffer from link rot)? The closest I
> could find to a spec were old UML patches for x86_64 that cleaned up
> some data types, so that the following was defined:
>
> struct cow_header_v2 {
>
> __u32 magic;
> __u32 version;
> char backing_file[PATH_LEN_V2];
> time_t mtime;
> __u64 size;
> int sectorsize;
> };
>
> That remains ambiguous, although given the era I suppose it could be
> argued that 32-bit architecture and alignment is assumed. But if this
> is the original spec, then it seems like a non-portable one.
Indeed. Not just the potential padding there, but of course
the size of time_t varies between hosts. And since we use
an int32_t not time_t, we're not even necessarily compatible
with UML.
r~
