Re: [Xen-devel] [PATCH v2] libxl: Reset toolstack_save file position in libxl

[Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>]

Jason Andryuk writes ("[PATCH v2] libxl: Reset toolstack_save file position in 
libxl"):
> toolstack_save data is written to a temporary file in libxl and read
> back in libxl-save-helper.  The file position must be reset prior to
> reading the file, which is done in libxl-save-helper with lseek.
> 
> lseek is unsupported for pipes and sockets, so a wrapper passing such an
> fd to libxl-save-helper fails the lseek.  Moving the lseek to libxl
> avoids the error, allowing the save to continue.

I don't object to this in principle, and arguably it's wrong that this
functionality should be in the save helper rather than libxl proper
(since the save helper is supposed to be an as-thin-as-possible
wrapper around the libxc functions).  So TBH I'm inclined to take
this change on those grounds.

But I'm curious as to what kind of wrapper you have devised, and for
what purpose.  Do you mean a wrapper program for libxl-save-helper ?
Which presumably interposes a pipe for the toolstack data fd ?

Thanks,
Ian.

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