Re: [Qemu-devel] [qemu-devel] [PATCH V2 0/3] [RFC] libqblock draft code v2

[Wenchao Xia]

   Thanks for your review, sorry I have forgot some fixing you
mentioned before, will correct them this time.

于 2012-8-10 1:12, Blue Swirl 写道:
> On Thu, Aug 9, 2012 at 10:10 AM, Wenchao Xia <address@hidden> wrote:
> >    This patch intrudce libqblock API, libqblock-test is used as a test case.
> >
> > V2:
> >    Using struct_size and [xxx]_new [xxx]_free to keep ABI.
> >    Using embbed structure to class format options in image creating.
> >    Format specific options were brought to surface.
> >    Image format was changed to enum interger instead of string.
> >    Some API were renamed.
> >    Internel error with errno was saved and with an API caller can get it.
> >    ALL flags used were defined in libqblock.h.
> >
> > Something need discuss:
> >    Embbed structure or union could make the model more friendly, but that
> > make ABI more difficult, because we need to check every embbed structure's
> > size and guess compiler's memory arrangement. This means #pragma pack(4)
> > or struct_size, offset_next in every structure. Any better way to solve it?
> > or make every structure a plain one?
>
> I'd still use accessor functions instead of structure passing, it
> would avoid these problems.
  Do you mean some function like :
  CreateOption_Filename_Set(const char *filename)
  CreateOption_Format_Set(const char *filename)

  It can solve the issue, with a cost of more small APIs in header
files that user should use. Not sure if there is a good way to make
it more friendly as an object language:
  "oc.filename = name;" automatically call CreateOption_Filename_Set,
API CreateOption_Filename_Set is invisible to user.


> Packing can even introduce a new set of problems since we don't
> control the CFLAGS of the client of the library.

  indeed, I tried to handle the difference in function qboo_adjust_o2n,
found that structure member alignment is hard to deal.

> >    AIO is missing, need a prototype.
> >
> > Wenchao Xia (3):
> >    adding libqblock
> >    libqblock API
> >    libqblock test case
> >
> >   Makefile         |    3 +
> >   block.c          |    2 +-
> >   block.h          |    1 +
> >   libqblock-test.c |  197 ++++++++++++++++
> >   libqblock.c      |  670 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
> >   libqblock.h      |  447 ++++++++++++++++++++++++++++++++++++
> >   6 files changed, 1319 insertions(+), 1 deletions(-)
> >   create mode 100644 libqblock-test.c
> >   create mode 100644 libqblock.c
> >   create mode 100644 libqblock.h


--
Best Regards

Wenchao Xia