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

[Blue Swirl <blauwirbel@gmail.com>]

On Thu, Aug 9, 2012 at 10:10 AM, Wenchao Xia <xiawenc@linux.vnet.ibm.com> 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.

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

>   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
>
>
>