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

[Wenchao Xia <xiawenc@linux.vnet.ibm.com>]

    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 <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.
>
   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