On 11/04/2015 10:44 PM, Eduardo Habkost wrote:
On Wed, Nov 04, 2015 at 11:17:09AM +0800, Xiao Guangrong wrote:

On 11/04/2015 07:21 AM, Eduardo Habkost wrote:
On Mon, Nov 02, 2015 at 05:13:13PM +0800, Xiao Guangrong wrote:
+size_t qemu_file_getlength(const char *file, Error **errp)
+    int64_t size;
+    return size;

Can you guarantee that SIZE_MAX >= INT64_MAX on all platforms supported
by QEMU?

Actually, this function is abstracted from the common function, raw_getlength(),
in raw-posix.c whose return value is int64_t.

And i think int64_t is large enough for block devices.

int64_t should be enough, but I don't know if size_t is large enough on
all platforms.

I believe it's going to be either one of those cases:

* If you are absolutely sure SIZE_MAX >= INT64_MAX on all platforms,
   please explain why (and maybe add a QEMU_BUILD_BUG_ON?). (I don't
   think this will be the case)
* If SIZE_MAX < INT64_MAX is possible but you believe
   size <= SIZE_MAX is always true here, please explain why (and maybe
   add an assert()).
* Otherwise, we need to set an appropriate error if size > SIZE_MAX
   or change the type of qemu_file_getlength(). What about making it

It sounds better, I will change the return value from size_t to uint64_t.

Thank you for pointing it out, Eduardo!

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