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Re: [Qemu-devel] [PATCH v5 1/1] Introduce "xen-load-devices-state"


From: Changlong Xie
Subject: Re: [Qemu-devel] [PATCH v5 1/1] Introduce "xen-load-devices-state"
Date: Fri, 3 Jun 2016 11:07:57 +0800
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0

On 06/03/2016 10:13 AM, Changlong Xie wrote:
On 06/03/2016 09:45 AM, Eric Blake wrote:
On 06/02/2016 07:26 PM, Changlong Xie wrote:

+
+    ioc = qio_channel_file_new_path(filename, O_WRONLY | O_CREAT,
0660, errp);

This does not look right, it looks like it's going to open the file
to write to it. You probably want O_RDONLY, also I don't think the
O_CREAT flag is needed. (and without O_WRONLY, mode can be 0 instead of
0660.)


Yes, as you said. We should use 0_RDONLY for open(2), so mode should
be 0.

Huh?  mode doesn't affect the current fd, but DOES affect the next
person to open the file.  If you are truly creating the file, then a
mode of 0 means you won't be able to reopen it without chmod.  And if
you are doing O_RDONLY | O_CREAT, all you will be able to create is an
empty file, which is a pretty boring read.  So drop the O_CREAT, and
then you don't need a mode argument at all.


Yes, i just mean qio_channel_file_new_path(filename, O_RDONLY, 0, errp)

I just notice that, qemu specifies flag 'O_BINARY' to allow system to differentiate between a text file and a binary file( I guess so?). For backward compatibility, refer to function test_io_channel_file(), i will use

qio_channel_file_new_path(filename, O_RDONLY | O_BINARY, 0, errp)

here.

here. Maybe my poor english make you confused :(

Thanks
     -Xie









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