Re: [PATCH] mount: avoid po_destroy to modify errno what we really want

[Bian Naimeng <biannm@cn.fujitsu.com>]

Steve Dickson wrote:
> 
> On 11/29/2010 09:45 AM, Chuck Lever wrote:
>> On Nov 25, 2010, at 5:07 AM, Mi Jinlong wrote:
>>
>>> We should return the errno that was set before po_destroy,
>>> rather than the errno that was set at po_destroy.
>>>
>>> Because the po_destroy function don't affect the return value,
>>> this patch just revert the saved errno after po_destroy.
>> The only library function used in po_destroy() is free(3).  
>> Does free(3) change the value of errno?
> Looking at the man page and taking a look a the 
> glibc code it appears the answer is no. free(3)
> does not set errno.
> 
> Bian, what was the problem you were seeing that this
> patch fixed? 
> 

 Actually, there's no problem now. But this's not a good style, po_destroy
maybe change the errno later on such as adding a printf.
 So if somebady want modify the po_destroy, he must be careful of it. :)

And, i don't think it's a good idea that explicitly set errno, it maybe make
some trouble in the future. It's better returning error in nfs_do_mount_v3v2,
or save the error in a input parameter. :)

Thanks
  Bian

> steved.
> 
>>> Signed-off-by: Bian Naimeng <biannm@cn.fujitsu.com>
>>> Signed-off-by: Mi Jinlong <mijinlong@cn.fujitsu.com>
>>> ---
>>> utils/mount/stropts.c |    8 ++++++--
>>> 1 files changed, 6 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/utils/mount/stropts.c b/utils/mount/stropts.c
>>> index 50a1a2a..d554877 100644
>>> --- a/utils/mount/stropts.c
>>> +++ b/utils/mount/stropts.c
>>> @@ -592,7 +592,7 @@ static int nfs_do_mount_v3v2(struct nfsmount_info *mi,
>>> 		struct sockaddr *sap, socklen_t salen)
>>> {
>>> 	struct mount_options *options = po_dup(mi->options);
>>> -	int result = 0;
>>> +	int result = 0, save = 0;
>>>
>>> 	if (!options) {
>>> 		errno = ENOMEM;
>>> @@ -637,7 +637,9 @@ static int nfs_do_mount_v3v2(struct nfsmount_info *mi,
>>> 	result = nfs_sys_mount(mi, options);
>>>
>>> out_fail:
>>> +	save = errno;
>>> 	po_destroy(options);
>>> +	errno = save;
>>> 	return result;
>>> }
>>>
>>> @@ -673,7 +675,7 @@ static int nfs_do_mount_v4(struct nfsmount_info *mi,
>>> 		struct sockaddr *sap, socklen_t salen)
>>> {
>>> 	struct mount_options *options = po_dup(mi->options);
>>> -	int result = 0;
>>> +	int result = 0, save = 0;
>>>
>>> 	if (!options) {
>>> 		errno = ENOMEM;
>>> @@ -724,7 +726,9 @@ static int nfs_do_mount_v4(struct nfsmount_info *mi,
>>> 	result = nfs_sys_mount(mi, options);
>>>
>>> out_fail:
>>> +	save = errno;
>>> 	po_destroy(options);
>>> +	errno = save;
>>> 	return result;
>>> }
>>>
>>> -- 
>>> 1.7.3.2
>>>
>>>
>>> --
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> 

-- 
Regards
Bian Naimeng