Re: [PATCH 3 of 4] libxl: Introduce pci_assignable_add and pci_assignable_remove

[George Dunlap <george.dunlap@eu.citrix.com>]

On 10/05/12 16:04, Ian Campbell wrote:
>>>> +    spath = libxl__sprintf(gc, SYSFS_PCI_DEV"/"PCI_BDF"/driver",
>>>> +                           pcidev->domain,
>>>> +                           pcidev->bus,
>>>> +                           pcidev->dev,
>>>> +                           pcidev->func);
>>>> +    if ( !lstat(spath,&st) ) {
>>>> +        /* Find the canonical path to the driver. */
>>>> +        *dp = libxl__zalloc(gc, PATH_MAX);
>>> Should we be actually using fpathconf / sysconf here?
>> I don't really follow.  What exactly is it you're proposing?
> PATH_MAX isn't really a constant these days, you can get the dynamic
> value for a particular filesystem from fpathconf. I honestly don't know
> how much of a concern this really is, especially given we are always
> necessarily talking to sysfs.
Ah right -- I didn't get that you were referring to PATH_MAX.  The 
"realpath" manpage specifies:   "The resulting path‐name is stored as a 
null-terminated string, up to a maximum of PATH_MAX bytes, in the buffer 
pointed to by resolved_path."  That's why I used PATH_MAX in the 
allocation.  I would hope that if the manpage says PATH_MAX, it means 
PATH_MAX, and not "some other thing which you can get by running this 
complicated command I haven't mentioned". :-)

OK -- I've also added a comment explaining why I'm doing what I'm doing 
with slots, which I'll include when I re-post the patch.

  -George

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