Re: [PATCH] fix NFSv4 acl detection on F39

[Paul Eggert]

On 5/1/23 19:27, Paul Eggert wrote:
> * Do not use llistxattr (name, NULL, 0). Instead, invoke llistxattr on a 
> small (say, 3 KiB) buffer on the stack. Use malloc only if llistxattr 
> returns ERANGE, and keep expanding this buffer (via free-then-malloc, 
> not realloc, since you don't need to save the old storage) while 
> llistxattr returns ERANGE. Check for integer overflow when multiplying 
> the buffer size by 1.5, by using ckd_add. Use 'free' at the end only if 
> we used 'malloc'.

On second thought, since llistxattr (name, NULL, 0) gives us a good 
hint, perhaps it'd be better to do the following:

Invoke llistxattr on a small (say, 3 KiB) buffer on the stack. If this 
fails with ERANGE, use llistxattr (name, NULL, 0) to estimate the size 
and then use malloc+llistxattr with that size, repeating as long as 
llistxattr fails with ERANGE.