[Xcb] [PATCH] Introduce xcb_aux_alloc_shm() to create anonymous files in RAM

[Julien Cristau]

On 04/17/2018 12:52 PM, Alexander Volkov wrote:
> 13.04.2018 09:47, Uli Schlachter пишет:
>>> +[],
>>> +[with_shared_memory_dir=yes])
>>> +
>>> +shmdirs="/run/shm /dev/shm /var/tmp /tmp"
>>> +
>>> +case x"$with_shared_memory_dir" in
>>> +xyes)
>>> +    for dir in $shmdirs; do
>>> +        case x"$with_shared_memory_dir" in
>>> +        xyes)
>> How many shells are there that do not like "break"? :-/
>> (And does autoconf provide some way to make this loop nicer?)
> 
>> So, if I do --with-shared-memory-dir=/foobar, configure will tell me
>> that I specified an invalid directory? Why?? And why does this flag
>> exist at all, i.e. what would be uses for it?
>>
>> Also, why does the existence of a directory at compile time have any
>> significance at run time? What about cross compiling? Building a distro
>> package with /run/shm existing and then running it on another system
>> that does not have /run/shm?
>>
>> I really think that this compile time check is plain wrong.
> 
> Well, I just copied it from 
> https://cgit.freedesktop.org/xorg/lib/libxshmfence/tree/configure.ac
> The same code is used in the X server: 
> https://cgit.freedesktop.org/xorg/xserver/tree/configure.ac#n1121
> Somehow it's working there...
> 
What's the use of replicating the code from libxshmfence instead of just 
calling into that library?  Or are they somehow subtly different (and if 
so why)?

Cheers,
Julien