Re: [PATCH v2] grub-mount: Support libfuse 3

[Daniel Kiper]

On Mon, Jan 17, 2022 at 03:34:37PM +0100, Fabian Vogt wrote:
> libfuse 3.0.0 got released in 2016, with some API changes compared to 2.x.
> This commit introduces support for 3.x while keeping it compatible with 2.6
> as a fallback still.
>
> To detect fuse3, switch configure over to use pkg-config, which is simpler yet
> more reliable than looking for library and header manually. Also set
> FUSE_USE_VERSION that way, as it depends on the used libfuse version.
>
> Now that the CFLAGS are read from pkg-config, use just <fuse.h>, which works
> with 2.x as well as 3.x and is recommended by libfuse upstream.
>
> One behaviour change of libfuse3 is that FUSE_ATOMIC_O_TRUNC is set by 
> default,
> which means that open with O_TRUNC is passed as-is instead of calling the
> truncate operation. With libfuse2, truncate failed with -ENOSYS and that was
> returned to the application. To make O_TRUNC fail with libfuse3, return -EROFS
> explicitly if writing was requested.
>
> Signed-off-by: Fabian Vogt <fvogt@suse.de>

Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

Daniel