The 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 behavior 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>
a385f10480