Users of the reftable library are expected to provide their own function
callback in cases they want to sync(3p) data to disk via the reftable
write options. But if no such function was provided we end up calling
fsync(3p) directly, which may not even be available on some systems.
While dropping the explicit call to fsync(3p) would work, it would lead
to an unsafe default behaviour where a project may have forgotten to set
up the callback function, and that could lead to potential data loss. So
this is not a great solution.
Instead, drop the callback function and make it mandatory for the
project to define fsync(3p). In the case of Git, we can then easily
inject our custom implementation via the "reftable-system.h" header so
that we continue to use `fsync_component()`.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We're including a couple of standard headers like <stdint.h> in a bunch
of locations, which makes it hard for a project to plug in their own
logic for making required functionality available. For us this is for
example via "compat/posix.h", which already includes all of the system
headers relevant to us.
Introduce a new "reftable-system.h" header that allows projects to
provide their own headers. This new header is supposed to contain all
the project-specific bits to provide the POSIX-like environment, and some
additional supporting code. With this change, we thus have the following
split in our system-specific code:
- "reftable/reftable-system.h" is the project-specific header that
provides a POSIX-like environment. Every project is expected to
provide their own implementation.
- "reftable/system.h" contains the project-independent definition of
the interfaces that a project needs to implement. This file should
not be touched by a project.
- "reftable/system.c" contains the project-specific implementation of
the interfaces defined in "system.h". Again, every project is
expected to provide their own implementation.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
