This is kind of long overdue. Reasons are the same as the other wrappers. I
debated adding `O_NOFOLLOW` support but the use cases for that are pretty
obscure, callers who want that can just use the syscall directly for now.
In a lot of places in ostree, we end up prefixing errors in the *caller*.
Often we only have 1-2 callers, and doing the error prefixing isn't
too duplicative. But there are definitely cases where it's cleaner
to do the prefixing in the callee. We have functions that aren't
ported to new style for this reason (they still do the prefixing
in `out:`).
Introduce a cleanup-oriented version of error prefixing so we can port those
functions too.
Mostly in ostree/rpm-ostree, we work in either raw `int fd`, or
`G{Input,Output}Stream`. One exception is the rpm-ostree `/etc/passwd`
handling, which uses `FILE*` since that's what glibc exposes.
And in general, there are use cases for `FILE*`; the raw `GUnixOutputStream` for
example isn't buffered, and doing so via e.g. `GBufferedOutputStream` means
allocating *two* GObjects and even worse going through multiple vfuncs for every
write.
`FILE*` is used heavily in systemd, and provides buffering. It is a bit cheaper
than gobjects, but has its own trap; by default every operation locks a mutex.
For more information on that, see `unlocked_stdio(3)`. However, callers can
avoid that by using e.g. `fwrite_unlocked`, which I plan to do for most users of
`FILE*` that aren't writing to one of the standard streams like `stdout` etc.
Looking at converting the ostree codebase, iterating over only the
values of a hash table (while ignoring the key) is actually a more
common pattern than I thought. So let's give it its own macro as well so
users don't have to resort to the _KV variant.
These macros make it much easier to iterate over a GHashTable. It takes
care of initializing an iterator and casting keys and values to their
proper types.
See the example usage in the docstring for more info.
I originally tried to get this into GLib:
https://bugzilla.gnome.org/show_bug.cgi?id=783751
But that looks like it's going to fail due to MSVC. Let's add it here at least
so I can start using it tomorrow and not wait for the MSVC team to catch up.
I renamed `glnx-alloca.h` to `glnx-macros.h` as a more natural collective
home for things from systemd's `macro.h`.
Finally, I used a Coccinelle spatch similar to the one referenced
in the above BZ to patch our uses.
We were missing the previous automatic `: ` addition; noticed in
a failing ostree test.
Fix this by just calling the new API as the non-prefix case does too.
These are equivalent to the non-null throw, except that the returned
value is a NULL pointer. They can be used in functions where one wants
to return a pointer. E.g.:
GKeyFile *foo(GError **error) {
return glnx_null_throw (error, "foobar");
}
The function call redirections are wrapped around a compound statement
expression[1] so that they represent a single top-level expression. This
allows us to avoid -Wunused-value warnings vs using a comma operator if
the return value isn't used.
I made the 'args...' absorb the fmt argument as well so that callers can
still use it without always having to specify at least one additional
variadic argument. I had to check to be sure that the expansion is all
done by the preprocessor, so we don't need to worry about stack
intricacies.
[1] https://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html
Following up to the previous commit, also shorten our use of
`g_set_error (..., G_IO_ERROR_FAILED, ...)`. There's a lot of
this in libostree at least.
See also https://bugzilla.gnome.org/show_bug.cgi?id=774061
I want the `RENAME_EXCHANGE` version for rpm-ostree, to atomically
swap `/usr/share/rpm` (a directory) with a new verison. While
we're here we might as well expose `RENAME_NOREPLACE` in case
something else wants it.
These both have fallbacks to the non-atomic version.
Closes: https://github.com/GNOME/libglnx/pull/36
This showed up in the ostree runs with `-fsanitize=undefined` - if we happened
to get `0` then `g_malloc` would return `NULL`. However, what's interesting is
it seemed to happen *consistently*. I think what's going on is GCC proved that
the value *could* be zero, and hence it *could* return NULL, and hence it was
undefined behavior. Hooray for `-fsanitize=undefined`.
