libinotify-kqueue is a library that implements inotify interface in terms of
kqueue/kevent API available on Mac OS and *BSD systems. The original kqueue
backend seems to be a predecessor version of the code that is currently present
in libinotify-kqueue. Under the hood the library implements a sophisticated
filesystem changes detection algorithm that is derived from the glib backend
code.
Updating the native glib kqueue backend requires substantial work, because code
bases have diverged greatly. Another approach is taken, instead. libinotify-kqueue
can serve as a drop-in replacement for Linux inotify API, thus allowing to
reuse the inotify backend code. The compatibility, however, comes at cost, since
the library has to emulate the inotify descriptor via an unix domain socket.
This means that delivering an event involves copying the data into the kernel
and then pulling it back.
The recent libinotify-kqueue release adds a new mode of operation called "direct".
In this mode the socket pipe is replaced with another kqueue that is used to
deliver events via a kevent(EVFILT_USER) call.
Employing the direct mode requires minor changes to the client code compared
to using plain inotify API, but in return it allows for reusing libinotify's
algorithms without a performance penalty. Luckily, all required changes are
consolidated in one file called inotify-kernel.c
This puts us in the best of possible worlds. On one hand we share a lot of code
with glib inotify backend, which is far more thoroughly tested and widely used.
On the other we support a range of non-Linux systems and consolidate the business
logic in one library. I plan to do the same trick for QFileSystemWatcher which
will give us the same behaviour between Gtk and Qt applications.
The glib test suite passes for both old kqueue backend and new libinotify-kqueue
one. However, the AppStream FileMonitor tests are failing with the old backend,
but pass with the new one, so this is still an observable improvement.
Relevant libinotify-kqueue PR: https://github.com/libinotify-kqueue/libinotify-kqueue/pull/19
This was intended to make it feasible to debug connection failures where
a modern GDBus client connects to a GDBusServer that is missing
glib!2826, but those GDBusServers should be increasingly rare: we have
had the fixed version of GDBusServer for 5 GNOME stable releases
(2 years), long enough to get into stable releases of Debian and Ubuntu
and a service-pack release of SUSE.
This debug message can be very noisy, especially when unit-testing
GLib code (which is frequently done with G_MESSAGES_DEBUG=all) or when
a third-party GLogFunc ignores the log_level parameter and logs all
messages as though they indicated a serious problem. I think it has
served its purpose now.
Signed-off-by: Simon McVittie <smcv@collabora.com>
Ideally, we would eventually move to always using the
cross-namespace-friendly authentication handshake and never sending an
initial response with the Unix uid or Windows SID, but that's blocked
on waiting for various LTS OS distributions to become unsupported or
otherwise irrelevant. Make a note of some major LTS distributions that
still have an old version that is missing glib!2826.
In the RHEL/CentOS family, CentOS Stream 10 has a fixed version, so
presumably RHEL 10 will have a fixed version when it is released.
In the Debian family, Debian 12 and Ubuntu 24.04 are stable releases
that contain a fixed version.
In the SUSE family, openSUSE 15.6 contains a fixed version, so
presumably so does SLES 15.6.
Faster-moving distributions like Fedora are not a concern here and
can be ignored: it's always the slow-moving and/or LTS distributions
that are going to be holding back interoperability breaks.
Signed-off-by: Simon McVittie <smcv@collabora.com>
The option defaults to 'auto' which keeps the current selection behavior, but
also allows user to override the choice.
Also make the chosen backend is reported to the code via CPP defines.
If the user passes -1 length to g_io_channel_set_line_term() along with
a nul-terminated string, then calls g_io_channel_get_line_term() and
decides to treat the result as nul-terminated rather than checking the
length parameter, then the application will have a problem, because it's
not nul-terminated. That's weird, since the input string was. Let's
ensure the result is consistent: if you pass a nul-terminated string,
the result is nul-terminated. If not, it's not.
Also add a warning to g_io_channel_get_line_term(), since it's very
strange for a gchar * return value to be anything other than a
nul-terminated UTF-8 string. This is an API design bug, but we cannot
fix it.
If %#Z is followed by %Z then we accidentally free the tmp variable from
the previous iteration of the loop a second time. Good job to the static
analysis tool (probably Coverity) that found this.
Fortunately it's unlikely that a realistic application would do this.
I've also added a new test that crashes without the fix
I just spent several hours convinced that there was a memory safety
issue in string_parse() and bytestring_parse(). There isn't. (At least,
I think so.) Add some comments to save the next person some time.
Coverity has improperly flagged this code as an instance of CWE-562. The
code is fine, but it's confusing, and humans are likely to wind up
examining it again in the future, so add some comments to explain what's
up.
This introduces no functional changes, but does squash a false positive
warning from `-Wfloat-conversion`:
```
../gio/gapplication.c:462:15: error: implicit conversion turns floating-point number into integer: 'gdouble' (aka 'double') to '_Bool' [-Werror,-Wfloat-conversion]
if (*(gdouble *) entry->arg_data)
~~ ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 error generated.
```
Signed-off-by: Philip Withnall <pwithnall@gnome.org>
It’s a false positive, but points to a slightly unnecessary use of a
global variable to store something which could be computed per-test.
scan-build thought that arrays of size `n_handlers` could have
uninitialised values accessed in them if `n_handlers` were to change
value part-way through a test (which it didn’t).
Signed-off-by: Philip Withnall <pwithnall@gnome.org>
These are typically files generated by the gobject-introspection dumper,
which we don’t want to scan as they are not part of GLib’s runtime code.
For example:
```
/builds/GNOME/glib/_scan_build/meson-private/tmpr3jwvyib/tmp-introspect5dmnb_je/GObject-2.0.c:799:27: warning: Access to field 'message' results in a dereference of a null pointer (loaded from variable 'error') [core.NullDereference]
799 | g_printerr ("%s\n", error->message);
| ^~~~~~~~~~~~~~
1 warning generated.
```
Signed-off-by: Philip Withnall <pwithnall@gnome.org>
Fixes commit 93271385f9.
Previously the `before_script` from `.build-linux` was used in whole for
these two jobs, but since the `.build-gobject-introspection` template
was also added, the `before_script`s from the two templates need to be
explicitly combined.
Signed-off-by: Philip Withnall <pwithnall@gnome.org>
Fixes: #3458
Remove cmake as we no longer need to build ninja. We can use the
official wheel now since the runner's Python is 3.9 (before: 3.8).
Use the same comment regarding '--wrap-mode' as in the other jobs.
Download and use official ccache binary.
Add myself to the 'only' section in .gitlab-ci.yml so I can have
CI in my fork.
Disable a few deprecation warnings due to the much newer SDK of
the Apple Silicon machine.
Meson 1.5.1 is available in the fd.o SDK and in Debian testing, so the
glib Meson policy says we can update. Update the minimum only as far as
1.4.0 because we don't yet have a need for 1.5.0.
This allows us to:
- Use file.full_path() to avoid deprecation warnings on str.format(file).
- Set c_std=gnu99,c99 to avoid deprecation warnings with gnu99 on MSVC.
Update all the CI builds to use the latest 1.4.x patch release, 1.4.2.
The FreeBSD runner cannot be updated via `gitlab-ci.yml`, so will be
broken for now.
Similarly, the macOS build will not work unless `-Dc_std=gnu99` is
specified at configure time, due to
https://github.com/mesonbuild/meson/issues/13639.
