Step up thread safety on g_source_set_name() to the same standard as all
other GSource functions: after we are attached to a main context, this
function should be threadsafe.
https://bugzilla.gnome.org/show_bug.cgi?id=736683
Document that one must not use the "by id" source APIs with non-existent
IDs. The real justification behind this restriction is that the reuse
of source ids makes it unsafe to call these functions unless you're
absolutely sure that the source exists and it belongs to you. If you
call one of these functions on a source that may already have been
removed then you run the risk of finding someone else's source (with
your reused id).
This also bails us out of a slightly tricky situation with respect to
the threadsafety of g_main_context_find_source_by_id(). The fact that
this function doesn't return a reference implies that its return value
cannot be safely accessed unless we already know for sure that a
reference is being held elsewhere (by example, by the main context
itself if we know that the source has not been removed). The function
itself, however, performs an access to the value, which could result in
a crash.
If we mandate that it is only valid to call this function on
known-to-exist source IDs then we dodge this problem.
https://bugzilla.gnome.org/show_bug.cgi?id=736683
Simplify our tracking of issued source id integers and fix some bugs.
Previously the source's id was remove from the 'used' table from
source_remove_from_context() which was also called if the source
priority was changed (in which case it would never be added back to the
table). The source id could be reissued in that case.
In the new approach, we just always keep a hash table of sources, by
source id. This simplifies the logic and will also allow us to improve
performance of g_main_context_find_source_by_id() which is called in some
fairly common cases, such as g_source_remove(). These improvements will be in
the following commits.
https://bugzilla.gnome.org/show_bug.cgi?id=724839
Clarify that _add_poll() _remove_poll() _add_unix_fd(),
_modify_unix_fd(), _remove_unix_fd(), _query_unix_fd(),
_set_ready_time(), _add_child_source() and _remove_child_source() are only
intended to be used by the implementation of a particular GSource -- not its
consumers.
https://bugzilla.gnome.org/show_bug.cgi?id=724707
g_main_context_acquire() mentions that you must have called it before
you make any calls to _prepare(), _query(), _check() or _dispatch().
For emphasis, add a note on each of those functions pointing back to the
fact that you must have called _acquire() before using them.
Due to its unusual interface, I suspect that nobody is using
g_main_context_wait() but there is no way to know.
Add a critical notice that will be displayed if anyone calls the
function, asking them to file a bug with us.
We'll let this go out with the 2.40 release and see if we get a response
before we proceed with actually breaking the functionality.
We now depend on CLOCK_MONOTONIC, but it's possible that people may
attempt to run GLib on systems where it isn't supported at runtime.
Check the return value of clock_gettime() and abort() if it fails in
order to save these people from wasting time on debugging a tricky
issue.
https://bugzilla.gnome.org/show_bug.cgi?id=670144
Add a note to the documentation that child sources cannot have their priority
changed independently from their parent. Add a g_return_if_fail() to the
public API in order to enforce this.
This was already a reality due to the check in
g_source_set_priority_unlocked(), but it was never explicitly documented.
https://bugzilla.gnome.org/show_bug.cgi?id=724706
We now assume the existence of clock_gettime() and CLOCK_MONOTONIC as
specified by POSIX.1-2001. This means that we always return truly
monotonic time, which will prevent problems in the case that the user
changes the time.
Mac OS doesn't have clock_gettime() but it does have
mach_absolute_time(), so we can use that there.
We keep our Windows case as well (although we should simplify it once XP
hits EOL later this year).
This patch removes the fallback to gettimeofday() in case of missing
clock_gettime(). We no longer have any way to test this codepath and
therefore it must go.
This patch also restructures the #ifdef a bit so that we repeat the
entire function definition inside of #ifdef instead of just the entire
body of one function.
https://bugzilla.gnome.org/show_bug.cgi?id=724687
Since we are no longer using sgml mode, using /* */ to
escape block comments inside examples does not work anymore.
Switch to using line comments with //
If we used a non-positive pid, we'd call waitpid(that_pid, ...)
which is exactly the situation this function can't deal with.
On Windows, GPid is a HANDLE (pointer), so I don't think the same thing
applies.
Bug: https://bugzilla.gnome.org/show_bug.cgi?id=723743
Reviewed-by: Ryan Lortie
It is possible (but unlikely) that there will be a non-empty list of
pending dispatches when we remove the last ref from a GMainContext.
Make sure we drop the refs on the sources appropriately.
Add a (now-working) testcase that demonstrates how to trigger the issue.
https://bugzilla.gnome.org/show_bug.cgi?id=139699
Fix some races introduced in be2c7b83c4a9c9d3aa76b1499c27ab19e0f4e470
while keeping the property that multiple handlers for the same unix
signal all get dispatched.
Also fix the behaviour of the source checking for pending signals when
it's created. No matter what we do here (clear the pending flag or not)
there is something that can go wrong.
If we clear the flag, we may prevent other sources from being
dispatched. If we don't clear it, we may end up dispatching the same
source twice (if we manage to dispatch it from its own thread before the
GLib worker has a chance to run).
Instead, run the full dispatch procedure when a new source is added. It
actually doesn't matter what thread this runs in since the lock is held.
https://bugzilla.gnome.org/show_bug.cgi?id=711090
In Windows development environments that have it, <unistd.h> is mostly
just a wrapper around several other native headers (in particular,
<io.h>, which contains read(), close(), etc, and <process.h>, which
contains getpid()). But given that some Windows dev environments don't
have <unistd.h>, everything that uses those functions on Windows
already needed to include the correct Windows header as well, and so
there is never any point to including <unistd.h> on Windows.
Also, remove some <unistd.h> includes (and a few others) that were
unnecessary even on unix.
https://bugzilla.gnome.org/show_bug.cgi?id=710519
Since the initial addition of BeOS support in 1999, there has only
been one update to it (in 2005, and it wasn't even very big). GLib is
known to not currently build on Haiku (or presumably actual BeOS)
without additional patching, and the fact that there isn't a single
G_OS_BEOS check in gio/ is suspicious.
Additionally, other than the GModule implementation, all of the
existing G_OS_BEOS checks are either (a) "G_OS_UNIX || G_OS_BEOS", or
(b) random minor POSIXy tweaks (include this header file rather than
that one, etc), suggesting that if we were going to support Haiku, it
would probably be simpler to treat it as a special kind of G_OS_UNIX
(as we do with Mac OS X) rather than as its own completely different
thing.
So, kill G_OS_BEOS.
https://bugzilla.gnome.org/show_bug.cgi?id=710519
g_source_add_child_source() releases the context lock before attaching
child_source to context. And this causes trouble if parent source is
blocked and g_main_dispatch() manages to lock the context mutex and call
unblock_source() before child_source gets attached to context.
To fix this we call g_source_attach_unlocked() before releasing the
context mutex.
https://bugzilla.gnome.org/show_bug.cgi?id=711064
When the source id reaches G_MAXUINT (just prior to overflow), we
record the existing source ids to prevent reassigning them. As we are
about to assign G_MAXUINT to the triggering source, that id should be
added as well.
https://bugzilla.gnome.org/show_bug.cgi?id=710002
This stack exists only to answer the question of "what is the currently
dispatching source" and is handled in a way that makes it very clear
that we don't need to be using a linked list at all...
Just store the GSource directly.
Independently discovered (and same solution) by Phillip Susi.
https://bugzilla.gnome.org/show_bug.cgi?id=709113
If someone creates a unix signal source for e.g. SIGINT, and then
removes it, reset the handler to SIG_DFL.
Not doing this was the source of race conditions in the
glib/tests/unix test, but this will also just make us a "good citizen"
by cleaning up.
For example, if a project temporarily creates a handler for SIGTERM,
and then later removes it, they almost certainly want SIGTERM to
revert to the default of terminating the process, rather than doing
nothing.
https://bugzilla.gnome.org/show_bug.cgi?id=704699
We can't reset the pending flag for a signal until we've traversed
the whole list, as the documentation clearly says that in case multiple
sources they all get invoked.
This is still racy if you get a signal after checking the flag
but before resetting it, but it was the same before. The correct
fix would be to use sigwait() or signalfd(), but that would mean
blocking all signals in all threads, which is not compatible
with existing applications.
https://bugzilla.gnome.org/show_bug.cgi?id=704322
When a child_source is added to a blocked source it has no context, yet we
call block_source on it that segfaults when it dereferences the NULL context
when it attempts to remove the file descriptors. To fix this we:
- Ensure that when we block a source, we don't attempt to remove its file
descriptors from a NULL context.
- Also ensure that when we attach a blocked source to a context, we don't add the
file descriptors to the context.
https://bugzilla.gnome.org/show_bug.cgi?id=701283
When unreffing a context with sources still attached, it would end up
unlocking an already-unlocked context, causing crashes on platforms
that (unlike Linux) actually check for that.
https://bugzilla.gnome.org/show_bug.cgi?id=697595
Since this is a new API this cycle it's a good time to add a doc comment
explicitly declaring that a confusing issue that could be resolved
either way has no specific defined behaviour.
This may allow us some additional freedom in future GMainContext work or
we may decide that one behaviour is more desirable than the other.
Adding file descriptors to a GSource provides similar functionality to
the old g_source_add_poll() API with two main differences.
First: the list of handles is managed internally and therefore users are
prevented from randomly modifying the ->events field. This prepares us
for an epoll future where changing the event mask is a syscall.
Second: keeping the list internally allows us to check the ->revents for
events for ourselves, allowing the source to skip implementing
check/prepare. This also prepares us for the future by allowing an
implementation that doesn't need to iterate over all of the sources
every time.
https://bugzilla.gnome.org/show_bug.cgi?id=686853
