222f6ceada
Taking a reference to the GFileMonitor when handling events may cause object destruction from th worker thread that calls the function. This condition happens if the surrounding code drops the otherwise last reference ot the GFileMonitor. The series of events causes destruction from an unrelated worker thread and also triggers g_file_monitor_cancel to be called from g_file_monitor_source_handle_event. For the inotify backend, this results in a deadlock as cancellation needs to take a lock that protects data structures from being modified while events are dispatched. One alternative to this approach might be to add an RCU (release, copy, update) approach to the lists contained in the wd_dir_hash and wd_file_hash hash tables. Fixes: #1941 An example stack trace of this happening is: Thread 2 (Thread 0x7fea68b1d640 (LWP 260961) "gmain"): #0 syscall () at ../sysdeps/unix/sysv/linux/x86_64/syscall.S:38 #1 0x00007fea692215dc in g_mutex_lock_slowpath (mutex=mutex@entry=0x7fea6911e148 <g.inotify_lock_lock>) at ../glib/gthread-posix.c:1493 #2 0x00007fea69222062 in g_mutex_lock (mutex=mutex@entry=0x7fea6911e148 <g.inotify_lock_lock>) at ../glib/gthread-posix.c:1517 #3 0x00007fea6908025a in _ih_sub_cancel (sub=0x1492620) at ../gio/inotify/inotify-helper.c:131 #4 0x00007fea6907f9da in g_inotify_file_monitor_cancel (monitor=0x14a3550) at ../gio/inotify/ginotifyfilemonitor.c:75 #5 0x00007fea68fae959 in g_file_monitor_cancel (monitor=0x14a3550) at ../gio/gfilemonitor.c:241 #6 0x00007fea68fae9dc in g_file_monitor_dispose (object=0x14a3550) at ../gio/gfilemonitor.c:123 #7 0x00007fea69139341 in g_object_unref (_object=<optimized out>) at ../gobject/gobject.c:3636 #8 g_object_unref (_object=0x14a3550) at ../gobject/gobject.c:3553 #9 0x00007fea6907507a in g_file_monitor_source_handle_event (fms=0x14c3560, event_type=<optimized out>, child=0x7fea64001460 "spawned-1", rename_to=rename_to@entry=0x0, other=other@entry=0x0, event_time=<optimized out>) at ../gio/glocalfilemonitor.c:457 #10 0x00007fea6907fe0e in ih_event_callback (event=0x7fea64001420, sub=0x1492620, file_event=<optimized out>) at ../gio/inotify/inotify-helper.c:218 #11 0x00007fea6908075c in ip_event_dispatch (dir_list=dir_list@entry=0x14c14c0, file_list=0x0, event=event@entry=0x7fea64001420) at ../gio/inotify/inotify-path.c:493 #12 0x00007fea6908094e in ip_event_dispatch (event=0x7fea64001420, file_list=<optimized out>, dir_list=0x14c14c0) at ../gio/inotify/inotify-path.c:448 #13 ip_event_callback (event=0x7fea64001420) at ../gio/inotify/inotify-path.c:548 #14 ip_event_callback (event=0x7fea64001420) at ../gio/inotify/inotify-path.c:530 #15 0x00007fea69081391 in ik_source_dispatch (source=0x14a2bf0, func=0x7fea69080890 <ip_event_callback>, user_data=<optimized out>) at ../gio/inotify/inotify-kernel.c:327 #16 0x00007fea691d0824 in g_main_dispatch (context=0x14a2cc0) at ../glib/gmain.c:3417 #17 g_main_context_dispatch (context=0x14a2cc0) at ../glib/gmain.c:4135 #18 0x00007fea691d0b88 in g_main_context_iterate (context=context@entry=0x14a2cc0, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>) at ../glib/gmain.c:4211 #19 0x00007fea691d0c2f in g_main_context_iteration (context=0x14a2cc0, may_block=may_block@entry=1) at ../glib/gmain.c:4276 #20 0x00007fea691d0c81 in glib_worker_main (data=<optimized out>) at ../glib/gmain.c:6176 #21 0x00007fea691f9c2d in g_thread_proxy (data=0x1487cc0) at ../glib/gthread.c:827 #22 0x00007fea68d93b1a in start_thread (arg=<optimized out>) at pthread_create.c:443 #23 0x00007fea68e18650 in clone3 () at ../sysdeps/unix/sysv/linux/x86_64/clone3.S:81
GLib
GLib is the low-level core library that forms the basis for projects such as GTK and GNOME. It provides data structure handling for C, portability wrappers, and interfaces for such runtime functionality as an event loop, threads, dynamic loading, and an object system.
The official download locations are: https://download.gnome.org/sources/glib
The official web site is: https://www.gtk.org/
Installation
See the file 'INSTALL.in'
Supported versions
Only the most recent unstable and stable release series are supported. All older versions are not supported upstream and may contain bugs, some of which may be exploitable security vulnerabilities.
See SECURITY.md for more details.
Documentation
API documentation is available online for GLib for the:
Discussion
If you have a question about how to use GLib, seek help on GNOME’s Discourse
instance. Alternatively, ask a question
on StackOverflow and tag it glib.
Reporting bugs
Bugs should be reported to the GNOME issue tracking system. You will need to create an account for yourself. You may also submit bugs by e-mail (without an account) by e-mailing incoming+gnome-glib-658-issue-@gitlab.gnome.org, but this will give you a degraded experience.
Bugs are for reporting problems in GLib itself, not for asking questions about how to use it. To ask questions, use one of our discussion forums.
In bug reports please include:
- Information about your system. For instance:
- What operating system and version
- For Linux, what version of the C library
- And anything else you think is relevant.
- How to reproduce the bug.
- If you can reproduce it with one of the test programs that are built
in the
tests/subdirectory, that will be most convenient. Otherwise, please include a short test program that exhibits the behavior. As a last resort, you can also provide a pointer to a larger piece of software that can be downloaded.
- If you can reproduce it with one of the test programs that are built
in the
- If the bug was a crash, the exact text that was printed out when the crash occurred.
- Further information such as stack traces may be useful, but is not necessary.
Contributing to GLib
Please follow the contribution guide to know how to start contributing to GLib.
Patches should be submitted as merge requests to gitlab.gnome.org. If the patch fixes an existing issue, please refer to the issue in your commit message with the following notation (for issue 123):
Closes: #123
Otherwise, create a new merge request that introduces the change. Filing a separate issue is not required.
Default branch renamed to main
The default development branch of GLib has been renamed to main. To update
your local checkout, use:
git checkout master
git branch -m master main
git fetch
git branch --unset-upstream
git branch -u origin/main
git symbolic-ref refs/remotes/origin/HEAD refs/remotes/origin/main