ccbebd3bd2
GChildWatchSource uses waitpid(), among pidfd and GetExitCodeProcess(). It thus only works for child processes which the user must ensure to exist and not being reaped yet. Also, the user must not kill() the PID after the child process is reaped and must not race kill() against waitpid(). Also, the user must not call waitpid()/kill() after the child process is reaped. Previously, GChildWatchSource would call waitpid() already when adding the source (g_child_watch_source_new()) and from the worker thread (dispatch_unix_signals_unlocked()). That is racy: - if a child watcher is attached and did not yet fire, you cannot call kill() on the PID without racing against the PID being reaped on the worker thread. That would then lead to ESRCH or even worse, killing the wrong process. - if you g_source_destroy() the source that didn't fire yet, the user doesn't know whether the PID was reaped in the background. Any subsequent kill()/waitpid() may fail with ESRCH/ECHILD or even address the wrong process. The race is most visible on Unix without pidfd support, because then the process gets reaped on the worker thread or during g_child_watch_source_new(). But it's also with Windows and pidfd, because we would have waited for the process in g_child_watch_check(), where other callbacks could fire between reaping the process status and emitting the source's callback. Fix all that by calling waitpid() right before dispatching the callback.
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'
How to report bugs
Bugs should be reported to the GNOME issue tracking system. (https://gitlab.gnome.org/GNOME/glib/issues/new). You will need to create an account for yourself.
In the bug report 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 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.
Patches
Patches should also 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.