When set to represent a zoneinfo file, TZ may start with :, therefore
glib needs to check it and ignore the first char when building the
resulting filename, or it won't be found.
Also, the path could be absolute, in which case it is wrong to
append /usr/share/timezone
https://bugzilla.gnome.org/show_bug.cgi?id=664237
* Represents an immutable reference counted block of memory.
* This is basically the internal glib GBuffer structure exposed,
renamed, and with some additional capabilities.
* The GBytes name comes from python3's immutable 'bytes' type
* GBytes can be safely used as keys in hash tables, and have
functions for doing so: g_bytes_hash, g_bytes_equal
* GByteArray is a mutable form of GBytes, and vice versa. There
are functions for converting from one to the other efficiently:
g_bytes_unref_to_array() and g_byte_array_free_to_bytes()
* Adds g_byte_array_new_take() to support above functions
https://bugzilla.gnome.org/show_bug.cgi?id=663291
The main rationale for adding it was to avoid having gnome-shell
mmap'ing /etc/localtime once a second. However, we can just as easily
run inotify there, and given no one else was clamoring for a way to
detect when the time zone changes, I don't see a need for public API
here - at least not yet.
In the bigger picture, I just don't believe that the vast majority of
applications are going to go out of their way to instantiate and keep
around a random GTimeZoneMonitor class. And if they do, it's has the
side effect that for other bits of code in the process, local GDateTime
instances may start varying again!
So, if code can't rely on local GDateTime instances being in a
consistent state anyways, let's just do that always. The
documentation now says that this is the case. Applications have
always been able to work in a consistent local time zone by
instantiating a zone and then using it for GDateTime constructors.
We fix the "gnome-shell stats /etc/localtime once a second" issue by
using timerfd (in glib) and inotify (in gnome-shell).
https://bugzilla.gnome.org/show_bug.cgi?id=655129
In the previous code, if the timezone was pulled out of the cache again
just as the last reference was being dropped, the cache code will
increase its refcount and return it while the unref code was freeing it.
Protect against that.
Closes#646435.
