When compiling third-party projects with -Wbad-function-cast, the inline
g_atomic_pointer_get() implementation which uses C11 __atomic_load*()
calls on GCC was causing compilation errors like:
error: cast from function call of type ‘long unsigned int’ to non-matching type ‘void *’
While we don’t want to compile all of GLib with -Wbad-function-cast, we
should support its headers being included in projects which do enable
that warning.
It doesn’t seem to be possible to cast away the warning (e.g. by casting
the function’s result through (void)), so we have to assign to an
intermediate integer of the right size first.
The same has to be done for the bool return value from
__sync_bool_compare_and_swap(). In that case, casting from bool to
gboolean raises a -Wbad-function-cast warning, since gboolean is
secretly int.
The atomic tests have been modified to enable -Wbad-function-cast to
catch regressions of this in future. The GLib build has conversely been
modified to set -Wno-bad-function-cast, just in case people have it set
in their environment CFLAGS.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
https://gitlab.gnome.org/GNOME/glib/issues/1041
This requires meson >= 0.47.0 otherwise building the doc fails:
https://github.com/mesonbuild/meson/issues/3379
While at it, no need to to pass --prefix --libdir to meson, other CIs
don't have them.
When the amount of free memory on the system is somewhat low, gnome-shell
will sometimes fail to launch apps, reporting the error:
fork(): Cannot allocate memory
fork() is failing here because while cloning the process virtual address
space, Linux worries that the thread being forked may end up COWing the
entire address space of the parent process (gnome-shell, which is
memory-hungry), and there is not enough free memory to permit that to
happen.
In this case we are simply calling fork() in order to quickly call exec(),
which will throw away the entirity of the duplicated VM, so we should
look for ways to avoid the overcommit check.
The well known solution to this is to use clone(CLONE_VM) or vfork(), which
completely avoids creating a new memory address space for the child.
However, that comes with a bunch of caveats and complications:
https://gist.github.com/nicowilliams/a8a07b0fc75df05f684c23c18d7db234https://ewontfix.com/7/
In 2016, glibc's posix_spawn() was rewritten to use this approach
while also resolving the concerns.
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=9ff72da471a509a8c19791efe469f47fa6977410
I experimented with a similar approach in glib, but it was not practical
because glibc has several items of important internal knowledge (such as
knowing which signals should be given special treatment because they are
NPTL implementation details) that are not cleanly exposed elsewhere.
Instead, this patch adapts the gspawn code to use posix_spawn() where
possible, which will reap the benefits of that implementation.
The posix_spawn API is more limited than the gspawn API though,
partly due to natural limitations of using CLONE_VM, so the posix_spawn
path is added as a separate codepath which is only executed when the
conditions are right. Callers such as gnome-shell will have to be modified
to meet these conditions, such as not having a child_setup function.
In addition to allowing for the gnome-shell "Cannot allocate memory"
failure to be avoided, this should result in a general speedup in this
area, because fork()'s behaviour of cloning the entire VM space
has a cost which is now avoided. posix_spawn() has also recently
been optimized on OpenSolaris as the most performant way to spawn
a child process.
We don’t strictly require this, but given that our CI runs it, we
essentially never test with 0.46.0, so it might as well be broken.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
We have not updated nor used this script for a long time, and nowadays
Meson makes it much easier to build on Windows for either Visual Studio
or MinGW, even straight from a GIT checkout, so it's about time that we
drop the glib-zip script from the source tree.
Autoconf macro AC_HEADER_MAJOR doesn't define a macro in config.h when
major is defined in sys/types.h. This was not a problem because major
is assumed to be always available. However, commit aefffa3fbc
changes this assumption in order to fix build on systems without major,
which causes code using major to be disabled on systems putting major
in sys/types.h.
This commit defines a new macro MAJOR_IN_TYPES for both autotools and
meson builds to make major useful on these systems again.
cc.has_header checks whether a header exists without knowing whether it
can be used. This is a problem on FreeBSD because its malloc.h is a
header with an '#error' line which always throw compilation error. To
avoid false positive in the check result, we use cc.compiles to do a
full compilation test instead of cc.has_header which only does check
with preprocessor.
We have no way to test Solaris builds atm, and it is not even clear how
to detect Solaris systems with meson. It will probably need to be
revisited when we get a proper CI in place.
See commit 4c2928a544 for why checking AT_SECURE is preferable compared
to UID checks as currently done in the fallback case.
getauxval() was added with glibc 2.16
While glibc <2.19 didn't provide a way to differentiate a 0 return value from an error,
passing AT_SECURE should always succeed according to
https://sourceware.org/ml/libc-alpha/2014-07/msg00407.html
I've added an errno check anyway, to be on the safe side.
Try and ensure that people don’t push code with misleading indentation
in future. This should give fairly few false positives.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
gcc defaults to utf-8 for both (see -fexec-charset and -finput-charset in the
gcc man page) so we should use it with msvc as well.
msvc by default uses the locale encoding unless there is a BOM, see
https://msdn.microsoft.com/en-us/library/mt708821.aspx
Our minimum requirement is already greater than that, so we don't need
to add checks there. We can always add -Wl,-framework,CoreFoundation
flag.
Fixes#1380.
- Compiler checks were failing because it were using C compiler to build
objc code.
- xdgmime is needed on osx too.
- -DGIO_COMPILATION must be passed to objc compiler too.
- gapplication doesn't build on osx, it is excluded in autotools too.
We have to be careful when we use add_project_link_arguments(): All
targets are built using link arguments for the C language, except for
libgio on osx which use the objc language, because it contains some ".m"
source files. See https://github.com/mesonbuild/meson/issues/3585.
https://bugzilla.gnome.org/show_bug.cgi?id=796214
Some compilers, particularly Android on armv5 and old versions of Clang
provide atomic ops, but don't define __GCC_HAVE_SYNC_COMPARE_AND_SWAP_4
so we need to define it ourselves.
This matches what configure does, with the exception that now it's only
done for Android since clang defines __GCC_HAVE_SYNC_COMPARE_AND_SWAP_4
now.
https://bugzilla.gnome.org/show_bug.cgi?id=796325
The latest patches have fixed the atomic check, which
uses __sync_bool_compare_and_swap , and thus fails on
MSVC.
As a result, in gatomic.c, we ended up trying to include
pthread.h, which failed.
This mimics the old behaviour a bit more closely, where
G_ATOMIC_LOCK_FREE was always defined in the win32
glibconfig.h
https://bugzilla.gnome.org/show_bug.cgi?id=796220
The 'no-builtin' checks were just plain wrong. For accurate detection of
functions, use has_function with a header in the prefix. This fixes
posix_memalign detection on Android and on MinGW32, MSYS-MinGW-w64, and
old versions of MSYS2-MinGW-w64.
Using the header in the `prefix:` is generally a good idea because of
how macOS does targetting of specific macOS releases at compile time.
This also allows cross-files to override the result by setting
`has_function_stpcpy = false`, etc in [extra properties]
https://bugzilla.gnome.org/show_bug.cgi?id=795876
