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dbus/cmake/ConfigureChecks.cmake
Simon McVittie 88b5749984 sysdeps: Use C11 stdatomic.h where possible 
On Unix, dbus has historically used gcc-specific lock-free atomic
intrinsics where available, falling back to a pthreads mutex where
possible. Meanwhile, on Windows, it has historically used
InterlockedIncrement() and similar library functions (in practice
wrappers around lock-free intrinsics on real Windows, but IPC calls into
wineserver on Wine).

ISO C11 provides a new header, stdatomic.h, with standardized support
for atomic operations. Exactly how these are implemented is a compiler
quality-of-implementation decision, but any reasonable compiler
implementation on a modern CPU should be using intrinsics. Let's use
this wherever possible, falling back to our old implementation only if
the C11 implementation is unsupported.

One concrete benefit that we get from this is that when compiling with
mingw-w64 gcc and running via Wine, this makes atomic reference counting
operations into a simple local operation, rather than IPC to wineserver
which can be very slow. This should make our CI tests considerably more
reliable.

In all vaguely modern gcc versions (gcc 5.5 or later) and in contemporary
versions of clang, the default compiler mode is C11 or later with GNU
extensions. We intentionally do not ask for any specific C standard, so
we can use C11 features like this one, as long as we do so conditionally.

The Microsoft Visual C compiler does not currently support this without
special options, so we still use the Interlocked family of functions
when compiling for Windows with MSVC.

Signed-off-by: Simon McVittie <smcv@collabora.com>
2023-08-15 12:54:41 +00:00

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CMake
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include(CheckIncludeFile)
include(CheckIncludeFiles)
include(CheckSymbolExists)
include(CheckStructMember)
include(CheckTypeSize)
include(CheckCSourceCompiles)
include(CheckCSourceRuns)
set(CMAKE_REQUIRED_DEFINITIONS -D_GNU_SOURCE)
# keep in sync with check_headers in meson.build
check_include_files("winsock2.h;afunix.h" HAVE_AFUNIX_H)
check_include_file(alloca.h HAVE_ALLOCA_H)
check_include_file(byteswap.h HAVE_BYTESWAP_H)
check_include_file(crt/externs.h HAVE_CRT_EXTERNS_H)
check_include_file(dirent.h HAVE_DIRENT_H) # dbus-sysdeps-util.c
check_include_file(errno.h HAVE_ERRNO_H) # dbus-sysdeps.c
check_include_file(inttypes.h HAVE_INTTYPES_H) # dbus-pipe.h
check_include_file(io.h HAVE_IO_H) # internal
check_include_file(linux/close_range.h HAVE_LINUX_CLOSE_RANGE_H)
check_include_file(linux/magic.h HAVE_LINUX_MAGIC_H)
check_include_file(locale.h HAVE_LOCALE_H)
check_include_file(signal.h HAVE_SIGNAL_H)
check_include_file(stdatomic.h HAVE_STDATOMIC_H)
check_include_file(stdio.h HAVE_STDIO_H) # dbus-sysdeps.h
check_include_files("stdint.h;sys/types.h;sys/event.h" HAVE_SYS_EVENT_H)
check_include_file(sys/inotify.h HAVE_SYS_INOTIFY_H)
check_include_file(sys/inotify.h DBUS_BUS_ENABLE_INOTIFY)
check_include_file(sys/prctl.h HAVE_SYS_PRCTL_H)
check_include_file(sys/random.h HAVE_SYS_RANDOM_H)
check_include_file(sys/resource.h HAVE_SYS_RESOURCE_H)
check_include_file(sys/syscall.h HAVE_SYS_SYSCALL_H)
check_include_file(sys/time.h HAVE_SYS_TIME_H)# dbus-sysdeps-win.c
check_include_file(sys/vfs.h HAVE_SYS_VFS_H)
check_include_file(syslog.h HAVE_SYSLOG_H)
check_include_file(unistd.h HAVE_UNISTD_H) # dbus-sysdeps-util-win.c
check_include_file(ws2tcpip.h HAVE_WS2TCPIP_H)# dbus-sysdeps-win.c
find_package(Backtrace) # dbus-sysdeps.c, dbus-sysdeps-win.c
set(HAVE_BACKTRACE ${Backtrace_FOUND})
# keep in sync with check_functions in meson.build
check_symbol_exists(LOG_PERROR "syslog.h" HAVE_DECL_LOG_PERROR)
check_symbol_exists(MSG_NOSIGNAL "sys/socket.h" HAVE_DECL_MSG_NOSIGNAL)
check_symbol_exists(SCM_RIGHTS "sys/types.h;sys/socket.h;sys/un.h" HAVE_UNIX_FD_PASSING)
check_symbol_exists(SYS_pidfd_open "sys/syscall.h" HAVE_DECL_SYS_PIDFD_OPEN) # dbus-sysdeps-unix.c
check_symbol_exists(accept4 "sys/socket.h" HAVE_ACCEPT4)
check_symbol_exists(clearenv "stdlib.h" HAVE_CLEARENV) # dbus-sysdeps.c
check_symbol_exists(close_range "unistd.h" HAVE_CLOSE_RANGE) # dbus-sysdeps-unix.c
check_symbol_exists(closefrom "unistd.h" HAVE_CLOSEFROM) # dbus-sysdeps-unix.c
check_symbol_exists(environ "unistd.h" HAVE_DECL_ENVIRON)
check_symbol_exists(fstatfs "sys/vfs.h" HAVE_FSTATFS)
check_symbol_exists(getgrouplist "grp.h" HAVE_GETGROUPLIST) # dbus-sysdeps.c
check_symbol_exists(getpeerucred "ucred.h" HAVE_GETPEERUCRED) # dbus-sysdeps.c, dbus-sysdeps-win.c
check_symbol_exists(getpwnam_r "errno.h;pwd.h" HAVE_GETPWNAM_R) # dbus-sysdeps-util-unix.c
check_symbol_exists(getrandom "sys/random.h" HAVE_GETRANDOM)
check_symbol_exists(getresuid "unistd.h" HAVE_GETRESUID)
check_symbol_exists(getrlimit "sys/resource.h;sys/time.h" HAVE_GETRLIMIT)
check_symbol_exists(inotify_init1 "sys/inotify.h" HAVE_INOTIFY_INIT1)
check_symbol_exists(localeconv "locale.h" HAVE_LOCALECONV) # dbus-sysdeps.c
check_symbol_exists(nanosleep "time.h" HAVE_NANOSLEEP) # dbus-sysdeps.c
check_symbol_exists(pipe2 "fcntl.h;unistd.h" HAVE_PIPE2)
check_symbol_exists(poll "poll.h" HAVE_POLL) # dbus-sysdeps-unix.c
check_symbol_exists(prctl "sys/prctl.h" HAVE_PRCTL)
check_symbol_exists(prlimit "sys/resource.h;sys/time.h" HAVE_PRLIMIT)
check_symbol_exists(raise "signal.h" HAVE_RAISE)
check_symbol_exists(setenv "stdlib.h" HAVE_SETENV) # dbus-sysdeps.c
check_symbol_exists(setlocale "locale.h" HAVE_SETLOCALE) # dbus-test-main.c
check_symbol_exists(setresuid "unistd.h" HAVE_SETRESUID)
check_symbol_exists(setrlimit "sys/resource.h" HAVE_SETRLIMIT) # dbus-sysdeps.c, dbus-sysdeps-win.c, test/test-segfault.c
check_symbol_exists(setrlimit "sys/resource.h;sys/time.h" HAVE_SETRLIMIT)
check_symbol_exists(socketpair "sys/socket.h" HAVE_SOCKETPAIR) # dbus-sysdeps.c
check_symbol_exists(unsetenv "stdlib.h" HAVE_UNSETENV) # dbus-sysdeps.c
check_symbol_exists(writev "sys/uio.h" HAVE_WRITEV) # dbus-sysdeps.c, dbus-sysdeps-win.c
# It doesn't really matter which specific header we use for these, as long as
# we include at least one glibc-provided header. time.h is suitable.
check_symbol_exists(__GLIBC__ "time.h" HAVE___GLIBC__)
check_symbol_exists(_FILE_OFFSET_BITS "time.h" HAVE__FILE_OFFSET_BITS)
check_symbol_exists(_TIME_BITS "time.h" HAVE__TIME_BITS)
# Opt-in to large inode number and timestamp support, which we know doesn't
# break libdbus ABI: https://gitlab.freedesktop.org/dbus/dbus/-/issues/465
if(HAVE___GLIBC__ AND CMAKE_SIZEOF_VOID_P EQUAL 4 AND NOT HAVE__FILE_OFFSET_BITS)
set(_FILE_OFFSET_BITS 64)
endif()
if(HAVE___GLIBC__ AND CMAKE_SIZEOF_VOID_P EQUAL 4 AND NOT HAVE__TIME_BITS)
set(_TIME_BITS 64)
endif()
check_struct_member(cmsgcred cmcred_pid "sys/types.h;sys/socket.h" HAVE_CMSGCRED) # dbus-sysdeps.c
CHECK_C_SOURCE_COMPILES("
#ifndef __linux__
#error This is not Linux
#endif
#include <sys/epoll.h>
int main() {
epoll_create1 (EPOLL_CLOEXEC);
}" DBUS_HAVE_LINUX_EPOLL)
CHECK_C_SOURCE_COMPILES("
int main() {
int a = 4;
int b = __sync_sub_and_fetch(&a, 4);
return b;
}
" DBUS_USE_SYNC)
set(DBUS_SIZEOF_VOID_P ${CMAKE_SIZEOF_VOID_P})
check_type_size("short" SIZEOF_SHORT)
check_type_size("int" SIZEOF_INT)
check_type_size("long" SIZEOF_LONG)
check_type_size("long long" SIZEOF_LONG_LONG)
check_type_size("__int64" SIZEOF___INT64)
set(CMAKE_EXTRA_INCLUDE_FILES "sys/socket.h")
check_type_size("socklen_t" HAVE_SOCKLEN_T) # dbus-sysdeps-unix.c
set(CMAKE_EXTRA_INCLUDE_FILES)
# DBUS_INT64_TYPE
if(SIZEOF_INT EQUAL 8)
set(DBUS_INT64_TYPE "int")
set(DBUS_INT64_CONSTANT "(val)")
set(DBUS_UINT64_CONSTANT "(val##U)")
set(DBUS_INT64_MODIFIER "")
elseif(SIZEOF_LONG EQUAL 8)
set(DBUS_INT64_TYPE "long")
set(DBUS_INT64_CONSTANT "(val##L)")
set(DBUS_UINT64_CONSTANT "(val##UL)")
set(DBUS_INT64_MODIFIER "l")
elseif(SIZEOF_LONG_LONG EQUAL 8)
set(DBUS_INT64_TYPE "long long")
set(DBUS_INT64_CONSTANT "(val##LL)")
set(DBUS_UINT64_CONSTANT "(val##ULL)")
set(DBUS_INT64_MODIFIER "ll")
elseif(SIZEOF___INT64 EQUAL 8)
set(DBUS_INT64_TYPE "__int64")
set(DBUS_INT64_CONSTANT "(val##i64)")
set(DBUS_UINT64_CONSTANT "(val##ui64)")
set(DBUS_INT64_MODIFIER "I64")
else(SIZEOF_INT EQUAL 8)
message(FATAL_ERROR "Could not find a 64-bit integer type")
endif()
# MSVCRT.dll printf() doesn't support %lld
if(WIN32 AND NOT CYGWIN)
set(DBUS_INT64_MODIFIER "I64")
endif()
# DBUS_INT32_TYPE
if(SIZEOF_INT EQUAL 4)
set(DBUS_INT32_TYPE "int")
elseif(SIZEOF_LONG EQUAL 4)
set(DBUS_INT32_TYPE "long")
elseif(SIZEOF_LONG_LONG EQUAL 4)
set(DBUS_INT32_TYPE "long long")
endif()
# DBUS_INT16_TYPE
if(SIZEOF_INT EQUAL 2)
set(DBUS_INT16_TYPE "int")
elseif(SIZEOF_SHORT EQUAL 2)
set(DBUS_INT16_TYPE "short")
endif()
find_program(DOXYGEN doxygen)
find_program(XMLTO xmlto)
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