safe_close() automatically becomes a NOP when a negative fd is passed,
and returns -1 unconditionally. This makes it easy to write lines like
this:
fd = safe_close(fd);
Which will close an fd if it is open, and reset the fd variable
correctly.
By making use of this new scheme we can drop a > 200 lines of code that
was required to test for non-negative fds or to reset the closed fd
variable afterwards.
This makes it possible to initialize the /etc/machine-id file on an
arbitrary filesystem hierarchy. This helps systems that wish to run
this at image creation time in a subdirectory, or from initramfs before
pivot-root is called.
[tomegun: converted to using _cleanup_free_ macros]
$ touch src/core/dbus.c; make CFLAGS=-O0
make --no-print-directory all-recursive
Making all in .
CC src/core/libsystemd_core_la-dbus.lo
CCLD libsystemd-core.la
$ touch src/core/dbus.c; make CFLAGS=-Og
make --no-print-directory all-recursive
Making all in .
CC src/core/libsystemd_core_la-dbus.lo
src/core/dbus.c: In function 'init_registered_system_bus':
src/core/dbus.c:798:18: warning: 'id' may be used uninitialized in this function [-Wmaybe-uninitialized]
dbus_free(id);
^
CCLD libsystemd-core.la
-Og Optimize debugging experience. -Og enables optimizations that do
not interfere with debugging. It should be the optimization level of
choice for the standard edit-compile-debug cycle, offering a
reasonable level of optimization while maintaining fast compilation
and a good debugging experience.
