This macro will read a pointer of any type, return it, and set the
pointer to NULL. This is useful as an explicit concept of passing
ownership of a memory area between pointers.
This takes inspiration from Rust:
https://doc.rust-lang.org/std/option/enum.Option.html#method.take
and was suggested by Alan Jenkins (@sourcejedi).
It drops ~160 lines of code from our codebase, which makes me like it.
Also, I think it clarifies passing of ownership, and thus helps
readability a bit (at least for the initiated who know the new macro)
In libudev (which es much older code than the rest of systemd), we
propagate errors in functions not returning an int, via (positive) errno
(i.e. libc-style), and as negative Exyz values in those returning an int
(much preferred, i.e. Linux kernel style). Let's fix up a few place,
where this was incorrectly done, or not done at all.
Fixes: #6613
Throughout the tree there's spurious use of spaces separating ++ and --
operators from their respective operands. Make ++ and -- operator
consistent with the majority of existing uses; discard the spaces.
GLIB has recently started to officially support the gcc cleanup
attribute in its public API, hence let's do the same for our APIs.
With this patch we'll define an xyz_unrefp() call for each public
xyz_unref() call, to make it easy to use inside a
__attribute__((cleanup())) expression. Then, all code is ported over to
make use of this.
The new calls are also documented in the man pages, with examples how to
use them (well, I only added docs where the _unref() call itself already
had docs, and the examples, only cover sd_bus_unrefp() and
sd_event_unrefp()).
This also renames sd_lldp_free() to sd_lldp_unref(), since that's how we
tend to call our destructors these days.
Note that this defines no public macro that wraps gcc's attribute and
makes it easier to use. While I think it's our duty in the library to
make our stuff easy to use, I figure it's not our duty to make gcc's own
features easy to use on its own. Most likely, client code which wants to
make use of this should define its own:
#define _cleanup_(function) __attribute__((cleanup(function)))
Or similar, to make the gcc feature easier to use.
Making this logic public has the benefit that we can remove three header
files whose only purpose was to define these functions internally.
See #2008.
There are more than enough calls doing string manipulations to deserve
its own files, hence do something about it.
This patch also sorts the #include blocks of all files that needed to be
updated, according to the sorting suggestions from CODING_STYLE. Since
pretty much every file needs our string manipulation functions this
effectively means that most files have sorted #include blocks now.
Also touches a few unrelated include files.
It is still possible to include uninitialized ones, but now that is opt-in. In most
cases people only want initialized devices. Exception is if you want to work without
udev running.
Suggested by David Herrmann.
This patch removes includes that are not used. The removals were found with
include-what-you-use which checks if any of the symbols from a header is
in use.
Returning anything else but NULL would suggest the caller's reference
might still be valid, but it isn't, because the caller just invoked
_unref() after all.
This turns the return value into a typesafe shortcut that allows
unreffing and resetting a reference in one line. In contrast to
solutions for this which take a pointer to a pointer to accomplish the
same this solution is just syntactic sugar the developer can make use of
but doesn't have to, and this is particularly useful when immediately
unreffing objects returned by function calls.
This extends 62678ded 'efi: never call qsort on potentially
NULL arrays' to all other places where qsort is used and it
is not obvious that the count is non-zero.
udev_device_get_subsystem() may return NULL if no subsystem could be
figured out by libudev. This might be due to OOM or if the device
disconnected between the udev_device_new() call and
udev_device_get_subsystem(). Therefore, we need to handle subsystem==NULL
safely.
Instead of testing for it in each helper, we treat subsystem==NULL as
empty subsystem in match_subsystem().
Backtrace of udev_enumerate with an input-device disconnecting in exactly
this time-frame:
(gdb) bt
#0 0x00007ffff569dc24 in strnlen () from /usr/lib/libc.so.6
#1 0x00007ffff56d9e04 in fnmatch@@GLIBC_2.2.5 () from /usr/lib/libc.so.6
#2 0x00007ffff5beb83d in match_subsystem (udev_enumerate=0x7a05f0, subsystem=0x0) at src/libudev/libudev-enumerate.c:727
#3 0x00007ffff5bebb30 in parent_add_child (enumerate=enumerate@entry=0x7a05f0, path=<optimized out>) at src/libudev/libudev-enumerate.c:834
#4 0x00007ffff5bebc3f in parent_crawl_children (enumerate=enumerate@entry=0x7a05f0, path=0x7a56b0 "/sys/devices/<shortened>/input/input97", maxdepth=maxdepth@entry=254) at src/libudev/libudev-enumerate.c:866
#5 0x00007ffff5bebc54 in parent_crawl_children (enumerate=enumerate@entry=0x7a05f0, path=0x79e8c0 "/sys/devices/<shortened>/input", maxdepth=maxdepth@entry=255) at src/libudev/libudev-enumerate.c:868
#6 0x00007ffff5bebc54 in parent_crawl_children (enumerate=enumerate@entry=0x7a05f0, path=path@entry=0x753190 "/sys/devices/<shortened>", maxdepth=maxdepth@entry=256) at src/libudev/libudev-enumerate.c:868
#7 0x00007ffff5bec7df in scan_devices_children (enumerate=0x7a05f0) at src/libudev/libudev-enumerate.c:882
#8 udev_enumerate_scan_devices (udev_enumerate=udev_enumerate@entry=0x7a05f0) at src/libudev/libudev-enumerate.c:919
#9 0x00007ffff5df8777 in <random_caller> () at some/file.c:181
We need to free udev-devices again if they don't match. Funny that no-one
noticed it yet since valgrind is quite verbose about it.
Fix it and free non-matching devices.
If a realloc() happens in syspath_add(), the move_later pointer could
point to an invalid memory region.
Let move_later store the array index, instead of the pointer to the
entry.
Lennart Poettering