If you're using `udevadm monitor` from a script, without a tty, then
libc defaults to being fully-buffered, and won't flush stdout after
newlines. This is fine for tools that dump a bunch of data and then
exit immediately. It's a problem for tools like `udevadm monitor` which
have long pauses: the buffered data can get stuck in the buffer for an
unbounded amount of time.
In the Cockpit project we've been working around this for some time with
`stdbuf` which is a `LD_PRELOAD` hack to change the libc buffering
behaviour, but we'd like to stop doing that.
Let's make sure we flush the buffer after each event.
udev's block device locking protocol has one pitfall not even the
example in the documentation got right so far (even though this is
explained in all detail above): udev's rescanning is only triggered when
an fd that is opened for writing is closed. This means that if a
separate locking fd is opened on a block device – one that is maintained
independently of the fd actually used for writing – it must be opened for
writing too, so that closing the lock definitely triggers a rescan. This
matters in cases where the lock fd is kept for longer than the fd used
for writing to disk. (Because otherwise udev might get the
IN_CLOSE_WRITE event, but when it tries to rescan will find the device
locked, and never retry because no IN_CLOSE_WRITE is triggred anymore.)
Let's fix that across the codebase, at 4 places:
1. in makefs (a lock fd is kept, and mkfs then invoked as child, which
uses a different fd, and the lock fd is closed only once the child
died)
2. in udevadm lock (embarassing!): which is intended to be used to wrap tools
that modify disk contents, very similar to the makefs case. The lock
is also kept until after the tool exited.
3. In storagetm: the kernel nvme-tcp layer writes to the device
directly, we just keep a lock fd.
4. the example in BLOCK_DEVICE_LOCKING.md
- Make sure forward headers have the iwyu pragma to always keep them
- Make sure we always include the daemon specific forward header
instead of shared-forward.h
- Remove shared-forward.h include where the daemon specific forward
header is already included
Let's not leak details from src/shared and src/libsystemd into
src/basic, even though you can't actually do anything useful with
just forward declarations from src/shared.
The sd-forward.h header is put in src/libsystemd/sd-common as we
don't have a directory for shared internal headers for libsystemd
yet.
Let's also rename forward.h to basic-forward.h to keep things
self-explanatory.
Let's rename the existing partition_verity_to_data() to
partition_verity_hash_to_data() and make a new partition_verity_to_data() that
handles both verity hash and verity signature partitions.
Rename other functions to match the new naming.
Add support for generating names like wldN based on DeviceTree aliases.
DeviceTree alias names follow de facto conventions. As of writing, there
are so far two ways WLAN devices are represented in DeviceTree aliases
in upstream Linux DTS files:
- Firstly, as wifi0, used for example in t600x-j314-j316.dtsi
- Secondly, as ethernet0 or ethernet1, used for example in
sun8i-q8-common.dtsi, with a comment saying the reason is to "Make
u-boot set mac-address for wifi without an eeprom"
So we need to handle both while generating names. Refactor most of the
logic in names_devicetree() into a helper
names_devicetree_alias_prefix() that takes an alias_prefix instead of
hardcoding "ethernet", and, in the new names_devicetree():
- For prefix "en", use alias_prefix "ethernet"
- For prefix "wl", try alias_prefix "wifi" first, and if that was not
found, fall back to alias_prefix "ethernet"
Since this is a naming scheme change, also gate this behind
NAMING_DEVICETREE_ALIASES_WLAN and NAMING_V259, and document this
change.
I initially didn't think it would be worth doing this, but I changed my
mind. People out there quite successfully build systemd without ACL
support, and that suggests life without it is quite possible. Moreover
we only use it as very specific places:
1. in udev/logind for "uaccess" mgmt
2. in tmpfiles to implement explicitly configured acl changes
3. in journald/coredump/pstore to manage access to unpriv users
4. in pid1 to manage access to credential files
5. when shifting UIDs of container trees
I specific container environments it should be entirely fine to live without all
of these, hence let's pull this in on demand only.
Add support for generating names like wldN based on DeviceTree aliases.
DeviceTree alias names follow de facto conventions. As of writing, there
are so far two ways WLAN devices are represented in DeviceTree aliases
in upstream Linux DTS files:
- Firstly, as wifi0, used for example in t600x-j314-j316.dtsi
- Secondly, as ethernet0 or ethernet1, used for example in
sun8i-q8-common.dtsi, with a comment saying the reason is to "Make
u-boot set mac-address for wifi without an eeprom"
Therefore for prefix "wl", try alias_prefix "wifi" first, and if that
was not found, fall back to alias_prefix "ethernet"
Since this is a naming scheme change, also gate this behind
NAMING_DEVICETREE_ALIASES_WLAN and NAMING_V259, and document this
change.
Refactor most of the logic in names_devicetree() into a helper
names_devicetree_alias_prefix() that takes an alias_prefix instead of
hardcoding "ethernet".
The return value names_devicetree_alias_prefix() will be used in further
commits to allow for alias_prefix fallback.
This doesn't work anymore, setting it to false still makes
udev link to libsystemd-shared, as an argument was mistakenly
dropped.
Follow-up for 6350d2dbd9
Otherwise, it is hard to find the dump in journal. With this change,
we can find the entry by e.g.
journalctl -b -u systemd-udevd.service DEVICE=eth0
Follow-up for b4ffb77669.
Previously, when the stdout of a spawned process (e.g. dmi_memory_id) is
truncated, the event source was not re-enabled, that will cause the process
to remain in a write-blocked state if the stdout buffer is full, and the
process will time out:
```
Spawned process 'dmi_memory_id' [1116] timed out after 2min 59s, killing.
Process 'dmi_memory_id' terminated by signal KILL.
```
The solution is to continue enabling the event source so that on_spawn_io()
can continue reading the stdout buffer. When the result buffer is full, the
local `buf` variable will be used to drain remaining stdout.
Co-authored-by: Deli Zhang <deli.zhang@cloud.com>
If the removal of the devlink is requested due to this is a 'remove' event,
it is trivial that the devlink will not be owned by this device anymore.
Let's read the devlink and if it points to our device node, then we need
to update the devlink. If it points to another device node, then it is already
owned by another device, hence we should not touch it and keep it as is.
Fixes#37823.
We had errno_to_name() which works for "known" errnos, and returns NULL for
unknown ones, and then ERRNO_NAME which always returns an answer, possibly just
a number as a string, but requires a helper buffer.
It is possible for the kernel to add a new errno. We recently learned that some
architectures define custom errno names. Or for some function to unexpectedly
return a bogus errno value. In almost all cases it's better to print that value
rather than "n/a" or "(null)". So let's use ERRNO_NAME is most error handling
code. Noteably, our code wasn't very good in handling the potential NULL, so
in various places we could print "(null)". Since this is supposed to be used
most of the time, let's shorten the names to ERRNO_NAME/errno_name.
There are a few places where we don't want to use the fallback path, in
particular for D-Bus error names or when saving the error name. Let's rename
errno_to_name() to errno_name_no_fallback() to make the distinction clearer.
Before 7d247d3cb8, we needed the file name
twice. But now we only need it once, so no need to overcomplicate things
by defining a variable with a single use.
When a variable is used, it's also easier to make a mistake and e.g.
accidentally reuse the variable later.
I noticed similar warnings in many VM boots:
fedora (udev-worker)[475]: sr0: Failed to open device node: No medium found
This particular one is from src/udev/udev-builtin-uaccess.c:125, but I think the
same principle should be used in all places: if we are ignoring errors that the
device has been removed, we should also ignore ENOMEDIUM.
Fixes a bug in a4a6e21673.
Fixes the following memleak:
```
$ sudo valgrind --leak-check=full build/udevadm cat /usr/lib/udev/rules.d
==3975939==
==3975939== HEAP SUMMARY:
==3975939== in use at exit: 640 bytes in 1 blocks
==3975939== total heap usage: 7,657 allocs, 7,656 frees, 964,328 bytes allocated
==3975939==
==3975939== 640 bytes in 1 blocks are definitely lost in loss record 1 of 1
==3975939== at 0x4841866: malloc (vg_replace_malloc.c:446)
==3975939== by 0x4ACA71F: malloc_multiply (alloc-util.h:92)
==3975939== by 0x4ACF988: _hashmap_dump_entries_sorted (hashmap.c:2167)
==3975939== by 0x4ACFC76: _hashmap_dump_sorted (hashmap.c:2209)
==3975939== by 0x4AA60A4: hashmap_dump_sorted (hashmap.h:311)
==3975939== by 0x4AA9077: dump_files (conf-files.c:397)
==3975939== by 0x4AAA14E: conf_files_list_strv_full (conf-files.c:596)
==3975939== by 0x42426A: search_rules_file (udevadm-util.c:301)
==3975939== by 0x424768: search_rules_files (udevadm-util.c:334)
==3975939== by 0x41287D: cat_main (udevadm-cat.c:110)
==3975939== by 0x4A7B911: dispatch_verb (verbs.c:139)
==3975939== by 0x427272: udevadm_main (udevadm.c:121)
==3975939==
==3975939== LEAK SUMMARY:
==3975939== definitely lost: 640 bytes in 1 blocks
==3975939== indirectly lost: 0 bytes in 0 blocks
==3975939== possibly lost: 0 bytes in 0 blocks
==3975939== still reachable: 0 bytes in 0 blocks
==3975939== suppressed: 0 bytes in 0 blocks
==3975939==
==3975939== For lists of detected and suppressed errors, rerun with: -s
==3975939== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)
```
Continuation of #37960.
The same concern as expalined in #37960 exists also in
missing_syscall.h. If we use enough new glibc, a function we want to use
may be already provided by glibc, but our baseline glibc may not. And it
is hard to detect in our daily development.
This moves all prototypes of syscalls to relevant headers, and missing
syscall functions are defined in relevant .c files of libc wrapper. This
way, we can use usual header as is, e.g. when we want to write code with
`move_mount()`, we can simply use sys/mount.h without checking if it is
supported by our baseline glibc.
- pass our system include directories to make generators use our libc
wrappers and latest kernel headers,
- include relevant headers in generated gperf file,
- use files() rather than find_program(), as the result of
find_program() cannot be passed to 'input' of custom_target(),
- move generate-bpf-delegate-configs.py to src/core/, as it is only used
by libcore.
manager_listen_fds() instructs sd_listen_fds_with_names() to unset
the environment which means that when sd_varlink_server_listen_auto()
is called from manager_start_varlink_server(), when it eventually calls
sd_listen_fds_with_names() it will return zero because the environment
has already been unset in manager_listen_fds().
Fix the issue by not using sd_varlink_server_listen_auto() but instead
keeping track of the varlink socket in manager_listen_fds() and returning
it and passing it to manager_start_varlink_server().
Some device node refuses to be opened with read-write mode.
Let's not open with O_RDWR, but open with O_PATH, and use
FORMAT_PROC_FD_PATH().
Follow-up for 1abb592f2f.
Fixes#38033.
We use symbols provided by unistd.h without including it. E.g.
open(), close(), read(), write(), access(), symlink(), unlink(), rmdir(),
fsync(), syncfs(), lseek(), ftruncate(), fchown(), dup2(), pipe2(),
getuid(), getgid(), gettid(), getppid(), pipe2(), execv(), _exit(),
environ, STDIN_FILENO, STDOUT_FILENO, STDERR_FILENO, F_OK, and their
friends and variants, so on.
Currently, unistd.h is indirectly included mainly in the following two paths:
- through missing_syscall.h, which is planned to covert to .c file.
- through signal.h -> bits/sigstksz.h, which is new since glibc-2.34.
Note, signal.h is included by sd-eevent.h. So, many source files
indirectly include unistd.h if newer glibc is used.
Currently, our baseline on glibc is 2.31. We need to support glibc older
than 2.34, but unfortunately, we do not have any CI environments with
such old glibc. CIFuzz uses glibc-2.31, but it builds only fuzzers, and
many files are even not compiled.
[1] says:
> Since 0.60.0 the name argument is optional and defaults to the basename of
> the first output
We specify >= 0.62 as the supported version, so drop the duplicate name in all cases
where it is the same as outputs[0], i.e. almost all cases.
[1] https://mesonbuild.com/Reference-manual_functions.html#custom_target
Otherwise, the result may point to outside of the root directory.
This also sets CONF_FILES_REGULAR and CONF_FILES_FILTER_MASKED, as the
callers will call fopen() or friends for the result, thus the enumerated
results must be non-empty regular files.
Then, make parse_cpu_set() as a tiny wrapper of it.
Note, previously when an invalid CPU range, e.g. "3-0", is specified,
we ignore the range but allocate an empty set. But, with this commit,
now the conf parser simply ignore it without no side effect.
This potentially changes behavior of a system with such invalid setting,
but the change should be favorable for consistency with other parsers.
- Previously, `LinkConfig.rps_cpu_mask == NULL` indicates setting RPS
will be skipped, but now make the condition is changed to
`LinkConfig.rps_cpu_mask.set == NULL`. Then, we can avoid allocating
CPUSet when something configured.
- When "disable" or "all", now allocate a temporal object, and then
replace with it.
No functional change, just refactoring.
More porting work to label_ops_pre()/label_ops_post()
This also enables labelling of the /etc/localtime symlink in
systemd-firstboot, which should address one small facet of #37857
Allison Karlitskaya
Yu Watanabe
Lennart Poettering
Daan De Meyer
dramforever
Luca Boccassi
Zbigniew Jędrzejewski-Szmek