i.e. let's pick some files we know are too large, or where struct stat's
.st_size is zero even though non-empty, and test read_virtual_file()
with that, to ensure things are handled sensibly. Goal is to ensure all
three major codepaths in read_virtual_file() are tested.
Prompted-by: #20743
We mishandled the case where the size we read from the file actually
matched the maximum size fully. In that case we cannot really make a
determination whether the file was fully read or only partially. In that
case let's do another loop, so that we operate with a buffer, and
we can detect the EOF (which will be signalled to us via a short read).
There's a very gradual increase of anonymous memory in systemd-journald that
blames to 2ac67221bb.
systemd-journald makes many calls to read /proc/PID/cmdline and
/proc/PID/status, both of which tend to be well under 4K. However the
combination of allocating 4M read buffers, then using `realloc()` to
shrink the buffer in `read_virtual_file()` appears to be creating
fragmentation in the heap (when combined with the other allocations
systemd-journald is doing).
To help mitigate this, try reading /proc with a 4K buffer as
`read_virtual_file()` did before 2ac67221bb.
If it isn't big enough then try again with the larger buffers.
According to the documentation, Setting the data threshold to zero disables the
data threshold alltogether. Let's make sure we actually implement this behaviour
in sd_journal_enumerate_fields() by only applying the data threshold if it exceeds
zero.
Device-tree based devices can't get the chassis type from DMI or ACPI,
and so far need a custom `/etc/machine-info` to set this property right.
A new 'chassis-type' toplevel device tree property has recently been
approved into the DT specification, making it possible to automate
chassis type detection on such devices.
This patch therefore falls back to reading this device-tree property if
nothing is available through both DMI and ACPI.
Signed-off-by: Arnaud Ferraris <arnaud.ferraris@collabora.com>
Currently `nulstr_contains` returns a boolean, making it difficult to
identify which of the input strings matches the "needle".
Adding a new `nulstr_get()` function, returning a const pointer to the
matching string, eases this process and allows us to directly re-use the
result of a call to this function without additional processing or
memory allocation.
Signed-off-by: Arnaud Ferraris <arnaud.ferraris@collabora.com>
let's do what we did for sysctl_write()/sysctl_write_ip_property() also
for the read paths: i.e. make one a wrapper of the other, and add more
careful input validation.
Let's add similar path validation to sysctl_read() as we already have in
sysctl_write().
Let's also drop the trailing newline from the returned string, like
sysctl_read_ip_property() already does it.
(I checked all users of this, they don't care)
It does the same stuff, let's use the same codepaths as much as we can.
And while we are at it, let's generate good error codes in case we are
called with unsupported parameters/let's validate stuff more that might
originate from user input.
The sysctl_write_ip_property() call already uses write_string_file(), so
let's do so here, too, to make the codepaths more uniform.
While we are at it, let's also validate the passed path a bit, since we
shouldn't allow sysctls with /../ or such in the name. Hence simplify
the path first, and then check if it is normalized, and refuse if not.
When reading virtual files (i.e. procfs, sysfs, …) we currently put a
limit of 4M-1 on that. We have to pick something, and we have to read
these files in a single read() (since the kernel generally doesn't
support continuation read()s for them). 4M-1 is actually the maximum
size the kernel allows for reads from files in /proc/sys/, all larger
reads will result in an ENOMEM error (which is really weird, but the
kernel does what the kernel does). Hence 4M-1 sounds like a smart
choice.
However, we made one mistake here: in order to be able to detect EOFs
properly we actually read one byte more than we actually intend to
return: if that extra byte can be read, then we know the file is
actually larger than our limit and we can generate an EFBIG error from
that. However, if it cannot be read then we know EOF was hit, and we are
good. So ultimately after all we issued a single 4M read, which the
kernel then responds with ENOMEM to. And that means read_virtual_file()
actually doesn't work properly right now on /proc/sys/. Let's fix that.
The fix is simple, lower the limit of the the buffer we intend to return
by one, i.e. 4M-2. That way, the read() we'll issue is exactly as large
as the limit the kernel allows, and we still get safely detect EOF from
it.
otherwise compilation with -Db_ndebug=true complains about a
set-but-not-used variable:
```
../src/partition/repart.c:907:33: error: variable 'left' set but not used [-Werror,-Wunused-but-set-variable]
uint64_t start, left;
^
1 error generated.
```
Even if journald was not running, flushing the volatile journal used to work if
the journal was already flushed (ie the flushed flag
/run/systemd/journald/flushed was created).
However since commit 4f413af2a0, this behavior changed and now '--flush' fails
because it tries to contact journald without checking the presence of the
flushed flag anymore.
This patch restores the previous behavior since there's no reason to fail when
journalctl can figure out that the flush is not necessary.
LLVM 13 introduced `-Wunused-but-set-variable` diagnostic flag, which
trips over some intentionally set-but-not-used variables or variables
attached to cleanup handlers with side effects (`_cleanup_umask_`,
`_cleanup_(notify_on_cleanup)`, `_cleanup_(restore_sigsetp)`, etc.):
```
../src/basic/process-util.c:1257:46: error: variable 'saved_ssp' set but not used [-Werror,-Wunused-but-set-variable]
_cleanup_(restore_sigsetp) sigset_t *saved_ssp = NULL;
^
1 error generated.
```
Frantisek Sumsal
Hugo Carvalho
Christian Wehrli
Lennart Poettering
Piotr Drąg
Yu Watanabe
Anita Zhang
Luca Boccassi
Daan De Meyer
Arnaud Ferraris
Jan Janssen
Franck Bui