We may want to propagate O_APPEND, or (try to) keep the current file position,
even if we use fd_reopen() to re-initialize (and "unshare") other file
description status.
For now, used only with --pty to keep/propagate O_APPEND (and/or) position
if set on stdin/stdout.
If we re-open stdout and "drop" the O_APPEND,
we get rather "unexpected" behavior,
for example with repeated "systemd-run --pty >> some-log".
If someone carefully pre-positioned the passed in original file descriptors,
we avoid surprises if we do not reset file postition to zero.
fcntl F_GETFL first, and propagate O_APPEND if present in the existing flags.
Then use lseek to propagate the file position.
This is a follow-up for 945a8210c7 and
makes the st_dev check generic, so that we can reuse it some other
places. It also incorporates the non-NULL check now, to be a
comprehensive one-stop solution.
The helper is static inline so that compilers can optimize the redundant
checks away in case it is combined with other checks.
For anonymous inodes, the result would be 0, but
the struct stat is initialized obviously.
So let's switch to st_dev for the check, which
is guaranteed to be non-zero.
Also this is completely unnecessary for statx(),
since we check stx_mask first and that on its own
denotes that the struct is initialized.
Let's make fd_verify_safe_flags() even more useful:
1. let's return the cleaned up flags (i.e. just the access mode) after
validation, hiding all the noise, such as O_NOFOLLOW, O_LARGEFILE and
similar.
2. let's add a "full" version of the call that allows passing additional
flags that are OK to be set.
Kernel commit cb12fd8e0dabb9a1c8aef55a6a41e2c255fcdf4b added pidfs.
Update filesystems-gperf.gperf and missing_magic.h accordingly.
This fixes the following error building against a bleeding edge kernel.
```
../src/basic/meson.build:234:8: ERROR: Problem encountered: Unknown filesystems defined in kernel headers:
Filesystem found in kernel header but not in filesystems-gperf.gperf: PID_FS_MAGIC
```
Also, use the more correct type of 'const char* const*' for the input strv.
This requires adding the cast in a few places, but also allows to remove some
casts in others.
Follow-up for f274f8bf25
We define *_SLOW_BUS_CALL_TIMEOUT in each component's
own file too. This one is no different and doesn't need
to be in constants.h IMO.
This is useful for two reasons:
1. it addresses a potential overflow in a graceful way
2. Gives callers the ability to just pass SIZE_MAX for a NOP
Prompted by: #31341
Dynamically load liblz4, libzstd and liblzma with dlopen().
This helps to reduce the size of the initrd image when these libraries
are not really needed.
I'm going to dlopen_many_sym_or_warn() in src/basic/compress.c, this
will introduce a circular dependency because libshared already depends
from libbasic.
To avoid this, move dlfcn-util.c from libshared to libbasic.
The glibc API is behind the wrapper is called "secure_getenv()", hence
our wrapper really should keep the order too, otherwise things are just
too confusing.
Currently scan_background_color_response only accepts BEL (\x07) to end
a response, however some terminals (namely kitty in my case) will reply
with the string terminator (ST - https://en.wikipedia.org/wiki/ANSI_escape_code).
This commit changes the behaviour to now accept either ending.
Currently the return value 0 is not checked for, this indicates a
timeout and should be handled to prevent doing a blocking read on a file
descriptor with no data ready.
Yu Watanabe
Lennart Poettering
Mike Yuan
Lars Ellenberg
cpackham-atlnz
Thomas Blume
Zbigniew Jędrzejewski-Szmek
Luca Boccassi
Matteo Croce
Sam Leonard