Similar as the previous commit, it's useful for a supervisor to know
what machine ID we settlted on, in particular as various other things
are deterministically derived from it, for example MAC addresses and
such.
We usually check return value of syscalls or glibc functions by it is
negative or not, something like that `if (stat(path, &st) < 0)`.
Let's also use the same style for lseek() and friends even the type of
their return value is off_t.
Note, fseeko() returns int, instead of off_t.
Let's hook up one more thing with credentials: the machine ID to use
when none is initialized yet.
This requires some reordering of initialization steps in PID 1: we need
to import credentials first, and only then initialize the machine ID.
If a root directory is specified, and e.g. /var under the root directory
is a symlink to the host's /var, then we wrongly read host's machine ID,
even if O_NOFOLLOW is set.
Let's chase the path with CHASE_NOFOLLOW to refuse such case.
Also, refuse null ID, otherwise we may setup machine ID with NULL.
-1 was used everywhere, but -EBADF or -EBADFD started being used in various
places. Let's make things consistent in the new style.
Note that there are two candidates:
EBADF 9 Bad file descriptor
EBADFD 77 File descriptor in bad state
Since we're initializating the fd, we're just assigning a value that means
"no fd yet", so it's just a bad file descriptor, and the first errno fits
better. If instead we had a valid file descriptor that became invalid because
of some operation or state change, the other errno would fit better.
In some places, initialization is dropped if unnecessary.
RUN_WITH_UMASK was initially conceived for spawning externals progs with the
umask set. But nowadays we use it various syscalls and stuff that doesn't "run"
anything, so the "RUN_" prefix has outlived its usefulness.
Same idea as 03677889f0.
No functional change intended. The type of the iterator is generally changed to
be 'const char*' instead of 'char*'. Despite the type commonly used, modifying
the string was not allowed.
I adjusted the naming of some short variables for clarity and reduced the scope
of some variable declarations in code that was being touched anyway.
Lennart Poettering
Mike Yuan
Rafaël Kooi
Yu Watanabe
Zbigniew Jędrzejewski-Szmek
Bertrand Jacquin
Kay Sievers