POSIX and GNU define conflicting versions of `strerror_r`. The GNU
version returns the string but doesn't necessilary write into buf.
The POSIX version writes into buf and returns the length but doesn't
necessilary append a terminate the string with a NUL if it's too long
to fit in buf.
This commit fixes building ostree-prepare-root with musl libc. The
stripped static build with musl on my machine is 30K vs. 724K with glibc
static and 11K with glibc shared.
Closes: #477
Approved by: cgwalters
I'm trying to improve the developer experience on OSTree-managed
systems, and I had an epiphany the other day - there's no reason we
have to be absolutely against mutating the current rootfs live. The
key should be making it easy to rollback/reset to a known good state.
I see this command as useful for two related but distinct workflows:
- `ostree admin unlock` will assume you're doing "development". The
semantics hare are that we mount an overlayfs on `/usr`, but the
overlay data is in `/var/tmp`, and is thus discarded on reboot.
- `ostree admin unlock --hotfix` first clones your current deployment,
then creates an overlayfs over `/usr` persistent
to this deployment. Persistent in that now the initramfs switchroot
tool knows how to mount it as well. In this model, if you want
to discard the hotfix, at the moment you roll back/reboot into
the clone.
Note originally, I tried using `rofiles-fuse` over `/usr` for this,
but then everything immediately explodes because the default (at least
CentOS 7) SELinux policy denies tons of things (including `sshd_t`
access to `fusefs_t`). Sigh.
So the switch to `overlayfs` came after experimentation. It still
seems to have some issues...specifically `unix_chkpwd` is broken,
possibly because it's setuid? Basically I can't ssh in anymore.
But I *can* `rpm -Uvh strace.rpm` which is handy.
NOTE: I haven't tested the hotfix path fully yet, specifically
the initramfs bits.
Linux creates a copy of the soure mount flags when creating a bind
mount; if the source is read-only, then the bind mount is.
The problem is that systemd will remount the rootfs read/write, but
each mount (/home, /var etc.) will still be read-only. We need to
remount every bind mount except for /usr to read-write too.
This only "worked" with the old ostree-switch-root because it
effectively force mounted the rootfs read-write always, ignoring the
"ro" flag.
William Manley
Giuseppe Scrivano
Colin Walters