Linus Heckemann <g...@sphalerite.org> 於 2024年4月19日 星期五寫道：
> We were having some difficulty switching out of our custom initramfs
> into the final filesystem, with the error "message '/init' is not a
> regular file". We were confused as to why it was looking for `/init`
> -- we didn't have `/init`, neither in our initrd nor in the
> destination filesystem -- we were using the rdinit= command line
> parameter to provide an alternative path for the init in the initrd,
> and the target init was determined by userspace.
>
> Thankfully, the error message was fairly clear and easy to find in the
> source!
>
> We thus propose removing this check, since not all initrds have their
> init at /init -- setting rdinit= on the kernel command line allows
> using an alternative path. Thus, this check can prevent switching root
> in a scenario where it would be perfectly appropriate.
> ---
> util-linux/switch_root.c | 3 ---
> 1 file changed, 3 deletions(-)
>
> diff --git a/util-linux/switch_root.c b/util-linux/switch_root.c
> index 14139736e..ef6669f5c 100644
> --- a/util-linux/switch_root.c
> +++ b/util-linux/switch_root.c
> @@ -238,9 +238,6 @@ int switch_root_main(int argc UNUSED_PARAM, char
**argv)
> // Additional sanity checks: we're about to rm -rf /, so be
REALLY SURE
> // we mean it. I could make this a CONFIG option, but I would get
email
> // from all the people who WILL destroy their filesystems.
> - if (stat("/init", &st) != 0 || !S_ISREG(st.st_mode)) {
> - bb_error_msg_and_die("'%s' is not a regular file",
"/init");
> - }
> statfs("/", &stfs); // this never fails
> if ((unsigned)stfs.f_type != RAMFS_MAGIC
> && (unsigned)stfs.f_type != TMPFS_MAGIC
> --
> 2.42.0
Did you read the code comments on the lines above what you deleted? It's a
sanity check before deleting everything on the "/" filesystem.
Perhaps a better approach is to check the existence of what's specified in
the "rdinit" parameter instead.
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