[systemd-devel] [PATCH 07/11] Support init=/bin/bash on the kernel command line
Tom Gundersen
teg at jklm.no
Fri Jun 13 08:49:24 PDT 2014
On Fri, Jun 13, 2014 at 4:41 PM, Werner Fink <werner at suse.de> wrote:
> From: Ruediger Oertel <ro at suse.de>
>
> Process 1 (aka init) needs to be started with an empty signal mask.
> That includes the process 1 that's started after the initrd is finished.
> When the initrd is using systemd (as it does with dracut based initrds)
> then it is systemd that calls the real init. Normally this is systemd
> again, except when the user uses for instance "init=/bin/bash" on the
> kernel command line.
Why is this necessary for /bin/bash, but not for /lib/systemd/systemd?
Please include the explanation in the commit message.
Cheers,
Tom
> ---
> src/core/main.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git src/core/main.c src/core/main.c
> index d5d1ee2..c082354 100644
> --- src/core/main.c
> +++ src/core/main.c
> @@ -1831,6 +1831,7 @@ finish:
> if (reexecute) {
> const char **args;
> unsigned i, args_size;
> + sigset_t ss, o_ss;
>
> /* Close and disarm the watchdog, so that the new
> * instance can reinitialize it, but doesn't get
> @@ -1914,6 +1915,11 @@ finish:
> args[i++] = NULL;
> assert(i <= args_size);
>
> + /* reenable any blocked signals, especially important
> + * if we switch from initial ramdisk to init=... */
> + sigemptyset(&ss);
> + sigprocmask(SIG_SETMASK,&ss,&o_ss);
> +
> if (switch_root_init) {
> args[0] = switch_root_init;
> execv(args[0], (char* const*) args);
> @@ -1932,6 +1938,9 @@ finish:
> log_error("Failed to execute /bin/sh, giving up: %m");
> } else
> log_warning("Failed to execute /sbin/init, giving up: %m");
> +
> + /* back to saved state if reexec failed */
> + sigprocmask(SIG_SETMASK,&o_ss,NULL);
> }
>
> if (arg_serialization) {
> --
> 1.7.9.2
>
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