[Buildroot] [PATCH] package/dropbear: Fix symlink only if pointing to the right directory

[Yann E. MORIN <yann.morin.1998@free.fr>]

Paul, All,

On 2015-07-15 11:55 +0200, paul at crapouillou.net spake thusly:
> From: Paul Cercueil <paul@crapouillou.net>
> 
> This commit ensures that the /etc/dropbear symlink won't be removed if
> it points elsewhere than /var/run/dropbear.
> 
> Signed-off-by: Paul Cercueil <paul@crapouillou.net>
> ---
>  package/dropbear/S50dropbear      | 4 ++--
>  package/dropbear/dropbear.service | 4 ++--
>  2 files changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/package/dropbear/S50dropbear b/package/dropbear/S50dropbear
> index af50ccf..d42fb60 100644
> --- a/package/dropbear/S50dropbear
> +++ b/package/dropbear/S50dropbear
> @@ -12,12 +12,12 @@ start() {
>  	echo -n "Starting dropbear sshd: "
>  	umask 077
>  
> -	# If /etc/dropbear is not a directory, and
> +	# If /etc/dropbear is a symlink to /var/run/dropbear, and
>  	#   - the filesystem is RO (i.e. we can not rm the symlink),
>  	#     create the directory pointed to by the symlink.
>  	#   - the filesystem is RW (i.e. we can rm the symlink),
>  	#     replace the symlink with an actual directory
> -	if ! [ -d /etc/dropbear ]; then
> +	if [ "$(readlink /etc/dropbear)" = "/var/run/dropbear" ]; then

/etc/dropbear is a relative symlink, so readlink (at least from
coreutils) would return the relative path, not the absolute path.

So, I can't see a way this can work as-is. However, what about this:

    if [    -L /etc/dropbear \
         -a "$(readlink -f /etc/dropbear)" = "/var/run/dropbear" ]
    then
        # trick-trac on .etc.dropbear
    fi

(Ditto the unit file, of course! ;-)

Care to fix and resend, please?

Regards,
Yann E. MORIN.

>  		if rm -f /etc/dropbear; then
>  			mkdir -p /etc/dropbear
>  		else
> diff --git a/package/dropbear/dropbear.service b/package/dropbear/dropbear.service
> index 0e2cf54..62ade1f 100644
> --- a/package/dropbear/dropbear.service
> +++ b/package/dropbear/dropbear.service
> @@ -3,13 +3,13 @@ Description=Dropbear SSH daemon
>  After=syslog.target network.target auditd.service
>  
>  [Service]
> -# If /etc/dropbear is not a directory, and
> +# If /etc/dropbear is a symlink to /var/run/dropbear, and
>  #   - the filesystem is RO (i.e. we can not rm the symlink),
>  #     create the directory pointed to by the symlink.
>  #   - the filesystem is RW (i.e. we can rm the symlink),
>  #     replace the symlink with an actual directory
>  ExecStartPre=/bin/sh -c '\
> -if ! [ -d /etc/dropbear ]; then \
> +if [ "$(readlink /etc/dropbear)" = "/var/run/dropbear" ]; then \
>      if rm -f /etc/dropbear; then \
>          mkdir -p /etc/dropbear; \
>      else \
> -- 
> 2.1.4
> 
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