Bug#573571: Potential fix for cwd bug

[Dmitry Bogatov]

[2018-12-16 12:35] Jesse Smith <jsmith at resonatingmedia.com>
> I did some poking around and believe I've found the issue with isserv
> jumping out whenever the current working directory (cwd) is not accessible.
> 
> Basically, in the pushd() function there are two checks - one to see if
> we can save the cwd, and another check to see if we can change to
> /etc/init.d. If either of these checks failed, insserv would bail out.
> The only important check is the second one (moving to /etc/init.d), but
> both were treated as the same, fatal error and resulted in the same
> error message being printed.
> 
> The attached patch fixes this situation so the two errors are handled
> separately. The first check (saving cwd) will fail gracefully with an
> error to stderr. The second check, moving to /etc/init.d, will fail with
> a fatal error.
> 
> This patch also addresses some potential segfault issues in popd().
> These probably would not happen in any practical environment, but the
> extra checks should avoid crashes in the future if a directory gets
> removed while insserv is running.
> 
> This fix will appear in upstream version 1.19.0 in the new year. This
> patch should address the issue in 1.18.0 and earlier releases.

> diff --git a/Makefile b/Makefile
> index cf84e66..5556965 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -76,7 +76,7 @@ endif
>  TODO	=	insserv insserv.8
>  
>  all:		$(TODO)
> -	ln -s ../insserv tests/insserv
> +	$(LINK) ../insserv tests/insserv

Improvements of style in Makefile are not strictly part of
resolution of this issue, aren't they?

> diff --git a/insserv.c b/insserv.c
> index e109341..4df4cdc 100644
> --- a/insserv.c
> +++ b/insserv.c
> [...]

I am not familiar with code, but why insserv need to save current
directory in first place? But otherwise patch works for me.

Any chance to something like insserv-1.18.1 release?