[PATCH weston] xwayland: fix lock file parsing

[Daniel Stone]

Hi,

On 14 November 2016 at 13:05, Pekka Paalanen <ppaalanen at gmail.com> wrote:
> Patch 139fcabe7cdb1f2296bf02ef917aaab84e00cd4e "xwayland: Improve error
> checking for strtol call" caused a regression in the X11 unix socket
> lock file parsing. Before that patch, only the first 10 characters were
> considered for parsing. After the patch, the newline as the 11th
> character caused strtol() to stop parsing at the 10th character which
> was then considered an error as not the whole input was consumed.
>
> The effect of the regression was that no X11 lock files were ever deemed
> stale, hence stale lock files were never removed. Up till now, I have
> accumulated 37 lock files, and Weston complaining for each of them on
> every start it cannot parse them.
>
> Fix this by terminating the string at the expected newline character.
>
> Also, it looks like 'pid' was being used uninitialized, risking strtol()
> reading past the end of the array. This patch fixes that too.

That all sounds pretty great. For bonus points, it's also broken in
that it tries to snprintf(pid, 11, "%10d\n"), where the size includes
the trailing NULL. So it'll just print %10d\0. Same as GNOME Shell at
least. I'll send a separate one, but this one is tested and pushed,
and I've re-enabled XWayland in my local test build:
To ssh://git.freedesktop.org/git/wayland/weston
   c027153..61beda6  push -> master

Cheers,
Daniel

> Signed-off-by: Pekka Paalanen <pekka.paalanen at collabora.co.uk>
> ---
>  xwayland/launcher.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/xwayland/launcher.c b/xwayland/launcher.c
> index dcc4b97..97d7c6e 100644
> --- a/xwayland/launcher.c
> +++ b/xwayland/launcher.c
> @@ -166,6 +166,9 @@ create_lockfile(int display, char *lockfile, size_t lsize)
>                         return -1;
>                 }
>
> +               /* Trim the newline, ensure terminated string. */
> +               pid[10] = '\0';
> +
>                 if (!safe_strtoint(pid, &other)) {
>                         weston_log("can't parse lock file %s\n",
>                                 lockfile);
> --
> 2.7.3
>
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