On Fri, Aug 02, 2019 at 10:47:10AM +0200, Martin Liška wrote:
> > Can you strace if other fds are opened and not closed in the spot you had it
> > before? Advantage of doing it there is that it will not be done for all the
> > -E/-S/-c compilations when the linker is not spawned.
>
> I've used the same trick which you used and I'm attaching the output.
> I believe it's fine, I can't see any opened fd by GCC.
LGTM.
> gcc/ChangeLog:
>
> 2019-08-02 Martin Liska <mli...@suse.cz>
>
> * gcc.c (driver::maybe_run_linker): Call detect_jobserver
> to detect working job server.
> (driver::detect_jobserver): Test whether jobserver
> is active from GCC driver. That will prevent situation where
> GCC is invoked from a LD plugin and the linker already uses
> file descriptors suggested by make. That leads to a wrong
> detection.
> * gcc.h (driver): Add detect_jobserver.
> * lto-wrapper.c (jobserver_active_p): Simplify sscanf by
> not scanning for --jobserver-auth prefix.
> ---
> gcc/gcc.c | 42 ++++++++++++++++++++++++++++++++++++++++++
> gcc/gcc.h | 1 +
> gcc/lto-wrapper.c | 2 +-
> 3 files changed, 44 insertions(+), 1 deletion(-)
>
> diff --git a/gcc/gcc.c b/gcc/gcc.c
> index a4323eb146e..18a07426290 100644
> --- a/gcc/gcc.c
> +++ b/gcc/gcc.c
> @@ -8268,6 +8268,8 @@ driver::maybe_run_linker (const char *argv0) const
> {
> int tmp = execution_count;
>
> + detect_jobserver ();
> +
> if (! have_c)
> {
> #if HAVE_LTO_PLUGIN > 0
> @@ -8357,6 +8359,46 @@ driver::final_actions () const
> }
> }
>
> +/* Detect whether jobserver is active and working. If not drop
> + --jobserver-auth from MAKEFLAGS. */
> +
> +void
> +driver::detect_jobserver () const
> +{
> + /* Detect jobserver and drop it if it's not working. */
> + const char *makeflags = env.get ("MAKEFLAGS");
> + if (makeflags != NULL)
> + {
> + const char *needle = "--jobserver-auth=";
> + const char *n = strstr (makeflags, needle);
> + if (n != NULL)
> + {
> + int rfd = -1;
> + int wfd = -1;
> +
> + bool jobserver
> + = (sscanf (n + strlen (needle), "%d,%d", &rfd, &wfd) == 2
> + && rfd > 0
> + && wfd > 0
> + && fcntl (rfd, F_GETFD) >= 0
> + && fcntl (wfd, F_GETFD) >= 0);
> +
> + /* Drop the jobserver if it's not working now. */
> + if (!jobserver)
> + {
> + unsigned offset = n - makeflags;
> + char *dup = xstrdup (makeflags);
> + dup[offset] = '\0';
> +
> + const char *space = strchr (makeflags + offset, ' ');
> + if (space != NULL)
> + strcpy (dup + offset, space);
> + xputenv (concat ("MAKEFLAGS=", dup, NULL));
> + }
> + }
> + }
> +}
> +
> /* Determine what the exit code of the driver should be. */
>
> int
> diff --git a/gcc/gcc.h b/gcc/gcc.h
> index a0a1d94c6e6..dc77dba67fb 100644
> --- a/gcc/gcc.h
> +++ b/gcc/gcc.h
> @@ -51,6 +51,7 @@ class driver
> void do_spec_on_infiles () const;
> void maybe_run_linker (const char *argv0) const;
> void final_actions () const;
> + void detect_jobserver () const;
> int get_exit_code () const;
>
> private:
> diff --git a/gcc/lto-wrapper.c b/gcc/lto-wrapper.c
> index 353187c6043..3414adedd26 100644
> --- a/gcc/lto-wrapper.c
> +++ b/gcc/lto-wrapper.c
> @@ -1234,7 +1234,7 @@ jobserver_active_p (void)
> int rfd = -1;
> int wfd = -1;
>
> - return ((sscanf(n, "--jobserver-auth=%d,%d", &rfd, &wfd) == 2)
> + return (sscanf (n + strlen (needle), "%d,%d", &rfd, &wfd) == 2
> && rfd > 0
> && wfd > 0
> && fcntl (rfd, F_GETFD) >= 0
> --
> 2.22.0
>
Jakub
