Re: Support open-process and friends on MS-Windows

[Andy Wingo <wingo@pobox.com>]

On Sat 25 Jun 2016 15:31, Eli Zaretskii <eliz@gnu.org> writes:

> [Please disregard the previous patch and use this one instead.]

Thanks for the updates.  I have a couple of additional nits, having
applied and built the patch.

> @@ -659,7 +663,7 @@ SCM_DEFINE (scm_kill, "kill", 2, 0, 0,
>  #else
>    /* Mingw has raise(), but not kill().  (Other raw DOS environments might
>       be similar.)  Use raise() when the requested pid is our own process,
> -     otherwise bomb.  */
> +     otherwise TerminateProcess.  */
>    if (scm_to_int (pid) == getpid ())
>      {
>        if (raise (scm_to_int (sig)) != 0)
> @@ -673,6 +677,10 @@ SCM_DEFINE (scm_kill, "kill", 2, 0, 0,
>            goto err;
>          }
>      }
> +#ifdef __MINGW32__
> +  if (w32_kill_proc (scm_to_int (pid), scm_to_int (sig)) != 0)
> +    SCM_SYSERROR;
> +#endif	/* __MINGW32__ */
>  #endif
>    return SCM_UNSPECIFIED;
>  }

Here we effectively have two mingw blocks.  Can the previous one be
removed?  If not, let's fold it into `w32_kill_proc', and in any case
let's rename `w32_kill_proc' to `kill', and then define HAVE_KILL.

> @@ -1141,7 +1143,7 @@ SCM_DEFINE (scm_execl, "execl", 1, 0, 1,
>  
>    exec_argv = scm_i_allocate_string_pointers (args);
>  
> -  execv (exec_file, exec_argv);
> +  execv (exec_file, (char const * const *)exec_argv);
>    SCM_SYSERROR;
>  
>    /* not reached.  */

make[3]: Entering directory '/home/wingo/src/guile-2.0/libguile'
  CC       libguile_2.0_la-posix.lo
posix.c: In function 'scm_execl':
posix.c:1146:21: warning: passing argument 2 of 'execv' from incompatible pointer type [-Wincompatible-pointer-types]
   execv (exec_file, (char const * const *)exec_argv);
                     ^
In file included from ../lib/unistd.h:40:0,
                 from posix.c:50:
/home/wingo/.guix-profile/include/unistd.h:566:12: note: expected 'char * const*' but argument is of type 'const char * const*'
 extern int execv (const char *__path, char *const __argv[])
            ^~~~~

What should be done here?

Similarly in the following cases.

> @@ -1408,16 +1433,16 @@ scm_open_process (SCM mode, SCM prog, SCM args)
>    if (err > 0)
>      {
>        char *msg = strerror (errno);
> -      fprintf (fdopen (err, "a"), "In execlp of %s: %s\n",
> +      fprintf (fdopen (err, "a"), "In execvp of %s: %s\n",
>                 exec_file, msg);
>      }
>  
>    _exit (EXIT_FAILURE);
> +#endif	/* HAVE_FORK */
>    /* Not reached.  */
>    return SCM_BOOL_F;
>  }
>  #undef FUNC_NAME
> -#endif /* HAVE_FORK */

This change updates to provide `open-process' effectively on all systems
instead of only if `fork' is available, but then it causes a runtime
error if the system doesn't have `fork' and isn't `mingw32'.  I guess
that's OK in practice.  Would you mind updating the documentation in
doc/ref/posix.texi to indicate this?  Thanks.

Cheers, and thanks for dealing with the late feedback.

Andy