ps: display applet names in process listing

In standalone shell mode all busybox-w32 applets are displayed as
'busybox.exe' in a process listing.

I haven't found a satisfactory way to query a running instance of
busybox-w32 to determine which applet it's running.  Handle a couple
of cases:

- the process running the process scan knows its own PID and knows
  which applet it is;
- just before invoking applet_main set an environment variable whose
  name contains the PID and whose value is the current applet name.
  Children running a process scan will inherit their parent's environment
  and can therefore match the parent's PID to its applet name.

1 files changed, 9 insertions, 0 deletions

diff --git a/libbb/appletlib.c b/libbb/appletlib.c
index 1bae940c2..733d9ca12 100644
--- a/libbb/appletlib.c
+++ b/libbb/appletlib.c
@@ -990,6 +990,15 @@ void FAST_FUNC run_applet_no_and_exit(int applet_no, const char *name, char **ar
         }
         if (ENABLE_FEATURE_SUID)
                 check_suid(applet_no);
+
+#if ENABLE_PLATFORM_MINGW32
+        {
+                char *var = xasprintf("BB_APPLET_%d=%s", getpid(), applet_name);
+                putenv(var);
+                free(var);
+        }
+#endif
+
         xfunc_error_retval = applet_main[applet_no](argc, argv);
         /* Note: applet_main() may also not return (die on a xfunc or such) */
         xfunc_die();