win32: allow preference for applets to be disabled at runtime

The default busybox-w32 configuration enables the PREFER_APPLETS
and SH_STANDALONE features.  Sometimes it may be desirable to
override the default preference for applets, for example, if an
applet needs to be replaced by an external program with additional
features.

Add support for the environment variable BB_OVERRIDE_APPLETS.
Its value may be:

- a single dash ('-'):  all applets are overridden;

- a space-separated list of names:  only the specified applets
  are overridden.

1 files changed, 8 insertions, 0 deletions

diff --git a/include/libbb.h b/include/libbb.h
index 740c25528..482fcce0c 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -1320,6 +1320,14 @@ void run_noexec_applet_and_exit(int a, const char *name, char **argv) NORETURN F
 #ifndef BUILD_INDIVIDUAL
 int find_applet_by_name(const char *name) FAST_FUNC;
 void run_applet_no_and_exit(int a, const char *name, char **argv) NORETURN FAST_FUNC;
+int find_preferred_applet_by_name(const char *name) FAST_FUNC;
+int is_applet_preferred(const char *name) FAST_FUNC;
+# if ENABLE_PLATFORM_MINGW32 && \
+                (ENABLE_FEATURE_PREFER_APPLETS || ENABLE_FEATURE_SH_STANDALONE)
+#  define find_applet_by_name(n) find_preferred_applet_by_name(n)
+# else
+#  define is_applet_preferred(n) (1)
+# endif
 #endif
 void show_usage_if_dash_dash_help(int applet_no, char **argv) FAST_FUNC;
 #if defined(__linux__)