ash: treat all applets as NOEXEC

In standalone shell mode tryexec() treats all applets as NOEXEC.
Except for the shell:  calling ash_main() recursively seems unwise.

This avoids creating a new process for the applet (which is a Good
Thing on Microsoft Windows where creating processes is expensive) but
leaves the resources used by the invoking shell in the current process.

2 files changed, 8 insertions, 0 deletions

diff --git a/libbb/appletlib.c b/libbb/appletlib.c
index b2c85905c..9caa04ac3 100644
--- a/libbb/appletlib.c
+++ b/libbb/appletlib.c
@@ -1122,6 +1122,9 @@ void FAST_FUNC run_applet_no_and_exit(int applet_no, const char *name, char **ar
 #  if defined APPLET_NO_false
          && applet_no != APPLET_NO_false
 #  endif
+#  if defined APPLET_NO_busybox
+         && applet_no != APPLET_NO_busybox
+#  endif
         ) {
                 if (argc == 2 && strcmp(argv[1], "--help") == 0) {
                         /* Make "foo --help" exit with 0: */
diff --git a/shell/ash.c b/shell/ash.c
index e21131b01..d76d3f571 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -8666,7 +8666,12 @@ tryexec(IF_FEATURE_SH_STANDALONE(int applet_no,) const char *cmd, char **argv, c
 {
 #if ENABLE_FEATURE_SH_STANDALONE
         if (applet_no >= 0) {
+# if ENABLE_PLATFORM_MINGW32
+                /* Treat all applets as NOEXEC apart from the shell itself */
+                if (applet_main[applet_no] != ash_main) {
+# else
                 if (APPLET_IS_NOEXEC(applet_no)) {
+# endif
                         clearenv();
                         while (*envp)
                                 putenv(*envp++);