ash: reinstate applet name variable after forkshell

When 'sh --forkshell' is invoked the BB_APPLET_<pid> environment
variable is set, but then it's cleared when the environment of the
child process is restored.  Reinstate it in reinitvar.

3 files changed, 16 insertions, 6 deletions

diff --git a/include/libbb.h b/include/libbb.h
index af234e7b0..da3459224 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -2075,6 +2075,7 @@ extern const char bb_path_wtmp_file[] ALIGN1;
 #define bb_dev_null "/dev/null"
 #if ENABLE_PLATFORM_MINGW32
 #define bb_busybox_exec_path get_busybox_exec_path()
+extern char *bb_applet_pid(void);
 #else
 extern const char bb_busybox_exec_path[] ALIGN1;
 #endif
diff --git a/libbb/appletlib.c b/libbb/appletlib.c
index 210f9ff4d..1488d4bd6 100644
--- a/libbb/appletlib.c
+++ b/libbb/appletlib.c
@@ -796,6 +796,13 @@ static void install_links(const char *busybox UNUSED_PARAM,
 
 static void run_applet_and_exit(const char *name, char **argv) NORETURN;
 
+#if ENABLE_PLATFORM_MINGW32
+char *bb_applet_pid(void)
+{
+        return auto_string(xasprintf("BB_APPLET_%d=%s", getpid(), applet_name));
+}
+#endif
+
 # if ENABLE_BUSYBOX
 #  if ENABLE_FEATURE_SH_STANDALONE && ENABLE_FEATURE_TAB_COMPLETION
     /*
@@ -1008,12 +1015,7 @@ void FAST_FUNC run_applet_no_and_exit(int applet_no, const char *name, char **ar
                 check_suid(applet_no);
 
 #if ENABLE_PLATFORM_MINGW32
-        {
-                char var[64];
-
-                sprintf(var, "BB_APPLET_%d=%s", getpid(), applet_name);
-                putenv(var);
-        }
+        putenv(bb_applet_pid());
 #endif
 
         xfunc_error_retval = applet_main[applet_no](argc, argv);
diff --git a/shell/ash.c b/shell/ash.c
index 6d24fb55a..2a1ddac39 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -14975,6 +14975,13 @@ reinitvar(void)
                 varinit[i].var_func = varinit_data[i].var_func;
         }
         vlineno.var_text = linenovar;
+
+        /*
+         * BB_APPLET_<pid> was correct when 'sh --forkshell' was started
+         * but has now been overwritten by the environment from the forkshell
+         * data block.  Reinstate it.
+         */
+        setvareq(bb_applet_pid(), VEXPORT);
 }
 
 /* FIXME: should consider running forkparent() and forkchild() */