su: add option to keep console open on shell exit

The '-N' option keeps the console window open after the elevated
shell exits.

Previously this was achieved by passing the '-s' option along with
'-c'.  Recent changes allow scripts to be run without using '-c'
so a new mechanism is required.

su passes the '-N' flag to the shell.  This causes the shell to
issue a prompt and wait for user input when it exits.

Costs 200-204 bytes.

2 files changed, 36 insertions, 7 deletions

diff --git a/loginutils/suw32.c b/loginutils/suw32.c
index b0fb26442..236d36a77 100644
--- a/loginutils/suw32.c
+++ b/loginutils/suw32.c
@@ -16,12 +16,13 @@
 //kbuild:lib-$(CONFIG_SUW32) += suw32.o
 
 //usage:#define suw32_trivial_usage
-//usage:       "[-W] [root]\n"
-//usage:       "or:    su [-W] -c CMD_STRING [[--] root [ARG0 [ARG...]]\n"
-//usage:       "or:    su [-W] [--] root [arbitrary sh arguments]"
+//usage:       "[-NW] [root]\n"
+//usage:       "or:    su [-NW] -c CMD_STRING [[--] root [ARG0 [ARG...]]\n"
+//usage:       "or:    su [-NW] [--] root [arbitrary sh arguments]"
 //usage:#define suw32_full_usage "\n\n"
 //usage:       "Run shell with elevated privileges\n"
 //usage:     "\n    -c CMD  Command to pass to 'sh -c'"
+//usage:     "\n    -N      Don't close console when shell exits"
 //usage:     "\n    -W      Wait for shell exit code"
 
 #include "libbb.h"
@@ -29,7 +30,8 @@
 
 enum {
         OPT_c = (1 << 0),
-        OPT_W = (1 << 1)
+        OPT_N = (1 << 1),
+        OPT_W = (1 << 2)
 };
 
 int suw32_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
@@ -41,7 +43,7 @@ int suw32_main(int argc UNUSED_PARAM, char **argv)
         char *bb_path, *cwd, *q, *args;
         DECLARE_PROC_ADDR(BOOL, ShellExecuteExA, SHELLEXECUTEINFOA *);
 
-        opt = getopt32(argv, "c:W", &opt_command);
+        opt = getopt32(argv, "c:NW", &opt_command);
         argv += optind;
         if (argv[0]) {
                 if (strcmp(argv[0], "root") != 0) {
@@ -78,8 +80,11 @@ int suw32_main(int argc UNUSED_PARAM, char **argv)
         free(q);
         free(cwd);
 
+        if (opt & OPT_N)
+                args = xappendword(args, "-N");
+
         if (opt_command) {
-                args = xappendword(args, "-s -c");
+                args = xappendword(args, "-c");
                 q = quote_arg(opt_command);
                 args = xappendword(args, q);
                 free(q);
diff --git a/shell/ash.c b/shell/ash.c
index 28f4ec47d..93c402a8b 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -238,6 +238,9 @@
 #else
 # define NUM_SCRIPTS 0
 #endif
+#if ENABLE_PLATFORM_MINGW32
+# include <conio.h>
+#endif
 
 /* So far, all bash compat is controlled by one config option */
 /* Separate defines document which part of code implements what */
@@ -540,6 +543,9 @@ struct globals_misc {
 #if ENABLE_PLATFORM_MINGW32
         char *dirarg;  /* argument to -d option */
         char *title;   /* argument to -t option */
+#if ENABLE_SUW32
+        int delayexit; /* set by -N option */
+# endif
 #endif
 
         char *curdir; // = nullstr;     /* current working directory */
@@ -651,6 +657,7 @@ extern struct globals_misc *BB_GLOBAL_CONST ash_ptr_to_globals_misc;
 #if ENABLE_PLATFORM_MINGW32
 #define dirarg      (G_misc.dirarg     )
 #define title       (G_misc.title      )
+#define delayexit   (G_misc.delayexit  )
 #endif
 #define curdir      (G_misc.curdir     )
 #define physdir     (G_misc.physdir    )
@@ -11556,7 +11563,7 @@ evalcommand(union node *cmd, int flags)
                  * we can just exec it.
                  */
 #if ENABLE_PLATFORM_MINGW32
-                if (!(flags & EV_EXIT) || may_have_traps) {
+                if (!(flags & EV_EXIT) || may_have_traps IF_SUW32(|| delayexit)) {
                         /* No, forking off a child is necessary */
                         struct forkshell fs;
 
@@ -12500,6 +12507,9 @@ options(int *login_sh)
 #if ENABLE_PLATFORM_MINGW32
                 dirarg = NULL;
                 title = NULL;
+# if ENABLE_SUW32
+                delayexit = 0;
+# endif
 #endif
         }
         while ((p = *argptr) != NULL) {
@@ -12535,6 +12545,7 @@ options(int *login_sh)
                                 /* Undocumented flags;
                                  *   -d force current directory
                                  *   -t title to display in console window
+                                 *   -N prompt user before exit
                                  * Must appear before -s or -c. */
                                 if (c == 'd' && val == 1) {
                                         if (*argptr == NULL)
@@ -12548,6 +12559,12 @@ options(int *login_sh)
                                         title = *argptr++;
                                         continue;
                                 }
+# if ENABLE_SUW32
+                                if (c == 'N' && val == 1) {
+                                        delayexit = 1;
+                                        continue;
+                                }
+# endif
 #endif
                                 if (c == 's') { /* -s, +s */
                                         sflag = 1;
@@ -15643,6 +15660,13 @@ exitshell(void)
                 /*free(p); - we'll exit soon */
         }
  out:
+#if ENABLE_SUW32
+        if (delayexit) {
+                freopen("CONOUT$", "w", stdout);
+                fputs_stdout("Press any key to exit...");
+                _getch();
+        }
+#endif
         exitreset();
         /* dash wraps setjobctl(0) in "if (setjmp(loc.loc) == 0) {...}".
          * our setjobctl(0) does not panic if tcsetpgrp fails inside it.