ash, su: add -d flag to set directory in ash, use it in su

When busybox-w32 is installed in C:/Windows/System32 su doesn't
run in the same directory as its parent as intended.

Work around this by adding a flag to the shell to set the working
directory.

1 files changed, 30 insertions, 3 deletions

diff --git a/shell/ash.c b/shell/ash.c
index b276544a6..b7fb29452 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -480,6 +480,9 @@ struct globals_misc {
         int errlinno;
 
         char *minusc;  /* argument to -c option */
+#if ENABLE_PLATFORM_MINGW32
+        char *dirarg;  /* argument to -d option */
+#endif
 
         char *curdir; // = nullstr;     /* current working directory */
         char *physdir; // = nullstr;    /* physical working directory */
@@ -573,6 +576,9 @@ extern struct globals_misc *BB_GLOBAL_CONST ash_ptr_to_globals_misc;
 #define loopnest    (G_misc.loopnest   )
 #endif
 #define minusc      (G_misc.minusc     )
+#if ENABLE_PLATFORM_MINGW32
+#define dirarg      (G_misc.dirarg     )
+#endif
 #define curdir      (G_misc.curdir     )
 #define physdir     (G_misc.physdir    )
 #define arg0        (G_misc.arg0       )
@@ -11672,8 +11678,12 @@ options(int cmdline, int *login_sh)
         int val;
         int c;
 
-        if (cmdline)
+        if (cmdline) {
                 minusc = NULL;
+#if ENABLE_PLATFORM_MINGW32
+                dirarg = NULL;
+#endif
+        }
         while ((p = *argptr) != NULL) {
                 c = *p++;
                 if (c != '-' && c != '+')
@@ -11699,6 +11709,14 @@ options(int cmdline, int *login_sh)
                         /* bash 3.2 indeed handles -c CMD and +c CMD the same */
                         if (c == 'c' && cmdline) {
                                 minusc = p;     /* command is after shell args */
+#if ENABLE_PLATFORM_MINGW32
+                        /* Undocumented -d option to force current directory.
+                         * Must appear before -s or -c. */
+                        } else if (c == 'd' && cmdline && val == 1) {
+                                if (*argptr == NULL)
+                                        ash_msg_and_raise_error(bb_msg_requires_arg, "-d");
+                                dirarg = *argptr++;
+#endif
                         } else if (c == 'o') {
                                 if (plus_minus_o(*argptr, val)) {
                                         /* it already printed err message */
@@ -14956,12 +14974,21 @@ int ash_main(int argc UNUSED_PARAM, char **argv)
                 hide_console();
 #endif
 
+#if ENABLE_PLATFORM_MINGW32
+        if (dirarg) {
+                chdir(dirarg);
+                setpwd(NULL, 0);
+        }
+#endif
+
         if (login_sh) {
                 const char *hp;
 
 #if ENABLE_PLATFORM_MINGW32
-                chdir(xgetpwuid(getuid())->pw_dir);
-                setpwd(NULL, 0);
+                if (!dirarg) {
+                        chdir(xgetpwuid(getuid())->pw_dir);
+                        setpwd(NULL, 0);
+                }
 #endif
 
                 state = 1;