hush: implement $-, set default PATH if it is not set on startup

function                                             old     new   delta
expand_one_var                                      2311    2362     +51
hush_main                                           1075    1104     +29
parse_dollar                                         790     791      +1
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 3/0 up/down: 81/0)               Total: 81 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 26 insertions, 5 deletions

diff --git a/shell/hush.c b/shell/hush.c
index 2b9abbdfd..9dd893aa6 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -466,9 +466,9 @@
 
 #define JOB_STATUS_FORMAT    "[%u] %-22s %.40s\n"
 
-#define _SPECIAL_VARS_STR     "_*@$!?#"
-#define SPECIAL_VARS_STR     ("_*@$!?#" + 1)
-#define NUMERIC_SPECVARS_STR ("_*@$!?#" + 3)
+#define _SPECIAL_VARS_STR     "_*@$!?#-"
+#define SPECIAL_VARS_STR     ("_*@$!?#-" + 1)
+#define NUMERIC_SPECVARS_STR ("_*@$!?#-" + 3)
 #if BASH_PATTERN_SUBST
 /* Support / and // replace ops */
 /* Note that // is stored as \ in "encoded" string representation */
@@ -1008,6 +1008,7 @@ struct globals {
         int debug_indent;
 #endif
         struct sigaction sa;
+        char optstring_buf[sizeof("eix")];
 #if BASH_EPOCH_VARS
         char epoch_buf[sizeof("%lu.nnnnnn") + sizeof(long)*3];
 #endif
@@ -4888,6 +4889,7 @@ static int parse_dollar(o_string *as_string,
         case '#': /* number of args */
         case '*': /* args */
         case '@': /* args */
+        case '-': /* $- option flags set by set builtin or shell options (-i etc) */
                 goto make_one_char_var;
         case '{': {
                 char len_single_ch;
@@ -5062,11 +5064,10 @@ static int parse_dollar(o_string *as_string,
         case '_':
                 goto make_var;
 #if 0
-        /* TODO: $_ and $-: */
+        /* TODO: $_: */
         /* $_ Shell or shell script name; or last argument of last command
          * (if last command wasn't a pipe; if it was, bash sets $_ to "");
          * but in command's env, set to full pathname used to invoke it */
-        /* $- Option flags set by set builtin or shell options (-i etc) */
                 ch = i_getch(input);
                 nommu_addchr(as_string, ch);
                 ch = i_peek_and_eat_bkslash_nl(input);
@@ -6397,6 +6398,23 @@ static NOINLINE int expand_one_var(o_string *output, int n,
                 case '#': /* argc */
                         val = utoa(G.global_argc ? G.global_argc-1 : 0);
                         break;
+                case '-': { /* active options */
+                        /* Check set_mode() to see what option chars we support */
+                        char *cp;
+                        val = cp = G.optstring_buf;
+                        if (G.o_opt[OPT_O_ERREXIT])
+                                *cp++ = 'e';
+                        if (G_interactive_fd)
+                                *cp++ = 'i';
+                        if (G_x_mode)
+                                *cp++ = 'x';
+                        /* If G.o_opt[OPT_O_NOEXEC] is true,
+                         * commands read but are not executed,
+                         * so $- can not execute too, 'n' is never seen in $-.
+                         */
+                        *cp = '\0';
+                        break;
+                }
                 default:
                         val = get_local_var_value(var);
                 }
@@ -9899,6 +9917,9 @@ int hush_main(int argc, char **argv)
         /* IFS is not inherited from the parent environment */
         set_local_var_from_halves("IFS", defifs);
 
+        if (!get_local_var_value("PATH"))
+                set_local_var_from_halves("PATH", bb_default_root_path);
+
         /* PS1/PS2 are set later, if we determine that we are interactive */
 
         /* bash also exports SHLVL and _,