hush: Don't parse the contents of a dereferenced var

When a variable which contains a user-supplied value is dereferenced
(e.g. to be echo'ed), make sure that the value is not further parsed
by hush.

Set the hush local variable "HUSH_NO_EVAL=1" to enable this behavior.

Without this patch, a sequence like this occurs:

	Panda # env set my_user_string Bob\'s favorite device
	Panda # print my_user_string
	my_user_string=Bob's favorite device
	Panda # echo $my_user_string
	syntax error hush.c:3007

With this patch, it looks like this:

	Panda # HUSH_NO_EVAL=1
	Panda # env set my_user_string Bob\'s favorite device
	Panda # print my_user_string
	my_user_string=Bob's favorite device
	Panda # echo $my_user_string
	Bob's favorite device

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>

diff --git a/common/hush.c b/common/hush.c
index 39cf203a9fc7849ad5ace771b17006e40a2d9c5c..4c84c2f50153fefe78e814729c5a84c55dc903f2 100644 (file)
--- a/common/hush.c
+++ b/common/hush.c
@@ -127,6 +127,7 @@
 #endif
 #endif
 #define SPECIAL_VAR_SYMBOL 03
+#define SUBSTED_VAR_SYMBOL 04
 #ifndef __U_BOOT__
 #define FLAG_EXIT_FROM_LOOP 1
 #define FLAG_PARSE_SEMICOLON (1 << 1)          /* symbol ';' is special for parser */
@@ -499,6 +500,7 @@ static void remove_bg_job(struct pipe *pi);
 /*     local variable support */
 static char **make_list_in(char **inp, char *name);
 static char *insert_var_value(char *inp);
+static char *insert_var_value_sub(char *inp, int tag_subst);
 
 #ifndef __U_BOOT__
 /* Table of built-in functions.  They can be forked or not, depending on
@@ -3088,6 +3090,21 @@ int parse_stream(o_string *dest, struct p_context *ctx,
                        return 1;
                        break;
 #endif
+               case SUBSTED_VAR_SYMBOL:
+                       dest->nonnull = 1;
+                       while (ch = b_getch(input), ch != EOF &&
+                           ch != SUBSTED_VAR_SYMBOL) {
+                               debug_printf("subst, pass=%d\n", ch);
+                               if (input->__promptme == 0)
+                                       return 1;
+                               b_addchr(dest, ch);
+                       }
+                       debug_printf("subst, term=%d\n", ch);
+                       if (ch == EOF) {
+                               syntax();
+                               return 1;
+                       }
+                       break;
                default:
                        syntax();   /* this is really an internal logic error */
                        return 1;
@@ -3129,6 +3146,10 @@ void update_ifs_map(void)
        mapset((uchar *)"\\$'\"`", 3);      /* never flow through */
        mapset((uchar *)"<>;&|(){}#", 1);   /* flow through if quoted */
 #else
+       {
+               uchar subst[2] = {SUBSTED_VAR_SYMBOL, 0};
+               mapset(subst, 3);       /* never flow through */
+       }
        mapset((uchar *)"\\$'\"", 3);       /* never flow through */
        mapset((uchar *)";&|#", 1);         /* flow through if quoted */
 #endif
@@ -3467,6 +3488,11 @@ final_return:
 #endif
 
 static char *insert_var_value(char *inp)
+{
+       return insert_var_value_sub(inp, 0);
+}
+
+static char *insert_var_value_sub(char *inp, int tag_subst)
 {
        int res_str_len = 0;
        int len;
@@ -3474,19 +3500,46 @@ static char *insert_var_value(char *inp)
        char *p, *p1, *res_str = NULL;
 
        while ((p = strchr(inp, SPECIAL_VAR_SYMBOL))) {
+               /* check the beginning of the string for normal charachters */
                if (p != inp) {
+                       /* copy any charachters to the result string */
                        len = p - inp;
                        res_str = xrealloc(res_str, (res_str_len + len));
                        strncpy((res_str + res_str_len), inp, len);
                        res_str_len += len;
                }
                inp = ++p;
+               /* find the ending marker */
                p = strchr(inp, SPECIAL_VAR_SYMBOL);
                *p = '\0';
+               /* look up the value to substitute */
                if ((p1 = lookup_param(inp))) {
-                       len = res_str_len + strlen(p1);
+                       if (tag_subst)
+                               len = res_str_len + strlen(p1) + 2;
+                       else
+                               len = res_str_len + strlen(p1);
                        res_str = xrealloc(res_str, (1 + len));
-                       strcpy((res_str + res_str_len), p1);
+                       if (tag_subst) {
+                               /*
+                                * copy the variable value to the result
+                                * string
+                                */
+                               strcpy((res_str + res_str_len + 1), p1);
+
+                               /*
+                                * mark the replaced text to be accepted as
+                                * is
+                                */
+                               res_str[res_str_len] = SUBSTED_VAR_SYMBOL;
+                               res_str[res_str_len + 1 + strlen(p1)] =
+                                       SUBSTED_VAR_SYMBOL;
+                       } else
+                               /*
+                                * copy the variable value to the result
+                                * string
+                                */
+                               strcpy((res_str + res_str_len), p1);
+
                        res_str_len = len;
                }
                *p = SPECIAL_VAR_SYMBOL;
@@ -3550,9 +3603,14 @@ static char * make_string(char ** inp)
        char *str = NULL;
        int n;
        int len = 2;
+       char *noeval_str;
+       int noeval = 0;
 
+       noeval_str = get_local_var("HUSH_NO_EVAL");
+       if (noeval_str != NULL && *noeval_str != '0' && *noeval_str != '\0')
+               noeval = 1;
        for (n = 0; inp[n]; n++) {
-               p = insert_var_value(inp[n]);
+               p = insert_var_value_sub(inp[n], noeval);
                str = xrealloc(str, (len + strlen(p)));
                if (n) {
                        strcat(str, " ");