shell/math: return string error indicator, not integer

function                                             old     new   delta
expand_and_evaluate_arith                             87     106     +19
expand_one_var                                      1563    1570      +7
arith                                                 12      18      +6
evaluate_string                                      678     680      +2
arith_apply                                         1269    1271      +2
builtin_umask                                        133     132      -1
ash_arith                                            118      75     -43
expand_vars_to_list                                 1094    1038     -56
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 5/3 up/down: 36/-100)           Total: -64 bytes

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>

1 files changed, 15 insertions, 25 deletions

diff --git a/shell/hush.c b/shell/hush.c
index 4ca5403de..ad30ac1ea 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -4461,7 +4461,7 @@ static char *encode_then_expand_string(const char *str, int process_bkslash, int
 }
 
 #if ENABLE_SH_MATH_SUPPORT
-static arith_t expand_and_evaluate_arith(const char *arg, int *errcode_p)
+static arith_t expand_and_evaluate_arith(const char *arg, const char **errmsg_p)
 {
         arith_state_t math_state;
         arith_t res;
@@ -4472,8 +4472,11 @@ static arith_t expand_and_evaluate_arith(const char *arg, int *errcode_p)
         //math_state.endofname = endofname;
         exp_str = encode_then_expand_string(arg, /*process_bkslash:*/ 1, /*unbackslash:*/ 1);
         res = arith(&math_state, exp_str ? exp_str : arg);
-        *errcode_p = math_state.errcode;
         free(exp_str);
+        if (errmsg_p)
+                *errmsg_p = math_state.errmsg;
+        if (math_state.errmsg)
+                die_if_script(math_state.errmsg);
         return res;
 }
 #endif
@@ -4714,22 +4717,26 @@ static NOINLINE const char *expand_one_var(char **to_be_freed_pp, char *arg, cha
                          * var:N<SPECIAL_VAR_SYMBOL>M<SPECIAL_VAR_SYMBOL>
                          */
                         arith_t beg, len;
-                        int errcode = 0;
+                        const char *errmsg;
 
-                        beg = expand_and_evaluate_arith(exp_word, &errcode);
+                        beg = expand_and_evaluate_arith(exp_word, &errmsg);
+                        if (errmsg)
+                                goto arith_err;
                         debug_printf_varexp("beg:'%s'=%lld\n", exp_word, (long long)beg);
                         *p++ = SPECIAL_VAR_SYMBOL;
                         exp_word = p;
                         p = strchr(p, SPECIAL_VAR_SYMBOL);
                         *p = '\0';
-                        len = expand_and_evaluate_arith(exp_word, &errcode);
+                        len = expand_and_evaluate_arith(exp_word, &errmsg);
+                        if (errmsg)
+                                goto arith_err;
                         debug_printf_varexp("len:'%s'=%lld\n", exp_word, (long long)len);
-
-                        if (errcode >= 0 && len >= 0) { /* bash compat: len < 0 is illegal */
+                        if (len >= 0) { /* bash compat: len < 0 is illegal */
                                 if (beg < 0) /* bash compat */
                                         beg = 0;
                                 debug_printf_varexp("from val:'%s'\n", val);
                                 if (len == 0 || !val || beg >= strlen(val)) {
+ arith_err:
                                         val = NULL;
                                 } else {
                                         /* Paranoia. What if user entered 9999999999999
@@ -4926,28 +4933,11 @@ static NOINLINE int expand_vars_to_list(o_string *output, int n, char *arg)
 #if ENABLE_SH_MATH_SUPPORT
                 case '+': { /* <SPECIAL_VAR_SYMBOL>+cmd<SPECIAL_VAR_SYMBOL> */
                         arith_t res;
-                        int errcode;
 
                         arg++; /* skip '+' */
                         *p = '\0'; /* replace trailing <SPECIAL_VAR_SYMBOL> */
                         debug_printf_subst("ARITH '%s' first_ch %x\n", arg, first_ch);
-                        res = expand_and_evaluate_arith(arg, &errcode);
-
-                        if (errcode < 0) {
-                                const char *msg = "error in arithmetic";
-                                switch (errcode) {
-                                case -3:
-                                        msg = "exponent less than 0";
-                                        break;
-                                case -2:
-                                        msg = "divide by 0";
-                                        break;
-                                case -5:
-                                        msg = "expression recursion loop detected";
-                                        break;
-                                }
-                                die_if_script(msg);
-                        }
+                        res = expand_and_evaluate_arith(arg, NULL);
                         debug_printf_subst("ARITH RES '"arith_t_fmt"'\n", res);
                         sprintf(arith_buf, arith_t_fmt, res);
                         val = arith_buf;