hush: speed up set_local_var

function                                             old     new   delta
set_local_var                                        265     290     +25

diff --git a/shell/hush.c b/shell/hush.c
index 58a57d96192f14a8719bd45a64b682453c426280..53b1f3f8bbf22f5b63461706a3ce47a9b6ac86b1 100644 (file)
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -1266,16 +1266,16 @@ static const char *get_local_var_value(const char *src)
 static int set_local_var(char *str, int flg_export, int flg_read_only)
 {
        struct variable *cur;
-       char *value;
+       char *eq_sign;
        int name_len;
 
-       value = strchr(str, '=');
-       if (!value) { /* not expected to ever happen? */
+       eq_sign = strchr(str, '=');
+       if (!eq_sign) { /* not expected to ever happen? */
                free(str);
                return -1;
        }
 
-       name_len = value - str + 1; /* including '=' */
+       name_len = eq_sign - str + 1; /* including '=' */
        cur = G.top_var; /* cannot be NULL (we have HUSH_VERSION and it's RO) */
        while (1) {
                if (strncmp(cur->varstr, str, name_len) != 0) {
@@ -1288,7 +1288,6 @@ static int set_local_var(char *str, int flg_export, int flg_read_only)
                        continue;
                }
                /* We found an existing var with this name */
-               *value = '\0';
                if (cur->flg_read_only) {
 #if !BB_MMU
                        if (!flg_read_only)
@@ -1297,11 +1296,13 @@ static int set_local_var(char *str, int flg_export, int flg_read_only)
                        free(str);
                        return -1;
                }
-//TODO: optimize out redundant unsetenv/putenv's?
-               debug_printf_env("%s: unsetenv '%s'\n", __func__, str);
-               unsetenv(str); /* just in case */
-               *value = '=';
-               if (strcmp(cur->varstr, str) == 0) {
+               if (flg_export == -1) {
+                       debug_printf_env("%s: unsetenv '%s'\n", __func__, str);
+                       *eq_sign = '\0';
+                       unsetenv(str);
+                       *eq_sign = '=';
+               }
+               if (strcmp(cur->varstr + name_len, eq_sign + 1) == 0) {
  free_and_exp:
                        free(str);
                        goto exp;