hush: speed up set_local_var

function                                             old     new   delta
set_local_var                                        265     290     +25

1 files changed, 11 insertions, 10 deletions

diff --git a/shell/hush.c b/shell/hush.c
index 58a57d961..53b1f3f8b 100644
--- 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;