refining vfs

kernel/lib/strtok.c

@@ -2,48 +2,63 @@
 
 #include <stddef.h>
 
-static int is_delim(char c, const char* delim) {
-    while (*delim) {
-        if (c == *delim) {
-            return 1;
+char* strtok_r(char *s, const char *delim, char **saveptr) {
+    char *token;
+
+    if (!saveptr) {
+        return NULL;
+    }
+
+    if (!s) {
+        s = *saveptr;
+    }
+
+    if (!s || *s == '\0') {
+        *saveptr = s;
+        return NULL;
+    }
+
+    while (*s != '\0') {
+        const char *d = delim;
+        int is_delim = 0;
+        while (*d != '\0') {
+            if (*s == *d) {
+                is_delim = 1;
+                break;
+            }
+            d++;
         }
-        delim++;
-    }
-    return 0;
-}
-
-char* strtok_r(char* str, const char* delim, char** saveptr) {
-    if (saveptr == NULL) {
-        return NULL;
-    }
-
-    char* next_token = (str != NULL) ? str : *saveptr;
-
-    if (next_token == NULL || *next_token == '\0') {
-        *saveptr = NULL;
-        return NULL;
-    }
-
-    while (*next_token && is_delim(*next_token, delim)) {
-        next_token++;
-    }
-
-    if (*next_token == '\0') {
-        *saveptr = next_token;
-        return NULL;
-    }
-
-    char* token_start = next_token;
-
-    while (*next_token) {
-        if (is_delim(*next_token, delim)) {
-            *next_token = '\0';        // Destructively null-terminate the token
-            *saveptr = next_token + 1; // Save the position right after the null-terminator
-            return token_start;
+        if (!is_delim) {
+            break;
         }
-        next_token++;
+        s++;
     }
 
-    *saveptr = next_token;
-    return token_start;
+    if (*s == '\0') {
+        *saveptr = s;
+        return NULL;
+    }
+
+    token = s;
+
+    while (*s != '\0') {
+        const char *d = delim;
+        int is_delim = 0;
+        while (*d != '\0') {
+            if (*s == *d) {
+                is_delim = 1;
+                break;
+            }
+            d++;
+        }
+        if (is_delim) {
+            *s = '\0';
+            *saveptr = s + 1;
+            return token;
+        }
+        s++;
+    }
+
+    *saveptr = s;
+    return token;
 }