Implemented strtok()

photon/libc/include/string.h

@@ -23,6 +23,9 @@ extern char *strrchr(const char *s, int c);
 
 extern char *strdup(const char *s);
 
+extern char *strtok(char *s, const char *delim);
+extern char *strtok_r(char *s, const char *delim, char **sp);
+
 #if defined(__cplusplus)
 } /* extern "C" */
 #endif

photon/libc/string/strtok.c

@@ -0,0 +1,62 @@
+#include <string.h>
+
+static char *global_sp = NULL;
+
+char *strtok(char *str, const char *delim)
+{
+    return strtok_r(str, delim, &global_sp);
+}
+
+char *strtok_r(char *str, const char *delim, char **sp)
+{
+    int i   = 0;
+    int len = strlen(delim);
+
+    if (len == 0) {
+        return NULL;
+    }
+
+    if (!str && !sp) {
+        return NULL;
+    }
+
+    if (str) {
+        *sp = str;
+    }
+
+    char *p_start = *sp;
+    while (1) {
+        for (i = 0; i < len; i++) {
+            if (*p_start == delim[i]) {
+                p_start++;
+                break;
+            }
+        }
+
+        if (i == len) {
+            *sp = p_start;
+            break;
+        }
+    }
+
+    if (**sp == '\0') {
+        *sp = NULL;
+        return *sp;
+    }
+
+    while (**sp != '\0') {
+        for (i = 0; i < len; i++) {
+            if (**sp == delim[i]) {
+                **sp = '\0';
+                break;
+            }
+        }
+
+        (*sp)++;
+        if (i < len) {
+            break;
+        }
+    }
+
+    return p_start;
+}