解决一个擦除的bug

Drivers/BSP/NET/lftpd/lftpd_string.c

@@ -0,0 +1,16 @@
+#include <string.h>
+#include <ctype.h>
+
+#include "private/lftpd_string.h"
+
+char *lftpd_string_trim(char *s)
+{
+    char *p = s;
+    for (int i = 0, len = (int)strlen(s); i < len && isspace((int)s[i]); i++) {
+        p++;
+    }
+    for (int i = (int)strlen(p); i >= 0 && isspace((int)p[i]); i--) {
+        p[i] = '\0';
+    }
+    return p;
+}