libc: Implement strndup()

libs/libc/include/string.h

@@ -27,6 +27,10 @@ extern "C"
     /* Returns a heap-allocated copy of the string str. Should be freed when it is not used anymore. */
     char* strdup(const char* str);
 
+    /* Returns a heap-allocated copy of the string str, copying at maximum max bytes. Should be freed when it is not
+     * used anymore. */
+    char* strndup(const char* str, size_t max);
+
     /* Returns the length of the string str. */
     size_t strlen(const char* str);
 

libs/libc/src/string.cpp

@@ -54,6 +54,16 @@ extern "C"
         return (char*)memcpy(dest, str, len + 1);
     }
 
+    char* strndup(const char* str, size_t max)
+    {
+        size_t len = strnlen(str, max);
+        char* dest = (char*)malloc(len + 1);
+        if (!dest) return dest;
+        memcpy(dest, str, len);
+        dest[len] = 0;
+        return dest;
+    }
+
     size_t strlen(const char* str)
     {
         const char* i = str;