Implement core::str::from_cstr_len, close #1666

Author: uasi

src/libcore/str.rs

@@ -17,6 +17,7 @@ export
    from_char,
    from_chars,
    from_cstr,
+   from_cstr_len,
    concat,
    connect,
 
@@ -210,6 +211,24 @@ unsafe fn from_cstr(cstr: sbuf) -> str {
     ret from_bytes(res);
 }
 
+/*
+Function: from_cstr_len
+
+Create a Rust string from a C string of the given length
+*/
+unsafe fn from_cstr_len(cstr: sbuf, len: uint) -> str {
+    let res = [];
+    let start = cstr;
+    let curr = start;
+    let i = 0u;
+    while i < len {
+        vec::push(res, *curr);
+        i += 1u;
+        curr = ptr::offset(start, i);
+    }
+    ret from_bytes(res);
+}
+
 /*
 Function: concat