Re: [PATCH] Tighten length error check in string::replace

[Paolo Carlini <pcarlini at unitus dot it>]

Benjamin Kosnik wrote:

>>2002-04-24  Paolo Carlini  <pcarlini@unitus.it>
>>
>>	* include/bits/basic_string.h (replace(__pos, __n1, __s, __n2):
>>	Tighten __throw_length_error check.
>>    
>>
>testcase?
>
Yes...
Indeed, it turned out to be much more interesting than the fix itself, 
in that a length_error may be thrown in many different places for many 
different reasons.

I'm not much into exception handling :-(, therefore if you can think of 
something appreciably simpler don't hesitate to point it out!

Ciao,
Paolo.

/////////////

2002-04-25  Paolo Carlini  <pcarlini@unitus.it>

        * include/bits/basic_string.h (replace(__pos, __n1, __s, __n2):
        Tighten __throw_length_error check.
        * testsuite/21_strings/replace: Add test05.

diff -urN libstdc++-v3-orig/include/bits/basic_string.h 
libstdc++-v3/include/bits/basic_string.h
--- libstdc++-v3-orig/include/bits/basic_string.h    2002-04-16 
04:29:20.000000000 +0200
+++ libstdc++-v3/include/bits/basic_string.h    2002-04-23 
23:55:33.000000000 +0200
@@ -642,10 +642,10 @@
     const size_type __size = this->size();
      if (__pos > __size)
       __throw_out_of_range("basic_string::replace");
-    if (__size - __n1 > this->max_size() - __n2)
-      __throw_length_error("basic_string::replace");
     const bool __testn1 = __n1 < __size - __pos;
     const size_type __foldn1 = __testn1 ? __n1 : __size - __pos;
+    if (__size - __foldn1 > this->max_size() - __n2)
+      __throw_length_error("basic_string::replace");
     if (_M_rep()->_M_is_shared() || less<const _CharT*>()(__s, _M_data())
         || less<const _CharT*>()(_M_data() + __size, __s))
       return _M_replace_safe(_M_ibegin() + __pos,
diff -urN libstdc++-v3-orig/testsuite/21_strings/replace.cc 
libstdc++-v3/testsuite/21_strings/replace.cc
--- libstdc++-v3-orig/testsuite/21_strings/replace.cc    2002-04-02 
14:07:07.000000000 +0200
+++ libstdc++-v3/testsuite/21_strings/replace.cc    2002-04-25 
21:06:33.000000000 +0200
@@ -175,11 +175,29 @@
   VERIFY(str02 == "geogaddi");
 }
 
+void
+test05()
+{
+  std::string str01 = "beyond skin";
+  std::string str02 = "glam";
+
+  try {
+    str01.replace(8, 7, str02.c_str(), str02.max_size() - 4);
+  }
+  catch(std::length_error& fail) {
+    VERIFY( std::string(fail.what()) == "basic_string::replace" );
+  }
+  catch(...) {
+    VERIFY( false );
+  }
+}
+
 int main()
 {
   test01();
   test02();
   test03();
   test04();
+  test05();
   return 0;
 }