* string/strxfrm_l.c (STRXFRM): Fix trailing \1 optimization

	if N is one bigger than return value.
	* string/tst-strxfrm2.c (do_test): Also test strxfrm with l1 + 1
	and l1 last arguments, if buf is defined, verify the return value
	equals to strlen (buf) and verify no byte beyond passed length
	is modified.

2 files changed, 46 insertions, 6 deletions

diff --git a/string/strxfrm_l.c b/string/strxfrm_l.c
index f158833f05..20f2f149bd 100644
--- a/string/strxfrm_l.c
+++ b/string/strxfrm_l.c
@@ -432,7 +432,7 @@ STRXFRM (STRING_TYPE *dest, const STRING_TYPE *src, size_t n, __locale_t l)
   if (needed > 2 && needed == last_needed + 1)
     {
       /* Remove the \1 byte.  */
-      if (--needed < n)
+      if (--needed <= n)
 	dest[needed - 1] = L('\0');
     }
 
diff --git a/string/tst-strxfrm2.c b/string/tst-strxfrm2.c
index 31fc42cc93..d5a1115338 100644
--- a/string/tst-strxfrm2.c
+++ b/string/tst-strxfrm2.c
@@ -7,14 +7,34 @@ do_test (void)
 {
   int res = 0;
 
-  char buf[10];
+  char buf[20];
   size_t l1 = strxfrm (NULL, "ab", 0);
   size_t l2 = strxfrm (buf, "ab", 1);
   size_t l3 = strxfrm (buf, "ab", sizeof (buf));
+  if (l3 < sizeof (buf) && strlen (buf) != l3)
+    {
+      puts ("C locale l3 test failed");
+      res = 1;
+    }
+
+  size_t l4 = strxfrm (buf, "ab", l1 + 1);
+  if (l4 < l1 + 1 && strlen (buf) != l4)
+    {
+      puts ("C locale l4 test failed");
+      res = 1;
+    }
+
+  buf[l1] = 'Z';
+  size_t l5 = strxfrm (buf, "ab", l1);
+  if (buf[l1] != 'Z')
+    {
+      puts ("C locale l5 test failed");
+      res = 1;
+    }
 
-  if (l1 != l2 || l1 != l3)
+  if (l1 != l2 || l1 != l3 || l1 != l4 || l1 != l5)
     {
-      puts ("C locale test failed");
+      puts ("C locale retval test failed");
       res = 1;
     }
 
@@ -28,10 +48,30 @@ do_test (void)
       l1 = strxfrm (NULL, "ab", 0);
       l2 = strxfrm (buf, "ab", 1);
       l3 = strxfrm (buf, "ab", sizeof (buf));
+      if (l3 < sizeof (buf) && strlen (buf) != l3)
+	{
+	  puts ("UTF-8 locale l3 test failed");
+	  res = 1;
+	}
+
+      l4 = strxfrm (buf, "ab", l1 + 1);
+      if (l4 < l1 + 1 && strlen (buf) != l4)
+	{
+	  puts ("UTF-8 locale l4 test failed");
+	  res = 1;
+	}
+
+      buf[l1] = 'Z';
+      l5 = strxfrm (buf, "ab", l1);
+      if (buf[l1] != 'Z')
+	{
+	  puts ("UTF-8 locale l5 test failed");
+	  res = 1;
+	}
 
-      if (l1 != l2 || l1 != l3)
+      if (l1 != l2 || l1 != l3 || l1 != l4 || l1 != l5)
 	{
-	  puts ("UTF-8 locale test failed");
+	  puts ("UTF-8 locale retval test failed");
 	  res = 1;
 	}
     }