Fixed bugs in replacement strndup, spotted by Avner BenHanoch.

argp/ChangeLog

+2014-10-02  Niels Möller  <nisse@lysator.liu.se>
+
+	* strndup.c (strndup): Fixed off-by-one error, and failure check.
+	Spotted by Avner BenHanoch.
+
 2008-08-26  Niels Möller  <nisse@lysator.liu.se>
 
 	* testsuite/Makefile.in (tags): Put TAGS file in the source

argp/strndup.c

@@ -17,15 +17,15 @@ strndup (const char *s, size_t size)
   char *end = memchr(s, 0, size);
   
   if (end)
-    /* Length + 1 */
-    size = end - s + 1;
+    /* strlen, i.e., excluding the terminating NUL. */
+    size = end - s;
   
-  r = malloc(size);
+  r = malloc(size+1);
 
-  if (size)
+  if (r)
     {
-      memcpy(r, s, size-1);
-      r[size-1] = '\0';
+      memcpy(r, s, size);
+      r[size] = '\0';
     }
   return r;
 }