r243950 - [UB] Avoid a really broken call to realloc that would later result in

[Chandler Carruth]

Author: chandlerc
Date: Mon Aug  3 22:53:04 2015
New Revision: 243950

URL: http://llvm.org/viewvc/llvm-project?rev=243950&view=rev
Log:
[UB] Avoid a really broken call to realloc that would later result in
a bad call to memcpy.

When we only have a buffer from one of the two reparse calls, we can
just return that buffer rather than going through the realloc/memcpy
dance.

Found with UBsan.

Modified:
    cfe/trunk/tools/c-index-test/c-index-test.c

Modified: cfe/trunk/tools/c-index-test/c-index-test.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/tools/c-index-test/c-index-test.c?rev=243950&r1=243949&r2=243950&view=diff
==============================================================================
--- cfe/trunk/tools/c-index-test/c-index-test.c (original)
+++ cfe/trunk/tools/c-index-test/c-index-test.c Mon Aug  3 22:53:04 2015
@@ -255,6 +255,17 @@ static int parse_remapped_files_with_try
   if (ret)
     return ret;
 
+  if (num_unsaved_files_no_try_idx == 0) {
+    *unsaved_files = unsaved_files_try_idx;
+    *num_unsaved_files = num_unsaved_files_try_idx;
+    return 0;
+  }
+  if (num_unsaved_files_try_idx == 0) {
+    *unsaved_files = unsaved_files_no_try_idx;
+    *num_unsaved_files = num_unsaved_files_no_try_idx;
+    return 0;
+  }
+
   *num_unsaved_files = num_unsaved_files_no_try_idx + num_unsaved_files_try_idx;
   *unsaved_files
     = (struct CXUnsavedFile *)realloc(unsaved_files_no_try_idx,