From 4035ef786de80d4d2fc27cd5f03c629702f54762 Mon Sep 17 00:00:00 2001
From: Ben Boeckel <ben.boeckel@kitware.com>
Date: Fri, 9 Jan 2015 10:33:36 -0500
Subject: [PATCH] cmake -E tar: error out on multiple compression formats

---
 Source/cmcmd.cxx | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/Source/cmcmd.cxx b/Source/cmcmd.cxx
index 91b9e94e0..27dd08b78 100644
--- a/Source/cmcmd.cxx
+++ b/Source/cmcmd.cxx
@@ -736,17 +736,27 @@ int cmcmd::ExecuteCMakeCommand(std::vector<std::string>& args)
       cmSystemTools::cmTarCompression compress =
         cmSystemTools::TarCompressNone;
       bool verbose = false;
+      int nCompress = 0;
       if ( flags.find_first_of('j') != flags.npos )
         {
         compress = cmSystemTools::TarCompressBZip2;
+        ++nCompress;
         }
       if ( flags.find_first_of('J') != flags.npos )
         {
         compress = cmSystemTools::TarCompressXZ;
+        ++nCompress;
         }
       if ( flags.find_first_of('z') != flags.npos )
         {
         compress = cmSystemTools::TarCompressGZip;
+        ++nCompress;
+        }
+      if ( nCompress > 1 )
+        {
+        cmSystemTools::Error("Can only compress a tar file one way; "
+                             "at most one flag of z, j, or J may be used");
+        return 1;
         }
       if ( flags.find_first_of('v') != flags.npos )
         {