From 0b4a56e64b52ac050e42192c635bd59527cd98b7 Mon Sep 17 00:00:00 2001
From: Johnny Jazeix <jazeix@gmail.com>
Date: Sat, 18 Sep 2021 18:52:28 +0200
Subject: cmake: -E cat stops when an empty file is encountered

Fixes: #22652
---
 Source/cmcmd.cxx                              | 2 ++
 Tests/RunCMake/CommandLine/RunCMakeTest.cmake | 3 ++-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/Source/cmcmd.cxx b/Source/cmcmd.cxx
index 1e0f497..3e36f97 100644
--- a/Source/cmcmd.cxx
+++ b/Source/cmcmd.cxx
@@ -1068,6 +1068,8 @@ int cmcmd::ExecuteCMakeCommand(std::vector<std::string> const& args,
         } else if (!cmSystemTools::FileExists(arg)) {
           cmSystemTools::Error(arg + ": no such file or directory (ignoring)");
           return_value = 1;
+        } else if (cmSystemTools::FileLength(arg) == 0) {
+          // Ignore empty files, this is not an error
         } else {
           // Destroy console buffers to drop cout/cerr encoding transform.
           consoleBuf.reset();
diff --git a/Tests/RunCMake/CommandLine/RunCMakeTest.cmake b/Tests/RunCMake/CommandLine/RunCMakeTest.cmake
index cea5b1b..dc066f1 100644
--- a/Tests/RunCMake/CommandLine/RunCMakeTest.cmake
+++ b/Tests/RunCMake/CommandLine/RunCMakeTest.cmake
@@ -647,9 +647,10 @@ run_cmake_command(E_cat_directory
 
 file(WRITE "${out}/first_file.txt" "first file to append\n")
 file(WRITE "${out}/second_file.txt" "second file to append\n")
+file(WRITE "${out}/empty_file.txt" "")
 file(WRITE "${out}/unicode_file.txt" "àéùç - 한국어") # Korean in Korean
 run_cmake_command(E_cat_good_cat
-  ${CMAKE_COMMAND} -E cat "${out}/first_file.txt" "${out}/second_file.txt" "${out}/unicode_file.txt")
+  ${CMAKE_COMMAND} -E cat "${out}/first_file.txt" "${out}/second_file.txt" "${out}/empty_file.txt" "${out}/unicode_file.txt")
 unset(out)
 
 run_cmake_command(E_cat_good_binary_cat
-- 
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