From ab7284679428197cc5d0e891db6f2ee1d00a6c6d Mon Sep 17 00:00:00 2001
From: Kyle Edwards <kyle.edwards@kitware.com>
Date: Thu, 2 Nov 2023 10:55:30 -0400
Subject: cmake -E cat: Add ability to print standard input

---
 Help/manual/cmake.1.rst                           |  4 ++++
 Help/release/dev/cmake-E-cat-stdin.rst            |  5 +++++
 Source/cmcmd.cxx                                  | 18 ++++++++++++++----
 Tests/RunCMake/CommandLine/E_cat-stdin-stdout.txt |  1 +
 Tests/RunCMake/CommandLine/E_cat-stdin.cmake      | 10 ++++++++++
 Tests/RunCMake/CommandLine/RunCMakeTest.cmake     |  2 ++
 6 files changed, 36 insertions(+), 4 deletions(-)
 create mode 100644 Help/release/dev/cmake-E-cat-stdin.rst
 create mode 100644 Tests/RunCMake/CommandLine/E_cat-stdin-stdout.txt
 create mode 100644 Tests/RunCMake/CommandLine/E_cat-stdin.cmake

diff --git a/Help/manual/cmake.1.rst b/Help/manual/cmake.1.rst
index 5223acb..15ae6ea 100644
--- a/Help/manual/cmake.1.rst
+++ b/Help/manual/cmake.1.rst
@@ -891,6 +891,10 @@ Available commands are:
     ``-`` will result in an error. Use ``--`` to indicate the end of options, in
     case a file starts with ``-``.
 
+  .. versionadded:: 3.29
+
+    ``cat`` can now print the standard input by passing the ``-`` argument.
+
 .. program:: cmake-E
 
 .. option:: chdir <dir> <cmd> [<arg>...]
diff --git a/Help/release/dev/cmake-E-cat-stdin.rst b/Help/release/dev/cmake-E-cat-stdin.rst
new file mode 100644
index 0000000..43a8aed
--- /dev/null
+++ b/Help/release/dev/cmake-E-cat-stdin.rst
@@ -0,0 +1,5 @@
+cmake-E-cat-stdin
+-----------------
+
+* :manual:`cmake(1)` :option:`-E cat <cmake-E cat>` can now print the standard
+  input by passing the ``-`` argument.
diff --git a/Source/cmcmd.cxx b/Source/cmcmd.cxx
index 43a945f..93b0086 100644
--- a/Source/cmcmd.cxx
+++ b/Source/cmcmd.cxx
@@ -203,11 +203,16 @@ bool cmTarFilesFrom(std::string const& file, std::vector<std::string>& files)
 void cmCatFile(const std::string& fileToAppend)
 {
 #ifdef _WIN32
+  _setmode(fileno(stdin), _O_BINARY);
   _setmode(fileno(stdout), _O_BINARY);
 #endif
-  cmsys::ifstream source(fileToAppend.c_str(),
-                         (std::ios::binary | std::ios::in));
-  std::cout << source.rdbuf();
+  std::streambuf* buf = std::cin.rdbuf();
+  cmsys::ifstream source;
+  if (fileToAppend != "-") {
+    source.open(fileToAppend.c_str(), (std::ios::binary | std::ios::in));
+    buf = source.rdbuf();
+  }
+  std::cout << buf;
 }
 
 bool cmRemoveDirectory(const std::string& dir, bool recursive = true)
@@ -1147,7 +1152,12 @@ int cmcmd::ExecuteCMakeCommand(std::vector<std::string> const& args,
       int return_value = 0;
       bool doing_options = true;
       for (auto const& arg : cmMakeRange(args).advance(2)) {
-        if (doing_options && cmHasLiteralPrefix(arg, "-")) {
+        if (arg == "-") {
+          doing_options = false;
+          // Destroy console buffers to drop cout/cerr encoding transform.
+          consoleBuf.reset();
+          cmCatFile(arg);
+        } else if (doing_options && cmHasLiteralPrefix(arg, "-")) {
           if (arg == "--") {
             doing_options = false;
           } else {
diff --git a/Tests/RunCMake/CommandLine/E_cat-stdin-stdout.txt b/Tests/RunCMake/CommandLine/E_cat-stdin-stdout.txt
new file mode 100644
index 0000000..8210d59
--- /dev/null
+++ b/Tests/RunCMake/CommandLine/E_cat-stdin-stdout.txt
@@ -0,0 +1 @@
+^Hello world$
diff --git a/Tests/RunCMake/CommandLine/E_cat-stdin.cmake b/Tests/RunCMake/CommandLine/E_cat-stdin.cmake
new file mode 100644
index 0000000..e83e619
--- /dev/null
+++ b/Tests/RunCMake/CommandLine/E_cat-stdin.cmake
@@ -0,0 +1,10 @@
+file(WRITE "${CMAKE_CURRENT_BINARY_DIR}/ell.txt" "ell")
+file(WRITE "${CMAKE_CURRENT_BINARY_DIR}/rld.txt" "rld")
+execute_process(
+  COMMAND ${CMAKE_COMMAND} -E echo_append "H"
+  COMMAND ${CMAKE_COMMAND} -E cat -
+  )
+execute_process(
+  COMMAND ${CMAKE_COMMAND} -E echo_append "o wo"
+  COMMAND ${CMAKE_COMMAND} -E cat "${CMAKE_CURRENT_BINARY_DIR}/ell.txt" - "${CMAKE_CURRENT_BINARY_DIR}/rld.txt"
+  )
diff --git a/Tests/RunCMake/CommandLine/RunCMakeTest.cmake b/Tests/RunCMake/CommandLine/RunCMakeTest.cmake
index 52be1bb..6d4e0e2 100644
--- a/Tests/RunCMake/CommandLine/RunCMakeTest.cmake
+++ b/Tests/RunCMake/CommandLine/RunCMakeTest.cmake
@@ -782,6 +782,8 @@ run_cmake_command(E_cat-without-double-dash ${CMAKE_COMMAND} -E cat "-file-start
 unset(RunCMake_TEST_COMMAND_WORKING_DIRECTORY)
 unset(out)
 
+run_cmake_command(E_cat-stdin ${CMAKE_COMMAND} -P ${RunCMake_SOURCE_DIR}/E_cat-stdin.cmake)
+
 # Unset environment variables that are used for testing cmake -E
 unset(ENV{TEST_ENV})
 unset(ENV{TEST_ENV_EXPECTED})
-- 
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