cmake: Fix '-E cat' command for binary files on Windows

Reset `std::cout` to write in binary mode with no encoding conversions.

Co-Author: Brad King <brad.king@kitware.com>
Fixes: #21295

Source/cmakemain.cxx

@@ -9,8 +9,10 @@
 #include <cstring>
 #include <iostream>
 #include <string>
+#include <utility>
 #include <vector>
 
+#include <cm/memory>
 #include <cmext/algorithm>
 
 #include <cm3p/uv.h>
@@ -107,13 +109,14 @@ const char* cmDocumentationOptions[][2] = {
 
 #endif
 
-int do_command(int ac, char const* const* av)
+int do_command(int ac, char const* const* av,
+               std::unique_ptr<cmConsoleBuf> consoleBuf)
 {
   std::vector<std::string> args;
   args.reserve(ac - 1);
   args.emplace_back(av[0]);
   cm::append(args, av + 2, av + ac);
-  return cmcmd::ExecuteCMakeCommand(args);
+  return cmcmd::ExecuteCMakeCommand(args, std::move(consoleBuf));
 }
 
 cmMakefile* cmakemainGetMakefile(cmake* cm)
@@ -687,8 +690,8 @@ int main(int ac, char const* const* av)
   cmSystemTools::EnsureStdPipes();
 
   // Replace streambuf so we can output Unicode to console
-  cmConsoleBuf consoleBuf;
-  consoleBuf.SetUTF8Pipes();
+  auto consoleBuf = cm::make_unique<cmConsoleBuf>();
+  consoleBuf->SetUTF8Pipes();
 
   cmsys::Encoding::CommandLineArguments args =
     cmsys::Encoding::CommandLineArguments::Main(ac, av);
@@ -708,7 +711,7 @@ int main(int ac, char const* const* av)
       return do_open(ac, av);
     }
     if (strcmp(av[1], "-E") == 0) {
-      return do_command(ac, av);
+      return do_command(ac, av, std::move(consoleBuf));
     }
   }
   int ret = do_cmake(ac, av);

Source/cmcmd.cxx

@@ -48,6 +48,12 @@
 #include <sstream>
 #include <utility>
 
+#ifdef _WIN32
+#  include <fcntl.h> // for _O_BINARY
+#  include <io.h>    // for _setmode
+#  include <stdio.h> // for std{out,err} and fileno
+#endif
+
 #include <cm/string_view>
 
 #include "cmsys/Directory.hxx"
@@ -178,6 +184,9 @@ static bool cmTarFilesFrom(std::string const& file,
 
 static void cmCatFile(const std::string& fileToAppend)
 {
+#ifdef _WIN32
+  _setmode(fileno(stdout), _O_BINARY);
+#endif
   cmsys::ifstream source(fileToAppend.c_str(),
                          (std::ios::binary | std::ios::in));
   std::cout << source.rdbuf();
@@ -497,7 +506,8 @@ int cmcmd::HandleCoCompileCommands(std::vector<std::string> const& args)
   return ret;
 }
 
-int cmcmd::ExecuteCMakeCommand(std::vector<std::string> const& args)
+int cmcmd::ExecuteCMakeCommand(std::vector<std::string> const& args,
+                               std::unique_ptr<cmConsoleBuf> consoleBuf)
 {
   // IF YOU ADD A NEW COMMAND, DOCUMENT IT ABOVE and in cmakemain.cxx
   if (args.size() > 1) {
@@ -951,6 +961,8 @@ int cmcmd::ExecuteCMakeCommand(std::vector<std::string> const& args)
           cmSystemTools::Error(arg + ": no such file or directory (ignoring)");
           return_value = 1;
         } else {
+          // Destroy console buffers to drop cout/cerr encoding transform.
+          consoleBuf.reset();
           cmCatFile(arg);
         }
       }

Source/cmcmd.h

@@ -5,11 +5,14 @@
 
 #include "cmConfigure.h" // IWYU pragma: keep
 
+#include <memory>
 #include <string>
 #include <vector>
 
 #include "cmCryptoHash.h"
 
+class cmConsoleBuf;
+
 class cmcmd
 {
 public:
@@ -17,7 +20,8 @@ public:
    * Execute commands during the build process. Supports options such
    * as echo, remove file etc.
    */
-  static int ExecuteCMakeCommand(std::vector<std::string> const&);
+  static int ExecuteCMakeCommand(std::vector<std::string> const&,
+                                 std::unique_ptr<cmConsoleBuf> consoleBuf);
 
 protected:
   static int HandleCoCompileCommands(std::vector<std::string> const& args);

Tests/RunCMake/CommandLine/.gitattributes

@@ -0,0 +1,2 @@
+E_cat_binary_files/binary.obj    -text
+E_cat_good_binary_cat-stdout.txt -text -whitespace

Tests/RunCMake/CommandLine/RunCMakeTest.cmake

@@ -498,6 +498,9 @@ run_cmake_command(E_cat_good_cat
   ${CMAKE_COMMAND} -E cat "${out}/first_file.txt" "${out}/second_file.txt" "${out}/unicode_file.txt")
 unset(out)
 
+run_cmake_command(E_cat_good_binary_cat
+  ${CMAKE_COMMAND} -E cat "${RunCMake_SOURCE_DIR}/E_cat_binary_files/binary.obj" "${RunCMake_SOURCE_DIR}/E_cat_binary_files/binary.obj")
+
 run_cmake_command(E_env-no-command0 ${CMAKE_COMMAND} -E env)
 run_cmake_command(E_env-no-command1 ${CMAKE_COMMAND} -E env TEST_ENV=1)
 run_cmake_command(E_env-bad-arg1 ${CMAKE_COMMAND} -E env -bad-arg1)