32-bit Windows x86: reinstate subsystem version of 5.01.

This went missing in the migration to CMake, and broke compatibility
of the standard 32-bit builds with Windows XP. (Of course, the
'buildold' versions should still have run.)

There doesn't seem to be a convenient CMake option to configure it
cleanly, so I had to do a bodgy string-replace on the variable
containing the linker flags, which I found by source-diving in CMake.
That's fragile enough that I've also put in a check after the fact, so
that we'll find out if it ever stops working.

2 files changed, 20 insertions, 1 deletions

diff --git a/Buildscr b/Buildscr
index 76cc7320..a2e23d9d 100644
--- a/Buildscr
+++ b/Buildscr
@@ -172,11 +172,21 @@ mkdir putty/windows/abuild64
 #
 # For the 32-bit ones, we set a subsystem version of 5.01, which
 # allows the resulting files to still run on Windows XP.
-in putty/windows/build32 with cmake_at_least_3.20 do cmake ../.. -DCMAKE_TOOLCHAIN_FILE=$(cmake_toolchain_clangcl32) -DCMAKE_BUILD_TYPE=Release -DCMAKE_MSVC_RUNTIME_LIBRARY=MultiThreaded -DPUTTY_LINK_MAPS=ON -DCMAKE_C_FLAGS_RELEASE="/MT /O2" -DSTRICT=ON
+in putty/windows/build32 with cmake_at_least_3.20 do cmake ../.. -DCMAKE_TOOLCHAIN_FILE=$(cmake_toolchain_clangcl32) -DCMAKE_BUILD_TYPE=Release -DCMAKE_MSVC_RUNTIME_LIBRARY=MultiThreaded -DPUTTY_LINK_MAPS=ON -DCMAKE_C_FLAGS_RELEASE="/MT /O2" -DPUTTY_SUBSYSTEM_VERSION=5.01 -DSTRICT=ON
 in putty/windows/build32 with cmake_at_least_3.20 do make -j$(nproc) VERBOSE=1
 in putty/windows/build64 with cmake_at_least_3.20 do cmake ../.. -DCMAKE_TOOLCHAIN_FILE=$(cmake_toolchain_clangcl64) -DCMAKE_BUILD_TYPE=Release -DCMAKE_MSVC_RUNTIME_LIBRARY=MultiThreaded -DPUTTY_LINK_MAPS=ON -DCMAKE_C_FLAGS_RELEASE="/MT /O2" -DSTRICT=ON
 in putty/windows/build64 with cmake_at_least_3.20 do make -j$(nproc) VERBOSE=1
 
+# The cmake mechanism used to set the subsystem version is a bit of a
+# bodge (it depends on knowing how cmake set up all its build command
+# variables), so just in case it breaks in future, double-check we
+# really did get the subsystem version we wanted.
+in putty/windows/build32 do objdump -x putty.exe > exe-headers.txt
+in putty/windows/build32 do grep -Ex 'MajorOSystemVersion[[:space:]]+5' exe-headers.txt
+in putty/windows/build32 do grep -Ex 'MinorOSystemVersion[[:space:]]+1' exe-headers.txt
+in putty/windows/build32 do grep -Ex 'MajorSubsystemVersion[[:space:]]+5' exe-headers.txt
+in putty/windows/build32 do grep -Ex 'MinorSubsystemVersion[[:space:]]+1' exe-headers.txt
+
 # Build experimental Arm Windows binaries.
 in putty/windows/abuild32 with cmake_at_least_3.20 do cmake ../.. -DCMAKE_TOOLCHAIN_FILE=$(cmake_toolchain_clangcl_a32) -DCMAKE_BUILD_TYPE=Release -DCMAKE_MSVC_RUNTIME_LIBRARY=MultiThreaded -DPUTTY_LINK_MAPS=ON -DCMAKE_C_FLAGS_RELEASE="/MT /O2" -DSTRICT=ON
 in putty/windows/abuild32 with cmake_at_least_3.20 do make -j$(nproc) VERBOSE=1
diff --git a/cmake/platforms/windows.cmake b/cmake/platforms/windows.cmake
index c4299b2c..a7ed7c7c 100644
--- a/cmake/platforms/windows.cmake
+++ b/cmake/platforms/windows.cmake
@@ -7,6 +7,15 @@ set(PUTTY_LINK_MAPS OFF
 set(PUTTY_EMBEDDED_CHM_FILE ""
   CACHE FILEPATH "Path to a .chm help file to embed in the binaries")
 
+if(PUTTY_SUBSYSTEM_VERSION)
+  string(REPLACE
+    "subsystem:windows" "subsystem:windows,${PUTTY_SUBSYSTEM_VERSION}"
+    CMAKE_C_CREATE_WIN32_EXE ${CMAKE_C_CREATE_WIN32_EXE})
+  string(REPLACE
+    "subsystem:console" "subsystem:console,${PUTTY_SUBSYSTEM_VERSION}"
+    CMAKE_C_CREATE_CONSOLE_EXE ${CMAKE_C_CREATE_CONSOLE_EXE})
+endif()
+
 function(define_negation newvar oldvar)
   if(${oldvar})
     set(${newvar} OFF PARENT_SCOPE)