fix: port POSIX-only files to Windows for HIP builds

[Sprize1]

Problem

The HIP backend fails to compile on Windows native because several source files use POSIX-only APIs (mmap, dirent, mkstemps, readlink, POSIX sockets) without Windows fallbacks.

Solution

Add cross-platform support behind #if defined(_WIN32), using:

• GgufMmap (existing project RAII class) instead of raw mmap
• std::filesystem instead of dirent/stat
• Winsock2 instead of POSIX sockets (http_server)
• _putenv_s instead of setenv
• _write/_read in io_utils
• ws2_32 + BUILD_SHARED_LIBS=OFF in CMakeLists

Files changed (13)

File	Change
gemma4_loader.cpp	Gemma4Mmap → cross-platform (CreateFileMappingA/MapViewOfFile)
laguna_backend.cpp	::mmap → GgufMmap RAII
qwen35moe_backend.cpp	2x mmap blocks → GgufMmap
qwen35_backend.cpp	open_dflash_floor_log → Windows fopen branch
io_utils.h	write_exact_fd/read_exact_fd → _write/_read on Windows
daemon_loop.cpp	mkstemps → std::filesystem temp dir
disk_prefix_cache.cpp	dirent/stat → std::filesystem
model_card.cpp	readlink(/proc/self/exe) → GetModuleFileNameA
server_main.cpp	setenv → _putenv_s
http_server.cpp	POSIX sockets → Winsock2 (helpers, casts)
http_server.h	Guard unistd.h
CMakeLists.txt	pthread conditional, ws2_32, BUILD_SHARED_LIBS=OFF

No functional change on Linux/macOS

All Windows-specific code is behind #if defined(_WIN32). POSIX paths are unchanged.

Tested

• ✅ dflash_server.exe builds cleanly (91 MB)
• ✅ test_dflash.exe builds cleanly (89 MB)
• Platform: Windows 11 + ROCm 7.1 HIP + gfx1102 (RX 7600 XT 16GB)

🤖 Generated with Claude Code

[cubic-dev-ai]

1 issue found across 13 files

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="server/src/server/server_main.cpp">

<violation number="1" location="server/src/server/server_main.cpp:37">
P1: Windows setenv shim ignores overwrite=0 parameter, silently overwriting existing environment variables on Windows instead of preserving them as POSIX requires.</violation>
</file>

<sub>Reply with feedback, questions, or to request a fix.

Re-trigger cubic</sub>

[cubic-dev-ai]

P1: Windows setenv shim ignores overwrite=0 parameter, silently overwriting existing environment variables on Windows instead of preserving them as POSIX requires.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At server/src/server/server_main.cpp, line 37:

<comment>Windows setenv shim ignores overwrite=0 parameter, silently overwriting existing environment variables on Windows instead of preserving them as POSIX requires.</comment>

<file context>
@@ -33,6 +33,11 @@
 #include <vector>
 
+#ifdef _WIN32
+#define setenv(name, value, overwrite) _putenv_s(name, value)
+#define unsetenv(name) _putenv_s(name, "")
+#endif
</file context>