Misc Windows fixes

1. Fix build by making the legacy SSH Storey's secret `logFD` setting
   not a setting on Windows. (It doesn't make sense to specify `void *`
   handles by integer cross-proccess, I don't think.)

2. Move some files that don't need to be Unix-only anymore back to their
   original locations.

maintainers/flake-module.nix

@@ -125,8 +125,8 @@
             ''^src/libfetchers/registry\.hh$''
             ''^src/libfetchers/tarball\.cc$''
             ''^src/libfetchers/tarball\.hh$''
-            ''^src/libfetchers/unix/git\.cc$''
-            ''^src/libfetchers/unix/mercurial\.cc$''
+            ''^src/libfetchers/git\.cc$''
+            ''^src/libfetchers/mercurial\.cc$''
             ''^src/libmain/common-args\.cc$''
             ''^src/libmain/common-args\.hh$''
             ''^src/libmain/loggers\.cc$''
@@ -237,11 +237,11 @@
             ''^src/libstore/build/substitution-goal\.hh$''
             ''^src/libstore/build/worker\.cc$''
             ''^src/libstore/build/worker\.hh$''
-            ''^src/libstore/unix/builtins/fetchurl\.cc$''
-            ''^src/libstore/unix/builtins/unpack-channel\.cc$''
+            ''^src/libstore/builtins/fetchurl\.cc$''
+            ''^src/libstore/builtins/unpack-channel\.cc$''
             ''^src/libstore/gc\.cc$''
-            ''^src/libstore/unix/local-overlay-store\.cc$''
-            ''^src/libstore/unix/local-overlay-store\.hh$''
+            ''^src/libstore/local-overlay-store\.cc$''
+            ''^src/libstore/local-overlay-store\.hh$''
             ''^src/libstore/local-store\.cc$''
             ''^src/libstore/local-store\.hh$''
             ''^src/libstore/unix/user-lock\.cc$''

src/libfetchers/git.cc

@@ -19,7 +19,10 @@
 #include <regex>
 #include <string.h>
 #include <sys/time.h>
-#include <sys/wait.h>
+
+#ifndef _WIN32
+#  include <sys/wait.h>
+#endif
 
 using namespace std::string_literals;
 
@@ -40,6 +43,7 @@ bool isCacheFileWithinTtl(time_t now, const struct stat & st)
 
 bool touchCacheFile(const Path & path, time_t touch_time)
 {
+#ifndef _WIN32 // TODO implement
     struct timeval times[2];
     times[0].tv_sec = touch_time;
     times[0].tv_usec = 0;
@@ -47,6 +51,9 @@ bool touchCacheFile(const Path & path, time_t touch_time)
     times[1].tv_usec = 0;
 
     return lutimes(path.c_str(), times) == 0;
+#else
+    return false;
+#endif
 }
 
 Path getCachePath(std::string_view key, bool shallow)
@@ -98,7 +105,15 @@ bool storeCachedHead(const std::string & actualUrl, const std::string & headRef)
     try {
         runProgram("git", true, { "-C", cacheDir, "--git-dir", ".", "symbolic-ref", "--", "HEAD", headRef });
     } catch (ExecError &e) {
-        if (!WIFEXITED(e.status)) throw;
+        if (
+#ifndef WIN32 // TODO abstract over exit status handling on Windows
+            !WIFEXITED(e.status)
+#else
+            e.status != 0
+#endif
+            )
+            throw;
+
         return false;
     }
     /* No need to touch refs/HEAD, because `git symbolic-ref` updates the mtime. */
@@ -329,7 +344,13 @@ struct GitInputScheme : InputScheme
             .program = "git",
             .args = {"-C", repoInfo.url, "--git-dir", repoInfo.gitDir, "check-ignore", "--quiet", std::string(path.rel())},
         });
-        auto exitCode = WEXITSTATUS(result.first);
+        auto exitCode =
+#ifndef WIN32 // TODO abstract over exit status handling on Windows
+            WEXITSTATUS(result.first)
+#else
+            result.first
+#endif
+            ;
 
         if (exitCode != 0) {
             // The path is not `.gitignore`d, we can add the file.

src/libfetchers/local.mk

@@ -5,16 +5,10 @@ libfetchers_NAME = libnixfetchers
 libfetchers_DIR := $(d)
 
 libfetchers_SOURCES := $(wildcard $(d)/*.cc)
-ifdef HOST_UNIX
-  libfetchers_SOURCES += $(wildcard $(d)/unix/*.cc)
-endif
 
 # Not just for this library itself, but also for downstream libraries using this library
 
 INCLUDE_libfetchers := -I $(d)
-ifdef HOST_UNIX
-  INCLUDE_libfetchers += -I $(d)/unix
-endif
 
 libfetchers_CXXFLAGS += $(INCLUDE_libutil) $(INCLUDE_libstore) $(INCLUDE_libfetchers)
 

src/libstore/legacy-ssh-store.hh

@@ -26,10 +26,14 @@ struct LegacySSHStoreConfig : virtual CommonSSHStoreConfig
 
 struct LegacySSHStore : public virtual LegacySSHStoreConfig, public virtual Store
 {
+#ifndef _WIN32
     // Hack for getting remote build log output.
     // Intentionally not in `LegacySSHStoreConfig` so that it doesn't appear in
     // the documentation
-    const Setting<int> logFD{this, -1, "log-fd", "file descriptor to which SSH's stderr is connected"};
+    const Setting<int> logFD{this, INVALID_DESCRIPTOR, "log-fd", "file descriptor to which SSH's stderr is connected"};
+#else
+    Descriptor logFD = INVALID_DESCRIPTOR;
+#endif
 
     struct Connection;
 

src/libstore/local.mk

@@ -6,7 +6,7 @@ libstore_DIR := $(d)
 
 libstore_SOURCES := $(wildcard $(d)/*.cc $(d)/builtins/*.cc $(d)/build/*.cc)
 ifdef HOST_UNIX
-  libstore_SOURCES += $(wildcard $(d)/unix/*.cc $(d)/unix/builtins/*.cc $(d)/unix/build/*.cc)
+  libstore_SOURCES += $(wildcard $(d)/unix/*.cc $(d)/unix/build/*.cc)
 endif
 ifdef HOST_LINUX
   libstore_SOURCES += $(wildcard $(d)/linux/*.cc)