Build a minimized Nix with MinGW

At this point many features are stripped out, but this works:

- Can run libnix{util,store,expr} unit tests
- Can run some Nix commands

Co-Authored-By volth <volth@volth.com>
Co-Authored-By Brian McKenna <brian@brianmckenna.org>

Makefile

@@ -7,6 +7,8 @@ clean-files += $(buildprefix)Makefile.config
 
 # List makefiles
 
+include mk/platform.mk
+
 ifeq ($(ENABLE_BUILD), yes)
 makefiles = \
   mk/precompiled-headers.mk \
@@ -20,7 +22,10 @@ makefiles = \
   src/nix/local.mk \
   src/libutil-c/local.mk \
   src/libstore-c/local.mk \
-  src/libexpr-c/local.mk \
+  src/libexpr-c/local.mk
+
+ifdef HOST_UNIX
+makefiles += \
   src/resolve-system-dependencies/local.mk \
   scripts/local.mk \
   misc/bash/local.mk \
@@ -30,6 +35,7 @@ makefiles = \
   misc/launchd/local.mk \
   misc/upstart/local.mk
 endif
+endif
 
 ifeq ($(ENABLE_UNIT_TESTS), yes)
 makefiles += \
@@ -43,6 +49,7 @@ makefiles += \
 endif
 
 ifeq ($(ENABLE_FUNCTIONAL_TESTS), yes)
+ifdef HOST_UNIX
 makefiles += \
   tests/functional/local.mk \
   tests/functional/ca/local.mk \
@@ -51,6 +58,7 @@ makefiles += \
   tests/functional/test-libstoreconsumer/local.mk \
   tests/functional/plugins/local.mk
 endif
+endif
 
 # Some makefiles require access to built programs and must be included late.
 makefiles-late =
@@ -79,8 +87,6 @@ else
   unexport NIX_HARDENING_ENABLE
 endif
 
-include mk/platform.mk
-
 ifdef HOST_WINDOWS
   # Windows DLLs are stricter about symbol visibility than Unix shared
   # objects --- see https://gcc.gnu.org/wiki/Visibility for details.

m4/gcc_bug_80431.m4

@@ -46,11 +46,13 @@ AC_DEFUN([ENSURE_NO_GCC_BUG_80431],
       ]])],
     [status_80431=0],
     [status_80431=$?],
-    [
-      # Assume we're bug-free when cross-compiling
-    ])
+    [status_80431=''])
   AC_LANG_POP(C++)
   AS_CASE([$status_80431],
+    [''],[
+      AC_MSG_RESULT(cannot check because cross compiling)
+      AC_MSG_NOTICE(assume we are bug free)
+    ],
     [0],[
       AC_MSG_RESULT(yes)
     ],

precompiled-headers.h

@@ -42,19 +42,22 @@
 #include <dirent.h>
 #include <errno.h>
 #include <fcntl.h>
-#include <grp.h>
-#include <netdb.h>
-#include <pwd.h>
 #include <signal.h>
-#include <sys/resource.h>
-#include <sys/select.h>
-#include <sys/socket.h>
 #include <sys/stat.h>
 #include <sys/time.h>
 #include <sys/types.h>
-#include <sys/utsname.h>
-#include <sys/wait.h>
-#include <termios.h>
 #include <unistd.h>
 
+#ifndef _WIN32
+# include <grp.h>
+# include <netdb.h>
+# include <pwd.h>
+# include <sys/resource.h>
+# include <sys/select.h>
+# include <sys/socket.h>
+# include <sys/utsname.h>
+# include <sys/wait.h>
+# include <termios.h>
+#endif
+
 #include <nlohmann/json.hpp>

src/libcmd/common-eval-args.cc

@@ -181,7 +181,7 @@ Bindings * MixEvalArgs::getAutoArgs(EvalState & state)
                 v->mkString(arg.s);
             },
             [&](const AutoArgFile & arg) {
-                v->mkString(readFile(arg.path));
+                v->mkString(readFile(arg.path.string()));
             },
             [&](const AutoArgStdin & arg) {
                 v->mkString(readFile(STDIN_FILENO));

src/libcmd/markdown.cc

@@ -3,9 +3,9 @@
 #include "finally.hh"
 #include "terminal.hh"
 
-#include <sys/queue.h>
 #if HAVE_LOWDOWN
-#include <lowdown.h>
+# include <sys/queue.h>
+# include <lowdown.h>
 #endif
 
 namespace nix {

src/libcmd/repl-interacter.cc

@@ -137,6 +137,7 @@ static constexpr const char * promptForType(ReplPromptType promptType)
 
 bool ReadlineLikeInteracter::getLine(std::string & input, ReplPromptType promptType)
 {
+#ifndef _WIN32 // TODO use more signals.hh for this
     struct sigaction act, old;
     sigset_t savedSignalMask, set;
 
@@ -161,9 +162,12 @@ bool ReadlineLikeInteracter::getLine(std::string & input, ReplPromptType promptT
     };
 
     setupSignals();
+#endif
     char * s = readline(promptForType(promptType));
     Finally doFree([&]() { free(s); });
+#ifndef _WIN32 // TODO use more signals.hh for this
     restoreSignals();
+#endif
 
     if (g_signal_received) {
         g_signal_received = 0;

src/libcmd/repl.cc

@@ -138,12 +138,14 @@ void runNix(Path program, const Strings & args,
     auto subprocessEnv = getEnv();
     subprocessEnv["NIX_CONFIG"] = globalConfig.toKeyValue();
 
+#ifndef _WIN32 // TODO re-enable on Windows, once we can start processes.
     runProgram2(RunOptions {
         .program = settings.nixBinDir+ "/" + program,
         .args = args,
         .environment = subprocessEnv,
         .input = input,
     });
+#endif
 
     return;
 }
@@ -480,6 +482,7 @@ ProcessLineResult NixRepl::processLine(std::string line)
         reloadFiles();
     }
 
+#ifndef _WIN32 // TODO re-enable on Windows, once we can start processes.
     else if (command == ":e" || command == ":edit") {
         Value v;
         evalString(arg, v);
@@ -514,6 +517,7 @@ ProcessLineResult NixRepl::processLine(std::string line)
         state->resetFileCache();
         reloadFiles();
     }
+#endif
 
     else if (command == ":t") {
         Value v;

src/libexpr/eval.cc

@@ -33,15 +33,17 @@
 #include <optional>
 #include <unistd.h>
 #include <sys/time.h>
-#include <sys/resource.h>
 #include <fstream>
 #include <functional>
 #include <iostream>
 
-#include <sys/resource.h>
 #include <nlohmann/json.hpp>
 #include <boost/container/small_vector.hpp>
 
+#ifndef _WIN32 // TODO use portable implementation
+# include <sys/resource.h>
+#endif
+
 #if HAVE_BOEHMGC
 
 #define GC_INCLUDE_NEW
@@ -2632,9 +2634,11 @@ void EvalState::maybePrintStats()
 
 void EvalState::printStatistics()
 {
+#ifndef _WIN32 // TODO use portable implementation
     struct rusage buf;
     getrusage(RUSAGE_SELF, &buf);
     float cpuTime = buf.ru_utime.tv_sec + ((float) buf.ru_utime.tv_usec / 1000000);
+#endif
 
     uint64_t bEnvs = nrEnvs * sizeof(Env) + nrValuesInEnvs * sizeof(Value *);
     uint64_t bLists = nrListElems * sizeof(Value *);
@@ -2651,7 +2655,9 @@ void EvalState::printStatistics()
     if (outPath != "-")
         fs.open(outPath, std::fstream::out);
     json topObj = json::object();
+#ifndef _WIN32 // TODO implement
     topObj["cpuTime"] = cpuTime;
+#endif
     topObj["envs"] = {
         {"number", nrEnvs},
         {"elements", nrValuesInEnvs},

src/libexpr/eval.hh

@@ -161,6 +161,8 @@ struct DebugTrace {
     bool isError;
 };
 
+// Don't want Windows function
+#undef SearchPath
 
 class EvalState : public std::enable_shared_from_this<EvalState>
 {

src/libexpr/primops.cc

@@ -11,7 +11,6 @@
 #include "path-references.hh"
 #include "store-api.hh"
 #include "util.hh"
-#include "processes.hh"
 #include "value-to-json.hh"
 #include "value-to-xml.hh"
 #include "primops.hh"
@@ -28,7 +27,11 @@
 #include <algorithm>
 #include <cstring>
 #include <regex>
-#include <dlfcn.h>
+
+#ifndef _WIN32
+# include <dlfcn.h>
+# include "processes.hh"
+#endif
 
 #include <cmath>
 
@@ -324,6 +327,8 @@ static RegisterPrimOp primop_import({
     }
 });
 
+#ifndef _WIN32 // TODO implement via DLL loading on Windows
+
 /* Want reasonable symbol names, so extern C */
 /* !!! Should we pass the Pos or the file name too? */
 extern "C" typedef void (*ValueInitializer)(EvalState & state, Value & v);
@@ -396,6 +401,8 @@ void prim_exec(EvalState & state, const PosIdx pos, Value * * args, Value & v)
     }
 }
 
+#endif
+
 /* Return a string representing the type of the expression. */
 static void prim_typeOf(EvalState & state, const PosIdx pos, Value * * args, Value & v)
 {
@@ -4581,6 +4588,7 @@ void EvalState::createBaseEnv()
         )",
     });
 
+#ifndef _WIN32 // TODO implement on Windows
     // Miscellaneous
     if (evalSettings.enableNativeCode) {
         addPrimOp({
@@ -4594,6 +4602,7 @@ void EvalState::createBaseEnv()
             .fun = prim_exec,
         });
     }
+#endif
 
     addPrimOp({
         .name = "__traceVerbose",

src/libexpr/search-path.hh

@@ -8,6 +8,9 @@
 
 namespace nix {
 
+// Do not want the windows macro (alias to `SearchPathA`)
+#undef SearchPath
+
 /**
  * A "search path" is a list of ways look for something, used with
  * `builtins.findFile` and `< >` lookup expressions.

src/libfetchers/git-utils.cc

@@ -5,7 +5,9 @@
 #include "memory-input-accessor.hh"
 #include "cache.hh"
 #include "finally.hh"
-#include "processes.hh"
+#ifndef _WIN32 // TODO re-enable on Windows, once we can start processes.
+# include "processes.hh"
+#endif
 #include "signals.hh"
 #include "users.hh"
 #include "fs-sink.hh"
@@ -151,11 +153,11 @@ struct GitRepoImpl : GitRepo, std::enable_shared_from_this<GitRepoImpl>
     {
         initLibGit2();
 
-        if (pathExists(path.native())) {
-            if (git_repository_open(Setter(repo), path.c_str()))
+        if (pathExists(path.string())) {
+            if (git_repository_open(Setter(repo), path.string().c_str()))
                 throw Error("opening Git repository '%s': %s", path, git_error_last()->message);
         } else {
-            if (git_repository_init(Setter(repo), path.c_str(), bare))
+            if (git_repository_init(Setter(repo), path.string().c_str(), bare))
                 throw Error("creating Git repository '%s': %s", path, git_error_last()->message);
         }
     }
@@ -210,7 +212,7 @@ struct GitRepoImpl : GitRepo, std::enable_shared_from_this<GitRepoImpl>
     std::vector<Submodule> parseSubmodules(const std::filesystem::path & configFile)
     {
         GitConfig config;
-        if (git_config_open_ondisk(Setter(config), configFile.c_str()))
+        if (git_config_open_ondisk(Setter(config), configFile.string().c_str()))
             throw Error("parsing .gitmodules file: %s", git_error_last()->message);
 
         ConfigIterator it;
@@ -282,7 +284,7 @@ struct GitRepoImpl : GitRepo, std::enable_shared_from_this<GitRepoImpl>
 
         /* Get submodule info. */
         auto modulesFile = path / ".gitmodules";
-        if (pathExists(modulesFile))
+        if (pathExists(modulesFile.string()))
             info.submodules = parseSubmodules(modulesFile);
 
         return info;
@@ -377,12 +379,13 @@ struct GitRepoImpl : GitRepo, std::enable_shared_from_this<GitRepoImpl>
         auto dir = this->path;
         Strings gitArgs;
         if (shallow) {
-            gitArgs = { "-C", dir, "fetch", "--quiet", "--force", "--depth", "1", "--", url, refspec };
+            gitArgs = { "-C", dir.string(), "fetch", "--quiet", "--force", "--depth", "1", "--", url, refspec };
         }
         else {
-            gitArgs = { "-C", dir, "fetch", "--quiet", "--force", "--", url, refspec };
+            gitArgs = { "-C", dir.string(), "fetch", "--quiet", "--force", "--", url, refspec };
         }
 
+        #ifndef _WIN32 // TODO re-enable on Windows, once we can start processes.
         runProgram(RunOptions {
             .program = "git",
             .searchPath = true,
@@ -392,6 +395,9 @@ struct GitRepoImpl : GitRepo, std::enable_shared_from_this<GitRepoImpl>
             .input = {},
             .isInteractive = true
         });
+        #else
+        throw UnimplementedError("Cannot shell out to git on Windows yet");
+        #endif
     }
 
     void verifyCommit(
@@ -420,6 +426,7 @@ struct GitRepoImpl : GitRepo, std::enable_shared_from_this<GitRepoImpl>
         }
         writeFile(allowedSignersFile, allowedSigners);
 
+#ifndef _WIN32 // TODO re-enable on Windows, once we can start processes.
         // Run verification command
         auto [status, output] = runProgram(RunOptions {
                 .program = "git",
@@ -450,6 +457,9 @@ struct GitRepoImpl : GitRepo, std::enable_shared_from_this<GitRepoImpl>
             printTalkative("Signature verification on commit %s succeeded.", rev.gitRev());
         else
             throw Error("Commit signature verification on commit %s failed: %s", rev.gitRev(), output);
+#else
+            throw Error("Commit signature verification not implemented on Windows yet");
+#endif
     }
 
     Hash treeHashToNarHash(const Hash & treeHash) override