Merge pull request #14984 from NixOS/more-windows-fixes

More windows fixes

Author: Ericson2314

src/libstore/local-binary-cache-store.cc

@@ -71,8 +71,8 @@ struct LocalBinaryCacheStore : virtual BinaryCacheStore
     {
         try {
             readFile(config->binaryCacheDir + "/" + path, sink);
-        } catch (SysError & e) {
-            if (e.errNo == ENOENT)
+        } catch (SystemError & e) {
+            if (e.is(std::errc::no_such_file_or_directory))
                 throw NoSuchBinaryCacheFile("file '%s' does not exist in binary cache", path);
             throw;
         }

src/libutil/file-system.cc

@@ -540,7 +540,21 @@ std::filesystem::path createTempDir(const std::filesystem::path & tmpRoot, const
 AutoCloseFD createAnonymousTempFile()
 {
     AutoCloseFD fd;
-#ifdef O_TMPFILE
+
+#ifdef _WIN32
+    auto path = makeTempPath(defaultTempDir(), "nix-anonymous");
+    fd = CreateFileW(
+        path.c_str(),
+        GENERIC_READ | GENERIC_WRITE,
+        /*dwShareMode=*/0,
+        /*lpSecurityAttributes=*/nullptr,
+        CREATE_NEW,
+        FILE_ATTRIBUTE_TEMPORARY | FILE_FLAG_DELETE_ON_CLOSE,
+        /*hTemplateFile=*/nullptr);
+    if (!fd)
+        throw windows::WinError("creating temporary file %1%", path);
+#else
+#  ifdef O_TMPFILE
     static std::atomic_flag tmpfileUnsupported{};
     if (!tmpfileUnsupported.test()) /* Try with O_TMPFILE first. */ {
         /* Use O_EXCL, because the file is never supposed to be linked into filesystem. */
@@ -555,14 +569,14 @@ AutoCloseFD createAnonymousTempFile()
             return fd; /* Successfully created. */
         }
     }
-#endif
+#  endif
     auto [fd2, path] = createTempFile("nix-anonymous");
     if (!fd2)
         throw SysError("creating temporary file '%s'", path);
     fd = std::move(fd2);
-#ifndef _WIN32
     unlink(requireCString(path)); /* We only care about the file descriptor. */
 #endif
+
     return fd;
 }
 
@@ -571,7 +585,6 @@ std::pair<AutoCloseFD, Path> createTempFile(const Path & prefix)
     Path tmpl(defaultTempDir().string() + "/" + prefix + ".XXXXXX");
     // Strictly speaking, this is UB, but who cares...
     // FIXME: use O_TMPFILE.
-    // FIXME: Windows should use FILE_ATTRIBUTE_TEMPORARY | FILE_FLAG_DELETE_ON_CLOSE
     AutoCloseFD fd = toDescriptor(mkstemp((char *) tmpl.c_str()));
     if (!fd)
         throw SysError("creating temporary file '%s'", tmpl);

src/libutil/include/nix/util/error.hh

@@ -240,9 +240,39 @@ MakeError(UsageError, Error);
 MakeError(UnimplementedError, Error);
 
 /**
- * To use in catch-blocks.
+ * To use in catch-blocks. Provides a convenience method to get the portable
+ * std::error_code. Use when you want to catch and check an error condition like
+ * no_such_file_or_directory (ENOENT) without ifdefs.
  */
-MakeError(SystemError, Error);
+class SystemError : public Error
+{
+    std::error_code errorCode;
+
+public:
+    template<typename... Args>
+    SystemError(std::errc posixErrNo, Args &&... args)
+        : Error(std::forward<Args>(args)...)
+        , errorCode(std::make_error_code(posixErrNo))
+    {
+    }
+
+    template<typename... Args>
+    SystemError(std::error_code errorCode, Args &&... args)
+        : Error(std::forward<Args>(args)...)
+        , errorCode(errorCode)
+    {
+    }
+
+    const std::error_code ec() const &
+    {
+        return errorCode;
+    }
+
+    bool is(std::errc e) const
+    {
+        return errorCode == e;
+    }
+};
 
 /**
  * POSIX system error, created using `errno`, `strerror` friends.
@@ -271,7 +301,7 @@ public:
      */
     template<typename... Args>
     SysError(int errNo, const Args &... args)
-        : SystemError("")
+        : SystemError(static_cast<std::errc>(errNo), "")
         , errNo(errNo)
     {
         auto hf = HintFmt(args...);
@@ -332,7 +362,7 @@ public:
      */
     template<typename... Args>
     WinError(DWORD lastError, const Args &... args)
-        : SystemError("")
+        : SystemError(std::error_code(lastError, std::system_category()), "")
         , lastError(lastError)
     {
         auto hf = HintFmt(args...);