version: dynamically get file version

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

1 files changed, 83 insertions, 0 deletions

diff --git a/version/version_windows.go b/version/version_windows.go
new file mode 100644
index 00000000..e567e7a0
--- /dev/null
+++ b/version/version_windows.go
@@ -0,0 +1,83 @@
+/* SPDX-License-Identifier: MIT
+ *
+ * Copyright (C) 2019 WireGuard LLC. All Rights Reserved.
+ */
+
+package version
+
+import (
+	"errors"
+	"fmt"
+	"golang.org/x/sys/windows"
+	"os"
+	"runtime"
+	"strings"
+	"unsafe"
+)
+
+//sys GetFileVersionInfoSize(filename *uint16, zero *uint32) (size uint32, err error) = version.GetFileVersionInfoSizeW
+//sys GetFileVersionInfo(filename *uint16, zero uint32, size uint32, block *byte) (err error) = version.GetFileVersionInfoW
+//sys VerQueryValue(block *byte, section *uint16, value **byte, size *uint32) (err error) = version.VerQueryValueW
+
+type vsFixedFileInfo struct {
+	Signature        uint32
+	StrucVersion     uint32
+	FileVersionMS    uint32
+	FileVersionLS    uint32
+	ProductVersionMS uint32
+	ProductVersionLS uint32
+	FileFlagsMask    uint32
+	FileFlags        uint32
+	FileOS           uint32
+	FileType         uint32
+	FileSubtype      uint32
+	FileDateMS       uint32
+	FileDateLS       uint32
+}
+
+const vsFixedFileInfoSignature = 0xFEEF04BD
+
+var cachedVersion string
+
+func RunningVersion() string {
+	if len(cachedVersion) != 0 {
+		return cachedVersion
+	}
+	key16 := []uint16{'\\', 0x00}
+	self, err := os.Executable()
+	if err != nil {
+		panic(err)
+	}
+	self16, err := windows.UTF16PtrFromString(self)
+	if err != nil {
+		panic(err)
+	}
+	var zero uint32
+	size, err := GetFileVersionInfoSize(self16, &zero)
+	if err != nil {
+		panic(err)
+	}
+	buffer := make([]byte, size)
+	err = GetFileVersionInfo(self16, zero, size, &buffer[0])
+	if err != nil {
+		panic(err)
+	}
+	var fixedFileInfo *vsFixedFileInfo
+	err = VerQueryValue(&buffer[0], &key16[0], (**byte)(unsafe.Pointer(&fixedFileInfo)), &size)
+	if err != nil {
+		panic(err)
+	}
+	if uintptr(size) < unsafe.Sizeof(vsFixedFileInfo{}) || fixedFileInfo == nil || fixedFileInfo.Signature != vsFixedFileInfoSignature {
+		panic(errors.New("Incorrect return of VS_FIXEDFILEINFO"))
+	}
+	version := fmt.Sprintf("%d.%d.%d.%d", (fixedFileInfo.FileVersionMS>>16)&0xffff, (fixedFileInfo.FileVersionMS>>0)&0xffff, (fixedFileInfo.FileVersionLS>>16)&0xffff, (fixedFileInfo.FileVersionLS>>0)&0xffff)
+	runtime.KeepAlive(buffer) // The win32 API aliases it in fixedFileInfo, but Go doesn't know that.
+	if strings.HasSuffix(version, ".0") {
+		version = version[:len(version)-2]
+	}
+	if strings.HasSuffix(version, ".0") {
+		version = version[:len(version)-2]
+	}
+	cachedVersion = version
+	return version
+}