all: Add build constants for runtime.GOOS comparisons (#8442)

all: Add package runtimeos for runtime.GOOS comparisons

I grew tired of hand written string comparisons. This adds generated
constants for the GOOS values, and predefined Is$OS constants that can
be iffed on. In a couple of places I rewrote trivial switch:es to if:s,
and added Illumos where we checked for Solaris (because they are
effectively the same, and if we're going to target one of them that
would be Illumos...).

lib/scanner/walk.go

@@ -11,13 +11,13 @@ import (
 	"errors"
 	"fmt"
 	"path/filepath"
-	"runtime"
 	"strings"
 	"sync/atomic"
 	"time"
 	"unicode/utf8"
 
 	metrics "github.com/rcrowley/go-metrics"
+	"github.com/syncthing/syncthing/lib/build"
 	"github.com/syncthing/syncthing/lib/events"
 	"github.com/syncthing/syncthing/lib/fs"
 	"github.com/syncthing/syncthing/lib/ignore"
@@ -470,7 +470,7 @@ func (w *walker) walkDir(ctx context.Context, relPath string, info fs.FileInfo,
 func (w *walker) walkSymlink(ctx context.Context, relPath string, info fs.FileInfo, finishedChan chan<- ScanResult) error {
 	// Symlinks are not supported on Windows. We ignore instead of returning
 	// an error.
-	if runtime.GOOS == "windows" {
+	if build.IsWindows {
 		return nil
 	}
 
@@ -519,7 +519,7 @@ func (w *walker) walkSymlink(ctx context.Context, relPath string, info fs.FileIn
 // normalizePath returns the normalized relative path (possibly after fixing
 // it on disk), or skip is true.
 func (w *walker) normalizePath(path string, info fs.FileInfo) (normPath string, err error) {
-	if runtime.GOOS == "darwin" {
+	if build.IsDarwin {
 		// Mac OS X file names should always be NFD normalized.
 		normPath = norm.NFD.String(path)
 	} else {
@@ -579,7 +579,7 @@ func (w *walker) normalizePath(path string, info fs.FileInfo) (normPath string,
 // do not depend on type, and things that should be preserved from the
 // previous version of the FileInfo.
 func (w *walker) updateFileInfo(dst, src protocol.FileInfo) protocol.FileInfo {
-	if dst.Type == protocol.FileInfoTypeFile && runtime.GOOS == "windows" {
+	if dst.Type == protocol.FileInfoTypeFile && build.IsWindows {
 		// If we have an existing index entry, copy the executable bits
 		// from there.
 		dst.Permissions |= (src.Permissions & 0111)

lib/scanner/walk_test.go

@@ -15,13 +15,13 @@ import (
 	"io"
 	"os"
 	"path/filepath"
-	"runtime"
 	rdebug "runtime/debug"
 	"sort"
 	"sync"
 	"testing"
 
 	"github.com/d4l3k/messagediff"
+	"github.com/syncthing/syncthing/lib/build"
 	"github.com/syncthing/syncthing/lib/events"
 	"github.com/syncthing/syncthing/lib/fs"
 	"github.com/syncthing/syncthing/lib/ignore"
@@ -178,7 +178,7 @@ func TestVerify(t *testing.T) {
 }
 
 func TestNormalization(t *testing.T) {
-	if runtime.GOOS == "darwin" {
+	if build.IsDarwin {
 		t.Skip("Normalization test not possible on darwin")
 		return
 	}
@@ -197,7 +197,7 @@ func TestNormalization(t *testing.T) {
 	}
 	numInvalid := 2
 
-	if runtime.GOOS == "windows" {
+	if build.IsWindows {
 		// On Windows, in case 5 the character gets replaced with a
 		// replacement character \xEF\xBF\xBD at the point it's written to disk,
 		// which means it suddenly becomes valid (sort of).
@@ -257,7 +257,7 @@ func TestNormalization(t *testing.T) {
 func TestNormalizationDarwinCaseFS(t *testing.T) {
 	// This tests that normalization works on Darwin, through a CaseFS.
 
-	if runtime.GOOS != "darwin" {
+	if !build.IsDarwin {
 		t.Skip("Normalization test not possible on non-Darwin")
 		return
 	}
@@ -321,7 +321,7 @@ func TestIssue1507(_ *testing.T) {
 }
 
 func TestWalkSymlinkUnix(t *testing.T) {
-	if runtime.GOOS == "windows" {
+	if build.IsWindows {
 		t.Skip("skipping unsupported symlink test")
 		return
 	}
@@ -351,7 +351,7 @@ func TestWalkSymlinkUnix(t *testing.T) {
 }
 
 func TestWalkSymlinkWindows(t *testing.T) {
-	if runtime.GOOS != "windows" {
+	if !build.IsWindows {
 		t.Skip("skipping unsupported symlink test")
 	}
 
@@ -386,7 +386,7 @@ func TestWalkRootSymlink(t *testing.T) {
 	dest, _ := filepath.Abs("testdata/dir1")
 	destFs := fs.NewFilesystem(testFsType, dest)
 	if err := fs.DebugSymlinkForTestsOnly(destFs, testFs, ".", "link"); err != nil {
-		if runtime.GOOS == "windows" {
+		if build.IsWindows {
 			// Probably we require permissions we don't have.
 			t.Skip("Need admin permissions or developer mode to run symlink test on Windows: " + err.Error())
 		} else {
@@ -406,7 +406,7 @@ func TestWalkRootSymlink(t *testing.T) {
 	files = walkDir(testFs, "link", nil, nil, 0)
 
 	// Verify that we got the one symlink, except on windows
-	if runtime.GOOS == "windows" {
+	if build.IsWindows {
 		if len(files) != 0 {
 			t.Errorf("expected no files, not %d", len(files))
 		}
@@ -588,7 +588,7 @@ func TestScanOwnershipPOSIX(t *testing.T) {
 }
 
 func TestScanOwnershipWindows(t *testing.T) {
-	if runtime.GOOS != "windows" {
+	if !build.IsWindows {
 		t.Skip("This test only works on Windows")
 	}