Fully revert windows support (#909)

We added support for Windows in #535. We then partially reverted the change, specifically the parts related to mmap (#706). This was okay because we no longer build for Windows.

This PR fully removes support to avoid being in a partially-implemented state.

cmd/zoekt-sourcegraph-indexserver/meta.go

@@ -8,6 +8,7 @@ import (
 
 	"github.com/sourcegraph/zoekt"
 	"github.com/sourcegraph/zoekt/index"
+	"golang.org/x/sys/unix"
 )
 
 // mergeMeta updates the .meta files for the shards on disk for o.
@@ -110,3 +111,8 @@ func jsonMarshalTmpFile(v interface{}, p string) (_ string, err error) {
 
 // respect process umask. build does this.
 var umask os.FileMode
+
+func init() {
+	umask = os.FileMode(unix.Umask(0))
+	unix.Umask(int(umask))
+}

cmd/zoekt-webserver/main.go

@@ -32,7 +32,6 @@ import (
 	"os"
 	"os/signal"
 	"path/filepath"
-	"runtime"
 	"strconv"
 	"strings"
 	"sync"
@@ -45,6 +44,7 @@ import (
 	"go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc"
 	"golang.org/x/net/http2"
 	"golang.org/x/net/http2/h2c"
+	"golang.org/x/sys/unix"
 	"google.golang.org/grpc"
 
 	"github.com/opentracing/opentracing-go"
@@ -374,8 +374,8 @@ func addProxyHandler(mux *http.ServeMux, socket string) {
 // times you will read the channel (used as buffer for signal.Notify).
 func shutdownSignalChan(maxReads int) <-chan os.Signal {
 	c := make(chan os.Signal, maxReads)
-	signal.Notify(c, os.Interrupt)     // terminal C-c and goreman
-	signal.Notify(c, PLATFORM_SIGTERM) // Kubernetes
+	signal.Notify(c, os.Interrupt) // terminal C-c and goreman
+	signal.Notify(c, unix.SIGTERM) // Kubernetes
 	return c
 }
 
@@ -484,28 +484,13 @@ Possible remediations:
 	}
 }
 
-func diskUsage(path string) (*disk.UsageStat, error) {
-	duPath := path
-	if runtime.GOOS == "windows" {
-		duPath = filepath.VolumeName(duPath)
-	}
-	usage, err := disk.Usage(duPath)
-	if err != nil {
-		return nil, fmt.Errorf("diskUsage: %w", err)
-	}
-	return usage, err
-}
-
 func mustRegisterDiskMonitor(path string) {
 	prometheus.MustRegister(prometheus.NewGaugeFunc(prometheus.GaugeOpts{
 		Name:        "src_disk_space_available_bytes",
 		Help:        "Amount of free space disk space.",
 		ConstLabels: prometheus.Labels{"path": path},
 	}, func() float64 {
-		// I know there is no error handling here, and I don't like it
-		// but there was no error handling in the previous version
-		// that used Statfs, either, so I'm assuming there's no need for it
-		usage, _ := diskUsage(path)
+		usage, _ := disk.Usage(path)
 		return float64(usage.Free)
 	}))
 
@@ -514,10 +499,7 @@ func mustRegisterDiskMonitor(path string) {
 		Help:        "Amount of total disk space.",
 		ConstLabels: prometheus.Labels{"path": path},
 	}, func() float64 {
-		// I know there is no error handling here, and I don't like it
-		// but there was no error handling in the previous version
-		// that used Statfs, either, so I'm assuming there's no need for it
-		usage, _ := diskUsage(path)
+		usage, _ := disk.Usage(path)
 		return float64(usage.Total)
 	}))
 }

index/builder.go

@@ -40,6 +40,7 @@ import (
 	"github.com/dustin/go-humanize"
 	"github.com/go-enry/go-enry/v2"
 	"github.com/rs/xid"
+	"golang.org/x/sys/unix"
 
 	"github.com/sourcegraph/zoekt"
 	"github.com/sourcegraph/zoekt/internal/ctags"
@@ -1090,9 +1091,6 @@ func (e *deltaIndexOptionsMismatchError) Error() string {
 	return fmt.Sprintf("one or more index options for shard %q do not match Builder's index options. These index option updates are incompatible with delta build. New index options: %+v", e.shardName, e.newOptions)
 }
 
-// umask holds the Umask of the current process
-var umask os.FileMode
-
 // Document holds a document (file) to index.
 type Document struct {
 	Name              string
@@ -1113,3 +1111,11 @@ type Document struct {
 type DocumentSection struct {
 	Start, End uint32
 }
+
+// umask holds the Umask of the current process
+var umask os.FileMode
+
+func init() {
+	umask = os.FileMode(unix.Umask(0))
+	unix.Umask(int(umask))
+}