build: fix linting issues reported by running golangci-lint with different GOOS

backend/azureblob/azureblob_unsupported.go

@@ -3,4 +3,5 @@
 
 //go:build plan9 || solaris || js
 
+// Package azureblob provides an interface to the Microsoft Azure blob object storage system
 package azureblob

backend/azurefiles/azurefiles_unsupported.go

@@ -3,4 +3,5 @@
 
 //go:build plan9 || js
 
+// Package azurefiles provides an interface to Microsoft Azure Files
 package azurefiles

backend/cache/cache_unsupported.go

@@ -3,4 +3,5 @@
 
 //go:build plan9 || js
 
+// Package cache implements a virtual provider to cache existing remotes.
 package cache

backend/cache/utils_test.go

@@ -1,3 +1,6 @@
+//go:build !plan9 && !js
+// +build !plan9,!js
+
 package cache
 
 import bolt "go.etcd.io/bbolt"

backend/hdfs/hdfs_unsupported.go

@@ -3,4 +3,5 @@
 
 //go:build plan9
 
+// Package hdfs provides an interface to the HDFS storage system.
 package hdfs

backend/local/about_unix.go

@@ -23,9 +23,9 @@ func (f *Fs) About(ctx context.Context) (*fs.Usage, error) {
 	}
 	bs := int64(s.Bsize) // nolint: unconvert
 	usage := &fs.Usage{
-		Total: fs.NewUsageValue(bs * int64(s.Blocks)),         // quota of bytes that can be used
-		Used:  fs.NewUsageValue(bs * int64(s.Blocks-s.Bfree)), // bytes in use
-		Free:  fs.NewUsageValue(bs * int64(s.Bavail)),         // bytes which can be uploaded before reaching the quota
+		Total: fs.NewUsageValue(bs * int64(s.Blocks)),         //nolint: unconvert // quota of bytes that can be used
+		Used:  fs.NewUsageValue(bs * int64(s.Blocks-s.Bfree)), //nolint: unconvert // bytes in use
+		Free:  fs.NewUsageValue(bs * int64(s.Bavail)),         //nolint: unconvert // bytes which can be uploaded before reaching the quota
 	}
 	return usage, nil
 }

backend/local/metadata_other.go

@@ -1,4 +1,4 @@
-//go:build plan9 || js
+//go:build dragonfly || plan9 || js
 
 package local
 

backend/local/xattr_unsupported.go

@@ -1,6 +1,7 @@
+// The pkg/xattr module doesn't compile for openbsd or plan9
+
 //go:build openbsd || plan9
 
-// The pkg/xattr module doesn't compile for openbsd or plan9
 package local
 
 import "github.com/rclone/rclone/fs"

backend/oracleobjectstorage/oracleobjectstorage_unsupported.go

@@ -3,4 +3,5 @@
 
 //go:build plan9 || solaris || js
 
+// Package oracleobjectstorage provides an interface to the OCI object storage system.
 package oracleobjectstorage

backend/qingstor/qingstor_unsupported.go

@@ -3,4 +3,6 @@
 
 //go:build plan9 || js
 
+// Package qingstor provides an interface to QingStor object storage
+// Home: https://www.qingcloud.com/
 package qingstor

backend/sftp/sftp_unsupported.go

@@ -3,4 +3,5 @@
 
 //go:build plan9
 
+// Package sftp provides a filesystem interface using github.com/pkg/sftp
 package sftp

backend/storj/storj_unsupported.go

@@ -1,3 +1,4 @@
 //go:build plan9
 
+// Package storj provides an interface to Storj decentralized object storage.
 package storj

cmd/cachestats/cachestats_unsupported.go

@@ -3,4 +3,5 @@
 
 //go:build plan9 || js
 
+// Package cachestats provides the cachestats command.
 package cachestats

cmd/ncdu/ncdu_unsupported.go

@@ -3,4 +3,5 @@
 
 //go:build plan9 || js
 
+// Package ncdu implements a text based user interface for exploring a remote
 package ncdu

cmd/serve/ftp/ftp_unsupported.go

@@ -3,9 +3,10 @@
 
 //go:build plan9
 
+// Package ftp implements an FTP server for rclone
 package ftp
 
 import "github.com/spf13/cobra"
 
 // Command definition is nil to show not implemented
-var Command *cobra.Command = nil
+var Command *cobra.Command

cmd/serve/sftp/sftp_unsupported.go

@@ -3,9 +3,10 @@
 
 //go:build plan9
 
+// Package sftp implements an SFTP server to serve an rclone VFS
 package sftp
 
 import "github.com/spf13/cobra"
 
 // Command definition is nil to show not implemented
-var Command *cobra.Command = nil
+var Command *cobra.Command

fs/fserrors/enospc_error_notsupported.go

@@ -2,7 +2,7 @@
 
 package fserrors
 
-// IsErrNoSpace() on plan9 returns false because
+// IsErrNoSpace on plan9 returns false because
 // plan9 does not support syscall.ENOSPC error.
 func IsErrNoSpace(cause error) (isNoSpc bool) {
 	isNoSpc = false

fs/fserrors/error_syscall_test.go

@@ -0,0 +1,74 @@
+//go:build !plan9
+// +build !plan9
+
+package fserrors
+
+import (
+	"fmt"
+	"net"
+	"net/url"
+	"os"
+	"syscall"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+// make a plausible network error with the underlying errno
+func makeNetErr(errno syscall.Errno) error {
+	return &net.OpError{
+		Op:     "write",
+		Net:    "tcp",
+		Source: &net.TCPAddr{IP: net.ParseIP("127.0.0.1"), Port: 123},
+		Addr:   &net.TCPAddr{IP: net.ParseIP("127.0.0.1"), Port: 8080},
+		Err: &os.SyscallError{
+			Syscall: "write",
+			Err:     errno,
+		},
+	}
+}
+
+func TestWithSyscallCause(t *testing.T) {
+	for i, test := range []struct {
+		err           error
+		wantRetriable bool
+		wantErr       error
+	}{
+		{makeNetErr(syscall.EAGAIN), true, syscall.EAGAIN},
+		{makeNetErr(syscall.Errno(123123123)), false, syscall.Errno(123123123)},
+	} {
+		gotRetriable, gotErr := Cause(test.err)
+		what := fmt.Sprintf("test #%d: %v", i, test.err)
+		assert.Equal(t, test.wantErr, gotErr, what)
+		assert.Equal(t, test.wantRetriable, gotRetriable, what)
+	}
+}
+
+func TestWithSyscallShouldRetry(t *testing.T) {
+	for i, test := range []struct {
+		err  error
+		want bool
+	}{
+		{makeNetErr(syscall.EAGAIN), true},
+		{makeNetErr(syscall.Errno(123123123)), false},
+		{
+			wrap(&url.Error{
+				Op:  "post",
+				URL: "http://localhost/",
+				Err: makeNetErr(syscall.EPIPE),
+			}, "potato error"),
+			true,
+		},
+		{
+			wrap(&url.Error{
+				Op:  "post",
+				URL: "http://localhost/",
+				Err: makeNetErr(syscall.Errno(123123123)),
+			}, "listing error"),
+			false,
+		},
+	} {
+		got := ShouldRetry(test.err)
+		assert.Equal(t, test.want, got, fmt.Sprintf("test #%d: %v", i, test.err))
+	}
+}

fs/fserrors/error_test.go

@@ -5,10 +5,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"net"
 	"net/url"
-	"os"
-	"syscall"
 	"testing"
 	"time"
 
@@ -41,20 +38,6 @@ func wrap(err error, message string) error {
 
 var errUseOfClosedNetworkConnection = errors.New("use of closed network connection")
 
-// make a plausible network error with the underlying errno
-func makeNetErr(errno syscall.Errno) error {
-	return &net.OpError{
-		Op:     "write",
-		Net:    "tcp",
-		Source: &net.TCPAddr{IP: net.ParseIP("127.0.0.1"), Port: 123},
-		Addr:   &net.TCPAddr{IP: net.ParseIP("127.0.0.1"), Port: 8080},
-		Err: &os.SyscallError{
-			Syscall: "write",
-			Err:     errno,
-		},
-	}
-}
-
 type myError1 struct {
 	Err error
 }
@@ -121,8 +104,6 @@ func TestCause(t *testing.T) {
 		{fmt.Errorf("potato: %w", errPotato), false, errPotato},
 		{fmt.Errorf("potato2: %w", wrap(errPotato, "potato")), false, errPotato},
 		{errUseOfClosedNetworkConnection, false, errUseOfClosedNetworkConnection},
-		{makeNetErr(syscall.EAGAIN), true, syscall.EAGAIN},
-		{makeNetErr(syscall.Errno(123123123)), false, syscall.Errno(123123123)},
 		{eNil1, false, eNil1},
 		{eNil2, false, eNil2.Err},
 		{myError1{io.EOF}, false, io.EOF},
@@ -151,27 +132,9 @@ func TestShouldRetry(t *testing.T) {
 		{fmt.Errorf("connection: %w", errUseOfClosedNetworkConnection), true},
 		{io.EOF, true},
 		{io.ErrUnexpectedEOF, true},
-		{makeNetErr(syscall.EAGAIN), true},
-		{makeNetErr(syscall.Errno(123123123)), false},
 		{&url.Error{Op: "post", URL: "/", Err: io.EOF}, true},
 		{&url.Error{Op: "post", URL: "/", Err: errUseOfClosedNetworkConnection}, true},
 		{&url.Error{Op: "post", URL: "/", Err: fmt.Errorf("net/http: HTTP/1.x transport connection broken: %v", fmt.Errorf("http: ContentLength=%d with Body length %d", 100663336, 99590598))}, true},
-		{
-			wrap(&url.Error{
-				Op:  "post",
-				URL: "http://localhost/",
-				Err: makeNetErr(syscall.EPIPE),
-			}, "potato error"),
-			true,
-		},
-		{
-			wrap(&url.Error{
-				Op:  "post",
-				URL: "http://localhost/",
-				Err: makeNetErr(syscall.Errno(123123123)),
-			}, "listing error"),
-			false,
-		},
 	} {
 		got := ShouldRetry(test.err)
 		assert.Equal(t, test.want, got, fmt.Sprintf("test #%d: %v", i, test.err))

fs/logger/logger_test.go

@@ -1,3 +1,6 @@
+//go:build !plan9
+// +build !plan9
+
 package logger_test
 
 import (

lib/kv/unsupported.go

@@ -1,5 +1,6 @@
 //go:build plan9 || js
 
+// Package kv provides key/value database.
 package kv
 
 import (

vfs/vfstest/write_other.go

@@ -0,0 +1,20 @@
+//go:build !linux && !darwin && !freebsd && !windows
+// +build !linux,!darwin,!freebsd,!windows
+
+package vfstest
+
+import (
+	"errors"
+	"runtime"
+	"testing"
+)
+
+// TestWriteFileDoubleClose tests double close on write
+func TestWriteFileDoubleClose(t *testing.T) {
+	t.Skip("not supported on " + runtime.GOOS)
+}
+
+// writeTestDup performs the platform-specific implementation of the dup() unix
+func writeTestDup(oldfd uintptr) (uintptr, error) {
+	return 0, errors.New("not supported on " + runtime.GOOS)
+}

vfs/vfstest/write_windows.go

@@ -1,4 +1,4 @@
-//go:build !linux && !darwin && !freebsd
+//go:build windows
 
 package vfstest