enable full linter across the codebase (#9620)

enable linter using golangci-lint across
codebase to run a bunch of linters together,
we shall enable new linters as we fix more
things the codebase.

This PR fixes the first stage of this
cleanup.

pkg/bucket/lifecycle/filter.go

@@ -84,8 +84,3 @@ func (f Filter) Validate() error {
 	}
 	return nil
 }
-
-// isEmpty - returns true if Filter tag is empty
-func (f Filter) isEmpty() bool {
-	return f.And.isEmpty() && f.Prefix == "" && f.Tag.IsEmpty()
-}

pkg/dsync/drwmutex_test.go

@@ -314,7 +314,7 @@ func benchmarkRWMutex(b *testing.B, localWork, writeRatio int) {
 				rwm.Unlock()
 			} else {
 				rwm.RLock(id, source)
-				for i := 0; i != localWork; i += 1 {
+				for i := 0; i != localWork; i++ {
 					foo *= 2
 					foo /= 2
 				}

pkg/dsync/retry.go

@@ -128,13 +128,6 @@ const (
 	defaultRetryCap  = 1 * time.Second // 1 second.
 )
 
-// newRetryTimer creates a timer with exponentially increasing delays
-// until the maximum retry attempts are reached. - this function provides
-// resulting retry values to be of maximum jitter.
-func newRetryTimer(ctx context.Context, unit time.Duration, cap time.Duration) <-chan int {
-	return newRetryTimerWithJitter(ctx, unit, cap, MaxJitter)
-}
-
 // newRetryTimerSimple creates a timer with exponentially increasing delays
 // until the maximum retry attempts are reached. - this function is a
 // simpler version with all default values.

pkg/event/target/nsq_test.go

@@ -17,8 +17,9 @@
 package target
 
 import (
-	xnet "github.com/minio/minio/pkg/net"
 	"testing"
+
+	xnet "github.com/minio/minio/pkg/net"
 )
 
 func TestNSQArgs_Validate(t *testing.T) {

pkg/iam/policy/admin-action.go

@@ -148,15 +148,6 @@ var supportedAdminActions = map[AdminAction]struct{}{
 	AllAdminActions:                {},
 }
 
-func parseAdminAction(s string) (AdminAction, error) {
-	action := AdminAction(s)
-	if action.IsValid() {
-		return action, nil
-	}
-
-	return action, Errorf("unsupported action '%v'", s)
-}
-
 // IsValid - checks if action is valid or not.
 func (action AdminAction) IsValid() bool {
 	_, ok := supportedAdminActions[action]

pkg/madmin/info-commands.go

@@ -21,7 +21,6 @@ import (
 	"context"
 	"encoding/json"
 	"io/ioutil"
-	"math"
 	"net/http"
 	"time"
 )
@@ -128,23 +127,6 @@ func (adm *AdminClient) StorageInfo(ctx context.Context) (StorageInfo, error) {
 	return storageInfo, nil
 }
 
-type objectHistogramInterval struct {
-	name       string
-	start, end int64
-}
-
-// ObjectsHistogramIntervals contains the list of intervals
-// of an histogram analysis of objects sizes.
-var ObjectsHistogramIntervals = []objectHistogramInterval{
-	{"LESS_THAN_1024_B", -1, 1024 - 1},
-	{"BETWEEN_1024_B_AND_1_MB", 1024, 1024*1024 - 1},
-	{"BETWEEN_1_MB_AND_10_MB", 1024 * 1024, 1024*1024*10 - 1},
-	{"BETWEEN_10_MB_AND_64_MB", 1024 * 1024 * 10, 1024*1024*64 - 1},
-	{"BETWEEN_64_MB_AND_128_MB", 1024 * 1024 * 64, 1024*1024*128 - 1},
-	{"BETWEEN_128_MB_AND_512_MB", 1024 * 1024 * 128, 1024*1024*512 - 1},
-	{"GREATER_THAN_512_MB", 1024 * 1024 * 512, math.MaxInt64},
-}
-
 // DataUsageInfo represents data usage of an Object API
 type DataUsageInfo struct {
 	// LastUpdate is the timestamp of when the data usage info was last updated.

pkg/madmin/retry.go

@@ -20,10 +20,7 @@ package madmin
 import (
 	"context"
 	"math/rand"
-	"net"
 	"net/http"
-	"net/url"
-	"strings"
 	"sync"
 	"time"
 )
@@ -116,37 +113,6 @@ func (adm AdminClient) newRetryTimer(ctx context.Context, maxRetry int, unit tim
 	return attemptCh
 }
 
-// isHTTPReqErrorRetryable - is http requests error retryable, such
-// as i/o timeout, connection broken etc..
-func isHTTPReqErrorRetryable(err error) bool {
-	if err == nil {
-		return false
-	}
-	switch e := err.(type) {
-	case *url.Error:
-		switch e.Err.(type) {
-		case *net.DNSError, *net.OpError, net.UnknownNetworkError:
-			return true
-		}
-		if strings.Contains(err.Error(), "Connection closed by foreign host") {
-			return true
-		} else if strings.Contains(err.Error(), "net/http: TLS handshake timeout") {
-			// If error is - tlsHandshakeTimeoutError, retry.
-			return true
-		} else if strings.Contains(err.Error(), "i/o timeout") {
-			// If error is - tcp timeoutError, retry.
-			return true
-		} else if strings.Contains(err.Error(), "connection timed out") {
-			// If err is a net.Dial timeout, retry.
-			return true
-		} else if strings.Contains(err.Error(), "net/http: HTTP/1.x transport connection broken") {
-			// If error is transport connection broken, retry.
-			return true
-		}
-	}
-	return false
-}
-
 // List of AWS S3 error codes which are retryable.
 var retryableS3Codes = map[string]struct{}{
 	"RequestError":         {},

pkg/s3select/csv/args.go

@@ -26,9 +26,8 @@ import (
 )
 
 const (
-	none   = "none"
-	use    = "use"
-	ignore = "ignore"
+	none = "none"
+	use  = "use"
 
 	defaultRecordDelimiter      = "\n"
 	defaultFieldDelimiter       = ","
@@ -36,7 +35,6 @@ const (
 	defaultQuoteEscapeCharacter = `"`
 	defaultCommentCharacter     = "#"
 
-	always   = "always"
 	asneeded = "asneeded"
 )
 

pkg/s3select/csv/errors.go

@@ -43,24 +43,6 @@ func (err *s3Error) Error() string {
 	return err.message
 }
 
-func errInvalidFileHeaderInfo(err error) *s3Error {
-	return &s3Error{
-		code:       "InvalidFileHeaderInfo",
-		message:    "The FileHeaderInfo is invalid. Only NONE, USE, and IGNORE are supported.",
-		statusCode: 400,
-		cause:      err,
-	}
-}
-
-func errInvalidQuoteFields(err error) *s3Error {
-	return &s3Error{
-		code:       "InvalidQuoteFields",
-		message:    "The QuoteFields is invalid. Only ALWAYS and ASNEEDED are supported.",
-		statusCode: 400,
-		cause:      err,
-	}
-}
-
 func errCSVParsingError(err error) *s3Error {
 	return &s3Error{
 		code:       "CSVParsingError",

pkg/s3select/select_test.go

@@ -996,7 +996,7 @@ func TestParquetInput(t *testing.T) {
 					offset = fi.Size() + offset
 				}
 
-				if _, err = file.Seek(offset, os.SEEK_SET); err != nil {
+				if _, err = file.Seek(offset, io.SeekStart); err != nil {
 					return nil, err
 				}
 

pkg/s3select/simdj/errors.go

@@ -45,15 +45,6 @@ func (err *s3Error) Error() string {
 	return err.message
 }
 
-func errInvalidJSONType(err error) *s3Error {
-	return &s3Error{
-		code:       "InvalidJsonType",
-		message:    "The JsonType is invalid. Only DOCUMENT and LINES are supported.",
-		statusCode: 400,
-		cause:      err,
-	}
-}
-
 func errJSONParsingError(err error) *s3Error {
 	return &s3Error{
 		code:       "JSONParsingError",

pkg/s3select/sql/value_test.go

@@ -160,9 +160,6 @@ func TestValue_Equals(t *testing.T) {
 }
 
 func TestValue_CSVString(t *testing.T) {
-	type fields struct {
-		value interface{}
-	}
 	type test struct {
 		name    string
 		want    string