Probe revamped to provide for a new WrappedError struct to wrap probes as error interface

This convenience was necessary to be used for golang library functions like io.Copy and io.Pipe
where we shouldn't be writing proxies and alternatives returning *probe.Error

This change also brings more changes across code base for clear separation regarding where an error
interface should be passed encapsulating *probe.Error and where it should be used as is.

pkg/server/api/logging-handlers.go

@@ -24,7 +24,6 @@ import (
 	"os"
 	"time"
 
-	"github.com/minio/minio/pkg/probe"
 	"github.com/minio/minio/pkg/utils/log"
 )
 
@@ -99,12 +98,12 @@ func fileLogger(filename string) (chan<- []byte, error) {
 	ch := make(chan []byte)
 	file, err := os.OpenFile(filename, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0600)
 	if err != nil {
-		return nil, probe.New(err)
+		return nil, err
 	}
 	go func() {
 		for message := range ch {
 			if _, err := io.Copy(file, bytes.NewBuffer(message)); err != nil {
-				log.Errorln(probe.New(err))
+				log.Errorln(err)
 			}
 		}
 	}()

pkg/server/api/range.go

@@ -41,7 +41,7 @@ func (r *httpRange) String() string {
 }
 
 // Grab new range from request header
-func getRequestedRange(hrange string, size int64) (*httpRange, error) {
+func getRequestedRange(hrange string, size int64) (*httpRange, *probe.Error) {
 	r := &httpRange{
 		start:  0,
 		length: 0,
@@ -51,16 +51,16 @@ func getRequestedRange(hrange string, size int64) (*httpRange, error) {
 	if hrange != "" {
 		err := r.parseRange(hrange)
 		if err != nil {
-			return nil, probe.New(err)
+			return nil, err.Trace()
 		}
 	}
 	return r, nil
 }
 
-func (r *httpRange) parse(ra string) error {
+func (r *httpRange) parse(ra string) *probe.Error {
 	i := strings.Index(ra, "-")
 	if i < 0 {
-		return probe.New(donut.InvalidRange{})
+		return probe.NewError(donut.InvalidRange{})
 	}
 	start, end := strings.TrimSpace(ra[:i]), strings.TrimSpace(ra[i+1:])
 	if start == "" {
@@ -68,7 +68,7 @@ func (r *httpRange) parse(ra string) error {
 		// range start relative to the end of the file.
 		i, err := strconv.ParseInt(end, 10, 64)
 		if err != nil {
-			return probe.New(donut.InvalidRange{})
+			return probe.NewError(donut.InvalidRange{})
 		}
 		if i > r.size {
 			i = r.size
@@ -78,7 +78,7 @@ func (r *httpRange) parse(ra string) error {
 	} else {
 		i, err := strconv.ParseInt(start, 10, 64)
 		if err != nil || i > r.size || i < 0 {
-			return probe.New(donut.InvalidRange{})
+			return probe.NewError(donut.InvalidRange{})
 		}
 		r.start = i
 		if end == "" {
@@ -87,7 +87,7 @@ func (r *httpRange) parse(ra string) error {
 		} else {
 			i, err := strconv.ParseInt(end, 10, 64)
 			if err != nil || r.start > i {
-				return probe.New(donut.InvalidRange{})
+				return probe.NewError(donut.InvalidRange{})
 			}
 			if i >= r.size {
 				i = r.size - 1
@@ -99,26 +99,26 @@ func (r *httpRange) parse(ra string) error {
 }
 
 // parseRange parses a Range header string as per RFC 2616.
-func (r *httpRange) parseRange(s string) error {
+func (r *httpRange) parseRange(s string) *probe.Error {
 	if s == "" {
-		return probe.New(errors.New("header not present"))
+		return probe.NewError(errors.New("header not present"))
 	}
 	if !strings.HasPrefix(s, b) {
-		return probe.New(donut.InvalidRange{})
+		return probe.NewError(donut.InvalidRange{})
 	}
 
 	ras := strings.Split(s[len(b):], ",")
 	if len(ras) == 0 {
-		return probe.New(errors.New("invalid request"))
+		return probe.NewError(errors.New("invalid request"))
 	}
 	// Just pick the first one and ignore the rest, we only support one range per object
 	if len(ras) > 1 {
-		return probe.New(errors.New("multiple ranges specified"))
+		return probe.NewError(errors.New("multiple ranges specified"))
 	}
 
 	ra := strings.TrimSpace(ras[0])
 	if ra == "" {
-		return probe.New(donut.InvalidRange{})
+		return probe.NewError(donut.InvalidRange{})
 	}
 	return r.parse(ra)
 }

pkg/server/api/signature.go

@@ -72,7 +72,7 @@ func InitSignatureV4(req *http.Request) (*donut.Signature, *probe.Error) {
 		var err error
 		accessKeyID, err = StripAccessKeyID(ah)
 		if err != nil {
-			return nil, probe.New(err)
+			return nil, probe.NewError(err)
 		}
 	}
 	authConfig, err := auth.LoadConfig()
@@ -80,7 +80,7 @@ func InitSignatureV4(req *http.Request) (*donut.Signature, *probe.Error) {
 		return nil, err.Trace()
 	}
 	if _, ok := authConfig.Users[accessKeyID]; !ok {
-		return nil, probe.New(errors.New("AccessID not found"))
+		return nil, probe.NewError(errors.New("AccessID not found"))
 	}
 	signature := &donut.Signature{
 		AccessKeyID:     authConfig.Users[accessKeyID].AccessKeyID,