Code cleanup and simplification

- Print in human-readable not amazon format
   - Send stat() before accessing object, error gracefully
   - Move client and bucket API operations to their own files
   - Remove unused functions, constants and variables
   - Rename API operations to sensible names
        * GetBucket --> ListObjects
        * Buckets --> ListBuckets

pkg/s3/auth.go

@@ -48,7 +48,6 @@ import (
 	"io"
 	"io/ioutil"
 	"net"
-	//"log"
 	"net/http"
 	"net/url"
 	"sort"

pkg/s3/bucket.go

@@ -0,0 +1,175 @@
+package s3
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"sort"
+	"strings"
+	"time"
+
+	"encoding/xml"
+	"io/ioutil"
+	"net/http"
+	"net/url"
+)
+
+// bySize implements sort.Interface for []Item based on the Size field.
+type bySize []*Item
+
+func (a bySize) Len() int           { return len(a) }
+func (a bySize) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
+func (a bySize) Less(i, j int) bool { return a[i].Size < a[j].Size }
+
+/// Bucket API operations
+
+// ListBuckets - Get list of buckets
+func (c *Client) ListBuckets() ([]*Bucket, error) {
+	req := newReq(c.endpoint() + "/")
+	c.Auth.signRequest(req)
+	res, err := c.transport().RoundTrip(req)
+	if err != nil {
+		return nil, err
+	}
+	defer res.Body.Close()
+	if res.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("s3: Unexpected status code %d fetching bucket list", res.StatusCode)
+	}
+	return parseListAllMyBuckets(res.Body)
+}
+
+// PutBucket - create new bucket
+func (c *Client) PutBucket(bucket string) error {
+	var url string
+	if IsValidBucket(bucket) && !strings.Contains(bucket, ".") {
+		url = fmt.Sprintf("%s/%s", c.endpoint(), bucket)
+	}
+	req := newReq(url)
+	req.Method = "PUT"
+	c.Auth.signRequest(req)
+	res, err := c.transport().RoundTrip(req)
+	if err != nil {
+		return err
+	}
+
+	if res != nil && res.Body != nil {
+		defer res.Body.Close()
+	}
+
+	if res.StatusCode != http.StatusOK {
+		return fmt.Errorf("Got response code %d from s3", res.StatusCode)
+	}
+	return nil
+
+}
+
+// ListObjects returns 0 to maxKeys (inclusive) items from the
+// provided bucket. Keys before startAt will be skipped. (This is the S3
+// 'marker' value). If the length of the returned items is equal to
+// maxKeys, there is no indication whether or not the returned list is truncated.
+func (c *Client) ListObjects(bucket string, startAt, prefix, delimiter string, maxKeys int) (items []*Item, prefixes []*Prefix, err error) {
+	var urlReq string
+	var buffer bytes.Buffer
+
+	if maxKeys <= 0 {
+		return nil, nil, fmt.Errorf("negative maxKeys are invalid")
+	}
+
+	marker := startAt
+	for len(items) < maxKeys {
+		fetchN := maxKeys - len(items)
+		if fetchN > MaxKeys {
+			fetchN = MaxKeys
+		}
+		var bres listBucketResults
+		buffer.WriteString(fmt.Sprintf("%s?max-keys=%d", c.bucketURL(bucket), fetchN))
+		switch true {
+		case marker != "":
+			buffer.WriteString(fmt.Sprintf("&marker=%s", url.QueryEscape(marker)))
+			fallthrough
+		case prefix != "":
+			buffer.WriteString(fmt.Sprintf("&prefix=%s", url.QueryEscape(prefix)))
+			fallthrough
+		case delimiter != "":
+			buffer.WriteString(fmt.Sprintf("&delimiter=%s", url.QueryEscape(delimiter)))
+		}
+
+		urlReq = buffer.String()
+		// Try the enumerate three times, since Amazon likes to close
+		// https connections a lot, and Go sucks at dealing with it:
+		// https://code.google.com/p/go/issues/detail?id=3514
+		const maxTries = 5
+		for try := 1; try <= maxTries; try++ {
+			time.Sleep(time.Duration(try-1) * 100 * time.Millisecond)
+			req := newReq(urlReq)
+			c.Auth.signRequest(req)
+			res, err := c.transport().RoundTrip(req)
+			if err != nil {
+				if try < maxTries {
+					continue
+				}
+				return nil, nil, err
+			}
+			if res.StatusCode != http.StatusOK {
+				if res.StatusCode < 500 {
+					body, _ := ioutil.ReadAll(io.LimitReader(res.Body, 1<<20))
+					aerr := &Error{
+						Op:     "ListBucket",
+						Code:   res.StatusCode,
+						Body:   body,
+						Header: res.Header,
+					}
+					aerr.parseXML()
+					res.Body.Close()
+					return nil, nil, aerr
+				}
+			} else {
+				bres = listBucketResults{}
+				var logbuf bytes.Buffer
+				err = xml.NewDecoder(io.TeeReader(res.Body, &logbuf)).Decode(&bres)
+				if err != nil {
+					fmt.Printf("Error parsing s3 XML response: %v for %q", err, logbuf.Bytes())
+				} else if bres.MaxKeys != fetchN || bres.Name != bucket || bres.Marker != marker {
+					err = fmt.Errorf("Unexpected parse from server: %#v from: %s", bres, logbuf.Bytes())
+					fmt.Print(err)
+				}
+			}
+			res.Body.Close()
+			if err != nil {
+				if try < maxTries-1 {
+					continue
+				}
+				fmt.Print(err)
+				return nil, nil, err
+			}
+			break
+		}
+		for _, it := range bres.Contents {
+			if it.Key == marker && it.Key != startAt {
+				// Skip first dup on pages 2 and higher.
+				continue
+			}
+			if it.Key < startAt {
+				return nil, nil, fmt.Errorf("Unexpected response from Amazon: item key %q but wanted greater than %q", it.Key, startAt)
+			}
+			items = append(items, it)
+			marker = it.Key
+		}
+
+		for _, pre := range bres.CommonPrefixes {
+			if pre.Prefix != "" {
+				prefixes = append(prefixes, pre)
+			}
+		}
+
+		if !bres.IsTruncated {
+			break
+		}
+
+		if len(items) == 0 {
+			return nil, nil, fmt.Errorf("No items replied")
+		}
+	}
+	sort.Sort(bySize(items))
+	return items, prefixes, nil
+}

pkg/s3/client.go

@@ -40,35 +40,64 @@ limitations under the License.
 package s3
 
 import (
-	"bytes"
-	"crypto/md5"
-	"encoding/base64"
-	"encoding/hex"
-	"encoding/xml"
-	"errors"
 	"fmt"
 	"io"
-	"io/ioutil"
-	"log"
 	"net"
 	"net/http"
-	"net/url"
-	"os"
 	"regexp"
-	"strconv"
 	"strings"
 	"time"
+
+	"encoding/xml"
 )
 
-const xmlTimeFormat = "2006-01-02T15:04:05.000Z"
+// Date format
+const (
+	xmlTimeFormat = "2006-01-02T15:04:05.000Z"
+)
+
+// Total max object list
+const (
+	MaxKeys = 1000
+)
 
 type xmlTime struct {
 	time.Time
 }
 
-func parseTime(t string) time.Time {
-	ti, _ := time.Parse(xmlTimeFormat, t)
-	return ti
+// Client is an Amazon S3 client.
+type Client struct {
+	*Auth
+	Transport http.RoundTripper // or nil for the default
+}
+
+// Bucket - carries s3 bucket reply header
+type Bucket struct {
+	Name         string
+	CreationDate xmlTime // 2006-02-03T16:45:09.000Z
+}
+
+// Item - object item list
+type Item struct {
+	Key          string
+	LastModified xmlTime
+	Size         int64
+}
+
+// Prefix - common prefix
+type Prefix struct {
+	Prefix string
+}
+
+type listBucketResults struct {
+	Contents       []*Item
+	IsTruncated    bool
+	MaxKeys        int
+	Name           string // bucket name
+	Marker         string
+	Delimiter      string
+	Prefix         string
+	CommonPrefixes []*Prefix
 }
 
 func (c *xmlTime) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
@@ -85,21 +114,8 @@ func (c *xmlTime) UnmarshalXMLAttr(attr xml.Attr) error {
 	return nil
 }
 
-// Total max object list
-const (
-	MaxKeys = 1000
-)
-
-// Client is an Amazon S3 client.
-type Client struct {
-	*Auth
-	Transport http.RoundTripper // or nil for the default
-}
-
-// Bucket - carries s3 bucket reply header
-type Bucket struct {
-	Name         string
-	CreationDate xmlTime
+func (c *xmlTime) format() string {
+	return c.Time.Format(xmlTimeFormat)
 }
 
 func (c *Client) transport() http.RoundTripper {
@@ -170,355 +186,6 @@ func parseListAllMyBuckets(r io.Reader) ([]*Bucket, error) {
 	return res.Buckets.Bucket, nil
 }
 
-/// Object API operations
-
-// Buckets - Get list of buckets
-func (c *Client) Buckets() ([]*Bucket, error) {
-	req := newReq(c.endpoint() + "/")
-	c.Auth.signRequest(req)
-	res, err := c.transport().RoundTrip(req)
-	if err != nil {
-		return nil, err
-	}
-	defer res.Body.Close()
-	if res.StatusCode != http.StatusOK {
-		return nil, fmt.Errorf("s3: Unexpected status code %d fetching bucket list", res.StatusCode)
-	}
-	return parseListAllMyBuckets(res.Body)
-}
-
-// Stat - returns 0, "", os.ErrNotExist if not on S3
-func (c *Client) Stat(key, bucket string) (size int64, date time.Time, reterr error) {
-	req := newReq(c.keyURL(bucket, key))
-	req.Method = "HEAD"
-	c.Auth.signRequest(req)
-	res, err := c.transport().RoundTrip(req)
-	if res != nil && res.Body != nil {
-		defer res.Body.Close()
-	}
-	if err != nil {
-		return 0, date, err
-	}
-
-	switch res.StatusCode {
-	case http.StatusNotFound:
-		return 0, date, os.ErrNotExist
-	case http.StatusOK:
-		size, err = strconv.ParseInt(res.Header.Get("Content-Length"), 10, 64)
-		if err != nil {
-			return 0, date, err
-		}
-		if dateStr := res.Header.Get("Last-Modified"); dateStr != "" {
-			// AWS S3 uses RFC1123 standard for Date in HTTP header, unlike XML content
-			date, err := time.Parse(time.RFC1123, dateStr)
-			if err != nil {
-				return 0, date, err
-			}
-			return size, date, nil
-		}
-	default:
-		return 0, date, fmt.Errorf("s3: Unexpected status code %d statting object %v", res.StatusCode, key)
-	}
-	return
-}
-
-// PutBucket - create new bucket
-func (c *Client) PutBucket(bucket string) error {
-	var url string
-	if IsValidBucket(bucket) && !strings.Contains(bucket, ".") {
-		url = fmt.Sprintf("%s/%s", c.endpoint(), bucket)
-	}
-	req := newReq(url)
-	req.Method = "PUT"
-	c.Auth.signRequest(req)
-	res, err := c.transport().RoundTrip(req)
-	if err != nil {
-		return err
-	}
-
-	if res != nil && res.Body != nil {
-		defer res.Body.Close()
-	}
-
-	if res.StatusCode != http.StatusOK {
-		return fmt.Errorf("Got response code %d from s3", res.StatusCode)
-	}
-	return nil
-
-}
-
-// Put - upload new object to bucket
-func (c *Client) Put(bucket, key string, size int64, contents io.Reader) error {
-	req := newReq(c.keyURL(bucket, key))
-	req.Method = "PUT"
-	req.ContentLength = size
-
-	h := md5.New()
-	// Memory where data is present
-	sink := new(bytes.Buffer)
-	mw := io.MultiWriter(h, sink)
-	written, err := io.Copy(mw, contents)
-	if written != size {
-		return fmt.Errorf("Data read mismatch")
-	}
-	if err != nil {
-		return err
-	}
-	req.Body = ioutil.NopCloser(sink)
-	b64 := base64.StdEncoding.EncodeToString(h.Sum(nil))
-	req.Header.Set("Content-MD5", b64)
-	c.Auth.signRequest(req)
-
-	res, err := c.transport().RoundTrip(req)
-	if res != nil && res.Body != nil {
-		defer res.Body.Close()
-	}
-
-	if err != nil {
-		return err
-	}
-	if res.StatusCode != http.StatusOK {
-		// res.Write(os.Stderr)
-		return fmt.Errorf("Got response code %d from s3", res.StatusCode)
-	}
-	return nil
-}
-
-// Item - object item list
-type Item struct {
-	Key          string
-	LastModified xmlTime
-	Size         int64
-}
-
-// Prefix - common prefix
-type Prefix struct {
-	Prefix string
-}
-
-// BySize implements sort.Interface for []Item based on
-// the Size field.
-type BySize []*Item
-
-func (a BySize) Len() int           { return len(a) }
-func (a BySize) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
-func (a BySize) Less(i, j int) bool { return a[i].Size < a[j].Size }
-
-type listBucketResults struct {
-	Contents       []*Item
-	IsTruncated    bool
-	MaxKeys        int
-	Name           string // bucket name
-	Marker         string
-	Delimiter      string
-	Prefix         string
-	CommonPrefixes []*Prefix
-}
-
-// BucketLocation - returns the S3 endpoint to be used with the given bucket.
-func (c *Client) BucketLocation(bucket string) (location string, err error) {
-	if !strings.HasSuffix(c.endpoint(), "amazonaws.com") {
-		return "", errors.New("BucketLocation not implemented for non-Amazon S3 endpoints")
-	}
-	urlReq := fmt.Sprintf("%s/%s/?location", c.endpoint(), url.QueryEscape(bucket))
-	req := newReq(urlReq)
-	c.Auth.signRequest(req)
-	res, err := c.transport().RoundTrip(req)
-	if err != nil {
-		return
-	}
-	var xres xmlLocationConstraint
-	if err := xml.NewDecoder(res.Body).Decode(&xres); err != nil {
-		return "", err
-	}
-	if xres.Location == "" {
-		return strings.TrimPrefix(c.endpoint(), "https://"), nil
-	}
-	return "s3-" + xres.Location + ".amazonaws.com", nil
-}
-
-// GetBucket (List Objects) returns 0 to maxKeys (inclusive) items from the
-// provided bucket. Keys before startAt will be skipped. (This is the S3
-// 'marker' value). If the length of the returned items is equal to
-// maxKeys, there is no indication whether or not the returned list is truncated.
-func (c *Client) GetBucket(bucket string, startAt, prefix, delimiter string, maxKeys int) (items []*Item, prefixes []*Prefix, err error) {
-	var urlReq string
-	var buffer bytes.Buffer
-
-	if maxKeys <= 0 {
-		return nil, nil, errors.New("negative maxKeys are invalid")
-	}
-
-	marker := startAt
-	for len(items) < maxKeys {
-		fetchN := maxKeys - len(items)
-		if fetchN > MaxKeys {
-			fetchN = MaxKeys
-		}
-		var bres listBucketResults
-		buffer.WriteString(fmt.Sprintf("%s?max-keys=%d", c.bucketURL(bucket), fetchN))
-		switch true {
-		case marker != "":
-			buffer.WriteString(fmt.Sprintf("&marker=%s", url.QueryEscape(marker)))
-			fallthrough
-		case prefix != "":
-			buffer.WriteString(fmt.Sprintf("&prefix=%s", url.QueryEscape(prefix)))
-			fallthrough
-		case delimiter != "":
-			buffer.WriteString(fmt.Sprintf("&delimiter=%s", url.QueryEscape(delimiter)))
-		}
-
-		urlReq = buffer.String()
-		// Try the enumerate three times, since Amazon likes to close
-		// https connections a lot, and Go sucks at dealing with it:
-		// https://code.google.com/p/go/issues/detail?id=3514
-		const maxTries = 5
-		for try := 1; try <= maxTries; try++ {
-			time.Sleep(time.Duration(try-1) * 100 * time.Millisecond)
-			req := newReq(urlReq)
-			c.Auth.signRequest(req)
-			res, err := c.transport().RoundTrip(req)
-			if err != nil {
-				if try < maxTries {
-					continue
-				}
-				return nil, nil, err
-			}
-			if res.StatusCode != http.StatusOK {
-				if res.StatusCode < 500 {
-					body, _ := ioutil.ReadAll(io.LimitReader(res.Body, 1<<20))
-					aerr := &Error{
-						Op:     "ListBucket",
-						Code:   res.StatusCode,
-						Body:   body,
-						Header: res.Header,
-					}
-					aerr.parseXML()
-					res.Body.Close()
-					return nil, nil, aerr
-				}
-			} else {
-				bres = listBucketResults{}
-				var logbuf bytes.Buffer
-				err = xml.NewDecoder(io.TeeReader(res.Body, &logbuf)).Decode(&bres)
-				if err != nil {
-					log.Printf("Error parsing s3 XML response: %v for %q", err, logbuf.Bytes())
-				} else if bres.MaxKeys != fetchN || bres.Name != bucket || bres.Marker != marker {
-					err = fmt.Errorf("Unexpected parse from server: %#v from: %s", bres, logbuf.Bytes())
-					log.Print(err)
-				}
-			}
-			res.Body.Close()
-			if err != nil {
-				if try < maxTries-1 {
-					continue
-				}
-				log.Print(err)
-				return nil, nil, err
-			}
-			break
-		}
-		for _, it := range bres.Contents {
-			if it.Key == marker && it.Key != startAt {
-				// Skip first dup on pages 2 and higher.
-				continue
-			}
-			if it.Key < startAt {
-				return nil, nil, fmt.Errorf("Unexpected response from Amazon: item key %q but wanted greater than %q", it.Key, startAt)
-			}
-			items = append(items, it)
-			marker = it.Key
-		}
-
-		for _, pre := range bres.CommonPrefixes {
-			if pre.Prefix != "" {
-				prefixes = append(prefixes, pre)
-			}
-		}
-
-		if !bres.IsTruncated {
-			break
-		}
-
-		if len(items) == 0 {
-			return nil, nil, errors.New("No items replied")
-		}
-	}
-	return items, prefixes, nil
-}
-
-// Get - download a requested object from a given bucket
-func (c *Client) Get(bucket, key string) (body io.ReadCloser, size int64, err error) {
-	req := newReq(c.keyURL(bucket, key))
-	c.Auth.signRequest(req)
-	res, err := c.transport().RoundTrip(req)
-	if err != nil {
-		return
-	}
-	switch res.StatusCode {
-	case http.StatusOK:
-		return res.Body, res.ContentLength, nil
-	case http.StatusNotFound:
-		res.Body.Close()
-		return nil, 0, os.ErrNotExist
-	default:
-		res.Body.Close()
-		return nil, 0, fmt.Errorf("Amazon HTTP error on GET: %d", res.StatusCode)
-	}
-}
-
-// GetPartial fetches part of the s3 key object in bucket.
-// If length is negative, the rest of the object is returned.
-// The caller must close rc.
-func (c *Client) GetPartial(bucket, key string, offset, length int64) (rc io.ReadCloser, err error) {
-	if offset < 0 {
-		return nil, errors.New("invalid negative length")
-	}
-
-	req := newReq(c.keyURL(bucket, key))
-	if length >= 0 {
-		req.Header.Set("Range", fmt.Sprintf("bytes=%d-%d", offset, offset+length-1))
-	} else {
-		req.Header.Set("Range", fmt.Sprintf("bytes=%d-", offset))
-	}
-	c.Auth.signRequest(req)
-
-	res, err := c.transport().RoundTrip(req)
-	if err != nil {
-		return
-	}
-	switch res.StatusCode {
-	case http.StatusOK, http.StatusPartialContent:
-		return res.Body, nil
-	case http.StatusNotFound:
-		res.Body.Close()
-		return nil, os.ErrNotExist
-	default:
-		res.Body.Close()
-		return nil, fmt.Errorf("Amazon HTTP error on GET: %d", res.StatusCode)
-	}
-}
-
-/* Not supporting Delete's
-func (c *Client) Delete(bucket, key string) error {
-	req := newReq(c.keyURL(bucket, key))
-	req.Method = "DELETE"
-	c.Auth.signRequest(req)
-	res, err := c.transport().RoundTrip(req)
-	if err != nil {
-		return err
-	}
-	if res != nil && res.Body != nil {
-		defer res.Body.Close()
-	}
-	if res.StatusCode == http.StatusNotFound || res.StatusCode == http.StatusNoContent ||
-		res.StatusCode == http.StatusOK {
-		return nil
-	}
-	return fmt.Errorf("Amazon HTTP error on DELETE: %d", res.StatusCode)
-}
-*/
-
 // NewClient - get new client
 func NewClient(auth *Auth) (client *Client) {
 	client = &Client{auth, http.DefaultTransport}
@@ -541,54 +208,3 @@ func IsValidBucket(bucket string) bool {
 	match, _ := regexp.MatchString("^[a-zA-Z][a-zA-Z0-9\\-]+[a-zA-Z0-9]$", bucket)
 	return match
 }
-
-// Error is the type returned by some API operations.
-type Error struct {
-	Op     string
-	Code   int         // HTTP status code
-	Body   []byte      // response body
-	Header http.Header // response headers
-
-	// UsedEndpoint and AmazonCode are the XML response's Endpoint and
-	// Code fields, respectively.
-	UseEndpoint string // if a temporary redirect (wrong endpoint)
-	AmazonCode  string
-}
-
-func (e *Error) Error() string {
-	if bytes.Contains(e.Body, []byte("<Error>")) {
-		return fmt.Sprintf("s3.%s: status %d: %s", e.Op, e.Code, e.Body)
-	}
-	return fmt.Sprintf("s3.%s: status %d", e.Op, e.Code)
-}
-
-func (e *Error) parseXML() {
-	var xe xmlError
-	_ = xml.NewDecoder(bytes.NewReader(e.Body)).Decode(&xe)
-	e.AmazonCode = xe.Code
-	if xe.Code == "TemporaryRedirect" {
-		e.UseEndpoint = xe.Endpoint
-	}
-	if xe.Code == "SignatureDoesNotMatch" {
-		want, _ := hex.DecodeString(strings.Replace(xe.StringToSignBytes, " ", "", -1))
-		log.Printf("S3 SignatureDoesNotMatch. StringToSign should be %d bytes: %q (%x)", len(want), want, want)
-	}
-
-}
-
-// xmlError is the Error response from Amazon.
-type xmlError struct {
-	XMLName           xml.Name `xml:"Error"`
-	Code              string
-	Message           string
-	RequestID         string
-	Bucket            string
-	Endpoint          string
-	StringToSignBytes string
-}
-
-// xmlLocationConstraint is the LocationConstraint returned from BucketLocation.
-type xmlLocationConstraint struct {
-	XMLName  xml.Name `xml:"LocationConstraint"`
-	Location string   `xml:",chardata"`
-}

pkg/s3/error.go

@@ -0,0 +1,56 @@
+package s3
+
+import (
+	"bytes"
+	"fmt"
+	"strings"
+
+	"encoding/hex"
+	"encoding/xml"
+	"net/http"
+)
+
+// Error is the type returned by some API operations.
+type Error struct {
+	Op     string
+	Code   int         // HTTP status code
+	Body   []byte      // response body
+	Header http.Header // response headers
+
+	// UsedEndpoint and AmazonCode are the XML response's Endpoint and
+	// Code fields, respectively.
+	UseEndpoint string // if a temporary redirect (wrong endpoint)
+	AmazonCode  string
+}
+
+// xmlError is the Error response from Amazon.
+type xmlError struct {
+	XMLName           xml.Name `xml:"Error"`
+	Code              string
+	Message           string
+	RequestID         string
+	Bucket            string
+	Endpoint          string
+	StringToSignBytes string
+}
+
+func (e *Error) Error() string {
+	if bytes.Contains(e.Body, []byte("<Error>")) {
+		return fmt.Sprintf("s3.%s: status %d: %s", e.Op, e.Code, e.Body)
+	}
+	return fmt.Sprintf("s3.%s: status %d", e.Op, e.Code)
+}
+
+func (e *Error) parseXML() {
+	var xe xmlError
+	_ = xml.NewDecoder(bytes.NewReader(e.Body)).Decode(&xe)
+	e.AmazonCode = xe.Code
+	if xe.Code == "TemporaryRedirect" {
+		e.UseEndpoint = xe.Endpoint
+	}
+	if xe.Code == "SignatureDoesNotMatch" {
+		want, _ := hex.DecodeString(strings.Replace(xe.StringToSignBytes, " ", "", -1))
+		fmt.Printf("S3 SignatureDoesNotMatch. StringToSign should be %d bytes: %q (%x)", len(want), want, want)
+	}
+
+}

pkg/s3/object.go

@@ -0,0 +1,141 @@
+package s3
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"os"
+	"strconv"
+	"time"
+
+	"crypto/md5"
+	"encoding/base64"
+	"io/ioutil"
+	"net/http"
+)
+
+/// Object API operations
+
+// Put - upload new object to bucket
+func (c *Client) Put(bucket, key string, size int64, contents io.Reader) error {
+	req := newReq(c.keyURL(bucket, key))
+	req.Method = "PUT"
+	req.ContentLength = size
+
+	h := md5.New()
+	// Memory where data is present
+	sink := new(bytes.Buffer)
+	mw := io.MultiWriter(h, sink)
+	written, err := io.Copy(mw, contents)
+	if written != size {
+		return fmt.Errorf("Data read mismatch")
+	}
+	if err != nil {
+		return err
+	}
+	req.Body = ioutil.NopCloser(sink)
+	b64 := base64.StdEncoding.EncodeToString(h.Sum(nil))
+	req.Header.Set("Content-MD5", b64)
+	c.Auth.signRequest(req)
+
+	res, err := c.transport().RoundTrip(req)
+	if res != nil && res.Body != nil {
+		defer res.Body.Close()
+	}
+
+	if err != nil {
+		return err
+	}
+	if res.StatusCode != http.StatusOK {
+		// res.Write(os.Stderr)
+		return fmt.Errorf("Got response code %d from s3", res.StatusCode)
+	}
+	return nil
+}
+
+// Stat - returns 0, "", os.ErrNotExist if not on S3
+func (c *Client) Stat(key, bucket string) (size int64, date time.Time, reterr error) {
+	req := newReq(c.keyURL(bucket, key))
+	req.Method = "HEAD"
+	c.Auth.signRequest(req)
+	res, err := c.transport().RoundTrip(req)
+	if res != nil && res.Body != nil {
+		defer res.Body.Close()
+	}
+	if err != nil {
+		return 0, date, err
+	}
+
+	switch res.StatusCode {
+	case http.StatusNotFound:
+		return 0, date, os.ErrNotExist
+	case http.StatusOK:
+		size, err = strconv.ParseInt(res.Header.Get("Content-Length"), 10, 64)
+		if err != nil {
+			return 0, date, err
+		}
+		if dateStr := res.Header.Get("Last-Modified"); dateStr != "" {
+			// AWS S3 uses RFC1123 standard for Date in HTTP header, unlike XML content
+			date, err := time.Parse(time.RFC1123, dateStr)
+			if err != nil {
+				return 0, date, err
+			}
+			return size, date, nil
+		}
+	default:
+		return 0, date, fmt.Errorf("s3: Unexpected status code %d statting object %v", res.StatusCode, key)
+	}
+	return
+}
+
+// Get - download a requested object from a given bucket
+func (c *Client) Get(bucket, key string) (body io.ReadCloser, size int64, err error) {
+	req := newReq(c.keyURL(bucket, key))
+	c.Auth.signRequest(req)
+	res, err := c.transport().RoundTrip(req)
+	if err != nil {
+		return
+	}
+	switch res.StatusCode {
+	case http.StatusOK:
+		return res.Body, res.ContentLength, nil
+	case http.StatusNotFound:
+		res.Body.Close()
+		return nil, 0, os.ErrNotExist
+	default:
+		res.Body.Close()
+		return nil, 0, fmt.Errorf("Amazon HTTP error on GET: %d", res.StatusCode)
+	}
+}
+
+// GetPartial fetches part of the s3 key object in bucket.
+// If length is negative, the rest of the object is returned.
+// The caller must close rc.
+func (c *Client) GetPartial(bucket, key string, offset, length int64) (rc io.ReadCloser, err error) {
+	if offset < 0 {
+		return nil, fmt.Errorf("invalid negative length")
+	}
+
+	req := newReq(c.keyURL(bucket, key))
+	if length >= 0 {
+		req.Header.Set("Range", fmt.Sprintf("bytes=%d-%d", offset, offset+length-1))
+	} else {
+		req.Header.Set("Range", fmt.Sprintf("bytes=%d-", offset))
+	}
+	c.Auth.signRequest(req)
+
+	res, err := c.transport().RoundTrip(req)
+	if err != nil {
+		return
+	}
+	switch res.StatusCode {
+	case http.StatusOK, http.StatusPartialContent:
+		return res.Body, nil
+	case http.StatusNotFound:
+		res.Body.Close()
+		return nil, os.ErrNotExist
+	default:
+		res.Body.Close()
+		return nil, fmt.Errorf("Amazon HTTP error on GET: %d", res.StatusCode)
+	}
+}

s3-errors.go

@@ -18,14 +18,13 @@ package main
 
 import "errors"
 
-// fs
-var errFspath = errors.New("Arguments missing <S3Path> or <LocalPath>")
-var errFskey = errors.New("Key is needed to get the file")
+var (
+	// fs
+	errFskey = errors.New("Key is needed to get the file")
 
-// uri
-var errInvalidScheme = errors.New("Invalid URI scheme only s3:// supported")
+	// uri
+	errInvalidScheme = errors.New("Invalid URI scheme only s3:// supported")
 
-// common
-var errMissingaccess = errors.New("Partial credentials found in the env, missing : AWS_ACCESS_KEY_ID")
-var errMissingsecret = errors.New("Partial credentials found in the env, missing : AWS_SECRET_ACCESS_KEY")
-var errInvalidbucket = errors.New("Invalid bucket name")
+	// common
+	errInvalidbucket = errors.New("Invalid bucket name")
+)

s3-fs-cp.go

@@ -85,6 +85,11 @@ func doFsCopy(c *cli.Context) {
 		var objectReader io.ReadCloser
 		var objectSize int64
 
+		// Send HEAD request to validate if file exists.
+		if _, _, err := s3c.Stat(fsoptions.key, fsoptions.bucket); err != nil {
+			fatal(err.Error())
+		}
+
 		objectReader, objectSize, err = s3c.Get(fsoptions.bucket, fsoptions.key)
 		if err != nil {
 			fatal(err.Error())

s3-fs-ls.go

@@ -19,7 +19,6 @@ package main
 import (
 	"fmt"
 	"os"
-	"sort"
 	"time"
 
 	"github.com/cheggaaa/pb"
@@ -27,16 +26,20 @@ import (
 	"github.com/minio-io/mc/pkg/s3"
 )
 
+const (
+	humanReadableFormat = "2006-01-02 15:04:05"
+)
+
 func printBuckets(v []*s3.Bucket) {
 	for _, b := range v {
-		msg := fmt.Sprintf("%v %13s %s", b.CreationDate.Local(), "", b.Name)
+		msg := fmt.Sprintf("%v %9s %s", b.CreationDate.Format(humanReadableFormat), "", b.Name)
 		info(msg)
 	}
 }
 
 func printObjects(v []*s3.Item) {
 	if len(v) > 0 {
-		sort.Sort(s3.BySize(v))
+		// Items are already sorted
 		for _, b := range v {
 			printObject(b.LastModified.Time, b.Size, b.Key)
 		}
@@ -44,7 +47,7 @@ func printObjects(v []*s3.Item) {
 }
 
 func printObject(date time.Time, v int64, key string) {
-	msg := fmt.Sprintf("%v  %13s %s", date.Local(), pb.FormatBytes(v), key)
+	msg := fmt.Sprintf("%v  %9s %s", date.Format(humanReadableFormat), pb.FormatBytes(v), key)
 	info(msg)
 }
 
@@ -66,13 +69,13 @@ func doFsList(c *cli.Context) {
 	}
 	switch true {
 	case fsoptions.bucket == "": // List all buckets
-		buckets, err := s3c.Buckets()
+		buckets, err := s3c.ListBuckets()
 		if err != nil {
 			fatal(err.Error())
 		}
 		printBuckets(buckets)
-	case fsoptions.key == "": // List the objects in a bucket
-		items, _, err = s3c.GetBucket(fsoptions.bucket, "", "", "", s3.MaxKeys)
+	case fsoptions.key == "": // List objects in a bucket
+		items, _, err = s3c.ListObjects(fsoptions.bucket, "", "", "", s3.MaxKeys)
 		if err != nil {
 			fatal(err.Error())
 		}
@@ -83,11 +86,11 @@ func doFsList(c *cli.Context) {
 
 		size, date, err = s3c.Stat(fsoptions.key, fsoptions.bucket)
 		switch err {
-		case nil: // List a single object. Exact key prefix match
+		case nil: // List a single object. Exact key
 			printObject(date, size, fsoptions.key)
 		case os.ErrNotExist:
 			// List all objects matching the key prefix
-			items, _, err = s3c.GetBucket(fsoptions.bucket, "", fsoptions.key, "", s3.MaxKeys)
+			items, _, err = s3c.ListObjects(fsoptions.bucket, "", fsoptions.key, "", s3.MaxKeys)
 			if err != nil {
 				fatal(err.Error())
 			}