Merge pull request #55 from mhoglan/nil-key-request

* mhoglan-nil-key-request:
  add nil path test
  Added guard protections for requests / responses Add guard to handle if nil path is requested Add guard to handle if content-length from response is -1 which represents that the response is chunked transfer encoding or EOF close response
  change naked URL to a link from "IAM role"
  Correct usage of help command.
  Correct version number.
  Handle cases where etag is missing gracefully.

getter.go

@@ -77,6 +77,13 @@ func newGetter(getURL url.URL, c *Config, b *Bucket) (io.ReadCloser, http.Header
 	if resp.StatusCode != 200 {
 		return nil, nil, newRespError(resp)
 	}
+
+	// Golang changes content-length to -1 when chunked transfer encoding / EOF close response detected
+	if resp.ContentLength == -1 {
+		return nil, nil, fmt.Errorf("Retrieving objects with undefined content-length " +
+			" responses (chunked transfer encoding / EOF close) is not supported")
+	}
+
 	g.contentLen = resp.ContentLength
 	g.chunkTotal = int((g.contentLen + g.bufsz - 1) / g.bufsz) // round up, integer division
 	logger.debugPrintf("object size: %3.2g MB", float64(g.contentLen)/float64((1*mb)))

s3gof3r.go

@@ -3,6 +3,7 @@
 package s3gof3r
 
 import (
+	"errors"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -84,6 +85,9 @@ func (s3 *S3) Bucket(name string) *Bucket {
 // Header data from the downloaded object is also returned, useful for reading object metadata.
 // DefaultConfig is used if c is nil
 func (b *Bucket) GetReader(path string, c *Config) (r io.ReadCloser, h http.Header, err error) {
+	if path == "" {
+		return nil, nil, errors.New("empty path requested")
+	}
 	if c == nil {
 		c = b.conf()
 	}

s3gof3r_test.go

@@ -40,6 +40,7 @@ func TestGetReader(t *testing.T) {
 		{"t1.test", nil, 1 * kb, nil},
 		{"no-md5", &Config{Scheme: "https", Client: ClientWithTimeout(clientTimeout), Md5Check: false}, 1, nil},
 		{"NoKey", nil, -1, &RespError{StatusCode: 404, Message: "The specified key does not exist."}},
+		{"", nil, -1, fmt.Errorf("empty path requested")},
 		{"6_mb_test",
 			&Config{Concurrency: 3, PartSize: 1 * mb, NTry: 2, Md5Check: true, Scheme: "https", Client: ClientWithTimeout(3 * time.Second)},
 			6 * mb,