1 files changed, 36 insertions, 12 deletions

diff --git a/vendor/cloud.google.com/go/storage/reader.go b/vendor/cloud.google.com/go/storage/reader.go
index c0f26bf..1fdc197 100644
--- a/vendor/cloud.google.com/go/storage/reader.go
+++ b/vendor/cloud.google.com/go/storage/reader.go
@@ -25,6 +25,7 @@ import (
 	"reflect"
 	"strconv"
 	"strings"
+	"time"
 
 	"cloud.google.com/go/internal/trace"
 	"golang.org/x/net/context"
@@ -130,7 +131,11 @@ func (o *ObjectHandle) NewRangeReader(ctx context.Context, offset, length int64)
 	if err != nil {
 		return nil, err
 	}
-	var size int64 // total size of object, even if a range was requested.
+	var (
+		size     int64 // total size of object, even if a range was requested.
+		checkCRC bool
+		crc      uint32
+	)
 	if res.StatusCode == http.StatusPartialContent {
 		cr := strings.TrimSpace(res.Header.Get("Content-Range"))
 		if !strings.HasPrefix(cr, "bytes ") || !strings.Contains(cr, "/") {
@@ -143,6 +148,18 @@ func (o *ObjectHandle) NewRangeReader(ctx context.Context, offset, length int64)
 		}
 	} else {
 		size = res.ContentLength
+		// Check the CRC iff all of the following hold:
+		// - We asked for content (length != 0).
+		// - We got all the content (status != PartialContent).
+		// - The server sent a CRC header.
+		// - The Go http stack did not uncompress the file.
+		// - We were not served compressed data that was uncompressed on download.
+		// The problem with the last two cases is that the CRC will not match -- GCS
+		// computes it on the compressed contents, but we compute it on the
+		// uncompressed contents.
+		if length != 0 && !goHTTPUncompressed(res) && !uncompressedByServer(res) {
+			crc, checkCRC = parseCRC32c(res)
+		}
 	}
 
 	remain := res.ContentLength
@@ -152,14 +169,6 @@ func (o *ObjectHandle) NewRangeReader(ctx context.Context, offset, length int64)
 		body.Close()
 		body = emptyBody
 	}
-	var (
-		checkCRC bool
-		crc      uint32
-	)
-	// Even if there is a CRC header, we can't compute the hash on partial data.
-	if remain == size {
-		crc, checkCRC = parseCRC32c(res)
-	}
 	return &Reader{
 		body:            body,
 		size:            size,
@@ -167,12 +176,20 @@ func (o *ObjectHandle) NewRangeReader(ctx context.Context, offset, length int64)
 		contentType:     res.Header.Get("Content-Type"),
 		contentEncoding: res.Header.Get("Content-Encoding"),
 		cacheControl:    res.Header.Get("Cache-Control"),
+		lastModified:    res.Header.Get("Last-Modified"),
 		wantCRC:         crc,
 		checkCRC:        checkCRC,
 		reopen:          reopen,
 	}, nil
 }
 
+func uncompressedByServer(res *http.Response) bool {
+	// If the data is stored as gzip but is not encoded as gzip, then it
+	// was uncompressed by the server.
+	return res.Header.Get("X-Goog-Stored-Content-Encoding") == "gzip" &&
+		res.Header.Get("Content-Encoding") != "gzip"
+}
+
 func parseCRC32c(res *http.Response) (uint32, bool) {
 	const prefix = "crc32c="
 	for _, spec := range res.Header["X-Goog-Hash"] {
@@ -200,10 +217,10 @@ type Reader struct {
 	contentType        string
 	contentEncoding    string
 	cacheControl       string
+	lastModified       string
 	checkCRC           bool   // should we check the CRC?
 	wantCRC            uint32 // the CRC32c value the server sent in the header
 	gotCRC             uint32 // running crc
-	checkedCRC         bool   // did we check the CRC? (For tests.)
 	reopen             func(seen int64) (*http.Response, error)
 }
 
@@ -222,8 +239,7 @@ func (r *Reader) Read(p []byte) (int, error) {
 		// Check CRC here. It would be natural to check it in Close, but
 		// everybody defers Close on the assumption that it doesn't return
 		// anything worth looking at.
-		if r.remain == 0 { // Only check if we have Content-Length.
-			r.checkedCRC = true
+		if err == io.EOF {
 			if r.gotCRC != r.wantCRC {
 				return n, fmt.Errorf("storage: bad CRC on read: got %d, want %d",
 					r.gotCRC, r.wantCRC)
@@ -288,3 +304,11 @@ func (r *Reader) ContentEncoding() string {
 func (r *Reader) CacheControl() string {
 	return r.cacheControl
 }
+
+// LastModified returns the value of the Last-Modified header.
+func (r *Reader) LastModified() (time.Time, error) {
+	if r.lastModified == "" {
+		return time.Time{}, errors.New("storage: no Last-Modified header")
+	}
+	return http.ParseTime(r.lastModified)
+}