internal/v5: Support symlink for files in archive.

internal/charmstore/archive.go

@@ -6,7 +6,9 @@ package charmstore // import "gopkg.in/juju/charmstore.v5/internal/charmstore"
 import (
 	"archive/zip"
 	"bytes"
+	"fmt"
 	"io"
+	"io/ioutil"
 	"os"
 	"path"
 	"strings"
@@ -113,6 +115,9 @@ func (r *multiReadSeekCloser) Close() error {
 // If no such file was found, it returns an error
 // with a params.ErrNotFound cause.
 //
+// If the file is a symlink, it returns an error ErrRedirect that holds the path
+// that the symbolic link refers to.
+//
 // If the file is actually a directory in the blob, it returns
 // an error with a params.ErrForbidden cause.
 func (s *Store) OpenBlobFile(blob *Blob, filePath string) (io.ReadCloser, int64, error) {
@@ -135,11 +140,30 @@ func (s *Store) OpenBlobFile(blob *Blob, filePath string) (io.ReadCloser, int64,
 		if err != nil {
 			return nil, 0, errgo.Notef(err, "unable to read file %q", filePath)
 		}
+		if file.Mode()&os.ModeSymlink != 0 {
+			defer content.Close()
+			url, err := ioutil.ReadAll(content)
+			if err != nil {
+				return nil, 0, errgo.Notef(err, "cannot read archive data for symlink %s", file.Name)
+			}
+			return nil, 0, &ErrRedirect{Path: string(url)}
+		}
 		return content, fileInfo.Size(), nil
 	}
 	return nil, 0, errgo.WithCausef(nil, params.ErrNotFound, "file %q not found in the archive", filePath)
 }
 
+// ErrRedirect holds the error returned by OpenBlobFile when a symbolic link
+// is opened. The Path field holds the name of the file that the symbolic link
+// refers to.
+type ErrRedirect struct {
+	Path string
+}
+
+func (e ErrRedirect) Error() string {
+	return fmt.Sprintf("file is a symbolic link to %q", e.Path)
+}
+
 // OpenCachedBlobFile opens a file from the given entity's archive blob.
 // The file is identified by the provided fileId. If the file has not
 // previously been opened on this entity, the isFile function will be

internal/storetesting/charm-repo/quantal/all-hooks/hooks/foo-relation-departed

@@ -0,0 +1 @@
+install

internal/v5/archive.go

@@ -23,6 +23,7 @@ import (
 	"gopkg.in/juju/charmstore.v5/internal/charmstore"
 	"gopkg.in/juju/charmstore.v5/internal/mongodoc"
 	"gopkg.in/juju/charmstore.v5/internal/router"
+	"path"
 )
 
 // GET id/archive
@@ -333,6 +334,17 @@ func (h *ReqHandler) serveArchiveFile(id *router.ResolvedURL, w http.ResponseWri
 // with the given id.
 func (h *ReqHandler) ServeBlobFile(w http.ResponseWriter, req *http.Request, id *router.ResolvedURL, blob *charmstore.Blob) error {
 	r, size, err := h.Store.OpenBlobFile(blob, req.URL.Path)
+	if redirect, ok := err.(*charmstore.ErrRedirect); ok {
+		p, err := router.RelativeURLPath(req.URL.Path, path.Join(path.Dir(req.URL.Path), redirect.Path))
+		if err != nil {
+			return errgo.Notef(err, "cannot make relative URL from %q and %q", req.URL.Path, path.Join(path.Dir(req.URL.Path), redirect.Path))
+		}
+		// We can't use the http.redirect function because it tries to build an absolute url but the path in the
+		// request URL has been changed.
+		w.Header().Set("Location", p)
+		w.WriteHeader(http.StatusMovedPermanently)
+		return nil
+	}
 	if err != nil {
 		return errgo.Mask(err, errgo.Is(params.ErrNotFound), errgo.Is(params.ErrForbidden))
 	}

internal/v5/archive_test.go

@@ -17,6 +17,7 @@ import (
 	"net/http/httptest"
 	"net/url"
 	"os"
+	"path"
 	"sort"
 	"strconv"
 	"strings"
@@ -1178,25 +1179,24 @@ func (s *ArchiveSuite) TestArchiveFileGet(c *gc.C) {
 	s.assertArchiveFileContents(c, zipFile, "~charmers/utopic/all-hooks-0/archive/hooks/install")
 }
 
+func (s *ArchiveSuite) TestSymLinkArchiveFileGet(c *gc.C) {
+	ch := storetesting.Charms.CharmArchive(c.MkDir(), "all-hooks")
+	id := newResolvedURL("cs:~charmers/utopic/all-hooks-0", 0)
+	s.addPublicCharm(c, ch, id)
+	zipFile, err := zip.OpenReader(ch.Path)
+	c.Assert(err, gc.Equals, nil)
+	defer zipFile.Close()
+
+	// Check a file in a subdirectory.
+	s.assertArchiveFileContents(c, zipFile, "~charmers/utopic/all-hooks-0/archive/hooks/foo-relation-departed")
+}
+
 // assertArchiveFileContents checks that the response returned by the
 // serveArchiveFile endpoint is correct for the given archive and URL path.
 func (s *ArchiveSuite) assertArchiveFileContents(c *gc.C, zipFile *zip.ReadCloser, path string) {
 	// For example: trusty/django/archive/hooks/install -> hooks/install.
 	filePath := strings.SplitN(path, "/archive/", 2)[1]
-
-	// Retrieve the expected bytes.
-	var expectBytes []byte
-	for _, file := range zipFile.File {
-		if file.Name == filePath {
-			r, err := file.Open()
-			c.Assert(err, gc.Equals, nil)
-			defer r.Close()
-			expectBytes, err = ioutil.ReadAll(r)
-			c.Assert(err, gc.Equals, nil)
-			break
-		}
-	}
-	c.Assert(expectBytes, gc.Not(gc.HasLen), 0)
+	expectBytes := retrieveExpectedBytes(c, zipFile, filePath)
 
 	// Make the request.
 	url := storeURL(path)
@@ -1207,14 +1207,33 @@ func (s *ArchiveSuite) assertArchiveFileContents(c *gc.C, zipFile *zip.ReadClose
 
 	// Ensure the response is what we expect.
 	c.Assert(rec.Code, gc.Equals, http.StatusOK)
-	c.Assert(rec.Body.Bytes(), gc.DeepEquals, expectBytes)
+	c.Assert(string(rec.Body.Bytes()), gc.DeepEquals, string(expectBytes))
 	headers := rec.Header()
 	c.Assert(headers.Get("Content-Length"), gc.Equals, strconv.Itoa(len(expectBytes)))
 	// We only have text files in the charm repository used for tests.
 	c.Assert(headers.Get("Content-Type"), gc.Equals, "text/plain; charset=utf-8")
 	assertCacheControl(c, rec.Header(), true)
 }
 
+func retrieveExpectedBytes(c *gc.C, zipFile *zip.ReadCloser, filePath string) (expectBytes []byte) {
+	for _, file := range zipFile.File {
+		if file.Name == filePath {
+			r, err := file.Open()
+			c.Assert(err, gc.Equals, nil)
+			defer r.Close()
+			expectBytes, err = ioutil.ReadAll(r)
+			c.Assert(err, gc.Equals, nil)
+			if file.Mode()&os.ModeSymlink != 0 {
+				newPath := path.Join(path.Dir(filePath), string(expectBytes))
+				return retrieveExpectedBytes(c, zipFile, newPath)
+			}
+			break
+		}
+	}
+	c.Assert(expectBytes, gc.Not(gc.HasLen), 0)
+	return expectBytes
+}
+
 func (s *ArchiveSuite) TestDelete(c *gc.C) {
 	// Add a charm to the database (including the archive).
 	id, _ := s.addPublicCharm(c, storetesting.NewCharm(nil), newResolvedURL("~charmers/utopic/mysql-42", -1))