Allow markdown files to read from the LFS (#5787)

This PR makes it possible for the markdown renderer to render images and media straight from the LFS.

Fix #5746

Signed-off-by: Andrew Thornton [art27@cantab.net](mailto:art27@cantab.net)

3 files changed, 101 insertions, 28 deletions

diff --git a/routers/repo/download.go b/routers/repo/download.go
index a863236d6e..57a1e65ac9 100644
--- a/routers/repo/download.go
+++ b/routers/repo/download.go
@@ -15,6 +15,7 @@ import (
 
 	"code.gitea.io/gitea/modules/base"
 	"code.gitea.io/gitea/modules/context"
+	"code.gitea.io/gitea/modules/lfs"
 )
 
 // ServeData download file from io.Reader
@@ -55,6 +56,29 @@ func ServeBlob(ctx *context.Context, blob *git.Blob) error {
 	return ServeData(ctx, ctx.Repo.TreePath, dataRc)
 }
 
+// ServeBlobOrLFS download a git.Blob redirecting to LFS if necessary
+func ServeBlobOrLFS(ctx *context.Context, blob *git.Blob) error {
+	dataRc, err := blob.DataAsync()
+	if err != nil {
+		return err
+	}
+	defer dataRc.Close()
+
+	if meta, _ := lfs.ReadPointerFile(dataRc); meta != nil {
+		meta, _ = ctx.Repo.Repository.GetLFSMetaObjectByOid(meta.Oid)
+		if meta == nil {
+			return ServeBlob(ctx, blob)
+		}
+		lfsDataRc, err := lfs.ReadMetaObject(meta)
+		if err != nil {
+			return err
+		}
+		return ServeData(ctx, ctx.Repo.TreePath, lfsDataRc)
+	}
+
+	return ServeBlob(ctx, blob)
+}
+
 // SingleDownload download a file by repos path
 func SingleDownload(ctx *context.Context) {
 	blob, err := ctx.Repo.Commit.GetBlobByPath(ctx.Repo.TreePath)
@@ -71,6 +95,22 @@ func SingleDownload(ctx *context.Context) {
 	}
 }
 
+// SingleDownloadOrLFS download a file by repos path redirecting to LFS if necessary
+func SingleDownloadOrLFS(ctx *context.Context) {
+	blob, err := ctx.Repo.Commit.GetBlobByPath(ctx.Repo.TreePath)
+	if err != nil {
+		if git.IsErrNotExist(err) {
+			ctx.NotFound("GetBlobByPath", nil)
+		} else {
+			ctx.ServerError("GetBlobByPath", err)
+		}
+		return
+	}
+	if err = ServeBlobOrLFS(ctx, blob); err != nil {
+		ctx.ServerError("ServeBlobOrLFS", err)
+	}
+}
+
 // DownloadByID download a file by sha1 ID
 func DownloadByID(ctx *context.Context) {
 	blob, err := ctx.Repo.GitRepo.GetBlob(ctx.Params("sha"))
@@ -86,3 +126,19 @@ func DownloadByID(ctx *context.Context) {
 		ctx.ServerError("ServeBlob", err)
 	}
 }
+
+// DownloadByIDOrLFS download a file by sha1 ID taking account of LFS
+func DownloadByIDOrLFS(ctx *context.Context) {
+	blob, err := ctx.Repo.GitRepo.GetBlob(ctx.Params("sha"))
+	if err != nil {
+		if git.IsErrNotExist(err) {
+			ctx.NotFound("GetBlob", nil)
+		} else {
+			ctx.ServerError("GetBlob", err)
+		}
+		return
+	}
+	if err = ServeBlobOrLFS(ctx, blob); err != nil {
+		ctx.ServerError("ServeBlob", err)
+	}
+}
diff --git a/routers/repo/view.go b/routers/repo/view.go
index 872dc5fa3a..02cf2cc0bd 100644
--- a/routers/repo/view.go
+++ b/routers/repo/view.go
@@ -12,7 +12,6 @@ import (
 	gotemplate "html/template"
 	"io/ioutil"
 	"path"
-	"strconv"
 	"strings"
 
 	"code.gitea.io/git"
@@ -179,34 +178,42 @@ func renderFile(ctx *context.Context, entry *git.TreeEntry, treeLink, rawLink st
 	buf = buf[:n]
 
 	isTextFile := base.IsTextFile(buf)
+	isLFSFile := false
 	ctx.Data["IsTextFile"] = isTextFile
 
 	//Check for LFS meta file
-	if isTextFile && setting.LFS.StartServer {
-		headString := string(buf)
-		if strings.HasPrefix(headString, models.LFSMetaFileIdentifier) {
-			splitLines := strings.Split(headString, "\n")
-			if len(splitLines) >= 3 {
-				oid := strings.TrimPrefix(splitLines[1], models.LFSMetaFileOidPrefix)
-				size, err := strconv.ParseInt(strings.TrimPrefix(splitLines[2], "size "), 10, 64)
-				if len(oid) == 64 && err == nil {
-					contentStore := &lfs.ContentStore{BasePath: setting.LFS.ContentPath}
-					meta := &models.LFSMetaObject{Oid: oid}
-					if contentStore.Exists(meta) {
-						ctx.Data["IsTextFile"] = false
-						isTextFile = false
-						ctx.Data["IsLFSFile"] = true
-						ctx.Data["FileSize"] = size
-						filenameBase64 := base64.RawURLEncoding.EncodeToString([]byte(blob.Name()))
-						ctx.Data["RawFileLink"] = fmt.Sprintf("%s%s.git/info/lfs/objects/%s/%s", setting.AppURL, ctx.Repo.Repository.FullName(), oid, filenameBase64)
-					}
+	if isTextFile {
+		if meta := lfs.IsPointerFile(&buf); meta != nil {
+			if meta, _ = ctx.Repo.Repository.GetLFSMetaObjectByOid(meta.Oid); meta != nil {
+				ctx.Data["IsLFSFile"] = true
+				isLFSFile = true
+
+				// OK read the lfs object
+				dataRc, err := lfs.ReadMetaObject(meta)
+				if err != nil {
+					ctx.ServerError("ReadMetaObject", err)
+					return
 				}
+				defer dataRc.Close()
+
+				buf = make([]byte, 1024)
+				n, _ = dataRc.Read(buf)
+				buf = buf[:n]
+
+				isTextFile = base.IsTextFile(buf)
+				ctx.Data["IsTextFile"] = isTextFile
+
+				ctx.Data["FileSize"] = meta.Size
+				filenameBase64 := base64.RawURLEncoding.EncodeToString([]byte(blob.Name()))
+				ctx.Data["RawFileLink"] = fmt.Sprintf("%s%s.git/info/lfs/objects/%s/%s", setting.AppURL, ctx.Repo.Repository.FullName(), meta.Oid, filenameBase64)
 			}
 		}
 	}
 
 	// Assume file is not editable first.
-	if !isTextFile {
+	if isLFSFile {
+		ctx.Data["EditFileTooltip"] = ctx.Tr("repo.editor.cannot_edit_lfs_files")
+	} else if !isTextFile {
 		ctx.Data["EditFileTooltip"] = ctx.Tr("repo.editor.cannot_edit_non_text_files")
 	}
 
@@ -263,14 +270,15 @@ func renderFile(ctx *context.Context, entry *git.TreeEntry, treeLink, rawLink st
 			}
 			ctx.Data["LineNums"] = gotemplate.HTML(output.String())
 		}
-
-		if ctx.Repo.CanEnableEditor() {
-			ctx.Data["CanEditFile"] = true
-			ctx.Data["EditFileTooltip"] = ctx.Tr("repo.editor.edit_this_file")
-		} else if !ctx.Repo.IsViewBranch {
-			ctx.Data["EditFileTooltip"] = ctx.Tr("repo.editor.must_be_on_a_branch")
-		} else if !ctx.Repo.CanWrite(models.UnitTypeCode) {
-			ctx.Data["EditFileTooltip"] = ctx.Tr("repo.editor.fork_before_edit")
+		if !isLFSFile {
+			if ctx.Repo.CanEnableEditor() {
+				ctx.Data["CanEditFile"] = true
+				ctx.Data["EditFileTooltip"] = ctx.Tr("repo.editor.edit_this_file")
+			} else if !ctx.Repo.IsViewBranch {
+				ctx.Data["EditFileTooltip"] = ctx.Tr("repo.editor.must_be_on_a_branch")
+			} else if !ctx.Repo.CanWrite(models.UnitTypeCode) {
+				ctx.Data["EditFileTooltip"] = ctx.Tr("repo.editor.fork_before_edit")
+			}
 		}
 
 	case base.IsPDFFile(buf):
diff --git a/routers/routes/routes.go b/routers/routes/routes.go
index 58274626c0..8ab7ff9bea 100644
--- a/routers/routes/routes.go
+++ b/routers/routes/routes.go
@@ -731,6 +731,15 @@ func RegisterRoutes(m *macaron.Macaron) {
 			})
 		}, repo.MustAllowPulls)
 
+		m.Group("/media", func() {
+			m.Get("/branch/*", context.RepoRefByType(context.RepoRefBranch), repo.SingleDownloadOrLFS)
+			m.Get("/tag/*", context.RepoRefByType(context.RepoRefTag), repo.SingleDownloadOrLFS)
+			m.Get("/commit/*", context.RepoRefByType(context.RepoRefCommit), repo.SingleDownloadOrLFS)
+			m.Get("/blob/:sha", context.RepoRefByType(context.RepoRefBlob), repo.DownloadByIDOrLFS)
+			// "/*" route is deprecated, and kept for backward compatibility
+			m.Get("/*", context.RepoRefByType(context.RepoRefLegacy), repo.SingleDownloadOrLFS)
+		}, repo.MustBeNotEmpty, reqRepoCodeReader)
+
 		m.Group("/raw", func() {
 			m.Get("/branch/*", context.RepoRefByType(context.RepoRefBranch), repo.SingleDownload)
 			m.Get("/tag/*", context.RepoRefByType(context.RepoRefTag), repo.SingleDownload)