Set the LastModified header for raw files

Although the use of LastModified dates for caching of git objects should be
discouraged (as it is not native to git - and there are a LOT of ways this
could be incorrect) - LastModified dates can be a helpful somewhat more human
way of caching for simple cases.

This PR adds this header and handles the If-Modified-Since header to the /raw/
routes.

Fix go-gitea#18354

Signed-off-by: Andrew Thornton <art27@cantab.net>

Author: zeripath

modules/httpcache/httpcache.go

@@ -37,18 +37,23 @@ func generateETag(fi os.FileInfo) string {
 
 // HandleTimeCache handles time-based caching for a HTTP request
 func HandleTimeCache(req *http.Request, w http.ResponseWriter, fi os.FileInfo) (handled bool) {
+	return HandleGenericTimeCache(req, w, fi.ModTime())
+}
+
+// HandleGenericTimeCache handles time-based caching for a HTTP request
+func HandleGenericTimeCache(req *http.Request, w http.ResponseWriter, lastModified time.Time) (handled bool) {
 	AddCacheControlToHeader(w.Header(), setting.StaticCacheTime)
 
 	ifModifiedSince := req.Header.Get("If-Modified-Since")
 	if ifModifiedSince != "" {
 		t, err := time.Parse(http.TimeFormat, ifModifiedSince)
-		if err == nil && fi.ModTime().Unix() <= t.Unix() {
+		if err == nil && lastModified.Unix() <= t.Unix() {
 			w.WriteHeader(http.StatusNotModified)
 			return true
 		}
 	}
 
-	w.Header().Set("Last-Modified", fi.ModTime().Format(http.TimeFormat))
+	w.Header().Set("Last-Modified", lastModified.Format(http.TimeFormat))
 	return false
 }
 

routers/web/repo/download.go

@@ -6,7 +6,10 @@
 package repo
 
 import (
+	"path"
+
 	"code.gitea.io/gitea/models"
+	"code.gitea.io/gitea/modules/cache"
 	"code.gitea.io/gitea/modules/context"
 	"code.gitea.io/gitea/modules/git"
 	"code.gitea.io/gitea/modules/httpcache"
@@ -79,34 +82,57 @@ func ServeBlobOrLFS(ctx *context.Context, blob *git.Blob) error {
 	return common.ServeBlob(ctx, blob)
 }
 
+func getBlobForEntry(ctx *context.Context) *git.Blob {
+	entry, err := ctx.Repo.Commit.GetTreeEntryByPath(ctx.Repo.TreePath)
+	if err != nil {
+		ctx.ServerError("GetBlobByPath", err)
+		return nil
+	}
+
+	if entry.IsDir() || entry.IsSubModule() {
+		ctx.NotFound("GetBlobByPath", nil)
+		return nil
+	}
+
+	var c *git.LastCommitCache
+	if setting.CacheService.LastCommit.Enabled && ctx.Repo.CommitsCount >= setting.CacheService.LastCommit.CommitsCount {
+		c = git.NewLastCommitCache(ctx.Repo.Repository.FullName(), ctx.Repo.GitRepo, setting.LastCommitCacheTTLSeconds, cache.GetCache())
+	}
+
+	info, _, err := git.Entries([]*git.TreeEntry{entry}).GetCommitsInfo(ctx, ctx.Repo.Commit, path.Dir("/" + ctx.Repo.TreePath)[1:], c)
+	if err != nil {
+		ctx.ServerError("GetCommitsInfo", err)
+		return nil
+	}
+
+	if len(info) == 1 && httpcache.HandleGenericTimeCache(ctx.Req, ctx.Resp, info[0].Commit.Committer.When) {
+		// Not Modified
+		return nil
+	}
+
+	return entry.Blob()
+}
+
 // SingleDownload download a file by repos path
 func SingleDownload(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)
-		}
+	blob := getBlobForEntry(ctx)
+	if blob == nil {
 		return
 	}
-	if err = common.ServeBlob(ctx, blob); err != nil {
+
+	if err := common.ServeBlob(ctx, blob); err != nil {
 		ctx.ServerError("ServeBlob", err)
 	}
 }
 
 // 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)
-		}
+	blob := getBlobForEntry(ctx)
+	if blob == nil {
 		return
 	}
-	if err = ServeBlobOrLFS(ctx, blob); err != nil {
+
+	if err := ServeBlobOrLFS(ctx, blob); err != nil {
 		ctx.ServerError("ServeBlobOrLFS", err)
 	}
 }