From 454e471af8f448d9c9cb1c8d985f10051c6f4f37 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ond=C5=99ej=20Budai?= <obudai@redhat.com>
Date: Tue, 14 Jul 2020 09:59:28 +0200
Subject: [PATCH] api/weldr: bring tars back from the future

By default, go's tar archiver uses USTAR header format. Unfortunately, this
format doesn't support sub-second resolution for ModTime. Go solves this by
*rounding* the time. Sometimes, this creates an archive containing a file
with modtime from the future. When such archive is untarred by GNU tar,
the following message is produced:

tar: bf548dfd-0a90-40e6-bbf2-dcdd82fcbb4e.json: time stamp 2020-07-13
13:34:31 is 0.356223173 s in the future

We have two options here:

1) Use gnu header format that supports sub-second resolution. Unfortunately,
   it seems that not all tar archivers support this format (e.g. 7-zip).

2) The other option is to truncate the date (instead of rounding).

I went with option 2.

Also, this commit adds a test to check that the header is not from the future.
Without this fix, the test is actually failing, I verified this manually.

Fixes #854
---
 internal/weldr/api.go      | 8 ++++----
 internal/weldr/api_test.go | 1 +
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/internal/weldr/api.go b/internal/weldr/api.go
index 7fffe1349..5a6a23f39 100644
--- a/internal/weldr/api.go
+++ b/internal/weldr/api.go
@@ -2270,7 +2270,7 @@ func (api *API) composeMetadataHandler(writer http.ResponseWriter, request *http
 		Name:    uuid.String() + ".json",
 		Mode:    0600,
 		Size:    int64(len(metadata)),
-		ModTime: time.Now(),
+		ModTime: time.Now().Truncate(time.Second),
 	}
 	err = tw.WriteHeader(hdr)
 	common.PanicOnError(err)
@@ -2331,7 +2331,7 @@ func (api *API) composeResultsHandler(writer http.ResponseWriter, request *http.
 		Name:    uuid.String() + ".json",
 		Mode:    0644,
 		Size:    int64(len(metadata)),
-		ModTime: time.Now(),
+		ModTime: time.Now().Truncate(time.Second),
 	}
 	err = tw.WriteHeader(hdr)
 	common.PanicOnError(err)
@@ -2348,7 +2348,7 @@ func (api *API) composeResultsHandler(writer http.ResponseWriter, request *http.
 			Name:    "logs/osbuild.log",
 			Mode:    0644,
 			Size:    int64(fileContents.Len()),
-			ModTime: time.Now(),
+			ModTime: time.Now().Truncate(time.Second),
 		}
 		err = tw.WriteHeader(hdr)
 		common.PanicOnError(err)
@@ -2362,7 +2362,7 @@ func (api *API) composeResultsHandler(writer http.ResponseWriter, request *http.
 			Name:    uuid.String() + "-" + compose.ImageBuild.ImageType.Filename(),
 			Mode:    0644,
 			Size:    int64(fileSize),
-			ModTime: time.Now(),
+			ModTime: time.Now().Truncate(time.Second),
 		}
 		err = tw.WriteHeader(hdr)
 		common.PanicOnError(err)
diff --git a/internal/weldr/api_test.go b/internal/weldr/api_test.go
index 1b6b10b80..4afef1baf 100644
--- a/internal/weldr/api_test.go
+++ b/internal/weldr/api_test.go
@@ -679,6 +679,7 @@ func TestComposeLogs(t *testing.T) {
 		h, err := tr.Next()
 
 		require.NoErrorf(t, err, "untarring failed with error")
+		require.Falsef(t, h.ModTime.After(time.Now()), "ModTime cannot be in the future")
 		require.Equalf(t, c.ExpectedFileName, h.Name, "%s: unexpected file name", c.Path)
 
 		var buffer bytes.Buffer