From: Dan Nicholson <nicholson@endlessm.com>
Date: Sat, 30 Jul 2016 15:14:17 +0000 (-0500)
Subject: deltas: Allow processing of empty delta parts
X-Git-Tag: archive/raspbian/2022.1-3+rpi1~1^2~4^2~49^2~42
X-Git-Url: https://dgit.raspbian.org/%22http:/www.example.com/cgi/%22https:/www.github.com/%22bookmarks:///%22http:/www.example.com/cgi/%22https:/www.github.com/%22bookmarks:/?a=commitdiff_plain;h=512090785e039e560f5e0df9b1e1db004298eeb6;p=ostree.git

deltas: Allow processing of empty delta parts

If a static delta is generated between 2 commits with the same content,
then the delta will contain 1 part with no checksums. While useless,
this is a valid delta that shouldn't raise an assertion. If the delta
part has no checksums, then there are no objects to recreate and the
processing can be skipped.

Closes: #420
Approved by: cgwalters
---

diff --git a/src/libostree/ostree-repo-static-delta-core.c b/src/libostree/ostree-repo-static-delta-core.c
index 68c45055..46fa5f86 100644
--- a/src/libostree/ostree-repo-static-delta-core.c
+++ b/src/libostree/ostree-repo-static-delta-core.c
@@ -42,8 +42,7 @@ _ostree_static_delta_parse_checksum_array (GVariant      *array,
 
   n_checksums = n / OSTREE_STATIC_DELTA_OBJTYPE_CSUM_LEN;
 
-  if (G_UNLIKELY(n == 0 ||
-                 n > (G_MAXUINT32/OSTREE_STATIC_DELTA_OBJTYPE_CSUM_LEN) ||
+  if (G_UNLIKELY(n > (G_MAXUINT32/OSTREE_STATIC_DELTA_OBJTYPE_CSUM_LEN) ||
                  (n_checksums * OSTREE_STATIC_DELTA_OBJTYPE_CSUM_LEN) != n))
     {
       g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED,
diff --git a/src/libostree/ostree-repo-static-delta-processing.c b/src/libostree/ostree-repo-static-delta-processing.c
index f78b7ab7..304d7b4a 100644
--- a/src/libostree/ostree-repo-static-delta-processing.c
+++ b/src/libostree/ostree-repo-static-delta-processing.c
@@ -210,8 +210,14 @@ _ostree_static_delta_part_execute (OstreeRepo      *repo,
                                                   error))
     goto out;
 
+  /* Skip processing for empty delta part */
+  if (state->n_checksums == 0)
+    {
+      ret = TRUE;
+      goto out;
+    }
+
   state->checksums = checksums_data;
-  g_assert (state->n_checksums > 0);
 
   g_variant_get (part, "(@a(uuu)@aa(ayay)@ay@ay)",
                  &mode_dict,