lib/repo: Support hardlink conversions from bare-user to bu-only

Thinking about the problem of flatpak converting from `bare-user` to `bare-user-only`
"in place" by creating a new repo and doing a `pull-local`, I realized
that we can optimize this process by doing hardlinks for both metadata
and regular files.  The repo formats are *almost* compatible, the
exception being symlinks.

An earlier patch caused us to do hardlinks for metadata, this patch takes things
to the next step and special cases this specific conversion. In this case we
need to parse the source object to determine whether or not it's a symlink.

Closes: #922
Approved by: alexlarsson

diff --git a/src/libostree/ostree-repo.c b/src/libostree/ostree-repo.c
index 33ca0ae8fc59d9304b557b257f19186e9921d8bb..49251284cb358713958d5dd0e4ae1683b411e48f 100644 (file)
--- a/src/libostree/ostree-repo.c
+++ b/src/libostree/ostree-repo.c
@@ -3073,6 +3073,20 @@ copy_detached_metadata (OstreeRepo    *self,
   return TRUE;
 }
 
+/* Special case between bare-user and bare-user-only,
+ * mostly for https://github.com/flatpak/flatpak/issues/845
+ * see below for any more comments.
+ */
+static gboolean
+import_is_bareuser_only_conversion (OstreeRepo *src_repo,
+                                    OstreeRepo *dest_repo,
+                                    OstreeObjectType objtype)
+{
+  return src_repo->mode == OSTREE_REPO_MODE_BARE_USER
+    && dest_repo->mode == OSTREE_REPO_MODE_BARE_USER_ONLY
+    && objtype == OSTREE_OBJECT_TYPE_FILE;
+}
+
 static gboolean
 import_one_object_link (OstreeRepo    *self,
                         OstreeRepo    *source,
@@ -3085,6 +3099,33 @@ import_one_object_link (OstreeRepo    *self,
   char loose_path_buf[_OSTREE_LOOSE_PATH_MAX];
   _ostree_loose_path (loose_path_buf, checksum, objtype, self->mode);
 
+  /* Hardlinking between bare-user → bare-user-only is only possible for regular
+   * files, *not* symlinks, which in bare-user are stored as regular files.  At
+   * this point we need to parse the file to see the difference.
+   */
+  if (import_is_bareuser_only_conversion (source, self, objtype))
+    {
+      g_autoptr(GFileInfo) finfo = NULL;
+
+      if (!ostree_repo_load_file (source, checksum, NULL, &finfo, NULL,
+                                  cancellable, error))
+        return FALSE;
+
+      switch (g_file_info_get_file_type (finfo))
+        {
+        case G_FILE_TYPE_REGULAR:
+          /* This is OK, we'll drop through and try a hardlink */
+          break;
+        case G_FILE_TYPE_SYMBOLIC_LINK:
+          /* NOTE early return */
+          *out_was_supported = FALSE;
+          return TRUE;
+        default:
+          g_assert_not_reached ();
+          break;
+        }
+    }
+
   if (!_ostree_repo_ensure_loose_objdir_at (self->objects_dir_fd, loose_path_buf, cancellable, error))
     return FALSE;
 
@@ -3157,6 +3198,11 @@ import_via_hardlink_is_possible (OstreeRepo *src_repo,
   /* Metadata is identical between all modes */
   if (OSTREE_OBJECT_TYPE_IS_META (objtype))
     return TRUE;
+  /* And now a special case between bare-user and bare-user-only,
+   * mostly for https://github.com/flatpak/flatpak/issues/845
+   */
+  if (import_is_bareuser_only_conversion (src_repo, dest_repo, objtype))
+    return TRUE;
   return FALSE;
 }
 

diff --git a/tests/libtest.sh b/tests/libtest.sh
index 1774a7b6d4690468147e221167a13233cc2f21d8..15802dfd604ea12f0b83dbf410db38dc78864f3c 100755 (executable)
--- a/tests/libtest.sh
+++ b/tests/libtest.sh
@@ -116,10 +116,16 @@ else
     fi
 fi
 
+files_are_hardlinked() {
+    f1=$(stat -c %i $1)
+    f2=$(stat -c %i $2)
+    [ "$f1" == "$f2" ]
+}
+
 assert_files_hardlinked() {
     f1=$(stat -c %i $1)
     f2=$(stat -c %i $2)
-    if [ "$f1" != "$f2" ]; then
+    if ! files_are_hardlinked "$f1" "$f2"; then
         fatal "Files '$1' and '$2' are not hardlinked"
     fi
 }
@@ -512,12 +518,22 @@ ostree_file_path_to_checksum() {
     $CMD_PREFIX ostree --repo=$repo ls -C $ref $path | awk '{ print $5 }'
 }
 
+# Given a path to a file in a repo for a ref, print the (relative) path to its
+# object
+ostree_file_path_to_relative_object_path() {
+    repo=$1
+    ref=$2
+    path=$3
+    checksum=$(ostree_file_path_to_checksum $repo $ref $path)
+    test -n "${checksum}"
+    echo objects/${checksum:0:2}/${checksum:2}.file
+}
+
 # Given a path to a file in a repo for a ref, print the path to its object
 ostree_file_path_to_object_path() {
-   repo=$1
-   ref=$2
-   path=$3
-   checksum=$(ostree_file_path_to_checksum $repo $ref $path)
-   test -n "${checksum}"
-   echo ${repo}/objects/${checksum:0:2}/${checksum:2}.file
+    repo=$1
+    ref=$2
+    path=$3
+    relpath=$(ostree_file_path_to_relative_object_path $repo $ref $path)
+    echo ${repo}/${relpath}
 }

diff --git a/tests/test-basic-user-only.sh b/tests/test-basic-user-only.sh
index 29fbbdd3bf7b67acc2b728b5fb167fbf71e0b835..fb071fe4c92d1269cb23f25a1b83601e2d4bd3d2 100755 (executable)
--- a/tests/test-basic-user-only.sh
+++ b/tests/test-basic-user-only.sh
@@ -22,7 +22,7 @@ set -euo pipefail
 . $(dirname $0)/libtest.sh
 
 setup_test_repository "bare-user-only"
-extra_basic_tests=3
+extra_basic_tests=4
 . $(dirname $0)/basic-test.sh
 
 # Reset things so we don't inherit a lot of state from earlier tests
@@ -71,3 +71,22 @@ $CMD_PREFIX ostree pull-local --repo=repo repo-input
 $CMD_PREFIX ostree --repo=repo checkout -U -H content-with-dir-world-writable dir-co
 assert_file_has_mode dir-co/worldwritable-dir 775
 echo "ok didn't make world-writable dir"
+
+cd ${test_tmpdir}
+rm repo-input -rf
+rm repo -rf
+ostree_repo_init repo init --mode=bare-user-only
+ostree_repo_init repo-input init --mode=bare-user
+rm files -rf && mkdir files
+echo afile > files/afile
+ln -s afile files/afile-link
+$CMD_PREFIX ostree --repo=repo-input commit --canonical-permissions -b testtree --tree=dir=files
+afile_relobjpath=$(ostree_file_path_to_relative_object_path repo-input testtree /afile)
+afile_link_relobjpath=$(ostree_file_path_to_relative_object_path repo-input testtree /afile-link)
+$CMD_PREFIX ostree pull-local --repo=repo repo-input
+assert_files_hardlinked repo/${afile_relobjpath} repo-input/${afile_relobjpath}
+if files_are_hardlinked repo/${afile_link_relobjpath} repo-input/${afile_link_relobjpath}; then
+    assert_not_reached "symlinks hardlinked across bare-user?"
+fi
+$OSTREE fsck -q
+echo "ok hardlink pull from bare-user"