Teach fsck about partial commits

An OSTree user noticed that `ostree fsck` would produce `missing
object` errors in the case of interrupted pulls.

It's possible to do e.g. `ostree pull --subpath=/usr/share/rpm ...`,
which gets you just that portion of the commit.  The use case for this
was being able to see what changes would appear in an update before
actually downloading all of it.

(I think this would be better covered by static deltas, but those
 aren't final yet, and `--subpath` predates it)

Further, `.commitpartial` is used as a successor to the `transaction`
symlink for more precise knowledge in the case where a pull was
interrupted that we needed to resume scanning.

So it makes sense for `ostree fsck` to be aware of it.

7 files changed, 114 insertions, 20 deletions

diff --git a/src/libostree/ostree-cmdprivate.c b/src/libostree/ostree-cmdprivate.c
index ea122434..99834937 100644
--- a/src/libostree/ostree-cmdprivate.c
+++ b/src/libostree/ostree-cmdprivate.c
@@ -21,6 +21,8 @@
 #include "config.h"
 
 #include "ostree-cmdprivate.h"
+#include "ostree-repo-private.h"
+#include "ostree-core-private.h"
 #include "ostree-sysroot.h"
 #include "ostree-bootloader-grub2.h"
 
diff --git a/src/libostree/ostree-repo-pull.c b/src/libostree/ostree-repo-pull.c
index 97c044f8..db91d1ec 100644
--- a/src/libostree/ostree-repo-pull.c
+++ b/src/libostree/ostree-repo-pull.c
@@ -1126,10 +1126,12 @@ scan_one_metadata_object_c (OtPullData         *pull_data,
       /* For commits, check whether we only had a partial fetch */
       if (!do_scan && objtype == OSTREE_OBJECT_TYPE_COMMIT)
         {
-          g_autofree char *commitpartial_path = _ostree_get_commitpartial_path (tmp_checksum);
-          struct stat stbuf;
+          OstreeRepoCommitState commitstate;
 
-          if (fstatat (pull_data->repo->repo_dir_fd, commitpartial_path, &stbuf, 0) == 0)
+          if (!ostree_repo_load_commit (pull_data->repo, tmp_checksum, NULL, &commitstate, error))
+            goto out;
+
+          if (commitstate & OSTREE_REPO_COMMIT_STATE_PARTIAL)
             {
               do_scan = TRUE;
               pull_data->commitpartial_exists = TRUE;
@@ -2178,14 +2180,8 @@ ostree_repo_pull_with_options (OstreeRepo             *self,
           const char *checksum = value;
           g_autofree char *commitpartial_path = _ostree_get_commitpartial_path (checksum);
 
-          if (unlinkat (pull_data->repo->repo_dir_fd, commitpartial_path, 0) != 0)
-            {
-              if (errno != ENOENT)
-                {
-                  glnx_set_error_from_errno (error);
-                  goto out;
-                }
-            }
+          if (!ot_ensure_unlinked_at (pull_data->repo->repo_dir_fd, commitpartial_path, 0))
+            goto out;
         }
         g_hash_table_iter_init (&hash_iter, commits_to_fetch);
         while (g_hash_table_iter_next (&hash_iter, &key, &value))
@@ -2193,14 +2189,8 @@ ostree_repo_pull_with_options (OstreeRepo             *self,
             const char *commit = value;
             g_autofree char *commitpartial_path = _ostree_get_commitpartial_path (commit);
 
-            if (unlinkat (pull_data->repo->repo_dir_fd, commitpartial_path, 0) != 0)
-              {
-                if (errno != ENOENT)
-                  {
-                    glnx_set_error_from_errno (error);
-                    goto out;
-                  }
-              }
+            if (!ot_ensure_unlinked_at (pull_data->repo->repo_dir_fd, commitpartial_path, 0))
+              goto out;
           }
     }
 
diff --git a/src/libostree/ostree-repo.c b/src/libostree/ostree-repo.c
index 5499dc11..106298a4 100644
--- a/src/libostree/ostree-repo.c
+++ b/src/libostree/ostree-repo.c
@@ -2652,6 +2652,58 @@ ostree_repo_load_variant (OstreeRepo       *self,
 }
 
 /**
+ * ostree_repo_load_commit:
+ * @self: Repo
+ * @checksum: Commit checksum
+ * @out_commit: (out) (allow-none): Commit
+ * @out_state: (out) (allow-none): Commit state
+ * @error: Error
+ *
+ * A version of ostree_repo_load_variant() specialized to commits,
+ * capable of returning extended state information.  Currently
+ * the only extended state is %OSTREE_REPO_COMMIT_STATE_PARTIAL, which
+ * means that only a sub-path of the commit is available.
+ */
+gboolean
+ostree_repo_load_commit (OstreeRepo            *self,
+                         const char            *checksum, 
+                         GVariant             **out_variant,
+                         OstreeRepoCommitState *out_state,
+                         GError               **error)
+{
+  gboolean ret = FALSE;
+
+  if (out_variant)
+    {
+      if (!load_metadata_internal (self, OSTREE_OBJECT_TYPE_COMMIT, checksum, TRUE,
+                                   out_variant, NULL, NULL, NULL, error))
+        goto out;
+    }
+
+  if (out_state)
+    {
+      g_autofree char *commitpartial_path = _ostree_get_commitpartial_path (checksum);
+      struct stat stbuf;
+
+      *out_state = 0;
+
+      if (fstatat (self->repo_dir_fd, commitpartial_path, &stbuf, 0) == 0)
+        {
+          *out_state |= OSTREE_REPO_COMMIT_STATE_PARTIAL;
+        }
+      else if (errno != ENOENT)
+        {
+          glnx_set_error_from_errno (error);
+          goto out;
+        }
+    }
+
+  ret = TRUE;
+ out:
+  return ret;
+}
+
+/**
  * ostree_repo_list_objects:
  * @self: Repo
  * @flags: Flags controlling enumeration
diff --git a/src/libostree/ostree-repo.h b/src/libostree/ostree-repo.h
index e6614dfa..c882356a 100644
--- a/src/libostree/ostree-repo.h
+++ b/src/libostree/ostree-repo.h
@@ -280,6 +280,16 @@ gboolean      ostree_repo_load_variant_if_exists (OstreeRepo  *self,
                                                   GVariant     **out_variant,
                                                   GError       **error);
 
+typedef enum {
+  OSTREE_REPO_COMMIT_STATE_PARTIAL = (1 << 0),
+} OstreeRepoCommitState;
+
+gboolean      ostree_repo_load_commit (OstreeRepo            *self,
+                                       const char            *checksum, 
+                                       GVariant             **out_commit,
+                                       OstreeRepoCommitState *out_state,
+                                       GError               **error);
+
 gboolean ostree_repo_load_file (OstreeRepo         *self,
                                 const char         *checksum,
                                 GInputStream      **out_input,
diff --git a/src/libotutil/ot-fs-utils.c b/src/libotutil/ot-fs-utils.c
index 040636bd..b0f41a64 100644
--- a/src/libotutil/ot-fs-utils.c
+++ b/src/libotutil/ot-fs-utils.c
@@ -22,6 +22,7 @@
 
 #include "ot-fs-utils.h"
 #include "libgsystem.h"
+#include "libglnx.h"
 #include <sys/xattr.h>
 #include <gio/gunixinputstream.h>
 
@@ -188,3 +189,20 @@ ot_openat_read_stream (int             dfd,
  out:
   return ret;
 }
+
+gboolean
+ot_ensure_unlinked_at (int dfd,
+                       const char *path,
+                       GError **error)
+{
+  if (unlinkat (dfd, path, 0) != 0)
+    {
+      if (G_UNLIKELY (errno != ENOENT))
+        {
+          glnx_set_error_from_errno (error);
+          return FALSE;
+        }
+    }
+  return TRUE;
+}
+
diff --git a/src/libotutil/ot-fs-utils.h b/src/libotutil/ot-fs-utils.h
index 0113da46..10686be6 100644
--- a/src/libotutil/ot-fs-utils.h
+++ b/src/libotutil/ot-fs-utils.h
@@ -57,4 +57,8 @@ gboolean ot_openat_read_stream (int             dfd,
                                 GCancellable   *cancellable,
                                 GError        **error);
 
+gboolean ot_ensure_unlinked_at (int dfd,
+                                const char *path,
+                                GError **error);
+
 G_END_DECLS
diff --git a/src/ostree/ot-builtin-fsck.c b/src/ostree/ot-builtin-fsck.c
index ae1dcce4..8f340439 100644
--- a/src/ostree/ot-builtin-fsck.c
+++ b/src/ostree/ot-builtin-fsck.c
@@ -25,6 +25,7 @@
 #include "ot-main.h"
 #include "ot-builtins.h"
 #include "ostree.h"
+#include "ostree-cmdprivate.h"
 #include "otutil.h"
 
 static gboolean opt_quiet;
@@ -242,6 +243,7 @@ ostree_builtin_fsck (int argc, char **argv, GCancellable *cancellable, GError **
   GHashTableIter hash_iter;
   gpointer key, value;
   gboolean found_corruption = FALSE;
+  guint n_partial = 0;
   gs_unref_hashtable GHashTable *objects = NULL;
   gs_unref_hashtable GHashTable *commits = NULL;
 
@@ -267,11 +269,22 @@ ostree_builtin_fsck (int argc, char **argv, GCancellable *cancellable, GError **
       GVariant *serialized_key = key;
       const char *checksum;
       OstreeObjectType objtype;
+      OstreeRepoCommitState commitstate = 0;
 
       ostree_object_name_deserialize (serialized_key, &checksum, &objtype);
 
       if (objtype == OSTREE_OBJECT_TYPE_COMMIT)
-        g_hash_table_insert (commits, g_variant_ref (serialized_key), serialized_key);
+        {
+          if (!ostree_repo_load_commit (repo, checksum, NULL, &commitstate, error))
+            goto out;
+
+          if (commitstate & OSTREE_REPO_COMMIT_STATE_PARTIAL)
+            {
+              n_partial++;
+            }
+          else
+            g_hash_table_insert (commits, g_variant_ref (serialized_key), serialized_key);
+        }
     }
 
   g_clear_pointer (&objects, (GDestroyNotify) g_hash_table_unref);
@@ -284,6 +297,11 @@ ostree_builtin_fsck (int argc, char **argv, GCancellable *cancellable, GError **
                                             cancellable, error))
     goto out;
 
+  if (n_partial > 0)
+    {
+      g_print ("%u partial commits not verified\n", n_partial);
+    }
+
   if (found_corruption)
     {
       g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_FAILED,