[ostree] Teach fsck about partial commits

[Colin Walters <walters src gnome org>]

commit 5becd5ccad47fff009c1578fc870ffad66b940af
Author: Colin Walters <walters verbum org>
Date:   Mon Apr 6 14:19:08 2015 -0400

    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.

 Makefile-tests.am                 |    1 +
 doc/ostree-sections.txt           |    1 +
 src/libostree/ostree-cmdprivate.c |    2 +
 src/libostree/ostree-repo-pull.c  |   28 ++++++-------------
 src/libostree/ostree-repo.c       |   52 +++++++++++++++++++++++++++++++++++++
 src/libostree/ostree-repo.h       |   10 +++++++
 src/libotutil/ot-fs-utils.c       |   18 +++++++++++++
 src/libotutil/ot-fs-utils.h       |    4 +++
 src/ostree/ot-builtin-fsck.c      |   20 +++++++++++++-
 tests/test-oldstyle-partial.sh    |   37 ++++++++++++++++++++++++++
 10 files changed, 153 insertions(+), 20 deletions(-)
---
diff --git a/Makefile-tests.am b/Makefile-tests.am
index bf58424..7350032 100644
--- a/Makefile-tests.am
+++ b/Makefile-tests.am
@@ -48,6 +48,7 @@ testfiles = test-basic \
        test-admin-locking \
        test-repo-checkout-subpath      \
        test-reset-nonlinear \
+       test-oldstyle-partial \
        test-setuid \
        test-delta \
        test-xattrs \
diff --git a/doc/ostree-sections.txt b/doc/ostree-sections.txt
index 9e2ef6c..b75efc9 100644
--- a/doc/ostree-sections.txt
+++ b/doc/ostree-sections.txt
@@ -255,6 +255,7 @@ ostree_repo_write_content_finish
 ostree_repo_resolve_rev
 ostree_repo_list_refs
 ostree_repo_load_variant
+ostree_repo_load_commit
 ostree_repo_load_variant_if_exists
 ostree_repo_load_file
 ostree_repo_load_object_stream
diff --git a/src/libostree/ostree-cmdprivate.c b/src/libostree/ostree-cmdprivate.c
index ea12243..9983493 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 97c044f..db91d1e 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 5499dc1..106298a 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 e6614df..c882356 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 040636b..b0f41a6 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 0113da4..10686be 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 ae1dcce..8f34043 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,
diff --git a/tests/test-oldstyle-partial.sh b/tests/test-oldstyle-partial.sh
new file mode 100644
index 0000000..84460e9
--- /dev/null
+++ b/tests/test-oldstyle-partial.sh
@@ -0,0 +1,37 @@
+#!/bin/bash
+#
+# Copyright (C) 2015 Red Hat, Inc.
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2 of the License, or (at your option) any later version.
+#
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this library; if not, write to the
+# Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+# Boston, MA 02111-1307, USA.
+
+set -e
+
+. $(dirname $0)/libtest.sh
+
+setup_fake_remote_repo1 "archive-z2"
+
+echo '1..1'
+
+cd ${test_tmpdir}
+rm repo -rf
+mkdir repo
+${CMD_PREFIX} ostree --repo=repo init
+${CMD_PREFIX} ostree --repo=repo remote add --set=gpg-verify=false origin $(cat 
httpd-address)/ostree/gnomerepo
+
+ostree --repo=repo pull origin main --subpath /baz
+ostree fsck --repo=repo >fsck.out
+assert_file_has_content fsck.out 'Verifying content integrity of 0 commit objects'
+assert_file_has_content fsck.out '1 partial commits not verified'