Add an API+CLI to inject metadata for bootable OSTree commits

I was doing some rpm-ostree work and I wanted to compare two
OSTree commits to see if the kernel has changed.  I think
this should be a lot more natural.

Add `ostree commit --bootable` which calls into a new generic
library API `ostree_commit_metadata_for_bootable()` that
discovers the kernel version and injects it as an `ostree.linux`
metadata key.  And for extra clarity, add an `ostree.bootable`
key.

It's interesting because the "core" OSTree layer is all about
generic files, but this is adding special APIs around bootable
OSTree commits (as opposed to e.g. flatpak as well as
things like rpm-ostree's pkgcache refs).

Eventually, I'd like to ensure everyone is using this and
hard require this metadata key for the `ostree admin deploy`
flow - mainly to prevent accidents.

Makefile-libostree-defines.am

@@ -28,6 +28,7 @@ libostree_public_headers = \
 	src/libostree/ostree-dummy-enumtypes.h \
 	src/libostree/ostree-mutable-tree.h \
 	src/libostree/ostree-repo.h \
+	src/libostree/ostree-repo-os.h \
 	src/libostree/ostree-types.h \
 	src/libostree/ostree-repo-file.h \
 	src/libostree/ostree-diff.h \

Makefile-libostree.am

@@ -92,6 +92,7 @@ libostree_1_la_SOURCES = \
 	src/libostree/ostree-ref.c \
 	src/libostree/ostree-remote.c \
 	src/libostree/ostree-remote-private.h \
+	src/libostree/ostree-repo-os.c \
 	src/libostree/ostree-repo.c \
 	src/libostree/ostree-repo-checkout.c \
 	src/libostree/ostree-repo-commit.c \
@@ -186,10 +187,10 @@ endif # USE_GPGME
 
 symbol_files = $(top_srcdir)/src/libostree/libostree-released.sym
 
-## Uncomment this include when adding new development symbols.
-#if BUILDOPT_IS_DEVEL_BUILD
-#symbol_files += $(top_srcdir)/src/libostree/libostree-devel.sym
-#endif
+# Uncomment this include when adding new development symbols.
+if BUILDOPT_IS_DEVEL_BUILD
+symbol_files += $(top_srcdir)/src/libostree/libostree-devel.sym
+endif
 
 # http://blog.jgc.org/2007/06/escaping-comma-and-space-in-gnu-make.html
 wl_versionscript_arg = -Wl,--version-script=

apidoc/ostree-sections.txt

@@ -152,6 +152,7 @@ ostree_validate_structureof_dirtree
 ostree_validate_structureof_dirmeta
 ostree_commit_get_parent
 ostree_commit_get_timestamp
+ostree_commit_metadata_for_bootable
 ostree_commit_get_content_checksum
 ostree_commit_get_object_sizes
 OstreeCommitSizesEntry

bash/ostree

@@ -321,6 +321,7 @@ _ostree_commit() {
         --canonical-permissions
         --editor -e
         --generate-sizes
+        --bootable
         --link-checkout-speedup
         --no-xattrs
         --orphan

man/ostree-commit.xml

@@ -186,6 +186,13 @@ Boston, MA 02111-1307, USA.
                 </para></listitem>
             </varlistentry>
 
+            <varlistentry>
+                <term><option>--bootable</option></term>
+                <listitem><para>
+                    Inject standard metadata for a bootable Linux filesystem tree.
+                </para></listitem>
+            </varlistentry>
+
             <varlistentry>
                 <term><option>--link-checkout-speedup</option></term>
 

src/libostree/libostree-devel.sym

@@ -22,6 +22,11 @@
    - uncomment the include in Makefile-libostree.am
 */
 
+LIBOSTREE_2021.1 {
+global:
+  ostree_commit_metadata_for_bootable;
+} LIBOSTREE_2020.8;
+
 /* Stub section for the stable release *after* this development one; don't
  * edit this other than to update the year.  This is just a copy/paste
  * source.  Replace $LASTSTABLE with the last stable version, and $NEWVERSION

src/libostree/ostree-repo-os.c

@@ -0,0 +1,83 @@
+/*
+ * SPDX-License-Identifier: LGPL-2.0+
+ *
+ * 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.
+ */
+
+#include "config.h"
+
+#include <sys/types.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <gio/gfiledescriptorbased.h>
+#include <gio/gunixinputstream.h>
+#include "libglnx.h"
+#include "ostree.h"
+#include "ostree-core-private.h"
+#include "ostree-repo-os.h"
+#include "otutil.h"
+
+/**
+ * ostree_commit_metadata_for_bootable:
+ * @root: Root filesystem to be committed
+ * @dict: Dictionary to update
+ *
+ * Update provided @dict with standard metadata for bootable OSTree commits.
+ * Since: 2021.1
+ */
+_OSTREE_PUBLIC
+gboolean
+ostree_commit_metadata_for_bootable (GFile *root, GVariantDict *dict, GCancellable *cancellable, GError **error)
+{
+  g_autoptr(GFile) modules = g_file_resolve_relative_path (root, "usr/lib/modules");
+  g_autoptr(GFileEnumerator) dir_enum 
+    = g_file_enumerate_children (modules, OSTREE_GIO_FAST_QUERYINFO,
+                                 G_FILE_QUERY_INFO_NOFOLLOW_SYMLINKS,
+                                 cancellable, error);
+  if (!dir_enum)
+    return glnx_prefix_error (error, "Opening usr/lib/modules");
+
+  g_autofree char *linux_release = NULL;
+  while (TRUE)
+    {
+      GFileInfo *child_info;
+      GFile *child_path;
+      if (!g_file_enumerator_iterate (dir_enum, &child_info, &child_path,
+                                      cancellable, error))
+        return FALSE;
+      if (child_info == NULL)
+        break;
+      if (g_file_info_get_file_type (child_info) != G_FILE_TYPE_DIRECTORY)
+        continue;
+    
+      g_autoptr(GFile) kernel_path = g_file_resolve_relative_path (child_path, "vmlinuz");
+      if (!g_file_query_exists (kernel_path, NULL))
+        continue;
+
+      if (linux_release != NULL)
+        return glnx_throw (error, "Multiple kernels found in /usr/lib/modules");
+
+      linux_release = g_strdup (g_file_info_get_name (child_info));
+    }
+
+  if (linux_release)
+    {
+      g_variant_dict_insert (dict, OSTREE_METADATA_KEY_BOOTABLE, "b", TRUE);
+      g_variant_dict_insert (dict, OSTREE_METADATA_KEY_LINUX, "s", linux_release);
+      return TRUE;
+    }
+  return glnx_throw (error, "No kernel found in /usr/lib/modules");
+}

src/libostree/ostree-repo-os.h

@@ -0,0 +1,47 @@
+/*
+ * SPDX-License-Identifier: LGPL-2.0+
+ *
+ * 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.
+ */
+
+#pragma once
+
+#include <sys/stat.h>
+#include <gio/gio.h>
+#include <ostree-types.h>
+
+G_BEGIN_DECLS
+
+/** 
+ * OSTREE_METADATA_KEY_BOOTABLE:
+ *
+ * GVariant type `b`: Set if this commit is intended to be bootable
+ * Since: 2021.1
+ */
+#define OSTREE_METADATA_KEY_BOOTABLE "ostree.bootable"
+/** 
+ * OSTREE_METADATA_KEY_LINUX:
+ *
+ * GVariant type `s`: Contains the Linux kernel release (i.e. `uname -r`)
+ * Since: 2021.1
+ */
+#define OSTREE_METADATA_KEY_LINUX "ostree.linux"
+
+_OSTREE_PUBLIC
+gboolean
+ostree_commit_metadata_for_bootable (GFile *root, GVariantDict *dict, GCancellable *cancellable, GError **error);
+
+G_END_DECLS

src/libostree/ostree.h

@@ -24,6 +24,7 @@
 #include <ostree-async-progress.h>
 #include <ostree-core.h>
 #include <ostree-repo.h>
+#include <ostree-repo-os.h>
 #include <ostree-mutable-tree.h>
 #include <ostree-remote.h>
 #include <ostree-repo-file.h>

src/ostree/ot-builtin-commit.c

@@ -35,6 +35,7 @@
 
 static char *opt_subject;
 static char *opt_body;
+static char *opt_bootable;
 static char *opt_body_file;
 static gboolean opt_editor;
 static char *opt_parent;
@@ -112,6 +113,7 @@ static GOptionEntry options[] = {
   { "owner-uid", 0, 0, G_OPTION_ARG_INT, &opt_owner_uid, "Set file ownership user id", "UID" },
   { "owner-gid", 0, 0, G_OPTION_ARG_INT, &opt_owner_gid, "Set file ownership group id", "GID" },
   { "canonical-permissions", 0, 0, G_OPTION_ARG_NONE, &opt_canonical_permissions, "Canonicalize permissions in the same way bare-user does for hardlinked files", NULL },
+  { "bootable", 0, 0, G_OPTION_ARG_NONE, &opt_bootable, "Flag this commit as a bootable OSTree (e.g. contains a Linux kernel)", NULL },
   { "mode-ro-executables", 0, 0, G_OPTION_ARG_NONE, &opt_ro_executables, "Ensure executable files are not writable", NULL },
   { "no-xattrs", 0, 0, G_OPTION_ARG_NONE, &opt_no_xattrs, "Do not import extended attributes", NULL },
   { "selinux-policy", 0, 0, G_OPTION_ARG_FILENAME, &opt_selinux_policy, "Set SELinux labels based on policy in root filesystem PATH (may be /)", "PATH" },
@@ -501,7 +503,7 @@ ostree_builtin_commit (int argc, char **argv, OstreeCommandInvocation *invocatio
       goto out;
     }
 
-  if (opt_metadata_strings || opt_metadata_variants || opt_metadata_keep)
+  if (opt_metadata_strings || opt_metadata_variants || opt_metadata_keep || opt_bootable)
     {
       g_autoptr(GVariantBuilder) builder =
         g_variant_builder_new (G_VARIANT_TYPE ("a{sv}"));
@@ -841,6 +843,17 @@ ostree_builtin_commit (int argc, char **argv, OstreeCommandInvocation *invocatio
           fill_bindings (repo, old_metadata, &metadata);
         }
 
+      if (opt_bootable)
+        {
+          g_autoptr(GVariant) old_metadata = g_steal_pointer (&metadata);
+          g_auto(GVariantDict) bootmeta;
+          g_variant_dict_init (&bootmeta, old_metadata);
+          if (!ostree_commit_metadata_for_bootable (root, &bootmeta, cancellable, error))
+            goto out;
+
+          metadata = g_variant_ref_sink (g_variant_dict_end (&bootmeta));
+        }
+
       if (!opt_timestamp)
         {
           if (!ostree_repo_write_commit (repo, parent, opt_subject, commit_body, metadata,

tests/admin-test.sh

@@ -65,6 +65,12 @@ assert_not_file_has_content status.txt "pending"
 assert_not_file_has_content status.txt "rollback"
 validate_bootloader
 
+# Test the bootable and linux keys
+${CMD_PREFIX} ostree --repo=sysroot/ostree/repo --print-metadata-key=ostree.linux show testos:testos/buildmaster/x86_64-runtime >out.txt
+assert_file_has_content_literal out.txt 3.6.0
+${CMD_PREFIX} ostree --repo=sysroot/ostree/repo --print-metadata-key=ostree.bootable show testos:testos/buildmaster/x86_64-runtime >out.txt
+assert_file_has_content_literal out.txt true
+
 echo "ok deploy command"
 
 ${CMD_PREFIX} ostree admin --print-current-dir > curdir

tests/basic-test.sh

@@ -21,7 +21,7 @@
 
 set -euo pipefail
 
-echo "1..$((86 + ${extra_basic_tests:-0}))"
+echo "1..$((87 + ${extra_basic_tests:-0}))"
 
 CHECKOUT_U_ARG=""
 CHECKOUT_H_ARGS="-H"
@@ -226,6 +226,13 @@ $OSTREE commit ${COMMIT_ARGS} -b test2-no-parent -s '' --parent=none $test_tmpdi
 assert_streq $($OSTREE log test2-no-parent |grep '^commit' | wc -l) "1"
 echo "ok commit no parent"
 
+cd ${test_tmpdir}
+if $OSTREE commit ${COMMIT_ARGS} -b test-bootable --bootable $test_tmpdir/checkout-test2-4 2>err.txt; then
+    fatal "committed non-bootable tree"
+fi
+assert_file_has_content err.txt "error: .*No such file or directory"
+echo "ok commit fails bootable if no kernel"
+
 cd ${test_tmpdir}
 # Do the --bind-ref=<the other test branch>, so we store both branches sorted
 # in metadata and thus the checksums remain the same.

tests/libtest.sh

@@ -415,11 +415,14 @@ setup_os_repository () {
     echo "an hmac file" > ${hmac_path}
     bootcsum=$(cat ${kernel_path} ${initramfs_path} | sha256sum | cut -f 1 -d ' ')
     export bootcsum
+    bootable_flag=""
     # Add the checksum for legacy dirs (/boot, /usr/lib/ostree-boot), but not
     # /usr/lib/modules.
     if [[ $bootdir != usr/lib/modules/* ]]; then
         mv ${kernel_path}{,-${bootcsum}}
         mv ${initramfs_path}{,-${bootcsum}}
+    else
+        bootable_flag="--bootable"
     fi
 
     echo "an executable" > usr/bin/sh
@@ -439,12 +442,12 @@ EOF
     mkdir -p usr/etc/testdirectory
     echo "a default daemon file" > usr/etc/testdirectory/test
 
-    ${CMD_PREFIX} ostree --repo=${test_tmpdir}/testos-repo commit --add-metadata-string version=1.0.9 -b testos/buildmaster/x86_64-runtime -s "Build"
+    ${CMD_PREFIX} ostree --repo=${test_tmpdir}/testos-repo commit ${bootable_flag} --add-metadata-string version=1.0.9 -b testos/buildmaster/x86_64-runtime -s "Build"
 
     # Ensure these commits have distinct second timestamps
     sleep 2
     echo "a new executable" > usr/bin/sh
-    ${CMD_PREFIX} ostree --repo=${test_tmpdir}/testos-repo commit --add-metadata-string version=1.0.10 -b testos/buildmaster/x86_64-runtime -s "Build"
+    ${CMD_PREFIX} ostree --repo=${test_tmpdir}/testos-repo commit ${bootable_flag} --add-metadata-string version=1.0.10 -b testos/buildmaster/x86_64-runtime -s "Build"
 
     cd ${test_tmpdir}
     rm -rf osdata-devel
@@ -453,7 +456,7 @@ EOF
     cd osdata-devel
     mkdir -p usr/include
     echo "a development header" > usr/include/foo.h
-    ${CMD_PREFIX} ostree --repo=${test_tmpdir}/testos-repo commit --add-metadata-string version=1.0.9 -b testos/buildmaster/x86_64-devel -s "Build"
+    ${CMD_PREFIX} ostree --repo=${test_tmpdir}/testos-repo commit ${bootable_flag} --add-metadata-string version=1.0.9 -b testos/buildmaster/x86_64-devel -s "Build"
 
     ${CMD_PREFIX} ostree --repo=${test_tmpdir}/testos-repo fsck -q