From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001

From: Peter Jones <pjones@redhat.com>

Date: Thu, 4 Oct 2018 14:22:09 -0400

Subject: [PATCH] Reimplement boot_counter

This adds "increment" and "decrement" commands, and uses them to maintain our

variables in 01_fallback_counter.  It also simplifies the counter logic, so

that there are no nested tests that conflict with each other.

Apparently, this *really* wasn't tested well enough.

Resolves: rhbz#1614637

Signed-off-by: Peter Jones <pjones@redhat.com>

[lorbus: add comments and revert logic changes in 01_fallback_counting]

Signed-off-by: Christian Glombek <lorbus@fedoraproject.org>

---

 Makefile.util.def                   |   6 +++

 grub-core/Makefile.core.def         |   5 ++

 grub-core/commands/increment.c      | 105 ++++++++++++++++++++++++++++++++++++

 util/grub.d/01_fallback_counting.in |  22 ++++++++

 4 files changed, 138 insertions(+)

 create mode 100644 grub-core/commands/increment.c

 create mode 100644 util/grub.d/01_fallback_counting.in

diff --git a/Makefile.util.def b/Makefile.util.def

index 08cc98ddb..eca3dfa75 100644

--- a/Makefile.util.def

+++ b/Makefile.util.def

@@ -448,6 +448,12 @@ script = {

   installdir = grubconf;

 };

+script = {

+  name = '01_fallback_counting';

+  common = util/grub.d/01_fallback_counting.in;

+  installdir = grubconf;

+};

+

 script = {

   name = '01_menu_auto_hide';

   common = util/grub.d/01_menu_auto_hide.in;

diff --git a/grub-core/Makefile.core.def b/grub-core/Makefile.core.def

index 6864e780f..c8a50b4fc 100644

--- a/grub-core/Makefile.core.def

+++ b/grub-core/Makefile.core.def

@@ -362,6 +362,11 @@ kernel = {

   extra_dist = kern/mips/cache_flush.S;

 };

+module = {

+  name = increment;

+  common = commands/increment.c;

+};

+

 program = {

   name = grub-emu;

   mansection = 1;

diff --git a/grub-core/commands/increment.c b/grub-core/commands/increment.c

new file mode 100644

index 000000000..79cf13765

--- /dev/null

+++ b/grub-core/commands/increment.c

@@ -0,0 +1,105 @@

+/* increment.c - Commands to increment and decrement variables. */

+/*

+ *  GRUB  --  GRand Unified Bootloader

+ *  Copyright (C) 2006,2007,2008  Free Software Foundation, Inc.

+ *

+ *  GRUB is free software: you can redistribute it and/or modify

+ *  it under the terms of the GNU General Public License as published by

+ *  the Free Software Foundation, either version 3 of the License, or

+ *  (at your option) any later version.

+ *

+ *  GRUB 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 General Public License for more details.

+ *

+ *  You should have received a copy of the GNU General Public License

+ *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.

+ */

+

+#include <grub/dl.h>

+#include <grub/term.h>

+#include <grub/time.h>

+#include <grub/types.h>

+#include <grub/misc.h>

+#include <grub/extcmd.h>

+#include <grub/i18n.h>

+#include <grub/env.h>

+

+GRUB_MOD_LICENSE ("GPLv3+");

+

+typedef enum {

+    INCREMENT,

+    DECREMENT,

+} operation;

+

+static grub_err_t

+incr_decr(operation op, int argc, char **args)

+{

+  const char *old;

+  char *new;

+  long value;

+

+  if (argc < 1)

+    return grub_error (GRUB_ERR_BAD_ARGUMENT, N_ ("no variable specified"));

+  if (argc > 1)

+    return grub_error (GRUB_ERR_BAD_ARGUMENT, N_ ("too many arguments"));

+

+  old = grub_env_get (*args);

+  if (!old)

+    return grub_error (GRUB_ERR_FILE_NOT_FOUND, N_("No such variable \"%s\""),

+		       *args);

+

+  value = grub_strtol (old, NULL, 0);

+  if (grub_errno != GRUB_ERR_NONE)

+    return grub_errno;

+

+  switch (op)

+    {

+    case INCREMENT:

+      value += 1;

+      break;

+    case DECREMENT:

+      value -= 1;

+      break;

+    }

+

+  new = grub_xasprintf ("%ld", value);

+  if (!new)

+    return grub_errno;

+

+  grub_env_set (*args, new);

+  grub_free (new);

+

+  return GRUB_ERR_NONE;

+}

+

+static grub_err_t

+grub_cmd_incr(struct grub_command *cmd UNUSED,

+              int argc, char **args)

+{

+  return incr_decr(INCREMENT, argc, args);

+}

+

+static grub_err_t

+grub_cmd_decr(struct grub_command *cmd UNUSED,

+              int argc, char **args)

+{

+  return incr_decr(DECREMENT, argc, args);

+}

+

+static grub_command_t cmd_incr, cmd_decr;

+

+GRUB_MOD_INIT(increment)

+{

+  cmd_incr = grub_register_command ("increment", grub_cmd_incr, N_("VARIABLE"),

+                                    N_("increment VARIABLE"));

+  cmd_decr = grub_register_command ("decrement", grub_cmd_decr, N_("VARIABLE"),

+                                    N_("decrement VARIABLE"));

+}

+

+GRUB_MOD_FINI(increment)

+{

+  grub_unregister_command (cmd_incr);

+  grub_unregister_command (cmd_decr);

+}

diff --git a/util/grub.d/01_fallback_counting.in b/util/grub.d/01_fallback_counting.in

new file mode 100644

index 000000000..be0e770ea

--- /dev/null

+++ b/util/grub.d/01_fallback_counting.in

@@ -0,0 +1,22 @@

+#! /bin/sh -e

+

+# Boot Counting

+# The boot_counter env var can be used to count down boot attempts after an

+# OSTree upgrade and choose the rollback deployment when 0 is reached.  Both

+# boot_counter and boot_success need to be (re-)set from userspace.

+cat << EOF

+insmod increment

+# Check if boot_counter exists and boot_success=0 to activate this behaviour.

+if [ -n "\${boot_counter}" -a "\${boot_success}" = "0" ]; then

+  # if countdown has ended, choose to boot rollback deployment (default=1 on

+  # OSTree-based systems)

+  if  [ "\${boot_counter}" = "0" -o "\${boot_counter}" = "-1" ]; then

+    set default=1

+    set boot_counter=-1

+  # otherwise decrement boot_counter

+  else

+    decrement boot_counter

+  fi

+  save_env boot_counter

+fi

+EOF