Merge ~beidl/grub:focal-devel-bootcounter into ~ubuntu-core-dev/grub/+git/ubuntu:focal-devel

[Alfred E. Neumayer]

Implements "increment" and "decrement" commands as an additional module for counting boot attempts.
Can be used in automatic failover mechanisms where booted userspace can reset the counter
while the bootloader can switch to a different target system in case of exceeding the attempts.

Based on a patch by Peter Jones at Red Hat.
Original patch:
https://git.centos.org/rpms/grub2/blob/98a0ca1734941a1b031d6af57480496779e0d0ca/f/SOURCES/0278-Reimplement-boot_counter.patch

I intend to upstream the patch ASAP, though the legal situation regarding
the CLA needs to be cleared in a dialog first.

Unmerged commits

d34d54d... by Alfred Neumayer on 2021-10-08

debian: Import RH patch for boot increment/decrement command

diff --git a/debian/patches/rhboot-based-failover-counter.patch b/debian/patches/rhboot-based-failover-counter.patch
new file mode 100644
index 0000000..be7d4af
--- /dev/null
+++ b/debian/patches/rhboot-based-failover-counter.patch
@@ -0,0 +1,148 @@
+From ad2d70e4104937aaba9fb95eb3af98ebbe767520 Mon Sep 17 00:00:00 2001
+From: Alfred Neumayer <[e-mail]>
+Date: Mon, 19 Apr 2021 09:10:14 +0200
+Subject: [PATCH] grub-core: Include bootcounter patch from RH
+
+Original message:
+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.
+
+This patch is based on work by Peter Jones, based on this source patch:
+https://git.centos.org/rpms/grub2/blob/98a0ca1734941a1b031d6af57480496779e0d0ca/f/SOURCES/0278-Reimplement-boot_counter.patch
+---
+ grub-core/Makefile.core.def         |   5 ++
+ grub-core/commands/increment.c      | 105 ++++++++++++++++++++++++++++
+ 4 files changed, 131 insertions(+)
+ create mode 100644 grub-core/commands/increment.c
+
+diff --git a/grub-core/Makefile.core.def b/grub-core/Makefile.core.def
+index 9b20f3335..16f723431 100644
+--- a/grub-core/Makefile.core.def
++++ b/grub-core/Makefile.core.def
+@@ -387,6 +387,11 @@ 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..f877fd04d
+--- /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 __attribute__((unused)),
++              int argc, char **args)
++{
++  return incr_decr(INCREMENT, argc, args);
++}
++
++static grub_err_t
++grub_cmd_decr(struct grub_command *cmd __attribute__((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);
++}
+-- 
+2.25.1
+
diff --git a/debian/patches/series b/debian/patches/series
index a9458c8..1c36a79 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -81,3 +81,4 @@ ubuntu-speed-zsys-history.patch
 ubuntu-flavour-order.patch
 ubuntu-dont-verify-loopback-images.patch
 ubuntu-recovery-dis_ucode_ldr.patch
+rhboot-based-failover-counter.patch