libostree: Add initial GRUB2 support

In this approach, we drop a /etc/grub.d/15_ostree file which is a
hybrid of shell/C that picks up bits from the GRUB2 library (e.g. the
block device script generation), and then calls into libostree's
GRUB2 code which knows about the BLS entries.

This is admittedly ugly.  There exists another approach for GRUB2 to
learn the BLS specification.  However, the spec has a few issues:

https://www.redhat.com/archives/anaconda-devel-list/2014-July/msg00002.html

This approach also gives a bit more control to the admin via the
naming of the 15_ostree symlink; they can easily disable it:

Or reorder the ostree entries ahead of 10_linux:

Also, this approach doesn't require patches for grub2, which is an
issue with the pressure to backport (rpm-)OSTree to EL7.
This commit is contained in:
Colin Walters committed 2014-10-16 14:15:00 -04:00
1 parent 92c5a9f992
commit d546abfa2a
19 files changed
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/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
*
* Copyright (C) 2014 Colin Walters <walters@verbum.org>
*
* This program 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 licence 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 "ostree-sysroot-private.h"
#include "ostree-bootloader-grub2.h"
#include "otutil.h"
#include <gio/gfiledescriptorbased.h>
#include <gio/gunixoutputstream.h>
#include "libgsystem.h"
#include <string.h>
struct _OstreeBootloaderGrub2
{
GObject parent_instance;
OstreeSysroot *sysroot;
GFile *config_path_bios;
};
typedef GObjectClass OstreeBootloaderGrub2Class;
static void _ostree_bootloader_grub2_bootloader_iface_init (OstreeBootloaderInterface *iface);
G_DEFINE_TYPE_WITH_CODE (OstreeBootloaderGrub2, _ostree_bootloader_grub2, G_TYPE_OBJECT,
G_IMPLEMENT_INTERFACE (OSTREE_TYPE_BOOTLOADER, _ostree_bootloader_grub2_bootloader_iface_init));
static gboolean
_ostree_bootloader_grub2_query (OstreeBootloader *bootloader)
{
OstreeBootloaderGrub2 *self = OSTREE_BOOTLOADER_GRUB2 (bootloader);
return g_file_query_exists (self->config_path_bios, NULL);
}
static const char *
_ostree_bootloader_grub2_get_name (OstreeBootloader *bootloader)
{
return "grub2";
}
gboolean
_ostree_bootloader_grub2_generate_config (OstreeBootloaderGrub2 *self,
int bootversion,
int target_fd,
GCancellable *cancellable,
GError **error)
{
gboolean ret = FALSE;
GString *output = g_string_new ("");
gs_unref_object GOutputStream *out_stream = NULL;
gs_unref_ptrarray GPtrArray *loader_configs = NULL;
guint i;
gsize bytes_written;
/* So... yeah. Just going to hardcode these. */
static const char hardcoded_video[] = "load_video\n"
"set gfxpayload=keep\n";
static const char hardcoded_insmods[] = "insmod gzio\n";
const char *grub2_boot_device_id =
g_getenv ("GRUB2_BOOT_DEVICE_ID");
const char *grub2_prepare_root_cache =
g_getenv ("GRUB2_PREPARE_ROOT_CACHE");
/* We must have been called via the wrapper script */
g_assert (grub2_boot_device_id != NULL);
g_assert (grub2_prepare_root_cache != NULL);
out_stream = g_unix_output_stream_new (target_fd, FALSE);
if (!_ostree_sysroot_read_boot_loader_configs (self->sysroot, bootversion,
&loader_configs,
cancellable, error))
goto out;
for (i = 0; i < loader_configs->len; i++)
{
OstreeBootconfigParser *config = loader_configs->pdata[i];
const char *title;
const char *options;
const char *kernel;
const char *initrd;
char *quoted_title = NULL;
char *uuid = NULL;
char *quoted_uuid = NULL;
title = ostree_bootconfig_parser_get (config, "title");
if (!title)
title = "(Untitled)";
kernel = ostree_bootconfig_parser_get (config, "linux");
quoted_title = g_shell_quote (title);
uuid = g_strdup_printf ("ostree-%u-%s", (guint)i, grub2_boot_device_id);
quoted_uuid = g_shell_quote (uuid);
g_string_append_printf (output, "menuentry %s --class gnu-linux --class gnu --class os --unrestricted %s {\n", quoted_title, quoted_uuid);
g_free (uuid);
g_free (quoted_title);
g_free (quoted_uuid);
/* Hardcoded sections */
g_string_append (output, hardcoded_video);
g_string_append (output, hardcoded_insmods);
g_string_append (output, grub2_prepare_root_cache);
g_string_append_c (output, '\n');
if (!kernel)
{
g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED,
"No \"linux\" key in bootloader config");
goto out;
}
g_string_append (output, "linux16 ");
g_string_append (output, kernel);
options = ostree_bootconfig_parser_get (config, "options");
if (options)
{
g_string_append_c (output, ' ');
g_string_append (output, options);
}
g_string_append_c (output, '\n');
initrd = ostree_bootconfig_parser_get (config, "initrd");
if (initrd)
{
g_string_append (output, "initrd16 ");
g_string_append (output, initrd);
g_string_append_c (output, '\n');
}
g_string_append (output, "}\n");
}
if (!g_output_stream_write_all (out_stream, output->str, output->len,
&bytes_written, cancellable, error))
goto out;
ret = TRUE;
out:
if (output)
g_string_free (output, TRUE);
return ret;
}
static gboolean
_ostree_bootloader_grub2_write_config (OstreeBootloader *bootloader,
int bootversion,
GCancellable *cancellable,
GError **error)
{
OstreeBootloaderGrub2 *self = OSTREE_BOOTLOADER_GRUB2 (bootloader);
gboolean ret = FALSE;
gs_unref_object GFile *new_config_path = NULL;
gs_unref_object GSSubprocessContext *procctx = NULL;
gs_unref_object GSSubprocess *proc = NULL;
gs_strfreev char **child_env = g_get_environ ();
gs_free char *bootversion_str = g_strdup_printf ("%u", (guint)bootversion);
new_config_path = ot_gfile_resolve_path_printf (self->sysroot->path, "boot/loader.%d/grub.cfg",
bootversion);
procctx = gs_subprocess_context_newv ("grub2-mkconfig", "-o",
gs_file_get_path_cached (new_config_path),
NULL);
child_env = g_environ_setenv (child_env, "_OSTREE_GRUB2_BOOTVERSION", bootversion_str, TRUE);
gs_subprocess_context_set_environment (procctx, child_env);
gs_subprocess_context_set_stdout_disposition (procctx, GS_SUBPROCESS_STREAM_DISPOSITION_NULL);
if (g_getenv ("OSTREE_DEBUG_GRUB2"))
gs_subprocess_context_set_stderr_disposition (procctx, GS_SUBPROCESS_STREAM_DISPOSITION_INHERIT);
else
gs_subprocess_context_set_stderr_disposition (procctx, GS_SUBPROCESS_STREAM_DISPOSITION_NULL);
/* In the current Fedora grub2 package, this script doesn't even try
to be atomic; it just does:
cat ${grub_cfg}.new > ${grub_cfg}
rm -f ${grub_cfg}.new
Upstream is fixed though.
*/
proc = gs_subprocess_new (procctx, cancellable, error);
if (!proc)
goto out;
if (!gs_subprocess_wait_sync_check (proc, cancellable, error))
goto out;
/* Now let's fdatasync() for the new file */
if (!gs_file_sync_data (new_config_path, cancellable, error))
goto out;
ret = TRUE;
out:
return ret;
}
static gboolean
_ostree_bootloader_grub2_is_atomic (OstreeBootloader *bootloader)
{
return TRUE;
}
static void
_ostree_bootloader_grub2_finalize (GObject *object)
{
OstreeBootloaderGrub2 *self = OSTREE_BOOTLOADER_GRUB2 (object);
g_clear_object (&self->sysroot);
g_clear_object (&self->config_path_bios);
G_OBJECT_CLASS (_ostree_bootloader_grub2_parent_class)->finalize (object);
}
void
_ostree_bootloader_grub2_init (OstreeBootloaderGrub2 *self)
{
}
static void
_ostree_bootloader_grub2_bootloader_iface_init (OstreeBootloaderInterface *iface)
{
iface->query = _ostree_bootloader_grub2_query;
iface->get_name = _ostree_bootloader_grub2_get_name;
iface->write_config = _ostree_bootloader_grub2_write_config;
iface->is_atomic = _ostree_bootloader_grub2_is_atomic;
}
void
_ostree_bootloader_grub2_class_init (OstreeBootloaderGrub2Class *class)
{
GObjectClass *object_class = G_OBJECT_CLASS (class);
object_class->finalize = _ostree_bootloader_grub2_finalize;
}
OstreeBootloaderGrub2 *
_ostree_bootloader_grub2_new (OstreeSysroot *sysroot)
{
OstreeBootloaderGrub2 *self = g_object_new (OSTREE_TYPE_BOOTLOADER_GRUB2, NULL);
self->sysroot = g_object_ref (sysroot);
self->config_path_bios = g_file_resolve_relative_path (self->sysroot->path, "boot/grub2/grub.cfg");
return self;
}