Refactor clean_grub_dir to create a backup of all the files, instead
of just irrevocably removing them as the first action. If available,
register on_exit handle to restore the backup if any errors occur, or
remove the backup if everything was successful. If on_exit is not
available, the backup remains on disk for manual recovery.
This allows safer upgrades of MBR & modules, such that
modules/images/fonts/translations are consistent with MBR in case of
errors. For example accidental grub-install /dev/non-existent-disk
currently clobbers and upgrades modules in /boot/grub, despite not
actually updating any MBR. This increases peak disk-usage slightly, by
requiring temporarily twice the disk space to complete grub-install.
Also add modinfo.sh to the cleanup/backup/restore codepath, to ensure
it is also cleaned / backed up / restored.
Signed-off-by: Dimitri John Ledkov <x...@ubuntu.com>
---
Changes since v1: as reported on linux-ext4 mailing list and debugged
by Colin Watson, the grub_util_path_concat_ext call was incorrect in
the restore backup case as there was no extention needed. Instead the
call is corrected to just grub_util_path_concat.
This patch is now shipped in Ubuntu & Debian in multiple series. It
would be nice to have this merged upstream, as it greatly improves
grub upgrades and prevents missmatches of MBR & modules.
configure.ac | 2 +-
util/grub-install-common.c | 105 +++++++++++++++++++++++++++++++------
2 files changed, 91 insertions(+), 16 deletions(-)
diff --git a/configure.ac b/configure.ac
index 7c10a4db7..71cd414c3 100644
--- a/configure.ac
+++ b/configure.ac
@@ -419,7 +419,7 @@ else
fi
# Check for functions and headers.
-AC_CHECK_FUNCS(posix_memalign memalign getextmntent)
+AC_CHECK_FUNCS(posix_memalign memalign getextmntent on_exit)
AC_CHECK_HEADERS(sys/param.h sys/mount.h sys/mnttab.h limits.h)
# glibc 2.25 still includes sys/sysmacros.h in sys/types.h but emits
deprecation
diff --git a/util/grub-install-common.c b/util/grub-install-common.c
index 277eaf4e2..74584b92b 100644
--- a/util/grub-install-common.c
+++ b/util/grub-install-common.c
@@ -185,38 +185,113 @@ grub_install_mkdir_p (const char *dst)
free (t);
}
+static int
+strcmp_ext (const char *a, const char *b, const char *ext)
+{
+ char *bsuffix = grub_util_path_concat_ext (1, b, ext);
+ int r = strcmp (a, bsuffix);
+ free (bsuffix);
+ return r;
+}
+
+enum clean_grub_dir_mode
+{
+ CLEAN = 0,
+ CLEAN_BACKUP = 1,
+ CREATE_BACKUP = 2,
+ RESTORE_BACKUP = 3,
+};
+
static void
-clean_grub_dir (const char *di)
+clean_grub_dir_real (const char *di, enum clean_grub_dir_mode mode)
{
grub_util_fd_dir_t d;
grub_util_fd_dirent_t de;
+ char suffix[2] = "";
+
+ if ((mode == CLEAN_BACKUP) || (mode == RESTORE_BACKUP))
+ {
+ strcpy (suffix, "-");
+ }
d = grub_util_fd_opendir (di);
if (!d)
- grub_util_error (_("cannot open directory `%s': %s"),
- di, grub_util_fd_strerror ());
+ {
+ if (mode == CLEAN_BACKUP)
+ return;
+ grub_util_error (_("cannot open directory `%s': %s"),
+ di, grub_util_fd_strerror ());
+ }
while ((de = grub_util_fd_readdir (d)))
{
const char *ext = strrchr (de->d_name, '.');
- if ((ext && (strcmp (ext, ".mod") == 0
- || strcmp (ext, ".lst") == 0
- || strcmp (ext, ".img") == 0
- || strcmp (ext, ".mo") == 0)
- && strcmp (de->d_name, "menu.lst") != 0)
- || strcmp (de->d_name, "efiemu32.o") == 0
- || strcmp (de->d_name, "efiemu64.o") == 0)
+ if ((ext && (strcmp_ext (ext, ".mod", suffix) == 0
+ || strcmp_ext (ext, ".lst", suffix) == 0
+ || strcmp_ext (ext, ".img", suffix) == 0
+ || strcmp_ext (ext, ".mo", suffix) == 0)
+ && strcmp_ext (de->d_name, "menu.lst", suffix) != 0)
+ || strcmp_ext (de->d_name, "modinfo.sh", suffix) == 0
+ || strcmp_ext (de->d_name, "efiemu32.o", suffix) == 0
+ || strcmp_ext (de->d_name, "efiemu64.o", suffix) == 0)
{
- char *x = grub_util_path_concat (2, di, de->d_name);
- if (grub_util_unlink (x) < 0)
- grub_util_error (_("cannot delete `%s': %s"), x,
- grub_util_fd_strerror ());
- free (x);
+ char *srcf = grub_util_path_concat (2, di, de->d_name);
+
+ if (mode == CREATE_BACKUP)
+ {
+ char *dstf = grub_util_path_concat_ext (2, di, de->d_name, "-");
+ if (grub_util_rename (srcf, dstf) < 0)
+ grub_util_error (_("cannot backup `%s': %s"), srcf,
+ grub_util_fd_strerror ());
+ free (dstf);
+ }
+ else if (mode == RESTORE_BACKUP)
+ {
+ char *dstf = grub_util_path_concat (2, di, de->d_name);
+ dstf[strlen (dstf) - 1] = 0;
+ if (grub_util_rename (srcf, dstf) < 0)
+ grub_util_error (_("cannot restore `%s': %s"), dstf,
+ grub_util_fd_strerror ());
+ free (dstf);
+ }
+ else
+ {
+ if (grub_util_unlink (srcf) < 0)
+ grub_util_error (_("cannot delete `%s': %s"), srcf,
+ grub_util_fd_strerror ());
+ }
+ free (srcf);
}
}
grub_util_fd_closedir (d);
}
+static void
+restore_backup_on_exit (int status, void *arg)
+{
+ if (status == 0)
+ {
+ clean_grub_dir_real ((char *) arg, CLEAN_BACKUP);
+ }
+ else
+ {
+ clean_grub_dir_real ((char *) arg, CLEAN);
+ clean_grub_dir_real ((char *) arg, RESTORE_BACKUP);
+ }
+ free (arg);
+ arg = NULL;
+}
+
+static void
+clean_grub_dir (const char *di)
+{
+ clean_grub_dir_real (di, CLEAN_BACKUP);
+ clean_grub_dir_real (di, CREATE_BACKUP);
+#if defined(HAVE_ON_EXIT)
+ on_exit (restore_backup_on_exit, strdup (di));
+#endif
+}
+
struct install_list
{
int is_default;
--
2.27.0
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