From 58dcf7985b20de876a6fc44a591aa377d0a0302c Mon Sep 17 00:00:00 2001
From: Michael Chang <[email protected]>
Date: Thu, 10 Feb 2022 22:16:58 +0800
Subject: [PATCH] grub-install: bailout root device probing

The root device is probed to test if the filesystem is btrfs in order to setup
boot configs for snapshot booting. However when the root device is a lvm thin
volume, due to lack in grub support, the probing will be errored out and entire
installation process aborts.

Here we call out stat to bailout the situation whenever grub fails to probe
filesystem in it's own right.

  stat -f -c %T /

The command is also used by grub-mkconfig for the same purpose.

Signed-off-by: Michael Chang <[email protected]>
---
 grub-core/osdep/basic/no_platform.c |  5 +++++
 grub-core/osdep/unix/platform.c     | 34 +++++++++++++++++++++++++++++
 grub-core/osdep/windows/platform.c  |  6 +++++
 include/grub/util/install.h         |  3 +++
 util/grub-install.c                 | 31 ++++++++++++++++++--------
 5 files changed, 70 insertions(+), 9 deletions(-)

--- a/grub-core/osdep/basic/no_platform.c
+++ b/grub-core/osdep/basic/no_platform.c
@@ -51,3 +51,8 @@
   grub_util_error ("%s", _("no zIPL routines are available for your platform"));
 }
 
+char *
+grub_install_get_filesystem (const char *path)
+{
+  return NULL;
+}
--- a/grub-core/osdep/unix/platform.c
+++ b/grub-core/osdep/unix/platform.c
@@ -250,3 +250,37 @@
 	"-z", dest, NULL }))
     grub_util_error (_("`%s' failed.\n"), PACKAGE"-zipl-setup");
 }
+
+char *
+grub_install_get_filesystem (const char *path)
+{
+  int fd;
+  pid_t pid;
+  FILE *fp;
+  ssize_t len;
+  char *buf = NULL;
+  size_t bufsz = 0;
+
+  pid = grub_util_exec_pipe ((const char * []){ "stat", "-f", "-c", "%T", path, NULL }, &fd);
+  if (!pid)
+    return NULL;
+
+  fp = fdopen (fd, "r");
+  if (!fp)
+    return NULL;
+
+  len = getline (&buf, &bufsz, fp);
+  if (len == -1)
+    {
+      free (buf);
+      fclose (fp);
+      return NULL;
+    }
+
+  fclose (fp);
+
+  if (len > 0 && buf[len - 1] == '\n')
+    buf[len - 1] = '\0';
+
+  return buf;
+}
--- a/grub-core/osdep/windows/platform.c
+++ b/grub-core/osdep/windows/platform.c
@@ -440,3 +440,9 @@
 {
   grub_util_error ("%s", _("no zIPL routines are available for your platform"));
 }
+
+char *
+grub_install_get_filesystem (const char *path)
+{
+  return NULL;
+}
--- a/include/grub/util/install.h
+++ b/include/grub/util/install.h
@@ -251,6 +251,9 @@
 void
 grub_install_zipl (const char *d, int i, int f);
 
+char *
+grub_install_get_filesystem (const char *path);
+
 int
 grub_install_compress_gzip (const char *src, const char *dest);
 int
--- a/util/grub-install.c
+++ b/util/grub-install.c
@@ -887,7 +887,6 @@
   const char *efi_file = NULL;
   char **grub_devices;
   grub_fs_t grub_fs;
-  grub_fs_t root_fs;
   grub_device_t grub_dev = NULL;
   enum grub_install_plat platform;
   char *grubdir, *device_map;
@@ -1067,8 +1066,10 @@
   grub_host_init ();
 
   {
-    char *rootdir_grub_devname;
-    grub_device_t rootdir_grub_dev;
+    grub_device_t rootdir_grub_dev = NULL;
+    char *rootdir_grub_devname = NULL;
+    char *root_fs_name = NULL;
+
     char *t = grub_util_path_concat (2, "/", rootdir);
 
     rootdir_path = grub_canonicalize_file_name (t);
@@ -1089,20 +1090,32 @@
 		       rootdir_devices[0]);
 
     rootdir_grub_dev = grub_device_open (rootdir_grub_devname);
-    if (! rootdir_grub_dev)
-      grub_util_error ("%s", grub_errmsg);
+    if (!rootdir_grub_dev)
+      {
+	root_fs_name = grub_install_get_filesystem (t);
+	if (root_fs_name)
+	  grub_errno = 0;
+      }
+    else
+      {
+	grub_fs_t root_fs = grub_fs_probe (rootdir_grub_dev);
+	if (root_fs)
+	  root_fs_name = grub_strdup (root_fs->name);
+      }
 
-    root_fs = grub_fs_probe (rootdir_grub_dev);
-    if (!root_fs)
+    if (!root_fs_name)
       grub_util_error ("%s", grub_errmsg);
 
     if (config.is_suse_btrfs_snapshot_enabled
-	&& grub_strncmp(root_fs->name, "btrfs", sizeof ("btrfs") - 1) == 0)
+	&& root_fs_name
+	&& grub_strncmp(root_fs_name, "btrfs", sizeof ("btrfs") - 1) == 0)
       use_relative_path_on_btrfs = 1;
 
+    free (root_fs_name);
     free (t);
     free (rootdir_grub_devname);
-    grub_device_close (rootdir_grub_dev);
+    if (rootdir_grub_dev)
+      grub_device_close (rootdir_grub_dev);
   }
 
   switch (platform)