[PATCH v5 3/3] search: new --efidisk-only option on EFI systems

[Renaud Métrich]

When using 'search' on EFI systems, we sometimes want to exclude devices
that are not EFI disks (e.g. md, lvm).
This is typically used when wanting to chainload when having a software
raid (md) for EFI partition:
with no option, 'search --file /EFI/redhat/shimx64.efi' sets root envvar
to 'md/boot_efi' which cannot be used for chainloading since there is no
effective EFI device behind.

Signed-off-by: Renaud Métrich <rmetrich@redhat.com>
---
 docs/grub.texi                   |  5 ++++-
 grub-core/commands/search.c      | 19 +++++++++++++++++++
 grub-core/commands/search_wrap.c |  5 +++++
 include/grub/search.h            |  3 ++-
 4 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/docs/grub.texi b/docs/grub.texi
index a72d73ce3..acdb479e0 100644
--- a/docs/grub.texi
+++ b/docs/grub.texi
@@ -5003,7 +5003,7 @@ unbootable. @xref{Using digital signatures}, for more 
information.
 
 @deffn Command search @
  [@option{--file}|@option{--label}|@option{--fs-uuid}] @
- [@option{--set} [var]] [@option{--no-floppy}] name
+ [@option{--set} [var]] [@option{--no-floppy}|@option{--efidisk-only}] name
 Search devices by file (@option{-f}, @option{--file}), filesystem label
 (@option{-l}, @option{--label}), or filesystem UUID (@option{-u},
 @option{--fs-uuid}).
@@ -5015,6 +5015,9 @@ set as the value of environment variable @var{var}. The 
default variable is
 The (@option{-n}, @option{--no-floppy}) option prevents searching floppy
 devices, which can be slow.
 
+The (@option{--efidisk-only}) option prevents searching any other devices then
+EFI disks. This is typically used when chainloading to local EFI partition.
+
 The @samp{search.file}, @samp{search.fs_label}, and @samp{search.fs_uuid}
 commands are aliases for @samp{search --file}, @samp{search --label}, and
 @samp{search --fs-uuid} respectively.
diff --git a/grub-core/commands/search.c b/grub-core/commands/search.c
index 197eccdf8..57d26ced8 100644
--- a/grub-core/commands/search.c
+++ b/grub-core/commands/search.c
@@ -66,6 +66,25 @@ iterate_device (const char *name, void *data)
       name[0] == 'f' && name[1] == 'd' && name[2] >= '0' && name[2] <= '9')
     return 0;
 
+  /* Limit to EFI disks when requested.  */
+  if (ctx->flags & SEARCH_FLAGS_EFIDISK_ONLY)
+    {
+      grub_device_t dev;
+      dev = grub_device_open (name);
+      if (! dev)
+       {
+         grub_errno = GRUB_ERR_NONE;
+         return 0;
+       }
+      if (! dev->disk || dev->disk->dev->id != GRUB_DISK_DEVICE_EFIDISK_ID)
+       {
+         grub_device_close (dev);
+         grub_errno = GRUB_ERR_NONE;
+         return 0;
+       }
+      grub_device_close (dev);
+    }
+
 #ifdef DO_SEARCH_FS_UUID
 #define compare_fn grub_strcasecmp
 #else
diff --git a/grub-core/commands/search_wrap.c b/grub-core/commands/search_wrap.c
index 8e90bbdcc..0b62acf85 100644
--- a/grub-core/commands/search_wrap.c
+++ b/grub-core/commands/search_wrap.c
@@ -40,6 +40,7 @@ static const struct grub_arg_option options[] =
      N_("Set a variable to the first device found."), N_("VARNAME"),
      ARG_TYPE_STRING},
     {"no-floppy",      'n', 0, N_("Do not probe any floppy drive."), 0, 0},
+    {"efidisk-only",   0, 0, N_("Only probe EFI disks."), 0, 0},
     {"hint",           'h', GRUB_ARG_OPTION_REPEATABLE,
      N_("First try the device HINT. If HINT ends in comma, "
        "also try subpartitions"), N_("HINT"), ARG_TYPE_STRING},
@@ -73,6 +74,7 @@ enum options
     SEARCH_FS_UUID,
     SEARCH_SET,
     SEARCH_NO_FLOPPY,
+    SEARCH_EFIDISK_ONLY,
     SEARCH_HINT,
     SEARCH_HINT_IEEE1275,
     SEARCH_HINT_BIOS,
@@ -184,6 +186,9 @@ grub_cmd_search (grub_extcmd_context_t ctxt, int argc, char 
**args)
   if (state[SEARCH_NO_FLOPPY].set)
     flags |= SEARCH_FLAGS_NO_FLOPPY;
 
+  if (state[SEARCH_EFIDISK_ONLY].set)
+    flags |= SEARCH_FLAGS_EFIDISK_ONLY;
+
   if (state[SEARCH_LABEL].set)
     grub_search_label (id, var, flags, hints, nhints);
   else if (state[SEARCH_FS_UUID].set)
diff --git a/include/grub/search.h b/include/grub/search.h
index bbfa6a787..4190aeb2c 100644
--- a/include/grub/search.h
+++ b/include/grub/search.h
@@ -21,7 +21,8 @@
 
 enum search_flags
   {
-    SEARCH_FLAGS_NO_FLOPPY     = 1
+    SEARCH_FLAGS_NO_FLOPPY     = 1,
+    SEARCH_FLAGS_EFIDISK_ONLY  = 2
   };
 
 void grub_search_fs_file (const char *key, const char *var,
-- 
2.35.1