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List:       grub-devel
Subject:    [CRYPTO-LUKS v1 13/19] fs: Allow number of blocks in block list to be optional, where length will be
From:       Glenn Washburn <development () efficientek ! com>
Date:       2020-07-31 12:01:54
Message-ID: aa9e5f75f7faf33267f268f53dcae8bb88d8b6d0.1596196383.git.development () efficientek ! com
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This is primarily useful to do something like "loopback newdev (dev)8+" to
create a device that skips the first 4K, which may contain a non-standard
RAID1 header that grub does not recognize. This would allow that initial
data to be accessed and potentially mounted by grub up to the rest of the
disk. There is currently not a good way with in grub to programmatically get
the number of sectors on a disk to select the appropriate number of sectors.

Signed-off-by: Glenn Washburn <development@efficientek.com>
---
 grub-core/kern/fs.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/grub-core/kern/fs.c b/grub-core/kern/fs.c
index 14c17df74..273115b5a 100644
--- a/grub-core/kern/fs.c
+++ b/grub-core/kern/fs.c
@@ -173,7 +173,11 @@ grub_fs_blocklist_open (grub_file_t file, const char *name)
 	}
 
       p++;
-      blocks[i].length = grub_strtoul (p, &p, 0);
+      if (*p == '\0' || *p == ',')
+        blocks[i].length = total_native_sectors - blocks[i].offset;
+      else
+        blocks[i].length = grub_strtoul (p, &p, 0);
+
       if (grub_errno != GRUB_ERR_NONE
 	  || blocks[i].length == 0
 	  || (*p && *p != ',' && ! grub_isspace (*p)))
-- 
2.25.1


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