use actually filled extent size if available

diff --git a/grub-core/fs/btrfs.c b/grub-core/fs/btrfs.c
index 7b1888502faf63dee4cc2670e7cb1fb041da4e5f..0b0e5259c5f68c39abe955ee5870c116ec2b96ae 100644 (file)
--- a/grub-core/fs/btrfs.c
+++ b/grub-core/fs/btrfs.c
@@ -83,6 +83,7 @@ struct grub_btrfs_data
 
   /* Cached extent data.  */
   grub_uint64_t extstart;
+  grub_uint64_t extend;
   grub_uint64_t extino;
   grub_uint64_t exttree;
   grub_size_t extsize;
@@ -202,6 +203,7 @@ struct grub_btrfs_extent_data
       grub_uint64_t laddr;
       grub_uint64_t compressed_size;
       grub_uint64_t offset;
+      grub_uint64_t filled;
     };
   };
 } __attribute__ ((packed));
@@ -872,12 +874,12 @@ grub_btrfs_extent_read (struct grub_btrfs_data *data,
       grub_err_t err;
       grub_off_t extoff;
       if (!data->extent || data->extstart > pos || data->extino != ino
-         || data->exttree != tree
-         || grub_le_to_cpu64 (data->extent->size) + data->extstart <= pos)
+         || data->exttree != tree || data->extend <= pos)
        {
          struct grub_btrfs_key key_in, key_out;
          grub_disk_addr_t elemaddr;
          grub_size_t elemsize;
+
          grub_free (data->extent);
          key_in.object_id = ino;
          key_in.type = GRUB_BTRFS_ITEM_TYPE_EXTENT_ITEM;
@@ -904,15 +906,29 @@ grub_btrfs_extent_read (struct grub_btrfs_data *data,
                                         data->extent, elemsize);
          if (err)
            return err;
-         if (grub_le_to_cpu64 (data->extent->size) + data->extstart <= pos)
-           return grub_error (GRUB_ERR_BAD_FS, "extent not found");
+
+         data->extend = data->extstart
+           + grub_le_to_cpu64 (data->extent->size);
+         if (data->extent->type == GRUB_BTRFS_EXTENT_REGULAR
+             && (char *) &data->extent + elemsize
+             >= (char *) &data->extent->filled
+             + sizeof (data->extent->filled))
+           data->extend = data->extstart
+             + grub_le_to_cpu64 (data->extent->filled);
+
          grub_dprintf ("btrfs", "extent 0x%" PRIxGRUB_UINT64_T "+0x%"
-                       PRIxGRUB_UINT64_T "\n",
+                       PRIxGRUB_UINT64_T " (0x%"
+                       PRIxGRUB_UINT64_T ")\n",
                        grub_le_to_cpu64 (key_out.offset),
-                       grub_le_to_cpu64 (data->extent->size));
+                       grub_le_to_cpu64 (data->extent->size),
+                       grub_le_to_cpu64 (data->extent->filled));
+         if (data->extend <= pos)
+           {
+             grub_error (GRUB_ERR_BAD_FS, "extent not found");
+             return -1;
+           }
        }
-      csize = grub_le_to_cpu64 (data->extent->size)
-       + grub_le_to_cpu64 (data->extstart) - pos;
+      csize = data->extend - pos;
       extoff = pos - data->extstart;
       if (csize > len)
        csize = len;