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From:   Ritesh Harjani <ritesh.list@gmail.com>
To:     Theodore Ts'o <tytso@mit.edu>
Cc:     Harshad Shirwadkar <harshadshirwadkar@gmail.com>,
        Andreas Dilger <adilger@dilger.ca>,
        linux-ext4 <linux-ext4@vger.kernel.org>, Li Xi <lixi@ddn.com>,
        Ritesh Harjani <ritesh.list@gmail.com>
Subject: [RFC 11/13] dblist: add dblist merge logic
Date:   Mon,  4 Jul 2022 12:37:00 +0530
Message-Id: <6150cdbeaeb1bb94a8cda5f138b6206362958d94.1656912918.git.ritesh.list@gmail.com>
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From: Li Xi <lixi@ddn.com>

This adds dblist merge logic.

TODO: Add a unit test for core operations of dblist. Currently there is
no such test for this.

Signed-off-by: Li Xi <lixi@ddn.com>
Signed-off-by: Ritesh Harjani <ritesh.list@gmail.com>
---
 lib/ext2fs/dblist.c | 36 ++++++++++++++++++++++++++++++++++++
 lib/ext2fs/ext2fs.h |  1 +
 2 files changed, 37 insertions(+)

diff --git a/lib/ext2fs/dblist.c b/lib/ext2fs/dblist.c
index bbdb221d..5568b8ec 100644
--- a/lib/ext2fs/dblist.c
+++ b/lib/ext2fs/dblist.c
@@ -119,6 +119,42 @@ errcode_t ext2fs_copy_dblist(ext2_dblist src, ext2_dblist *dest)
 	return 0;
 }
 
+/*
+ * Merge a directory block list @src to @dest
+ */
+errcode_t ext2fs_merge_dblist(ext2_dblist src, ext2_dblist dest)
+{
+   unsigned long long src_count = src->count;
+   unsigned long long dest_count = dest->count;
+   unsigned long long size = src_count + dest_count;
+   size_t size_entry = sizeof(struct ext2_db_entry2);
+   struct ext2_db_entry2 *array, *array2;
+   errcode_t retval;
+
+   if (src_count == 0)
+       return 0;
+
+   if (src->sorted || (dest->sorted && dest_count != 0))
+       return EINVAL;
+
+   retval = ext2fs_get_array(size, size_entry, &array);
+   if (retval)
+       return retval;
+
+   array2 = array;
+   memcpy(array, src->list, src_count * size_entry);
+   array += src_count;
+   memcpy(array, dest->list, dest_count * size_entry);
+   ext2fs_free_mem(&dest->list);
+
+   dest->list = array2;
+   dest->count = src_count + dest_count;
+   dest->size = size;
+   dest->sorted = 0;
+
+   return 0;
+}
+
 /*
  * Close a directory block list
  *
diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
index 13404f3d..29e7be9f 100644
--- a/lib/ext2fs/ext2fs.h
+++ b/lib/ext2fs/ext2fs.h
@@ -1146,6 +1146,7 @@ extern errcode_t ext2fs_add_dir_block(ext2_dblist dblist, ext2_ino_t ino,
 				      blk_t blk, int blockcnt);
 extern errcode_t ext2fs_add_dir_block2(ext2_dblist dblist, ext2_ino_t ino,
 				       blk64_t blk, e2_blkcnt_t blockcnt);
+extern errcode_t ext2fs_merge_dblist(ext2_dblist src, ext2_dblist dest);
 extern void ext2fs_dblist_sort(ext2_dblist dblist,
 			       EXT2_QSORT_TYPE (*sortfunc)(const void *,
 							   const void *));
-- 
2.35.3