Add a "do not deduplicate" block flag

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>

3 files changed, 23 insertions, 11 deletions

diff --git a/include/sqfs/block.h b/include/sqfs/block.h
index b4860ac..5e79ff7 100644
--- a/include/sqfs/block.h
+++ b/include/sqfs/block.h
@@ -89,6 +89,14 @@ typedef enum {
 	SQFS_BLK_DONT_FRAGMENT = 0x0004,
 
 	/**
+	 * @brief Surpress deduplication.
+	 *
+	 * If set on fragments or the last block of a file, it is always
+	 * written to disk, even if a duplicate copy already exists.
+	 */
+	SQFS_BLK_DONT_DEDUPLICATE = 0x0008,
+
+	/**
 	 * @brief Set by the @ref sqfs_block_processor_t if it determines a
 	 *        block of a file to be sparse, i.e. only zero bytes.
 	 */
@@ -127,7 +135,7 @@ typedef enum {
 	/**
 	 * @brief The combination of all flags that are user settable.
 	 */
-	SQFS_BLK_USER_SETTABLE_FLAGS = 0x0007,
+	SQFS_BLK_USER_SETTABLE_FLAGS = 0x000F,
 } E_SQFS_BLK_FLAGS;
 
 #endif /* SQFS_BLOCK_H */
diff --git a/lib/sqfs/block_processor/common.c b/lib/sqfs/block_processor/common.c
index ab83b5d..2c6e59e 100644
--- a/lib/sqfs/block_processor/common.c
+++ b/lib/sqfs/block_processor/common.c
@@ -142,11 +142,15 @@ int process_completed_fragment(sqfs_block_processor_t *proc, sqfs_block_t *frag,
 
 	proc->stats.total_frag_count += 1;
 
-	err = sqfs_frag_table_find_tail_end(proc->frag_tbl, frag->checksum,
-					    frag->size, &index, &offset);
-	if (err == 0) {
-		sqfs_inode_set_frag_location(*(frag->inode), index, offset);
-		return 0;
+	if (!(frag->flags & SQFS_BLK_DONT_DEDUPLICATE)) {
+		err = sqfs_frag_table_find_tail_end(proc->frag_tbl,
+						    frag->checksum, frag->size,
+						    &index, &offset);
+		if (err == 0) {
+			sqfs_inode_set_frag_location(*(frag->inode),
+						     index, offset);
+			return 0;
+		}
 	}
 
 	if (proc->frag_block != NULL) {
diff --git a/lib/sqfs/block_writer.c b/lib/sqfs/block_writer.c
index 73dcb14..e252c89 100644
--- a/lib/sqfs/block_writer.c
+++ b/lib/sqfs/block_writer.c
@@ -229,7 +229,7 @@ int sqfs_block_writer_write(sqfs_block_writer_t *wr, sqfs_u32 size,
 
 		if (count == 0) {
 			*location = 0;
-		} else {
+		} else if (!(flags & SQFS_BLK_DONT_DEDUPLICATE)) {
 			start = deduplicate_blocks(wr, count);
 			offset = wr->blocks[start].offset;
 
@@ -244,11 +244,11 @@ int sqfs_block_writer_write(sqfs_block_writer_t *wr, sqfs_u32 size,
 			} else {
 				wr->num_blocks = wr->file_start;
 			}
-		}
 
-		err = wr->file->truncate(wr->file, wr->start);
-		if (err)
-			return err;
+			err = wr->file->truncate(wr->file, wr->start);
+			if (err)
+				return err;
+		}
 
 		wr->stats.blocks_written = wr->num_blocks;
 		wr->stats.bytes_written = wr->start - wr->data_area_start;