Add flags to data writer to micro manage behaviour

The added flags allow controlling the following on a per file level:
 - forcing a file to be written uncompressed
 - forcing a file to not have a fragment, i.e. the last truncated block
   actually being written as a block
 - padding a file to be alligned to device block size

The flags are not yet exposed to anything user controllable (such as
command line flags).

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

1 files changed, 24 insertions, 3 deletions

diff --git a/include/data_writer.h b/include/data_writer.h
index 2ace899..a52b37f 100644
--- a/include/data_writer.h
+++ b/include/data_writer.h
@@ -9,6 +9,22 @@
 
 typedef struct data_writer_t data_writer_t;
 
+enum {
+	/* Don't generate fragments, always write the last block to disk as a
+	   block, even if it is incomplete. */
+	DW_DONT_FRAGMENT = 0x01,
+
+	/* Intentionally write all blocks uncompressed. This implies
+	   DW_DONT_FRAGMENT since sharing a fragment block with other files
+	   would otherwise require the entire fragment block to be
+	   uncompressed. */
+	DW_DONT_COMPRESS = 0x03,
+
+	/* Make sure the first block of a file is alligned to
+	   device block size */
+	DW_ALLIGN_DEVBLK = 0x04,
+};
+
 /*
   Create a data writer. The pointer to the super block is kept internally and
   used to automatically update various counters when writing data.
@@ -16,7 +32,7 @@ typedef struct data_writer_t data_writer_t;
   Returns NULL on failure and prints errors to stderr.
  */
 data_writer_t *data_writer_create(sqfs_super_t *super, compressor_t *cmp,
-				  int outfd);
+				  int outfd, size_t devblksize);
 
 void data_writer_destroy(data_writer_t *data);
 
@@ -46,18 +62,23 @@ int data_writer_flush_fragments(data_writer_t *data);
   Blocks or fragments that are all zero bytes automatically detected,
   not written out and the sparse file accounting updated accordingly.
 
+  The flags argument is a combination of DW_* flags.
+
   Returns 0 on success, prints errors to stderr.
 */
-int write_data_from_fd(data_writer_t *data, file_info_t *fi, int infd);
+int write_data_from_fd(data_writer_t *data, file_info_t *fi, int infd,
+		       int flags);
 
 /*
   Does the same as write_data_from_fd but the input file is the condensed
   representation of a sparse file. The layout must be in order and
   non-overlapping.
 
+  The flags argument is a combination of DW_* flags.
+
   Returns 0 on success, prints errors to stderr.
  */
 int write_data_from_fd_condensed(data_writer_t *data, file_info_t *fi,
-				 int infd, sparse_map_t *map);
+				 int infd, sparse_map_t *map, int flags);
 
 #endif /* DATA_WRITER_H */