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>

4 files changed, 77 insertions, 23 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 */
diff --git a/lib/sqfs/data_writer.c b/lib/sqfs/data_writer.c
index 557b85b..cbe2351 100644
--- a/lib/sqfs/data_writer.c
+++ b/lib/sqfs/data_writer.c
@@ -18,6 +18,8 @@ struct data_writer_t {
 	size_t max_fragments;
 	size_t frag_offset;
 
+	size_t devblksz;
+
 	int block_idx;
 
 	sqfs_super_t *super;
@@ -26,14 +28,16 @@ struct data_writer_t {
 };
 
 static int write_compressed(data_writer_t *data, const void *in, size_t size,
-			    uint32_t *outsize)
+			    uint32_t *outsize, int flags)
 {
-	ssize_t ret;
+	ssize_t ret = 0;
 
-	ret = data->cmp->do_block(data->cmp, in, size, data->scratch,
-				  data->super->block_size);
-	if (ret < 0)
-		return -1;
+	if (!(flags & DW_DONT_COMPRESS)) {
+		ret = data->cmp->do_block(data->cmp, in, size, data->scratch,
+					  data->super->block_size);
+		if (ret < 0)
+			return -1;
+	}
 
 	if (ret > 0 && (size_t)ret < size) {
 		size = ret;
@@ -85,6 +89,20 @@ static bool is_zero_block(unsigned char *ptr, size_t size)
 	return ptr[0] == 0 && memcmp(ptr, ptr + 1, size - 1) == 0;
 }
 
+static int allign_file(data_writer_t *data)
+{
+	size_t diff = data->super->bytes_used % data->devblksz;
+
+	if (diff == 0)
+		return 0;
+
+	if (padd_file(data->outfd, data->super->bytes_used, data->devblksz))
+		return -1;
+
+	data->super->bytes_used += data->devblksz - diff;
+	return 0;
+}
+
 int data_writer_flush_fragments(data_writer_t *data)
 {
 	uint64_t offset;
@@ -98,7 +116,7 @@ int data_writer_flush_fragments(data_writer_t *data)
 
 	offset = data->super->bytes_used;
 
-	if (write_compressed(data, data->fragment, data->frag_offset, &out))
+	if (write_compressed(data, data->fragment, data->frag_offset, &out, 0))
 		return -1;
 
 	data->fragments[data->num_fragments].start_offset = htole64(offset);
@@ -113,7 +131,8 @@ int data_writer_flush_fragments(data_writer_t *data)
 	return 0;
 }
 
-static int flush_data_block(data_writer_t *data, size_t size, file_info_t *fi)
+static int flush_data_block(data_writer_t *data, size_t size,
+			    file_info_t *fi, int flags)
 {
 	uint32_t out;
 
@@ -123,7 +142,7 @@ static int flush_data_block(data_writer_t *data, size_t size, file_info_t *fi)
 		return 0;
 	}
 
-	if (size < data->super->block_size) {
+	if (size < data->super->block_size && !(flags & DW_DONT_FRAGMENT)) {
 		if (data->frag_offset + size > data->super->block_size) {
 			if (data_writer_flush_fragments(data))
 				return -1;
@@ -136,7 +155,7 @@ static int flush_data_block(data_writer_t *data, size_t size, file_info_t *fi)
 		       data->block, size);
 		data->frag_offset += size;
 	} else {
-		if (write_compressed(data, data->block, size, &out))
+		if (write_compressed(data, data->block, size, &out, flags))
 			return -1;
 
 		fi->blocksizes[data->block_idx++] = out;
@@ -145,12 +164,16 @@ static int flush_data_block(data_writer_t *data, size_t size, file_info_t *fi)
 	return 0;
 }
 
-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)
 {
 	uint64_t count;
 	ssize_t ret;
 	size_t diff;
 
+	if ((flags & DW_ALLIGN_DEVBLK) && allign_file(data) != 0)
+		return -1;
+
 	fi->startblock = data->super->bytes_used;
 	fi->sparse = 0;
 	data->block_idx = 0;
@@ -165,10 +188,13 @@ int write_data_from_fd(data_writer_t *data, file_info_t *fi, int infd)
 		if ((size_t)ret < diff)
 			goto fail_trunc;
 
-		if (flush_data_block(data, diff, fi))
+		if (flush_data_block(data, diff, fi, flags))
 			return -1;
 	}
 
+	if ((flags & DW_ALLIGN_DEVBLK) && allign_file(data) != 0)
+		return -1;
+
 	return 0;
 fail_read:
 	perror(fi->input_file);
@@ -179,13 +205,16 @@ fail_trunc:
 }
 
 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)
 {
 	size_t start, count, diff;
 	sparse_map_t *m;
 	uint64_t offset;
 	ssize_t ret;
 
+	if ((flags & DW_ALLIGN_DEVBLK) && allign_file(data) != 0)
+		return -1;
+
 	fi->startblock = data->super->bytes_used;
 	fi->sparse = 0;
 	data->block_idx = 0;
@@ -235,10 +264,13 @@ int write_data_from_fd_condensed(data_writer_t *data, file_info_t *fi,
 			map = map->next;
 		}
 
-		if (flush_data_block(data, diff, fi))
+		if (flush_data_block(data, diff, fi, flags))
 			return -1;
 	}
 
+	if ((flags & DW_ALLIGN_DEVBLK) && allign_file(data) != 0)
+		return -1;
+
 	return 0;
 fail_map_size:
 	fprintf(stderr, "%s: sparse file map spans beyond file size\n",
@@ -258,7 +290,7 @@ fail_trunc:
 }
 
 data_writer_t *data_writer_create(sqfs_super_t *super, compressor_t *cmp,
-				  int outfd)
+				  int outfd, size_t devblksize)
 {
 	data_writer_t *data;
 
@@ -275,6 +307,7 @@ data_writer_t *data_writer_create(sqfs_super_t *super, compressor_t *cmp,
 	data->super = super;
 	data->cmp = cmp;
 	data->outfd = outfd;
+	data->devblksz = devblksize;
 	return data;
 }
 
diff --git a/mkfs/mkfs.c b/mkfs/mkfs.c
index e72b669..f1c1f1b 100644
--- a/mkfs/mkfs.c
+++ b/mkfs/mkfs.c
@@ -18,7 +18,7 @@ static int process_file(data_writer_t *data, tree_node_t *n, bool quiet)
 		return -1;
 	}
 
-	ret = write_data_from_fd(data, n->data.file, infd);
+	ret = write_data_from_fd(data, n->data.file, infd, 0);
 
 	close(infd);
 	return ret;
@@ -172,7 +172,7 @@ int main(int argc, char **argv)
 		super.bytes_used += ret;
 	}
 
-	data = data_writer_create(&super, cmp, outfd);
+	data = data_writer_create(&super, cmp, outfd, opt.devblksz);
 	if (data == NULL)
 		goto out_cmp;
 
diff --git a/tar/tar2sqfs.c b/tar/tar2sqfs.c
index 1b7d3aa..3417fd0 100644
--- a/tar/tar2sqfs.c
+++ b/tar/tar2sqfs.c
@@ -185,14 +185,14 @@ static int write_file(tar_header_decoded_t *hdr, file_info_t *fi,
 
 	if (hdr->sparse != NULL) {
 		ret = write_data_from_fd_condensed(data, fi, STDIN_FILENO,
-						   hdr->sparse);
+						   hdr->sparse, 0);
 		if (ret)
 			return -1;
 
 		return skip_padding(STDIN_FILENO, hdr->record_size);
 	}
 
-	if (write_data_from_fd(data, fi, STDIN_FILENO))
+	if (write_data_from_fd(data, fi, STDIN_FILENO, 0))
 		return -1;
 
 	return skip_padding(STDIN_FILENO, fi->size);
@@ -361,7 +361,7 @@ int main(int argc, char **argv)
 		super.bytes_used += ret;
 	}
 
-	data = data_writer_create(&super, cmp, outfd);
+	data = data_writer_create(&super, cmp, outfd, devblksize);
 	if (data == NULL)
 		goto out_cmp;