3 files changed, 64 insertions, 4 deletions

diff --git a/lib/sqfs/meta_reader.c b/lib/sqfs/meta_reader.c
index 1a70238..e9b599f 100644
--- a/lib/sqfs/meta_reader.c
+++ b/lib/sqfs/meta_reader.c
@@ -7,6 +7,29 @@
 #include <string.h>
 #include <stdio.h>
 
+struct meta_reader_t {
+	/* The location of the current block in the image */
+	uint64_t block_offset;
+
+	/* The location of the next block after the current one */
+	uint64_t next_block;
+
+	/* A byte offset into the uncompressed data of the current block */
+	size_t offset;
+
+	/* The underlying file descriptor to read from */
+	int fd;
+
+	/* A pointer to the compressor to use for extracting data */
+	compressor_t *cmp;
+
+	/* The raw data read from the input file */
+	uint8_t data[SQFS_META_BLOCK_SIZE];
+
+	/* The uncompressed data read from the input file */
+	uint8_t scratch[SQFS_META_BLOCK_SIZE];
+};
+
 meta_reader_t *meta_reader_create(int fd, compressor_t *cmp)
 {
 	meta_reader_t *m = calloc(1, sizeof(*m));
diff --git a/lib/sqfs/meta_writer.c b/lib/sqfs/meta_writer.c
index 77ceeb9..2dacaa0 100644
--- a/lib/sqfs/meta_writer.c
+++ b/lib/sqfs/meta_writer.c
@@ -8,6 +8,26 @@
 #include <unistd.h>
 #include <stdio.h>
 
+struct meta_writer_t {
+	/* A byte offset into the uncompressed data of the current block */
+	size_t offset;
+
+	/* The location of the current block in the file */
+	size_t block_offset;
+
+	/* The underlying file descriptor to write to */
+	int outfd;
+
+	/* A pointer to the compressor to use for compressing the data */
+	compressor_t *cmp;
+
+	/* The raw data chunk that data is appended to */
+	uint8_t data[SQFS_META_BLOCK_SIZE + 2];
+
+	/* Scratch buffer for compressing data */
+	uint8_t scratch[SQFS_META_BLOCK_SIZE + 2];
+};
+
 meta_writer_t *meta_writer_create(int fd, compressor_t *cmp)
 {
 	meta_writer_t *m = calloc(1, sizeof(*m));
@@ -95,3 +115,16 @@ int meta_writer_append(meta_writer_t *m, const void *data, size_t size)
 
 	return 0;
 }
+
+void meta_writer_get_position(const meta_writer_t *m, uint64_t *block_start,
+			      uint32_t *offset)
+{
+	*block_start = m->block_offset;
+	*offset = m->offset;
+}
+
+void meta_writer_reset(meta_writer_t *m)
+{
+	m->block_offset = 0;
+	m->offset = 0;
+}
diff --git a/lib/sqfs/table.c b/lib/sqfs/table.c
index 882d9ba..4e0f9d1 100644
--- a/lib/sqfs/table.c
+++ b/lib/sqfs/table.c
@@ -11,9 +11,10 @@ int sqfs_write_table(int outfd, sqfs_super_t *super, const void *data,
 		     compressor_t *cmp)
 {
 	size_t ent_per_blocks = SQFS_META_BLOCK_SIZE / entsize;
-	uint64_t blocks[count / ent_per_blocks + 1];
+	uint64_t blocks[count / ent_per_blocks + 1], block;
 	size_t i, blkidx = 0, tblsize;
 	meta_writer_t *m;
+	uint32_t offset;
 	ssize_t ret;
 
 	/* Write actual data. Whenever we cross a block boundary, remember
@@ -23,8 +24,10 @@ int sqfs_write_table(int outfd, sqfs_super_t *super, const void *data,
 		return -1;
 
 	for (i = 0; i < count; ++i) {
-		if (blkidx == 0 || m->block_offset > blocks[blkidx - 1])
-			blocks[blkidx++] = m->block_offset;
+		meta_writer_get_position(m, &block, &offset);
+
+		if (blkidx == 0 || block > blocks[blkidx - 1])
+			blocks[blkidx++] = block;
 
 		if (meta_writer_append(m, data, entsize))
 			goto fail;
@@ -38,7 +41,8 @@ int sqfs_write_table(int outfd, sqfs_super_t *super, const void *data,
 	for (i = 0; i < blkidx; ++i)
 		blocks[i] = htole64(blocks[i] + super->bytes_used);
 
-	super->bytes_used += m->block_offset;
+	meta_writer_get_position(m, &block, &offset);
+	super->bytes_used += block;
 	meta_writer_destroy(m);
 
 	/* write new index table */