From a26a6bd6f36d29cdc959f746b495f79f74c7fad7 Mon Sep 17 00:00:00 2001
From: Adrien Schildknecht <adriens@google.com>
Date: Wed, 30 Nov 2016 11:49:47 -0800
Subject: [PATCH] libsparse: add a function to retrieve the data blocks

Test: m libsparse

Change-Id: I04bd3912bb4364e591b064ec2aab782cf02f6bd7
---
 libsparse/include/sparse/sparse.h | 25 ++++++++++++++
 libsparse/sparse.c                | 56 +++++++++++++++++++++++++++++++
 2 files changed, 81 insertions(+)

diff --git a/libsparse/include/sparse/sparse.h b/libsparse/include/sparse/sparse.h
index 42d4adb87..356f65fd0 100644
--- a/libsparse/include/sparse/sparse.h
+++ b/libsparse/include/sparse/sparse.h
@@ -175,6 +175,13 @@ int sparse_file_write(struct sparse_file *s, int fd, bool gz, bool sparse,
  */
 int64_t sparse_file_len(struct sparse_file *s, bool sparse, bool crc);
 
+/**
+ * sparse_file_block_size
+ *
+ * @s - sparse file cookie
+ */
+unsigned int sparse_file_block_size(struct sparse_file *s);
+
 /**
  * sparse_file_callback - call a callback for blocks in sparse file
  *
@@ -196,6 +203,24 @@ int64_t sparse_file_len(struct sparse_file *s, bool sparse, bool crc);
 int sparse_file_callback(struct sparse_file *s, bool sparse, bool crc,
 		int (*write)(void *priv, const void *data, int len), void *priv);
 
+/**
+ * sparse_file_foreach_chunk - call a callback for data blocks in sparse file
+ *
+ * @s - sparse file cookie
+ * @sparse - write in the Android sparse file format
+ * @crc - append a crc chunk
+ * @write - function to call for each block
+ * @priv - value that will be passed as the first argument to write
+ *
+ * The function has the same behavior as 'sparse_file_callback', except it only
+ * iterates on blocks that contain data.
+ *
+ * Returns 0 on success, negative errno on error.
+ */
+int sparse_file_foreach_chunk(struct sparse_file *s, bool sparse, bool crc,
+	int (*write)(void *priv, const void *data, int len, unsigned int block,
+		     unsigned int nr_blocks),
+	void *priv);
 /**
  * sparse_file_read - read a file into a sparse file cookie
  *
diff --git a/libsparse/sparse.c b/libsparse/sparse.c
index 311678a34..b17586066 100644
--- a/libsparse/sparse.c
+++ b/libsparse/sparse.c
@@ -199,6 +199,57 @@ int sparse_file_callback(struct sparse_file *s, bool sparse, bool crc,
 	return ret;
 }
 
+struct chunk_data {
+	void		*priv;
+	unsigned int	block;
+	unsigned int	nr_blocks;
+	int (*write)(void *priv, const void *data, int len, unsigned int block,
+		     unsigned int nr_blocks);
+};
+
+static int foreach_chunk_write(void *priv, const void *data, int len)
+{
+	struct chunk_data *chk = priv;
+
+	return chk->write(chk->priv, data, len, chk->block, chk->nr_blocks);
+}
+
+int sparse_file_foreach_chunk(struct sparse_file *s, bool sparse, bool crc,
+	int (*write)(void *priv, const void *data, int len, unsigned int block,
+		     unsigned int nr_blocks),
+	void *priv)
+{
+	int ret;
+	int chunks;
+	struct chunk_data chk;
+	struct output_file *out;
+	struct backed_block *bb;
+
+	chk.priv = priv;
+	chk.write = write;
+	chk.block = chk.nr_blocks = 0;
+	chunks = sparse_count_chunks(s);
+	out = output_file_open_callback(foreach_chunk_write, &chk,
+					s->block_size, s->len, false, sparse,
+					chunks, crc);
+
+	if (!out)
+		return -ENOMEM;
+
+	for (bb = backed_block_iter_new(s->backed_block_list); bb;
+			bb = backed_block_iter_next(bb)) {
+		chk.block = backed_block_block(bb);
+		chk.nr_blocks = (backed_block_len(bb) - 1) / s->block_size + 1;
+		ret = sparse_file_write_block(out, bb);
+		if (ret)
+			return ret;
+	}
+
+	output_file_close(out);
+
+	return ret;
+}
+
 static int out_counter_write(void *priv, const void *data __unused, int len)
 {
 	int64_t *count = priv;
@@ -230,6 +281,11 @@ int64_t sparse_file_len(struct sparse_file *s, bool sparse, bool crc)
 	return count;
 }
 
+unsigned int sparse_file_block_size(struct sparse_file *s)
+{
+	return s->block_size;
+}
+
 static struct backed_block *move_chunks_up_to_len(struct sparse_file *from,
 		struct sparse_file *to, unsigned int len)
 {