libsparse: Add sparse typed callback

Currently, sparse_file_callback uses libsparse's
own logic for reading a file into a buffer. However,
a caller may want to use their own logic for doing
this in order to customize the buffer size and parallelize
the reads/writes. Also, a caller may want to implement
fill blocks with their own logic as well. To do this
add sparse_file_typed_callback which calls a different
callback function depending on the type of the sparse
chunk being written.

Test: Use typed callback for fd writes
Bug: 78793464
Change-Id: I75955a464fc05991f806339830fdfa05fda354b9

1 files changed, 31 insertions, 0 deletions

diff --git a/libsparse/include/sparse/sparse.h b/libsparse/include/sparse/sparse.h
index 3d5fb0c53..586578633 100644
--- a/libsparse/include/sparse/sparse.h
+++ b/libsparse/include/sparse/sparse.h
@@ -210,6 +210,37 @@ int sparse_file_callback(struct sparse_file *s, bool sparse, bool crc,
 		int (*write)(void *priv, const void *data, size_t len), void *priv);
 
 /**
+ * sparse_file_callback_typed - call a callback for blocks based on type
+ *
+ * @s - sparse file cookie
+ * @sparse - write in the Android sparse file format
+ * @data_write - function to call for data blocks. must not be null
+ * @fd_write - function to call for fd blocks
+ * @fill_write - function to call for fill blocks
+ * @skip_write - function to call for skip blocks
+ * @priv - value that will be passed as the first argument to each write
+ *
+ * Writes a sparse file by calling callback functions.  If sparse is true, the
+ * file will be written in the Android sparse file format, and fill and skip blocks
+ * along with metadata will be written with data_write. If sparse is false, the file
+ * will be expanded into normal format and fill and skip blocks will be written with
+ * the given callbacks.
+ * If a callback function is provided, the library will not unroll data into a buffer,
+ * and will instead pass it directly to the caller for custom implementation. If a
+ * callback is not provided, that type of block will be converted into a void* and
+ * written with data_write. If no callbacks other than data are provided, the behavior
+ * is the same as sparse_file_callback(). The callback should return negative on error,
+ * 0 on success.
+ *
+ * Returns 0 on success, negative errno on error.
+ */
+int sparse_file_callback_typed(struct sparse_file* s, bool sparse,
+                               int (*data_write)(void* priv, const void* data, size_t len),
+                               int (*fd_write)(void* priv, int fd, size_t len),
+                               int (*fill_write)(void* priv, uint32_t fill_val, size_t len),
+                               int (*skip_write)(void* priv, int64_t len), void* priv);
+
+/**
  * sparse_file_foreach_chunk - call a callback for data blocks in sparse file
  *
  * @s - sparse file cookie