libsparse: Use 'size_t' for the 'len' parameter in callbacks.

This CL updates the callback function signature in
sparse_file_callback() and sparse_file_foreach_chunk().

Before:
int sparse_file_callback(
    struct sparse_file *s, bool sparse, bool crc,
    int (*write)(void *priv, const void *data, int len), void *priv);

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);

After:
int sparse_file_callback(
    struct sparse_file *s, bool sparse, bool crc,
    int (*write)(void *priv, const void *data, size_t len), void *priv);

int sparse_file_foreach_chunk(
    struct sparse_file *s, bool sparse, bool crc,
    int (*write)(
        void *priv, const void *data, size_t len, unsigned int block,
        unsigned int nr_blocks),
    void *priv);

The length (i.e. 'len') comes from the size of a chunk, which could be
legitimately larger than INT_MAX. Prior to this CL, callers (e.g.
write_sparse_data_chunk()) were already passing unsigned int to the
callbacks. When a chunk size exceeds INT_MAX, the callback would see a
negative value, which could lead to undesired behavior. For example,
out_counter_write(), as one of the internal callbacks in libsparse,
gives a wrong sum of chunk sizes, which in turn fails the fastboot
flashing when given a huge sparse image.

It also defines SPARSE_CALLBACK_USES_SIZE_T that allows clients to keep
their codes compatibile with both versions.

Bug: 78432315
Test: `m dist` (with matching changes to all the clients)
Test: Build fastboot and successfully flash a previously failing (huge)
      sparse image.
Change-Id: Iac4bcf7b57039d08af3c57f4be00d75f6b693d93

1 files changed, 8 insertions, 2 deletions

diff --git a/libsparse/include/sparse/sparse.h b/libsparse/include/sparse/sparse.h
index 356f65fd0..1b91ead5c 100644
--- a/libsparse/include/sparse/sparse.h
+++ b/libsparse/include/sparse/sparse.h
@@ -18,6 +18,7 @@
 #define _LIBSPARSE_SPARSE_H_
 
 #include <stdbool.h>
+#include <stddef.h>
 #include <stdint.h>
 
 #ifdef	__cplusplus
@@ -26,6 +27,11 @@ extern "C" {
 
 struct sparse_file;
 
+// The callbacks in sparse_file_callback() and sparse_file_foreach_chunk() take
+// size_t as the length type (was `int` in past). This allows clients to keep
+// their codes compatibile with both versions as needed.
+#define	SPARSE_CALLBACK_USES_SIZE_T
+
 /**
  * sparse_file_new - create a new sparse file cookie
  *
@@ -201,7 +207,7 @@ unsigned int sparse_file_block_size(struct sparse_file *s);
  * Returns 0 on success, negative errno on error.
  */
 int sparse_file_callback(struct sparse_file *s, bool sparse, bool crc,
-		int (*write)(void *priv, const void *data, int len), void *priv);
+		int (*write)(void *priv, const void *data, size_t len), void *priv);
 
 /**
  * sparse_file_foreach_chunk - call a callback for data blocks in sparse file
@@ -218,7 +224,7 @@ int sparse_file_callback(struct sparse_file *s, bool sparse, bool crc,
  * 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,
+	int (*write)(void *priv, const void *data, size_t len, unsigned int block,
 		     unsigned int nr_blocks),
 	void *priv);
 /**