odb: wrap the stream reading and writing functions

This is in preparation for moving the hashing to the frontend, which
requires us to handle the incoming data before passing it to the
backend's stream.

include/git2/odb.h

@@ -219,16 +219,9 @@ GIT_EXTERN(int) git_odb_write(git_oid *out, git_odb *odb, const void *data, size
  * The type and final length of the object must be specified
  * when opening the stream.
  *
- * The returned stream will be of type `GIT_STREAM_WRONLY` and
- * will have the following methods:
- *
- *		- stream->write: write `n` bytes into the stream
- *		- stream->finalize_write: close the stream and store the object in
- *			the odb
- *		- stream->free: free the stream
- *
- * The streaming write won't be effective until `stream->finalize_write`
- * is called and returns without an error
+ * The returned stream will be of type `GIT_STREAM_WRONLY`, and it
+ * won't be effective until `git_odb_stream_finalize_write` is called
+ * and returns without an error
  *
  * The stream must always be free'd or will leak memory.
  *
@@ -243,6 +236,42 @@ GIT_EXTERN(int) git_odb_write(git_oid *out, git_odb *odb, const void *data, size
 GIT_EXTERN(int) git_odb_open_wstream(git_odb_stream **out, git_odb *db, size_t size, git_otype type);
 
 /**
+ * Write to an odb stream
+ *
+ * @param stream the stream
+ * @param buffer the data to write
+ * @param len the buffer's length
+ * @return 0 if the write succeeded; error code otherwise
+ */
+GIT_EXTERN(int) git_odb_stream_write(git_odb_stream *stream, const char *buffer, size_t len);
+
+/**
+ * Finish writing to an odb stream
+ *
+ * The object will take its final name and will be available to the
+ * odb.
+ *
+ * @param out pointer to store the resulting object's id
+ * @param stream the stream
+ * @return 0 on success; an error code otherwise
+ */
+GIT_EXTERN(int) git_odb_stream_finalize_write(git_oid *out, git_odb_stream *stream);
+
+/**
+ * Read from an odb stream
+ *
+ * Most backends don't implement streaming reads
+ */
+GIT_EXTERN(int) git_odb_stream_read(git_odb_stream *stream, char *buffer, size_t len);
+
+/**
+ * Free an odb stream
+ *
+ * @param stream the stream to free
+ */
+GIT_EXTERN(void) git_odb_stream_free(git_odb_stream *stream);
+
+/**
  * Open a stream to read an object from the ODB
  *
  * Note that most backends do *not* support streaming reads

src/blob.c

@@ -60,10 +60,10 @@ int git_blob_create_frombuffer(git_oid *oid, git_repository *repo, const void *b
 		(error = git_odb_open_wstream(&stream, odb, len, GIT_OBJ_BLOB)) < 0)
 		return error;
 
-	if ((error = stream->write(stream, buffer, len)) == 0)
-		error = stream->finalize_write(oid, stream);
+	if ((error = git_odb_stream_write(stream, buffer, len)) == 0)
+		error = git_odb_stream_finalize_write(oid, stream);
 
-	stream->free(stream);
+	git_odb_stream_free(stream);
 	return error;
 }
 
@@ -80,12 +80,12 @@ static int write_file_stream(
 		return error;
 
 	if ((fd = git_futils_open_ro(path)) < 0) {
-		stream->free(stream);
+		git_odb_stream_free(stream);
 		return -1;
 	}
 
 	while (!error && (read_len = p_read(fd, buffer, sizeof(buffer))) > 0) {
-		error = stream->write(stream, buffer, read_len);
+		error = git_odb_stream_write(stream, buffer, read_len);
 		written += read_len;
 	}
 
@@ -97,9 +97,9 @@ static int write_file_stream(
 	}
 
 	if (!error)
-		error = stream->finalize_write(oid, stream);
+		error = git_odb_stream_finalize_write(oid, stream);
 
-	stream->free(stream);
+	git_odb_stream_free(stream);
 	return error;
 }
 

src/odb.c

@@ -864,9 +864,9 @@ int git_odb_write(
 	if ((error = git_odb_open_wstream(&stream, db, len, type)) != 0)
 		return error;
 
-	stream->write(stream, data, len);
-	error = stream->finalize_write(oid, stream);
-	stream->free(stream);
+	git_odb_stream_write(stream, data, len);
+	error = git_odb_stream_finalize_write(oid, stream);
+	git_odb_stream_free(stream);
 
 	return error;
 }
@@ -904,6 +904,26 @@ int git_odb_open_wstream(
 	return error;
 }
 
+int git_odb_stream_write(git_odb_stream *stream, const char *buffer, size_t len)
+{
+	return stream->write(stream, buffer, len);
+}
+
+int git_odb_stream_finalize_write(git_oid *out, git_odb_stream *stream)
+{
+	return stream->finalize_write(out, stream);
+}
+
+int git_odb_stream_read(git_odb_stream *stream, char *buffer, size_t len)
+{
+	return stream->read(stream, buffer, len);
+}
+
+void git_odb_stream_free(git_odb_stream *stream)
+{
+	stream->free(stream);
+}
+
 int git_odb_open_rstream(git_odb_stream **stream, git_odb *db, const git_oid *oid)
 {
 	size_t i, reads = 0;

src/tag.c

@@ -366,10 +366,10 @@ int git_tag_create_frombuffer(git_oid *oid, git_repository *repo, const char *bu
 	if (git_odb_open_wstream(&stream, odb, strlen(buffer), GIT_OBJ_TAG) < 0)
 		return -1;
 
-	stream->write(stream, buffer, strlen(buffer));
+	git_odb_stream_write(stream, buffer, strlen(buffer));
 
-	error = stream->finalize_write(oid, stream);
-	stream->free(stream);
+	error = git_odb_stream_finalize_write(oid, stream);
+	git_odb_stream_free(stream);
 
 	if (error < 0) {
 		git_buf_free(&ref_name);

src/transports/local.c

@@ -287,9 +287,9 @@ static int local_push_copy_object(
 		odb_obj_size, odb_obj_type)) < 0)
 		goto on_error;
 
-	if (odb_stream->write(odb_stream, (char *)git_odb_object_data(odb_obj),
+	if (git_odb_stream_write(odb_stream, (char *)git_odb_object_data(odb_obj),
 		odb_obj_size) < 0 ||
-		odb_stream->finalize_write(&remote_odb_obj_oid, odb_stream) < 0) {
+		git_odb_stream_finalize_write(&remote_odb_obj_oid, odb_stream) < 0) {
 		error = -1;
 	} else if (git_oid__cmp(&obj->id, &remote_odb_obj_oid) != 0) {
 		giterr_set(GITERR_ODB, "Error when writing object to remote odb "
@@ -298,7 +298,7 @@ static int local_push_copy_object(
 		error = -1;
 	}
 
-	odb_stream->free(odb_stream);
+	git_odb_stream_free(odb_stream);
 
 on_error:
 	git_odb_object_free(odb_obj);

tests-clar/object/raw/write.c

@@ -31,9 +31,9 @@ static void streaming_write(git_oid *oid, git_odb *odb, git_rawobj *raw)
    int error;
 
    cl_git_pass(git_odb_open_wstream(&stream, odb, raw->len, raw->type));
-   stream->write(stream, raw->data, raw->len);
-   error = stream->finalize_write(oid, stream);
-   stream->free(stream);
+   git_odb_stream_write(stream, raw->data, raw->len);
+   error = git_odb_stream_finalize_write(oid, stream);
+   git_odb_stream_free(stream);
    cl_git_pass(error);
 }