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/*
* Copyright (c) 2011, Google Inc.
*/
#ifndef STREAMING_H
#define STREAMING_H 1
#include "object.h"
#include "odb.h"
struct object_database;
struct odb_read_stream;
struct stream_filter;
typedef int (*odb_read_stream_close_fn)(struct odb_read_stream *);
typedef ssize_t (*odb_read_stream_read_fn)(struct odb_read_stream *, char *, size_t);
/*
* A stream that can be used to read an object from the object database without
* loading all of it into memory.
*/
struct odb_read_stream {
odb_read_stream_close_fn close;
odb_read_stream_read_fn read;
enum object_type type;
size_t size; /* inflated size of full object */
};
/*
* Create a new object stream for the given object database. An optional filter
* can be used to transform the object's content.
*
* Returns the stream on success, a `NULL` pointer otherwise.
*/
struct odb_read_stream *odb_read_stream_open(struct object_database *odb,
const struct object_id *oid,
struct stream_filter *filter);
/*
* Close the given read stream and release all resources associated with it.
* Returns 0 on success, a negative error code otherwise.
*/
int odb_read_stream_close(struct odb_read_stream *stream);
/*
* Read data from the stream into the buffer. Returns 0 on EOF and the number
* of bytes read on success. Returns a negative error code in case reading from
* the stream fails.
*/
ssize_t odb_read_stream_read(struct odb_read_stream *stream, void *buf, size_t len);
/*
* A stream that provides an object to be written to the object database without
* loading all of it into memory.
*/
struct odb_write_stream {
ssize_t (*read)(struct odb_write_stream *, unsigned char *, size_t);
void *data;
int is_finished;
};
/*
* Read data from the stream into the buffer. Returns 0 when finished and the
* number of bytes read on success. Returns a negative error code in case
* reading from the stream fails.
*/
ssize_t odb_write_stream_read(struct odb_write_stream *stream, void *buf,
size_t len);
/*
* Releases memory allocated for underlying stream data.
*/
void odb_write_stream_release(struct odb_write_stream *stream);
/*
* Look up the object by its ID and write the full contents to the file
* descriptor. The object must be a blob, or the function will fail. When
* provided, the filter is used to transform the blob contents.
*
* `can_seek` should be set to 1 in case the given file descriptor can be
* seek(3p)'d on. This is used to support files with holes in case a
* significant portion of the blob contains NUL bytes.
*
* Returns a negative error code on failure, 0 on success.
*/
int odb_stream_blob_to_fd(struct object_database *odb,
int fd,
const struct object_id *oid,
struct stream_filter *filter,
int can_seek);
/*
* Sets up an ODB write stream that reads from an fd.
*/
void odb_write_stream_from_fd(struct odb_write_stream *stream, int fd,
size_t size);
#endif /* STREAMING_H */
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