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/* SPDX-License-Identifier: GPL-3.0-or-later */
/*
* ostream.h
*
* Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
*/
#ifndef IO_OSTREAM_H
#define IO_OSTREAM_H
#include "sqfs/predef.h"
/**
* @struct ostream_t
*
* @extends sqfs_object_t
*
* @brief An append-only data stream.
*/
typedef struct ostream_t {
sqfs_object_t base;
int (*append)(struct ostream_t *strm, const void *data, size_t size);
int (*append_sparse)(struct ostream_t *strm, size_t size);
int (*flush)(struct ostream_t *strm);
const char *(*get_filename)(struct ostream_t *strm);
} ostream_t;
enum {
OSTREAM_OPEN_OVERWRITE = 0x01,
OSTREAM_OPEN_SPARSE = 0x02,
};
#ifdef __cplusplus
extern "C" {
#endif
/**
* @brief Append a block of data to an output stream.
*
* @memberof ostream_t
*
* @param strm A pointer to an output stream.
* @param data A pointer to the data block to append.
* @param size The number of bytes to append.
*
* @return Zero on success, -1 on failure.
*/
SQFS_INLINE int ostream_append(ostream_t *strm, const void *data,
size_t size)
{
return strm->append(strm, data, size);
}
/**
* @brief Append a number of zero bytes to an output stream.
*
* @memberof ostream_t
*
* If the unerlying implementation supports sparse files, this function can be
* used to create a "hole". If the implementation does not support it, a
* fallback is used that just appends a block of zeros manualy.
*
* @param strm A pointer to an output stream.
* @param size The number of zero bytes to append.
*
* @return Zero on success, -1 on failure.
*/
SQFS_INTERNAL int ostream_append_sparse(ostream_t *strm, size_t size);
/**
* @brief Process all pending, buffered data and flush it to disk.
*
* @memberof ostream_t
*
* If the stream performs some kind of transformation (e.g. transparent data
* compression), flushing caues the wrapped format to insert a termination
* token. Only call this function when you are absolutely DONE appending data,
* shortly before destroying the stream.
*
* @param strm A pointer to an output stream.
*
* @return Zero on success, -1 on failure.
*/
SQFS_INLINE int ostream_flush(ostream_t *strm)
{
return strm->flush(strm);
}
/**
* @brief Get the underlying filename of a output stream.
*
* @memberof ostream_t
*
* @param strm The output stream to get the filename from.
*
* @return A string holding the underlying filename.
*/
SQFS_INLINE const char *ostream_get_filename(ostream_t *strm)
{
return strm->get_filename(strm);
}
#ifdef __cplusplus
}
#endif
#endif /* IO_OSTREAM_H */
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