blender-archive/source/blender/blenlib/BLI_filereader.h

/* SPDX-License-Identifier: GPL-2.0-or-later
 * Copyright 2001-2002 NaN Holding BV. All rights reserved. */

/** \file
 * \ingroup bli
 * \brief Wrapper for reading from various sources (e.g. raw files, compressed files, memory...).
 */

#pragma once

#ifdef WIN32
#  include "BLI_winstuff.h"
#else
#  include <sys/types.h>
#endif

#include "BLI_compiler_attrs.h"
#include "BLI_utildefines.h"

#if defined(_MSC_VER) || defined(__APPLE__) || defined(__HAIKU__) || defined(__NetBSD__)
typedef int64_t off64_t;
#endif

#ifdef __cplusplus
extern "C" {
#endif

struct FileReader;

typedef ssize_t (*FileReaderReadFn)(struct FileReader *reader, void *buffer, size_t size);
typedef off64_t (*FileReaderSeekFn)(struct FileReader *reader, off64_t offset, int whence);
typedef void (*FileReaderCloseFn)(struct FileReader *reader);

/** General structure for all #FileReaders, implementations add custom fields at the end. */
typedef struct FileReader {
  FileReaderReadFn read;
  FileReaderSeekFn seek;
  FileReaderCloseFn close;

  off64_t offset;
} FileReader;

/* Functions for opening the various types of FileReader.
 * They either succeed and return a valid FileReader, or fail and return NULL.
 *
 * If a FileReader is created, it has to be cleaned up and freed by calling its close()
 * function unless another FileReader has taken ownership - for example, `Zstd` & `Gzip`
 * take over the base FileReader and will clean it up when their clean() is called.
 */

/** Create #FileReader from raw file descriptor. */
FileReader *BLI_filereader_new_file(int filedes) ATTR_WARN_UNUSED_RESULT;
/** Create #FileReader from raw file descriptor using memory-mapped IO. */
FileReader *BLI_filereader_new_mmap(int filedes) ATTR_WARN_UNUSED_RESULT;
/** Create #FileReader from a region of memory. */
FileReader *BLI_filereader_new_memory(const void *data, size_t len) ATTR_WARN_UNUSED_RESULT
    ATTR_NONNULL();
/** Create #FileReader from applying `Zstd` decompression on an underlying file. */
FileReader *BLI_filereader_new_zstd(FileReader *base) ATTR_WARN_UNUSED_RESULT ATTR_NONNULL();
/** Create #FileReader from applying `Gzip` decompression on an underlying file. */
FileReader *BLI_filereader_new_gzip(FileReader *base) ATTR_WARN_UNUSED_RESULT ATTR_NONNULL();

#ifdef __cplusplus
}
#endif