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/* io.h -- Code for file and memory I/O.
Copyright (C) 2017 Jakob Tsar-Fox, All Rights Reserved.
This file is part of Nekopack.
Nekopack is free software: you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation, either version 3 of the License, or (at
your option) any later version.
Nekopack is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with Nekopack. If not, see <http://www.gnu.org/licenses/>. */
#pragma once
#include <stdint.h>
#include <stddef.h>
/* Internal enumerable type for representing the location of a memory
segment. Used for freeing and unmapping purposes, if necessary. */
enum _location {
HEAP,
};
/* Structure to emulate a stream of data that maintains a current
position. The structure additionally maintains a `length` variable
containing the stream's length. */
struct stream {
size_t len; /* Length of the stream. */
char *_start; /* Pointer to the stream's start. */
char *_cur; /* Pointer to the current position. */
enum _location _loc; /* Location of the stream in memory. */
};
/* Allocates `len` bytes of non-zeroed memory and returns a new stream
structure pointing to it. */
struct stream *stream_new(size_t len);
/* Called to free or unmap the memory chunk associated with the given
stream, as well as the stream structure itself. */
void stream_free(struct stream *s);
/* Copies `n` bytes from the given stream into the memory area specified
by `dest`. The stream's cursor is advanced appropriately. */
void stream_read(void *dest, struct stream *s, size_t n);
/* Copies `n` bytes into the given stream from the memory area specified
by `src`. The stream's cursor is advanced appropriately. */
void stream_write(struct stream *s, void *src, size_t n);
/* Applies an initial and primary key to the given stream, effectively
encrypting or decrypting it. */
void stream_xor(struct stream *s, uint8_t initial, uint8_t primary);
/* Obtains the current value of the stream's position indicator. */
size_t stream_tell(struct stream *s);
/* Sets the stream's position indicator to the given `pos`. */
void stream_seek(struct stream *s, size_t pos);
/* Sets the stream's position indicator to the beginning. */
void stream_rewind(struct stream *s);
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