/* Copyright (C) 2019  C. McEnroe <june@causal.agency>
 *
 * This program 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.
 *
 * This program 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 this program.  If not, see <https://www.gnu.org/licenses/>.
 */

#ifdef __linux__

#define _GNU_SOURCE

#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

// Defined in libcrypto:
void arc4random_buf(void *buf, size_t nbytes);

#define NO_READPASSPHRASE_H
#define RPP_STDIN 1
static inline char *
readpassphrase(const char *prompt, char *buf, size_t bufsiz, int flags) {
	if (flags) {
		if (!fgets(buf, bufsiz, stdin)) return NULL;
		return strsep(&buf, "\n");
	}
	return getpass(prompt);
}

typedef int _readfn(void *, char *, int);
typedef int _writefn(void *, const char *, int);
typedef fpos_t _seekfn(void *, fpos_t, int);
typedef int _closefn(void *);

struct _funopen {
	void *cookie;
	_readfn *readfn;
	_writefn *writefn;
	_closefn *closefn;
};

static inline ssize_t
_cookie_read(void *cookie, char *buf, size_t size) {
	struct _funopen *funopen = cookie;
	assert((size_t)(int)size == size);
	return funopen->readfn(funopen->cookie, buf, size);
}

static inline ssize_t
_cookie_write(void *cookie, const char *buf, size_t size) {
	struct _funopen *funopen = cookie;
	assert((size_t)(int)size == size);
	return funopen->writefn(funopen->cookie, buf, size);
}

static inline int
_cookie_close(void *cookie) {
	struct _funopen *funopen = cookie;
	int ret = (funopen->closefn ? funopen->closefn(funopen->cookie) : 0);
	free(cookie);
	return ret;
}

static const cookie_io_functions_t _cookie_fns = {
	.read = _cookie_read,
	.write = _cookie_write,
	.close = _cookie_close,
};

static inline FILE *
funopen(
	const void *cookie,
	_readfn *readfn, _writefn *writefn, _seekfn *seekfn, _closefn *closefn
) {
	struct _funopen *funopen = malloc(sizeof(*funopen));
	if (!funopen) return NULL;
	assert(!seekfn);
	*funopen = (struct _funopen) { (void *)cookie, readfn, writefn, closefn };
	const char *mode = (!readfn ? "w" : !writefn ? "r" : "r+");
	return fopencookie(funopen, mode, _cookie_fns);
}

#endif /* __linux__ */