/*
 * sbio.c
 *
 * IO functions.
 *
 * Copyright 1999-2006 Gentoo Foundation
 *
 *
 *      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 version 2 of the License.
 *
 *      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, write to the Free Software Foundation, Inc.,
 *      675 Mass Ave, Cambridge, MA 02139, USA.
 *
 * $Header$
 */


#include <errno.h>
#include <stdio.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>

#include "sbutil.h"


static int (*sbio_open)(const char *, int, mode_t) = (void *)open;


void sb_set_open(void *new_open)
{
	if (!check_ptr(new_open))
		return;

	sbio_open = new_open;
}

/* General purpose function to _reliably_ open a file
 *
 * Returns the file descriptor or -1 on error (and errno set)
 */

int sb_open(const char *path, int flags, mode_t mode)
{
	int fd;

	fd = sbio_open(path, flags, mode);
	if (-1 == fd)
		DBG_MSG("Failed to open file '%s'!\n", path);

	return fd;
}

/* General purpose function to _reliably_ read from a file.
 *
 * Returns total read bytes or -1 on error.
 */

size_t sb_read(int fd, void *buf, size_t count)
{
	ssize_t n;
	size_t accum = 0;

	do {
		n = read(fd, buf + accum, count - accum);

		if (n > 0) {
			accum += n;
			continue;
		}

		if (n < 0) {
			if (EINTR == errno) {
				/* Reset errno to not trigger DBG_MSG */
				errno = 0;
				continue;
			}

			DBG_MSG("Failed to read from fd=%i!\n", fd);
			return -1;
		}

		/* Found EOF */
		break;
	} while (accum < count);

	return accum;
}

/* General purpose function to _reliably_ write to a file
 *
 * If returned value is less than count, there was a fatal
 * error and value tells how many bytes were actually written
 */

size_t sb_write(int fd, const void *buf, size_t count)
{
	ssize_t n;
	size_t accum = 0;

	do {
		n = write(fd, buf + accum, count - accum);
		if (n < 0) {
			if (EINTR == errno) {
				/* Reset errno to not trigger DBG_MSG */
				errno = 0;
				continue;
			}

			DBG_MSG("Failed to write to fd=%i!\n", fd);
			break;
		}

		accum += n;
	} while (accum < count);
	
	return accum;
}

/* General purpose function to _reliably_ close a file
 *
 * Returns 0 if successful or negative number on error (and errno set)
 */

int sb_close(int fd)
{
	int res;

	do {
		res = close(fd);
	} while ((res < 0) && (EINTR == errno));

	/* Do not care about errors here */
	errno = 0;

	return res;
}