/*
 *	aegis - project change supervisor
 *	Copyright (C) 2001 Peter Miller;
 *	All rights reserved.
 *
 *	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 2 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, write to the Free Software
 *	Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
 *
 * MANIFEST: functions to manipulate copyfiles
 */

#include <ac/errno.h>
#include <ac/fcntl.h>
#include <ac/stdlib.h>
#include <ac/unistd.h>

#include <glue.h>
#include <os.h>
#include <trace.h>


/*
 * NAME
 *	copyfile - copy a file
 *
 * SYNOPSIS
 *	int copyfile(char *src, char *dst);
 *
 * DESCRIPTION
 *	The copyfile function complements the link and rename functions.
 *
 * ARGUMENTS
 *	src	- pathname of source file
 *	dst	- pathname of destination file
 *
 * RETURNS
 *	0	on success
 *	-1	on error, setting errno appropriately
 */

int
copyfile(src, dst)
	char	*src;
	char	*dst;
{
	int	src_fd;
	int	dst_fd;
	char	*buffer;
	long	max;
	long	nbytes;
	long	nbytes2;
	int	err;
	int	result;

	trace(("copyfile(\"%s\", \"%s\")\n{\n"/*}*/, src, dst));
	os_interrupt_cope();
	result = -1;
	src_fd = open(src, O_RDONLY, 0666);
	if (src_fd < 0)
		goto done;
	dst_fd = open(dst, O_WRONLY | O_CREAT | O_TRUNC, 0666);
	if (dst_fd < 0)
	{
		err = errno;
		close(src_fd);
		errno = err;
		goto done;
	}

	max = 1L << 13;
	errno = 0;
	buffer = malloc(max);
	if (!buffer)
	{
		err = errno ? errno : ENOMEM;
		close(dst_fd);
		close(src_fd);
		errno = err;
		goto done;
	}

	for (;;)
	{
		nbytes = read(src_fd, buffer, max);
		if (nbytes < 0)
		{
			err = errno;
			close(src_fd);
			close(dst_fd);
			free(buffer);
			errno = err;
			goto done;
		}
		if (nbytes == 0)
			break;
		
		nbytes2 = write(dst_fd, buffer, nbytes);
		if (nbytes2 < 0)
		{
			err = errno;
			close(src_fd);
			close(dst_fd);
			free(buffer);
			errno = err;
			goto done;
		}
		if (nbytes2 != nbytes)
		{
			close(src_fd);
			close(dst_fd);
			free(buffer);
			errno = EIO; /* weird device, probably */
			goto done;
		}
	}
	free(buffer);
	if (close(src_fd))
	{
		err = errno;
		close(dst_fd);
		errno = err;
		goto done;
	}
	result = close(dst_fd);

	/*
	 * here for all exits
	 */
	done:
	trace(("return %d; /* errno = %d */\n", result, errno));
	trace((/*{*/"}\n"));
	return result;
}