/*
 *  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 02111-1307, USA.
 */

// Contains code handling files

#include <string.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include "port.h"
#include "libs/uio.h"
#include "config.h"
#include "types.h"
#include "filintrn.h"
#include "libs/memlib.h"
#include "libs/log.h"

static int copyError(uio_Handle *srcHandle, uio_Handle *dstHandle,
		uio_DirHandle *unlinkHandle, const char *unlinkPath, uint8 *buf);

bool
fileExists (const char *name)
{
	return access (name, F_OK) == 0;
}

bool
fileExists2(uio_DirHandle *dir, const char *fileName)
{
	uio_Stream *stream;

	stream = uio_fopen (dir, fileName, "rb");
	if (stream == NULL)
		return 0;

	uio_fclose (stream);
	return 1;
}

/*
 * Copy a file with path srcName to a file with name newName.
 * If the destination already exists, the operation fails.
 * Links are followed.
 * Special files (fifos, char devices, block devices, etc) will be
 * read as long as there is data available and the destination will be
 * a regular file with that data.
 * The new file will have the same permissions as the old.
 * If an error occurs during copying, an attempt will be made to
 * remove the copy.
 */
int
copyFile (uio_DirHandle *srcDir, const char *srcName,
		uio_DirHandle *dstDir, const char *newName)
{
	uio_Handle *src, *dst;
	struct stat sb;
#define BUFSIZE 65536
	uint8 *buf, *bufPtr;
	ssize_t numInBuf, numWritten;
	
	src = uio_open (srcDir, srcName, O_RDONLY
#ifdef WIN32
			| O_BINARY
#endif
			, 0);
	if (src == NULL)
		return -1;
	
	if (uio_fstat (src, &sb) == -1)
		return copyError (src, NULL, NULL, NULL, NULL);
	
	dst = uio_open (dstDir, newName, O_WRONLY | O_CREAT | O_EXCL
#ifdef WIN32
			| O_BINARY
#endif
			, sb.st_mode & (S_IRWXU | S_IRWXG | S_IRWXO));
	if (dst == NULL)
		return copyError (src, NULL, NULL, NULL, NULL);
	
	buf = HMalloc(BUFSIZE);
			// This was originally a statically allocated buffer,
			// but as this function might be run from a thread with
			// a small stack, this is better.
	while (1)
	{
		numInBuf = uio_read (src, buf, BUFSIZE);
		if (numInBuf == -1)
		{
			if (errno == EINTR)
				continue;
			return copyError (src, dst, dstDir, newName, buf);
		}
		if (numInBuf == 0)
			break;
		
		bufPtr = buf;
		do
		{
			numWritten = uio_write (dst, bufPtr, numInBuf);
			if (numWritten == -1)
			{
				if (errno == EINTR)
					continue;
				return copyError (src, dst, dstDir, newName, buf);
			}
			numInBuf -= numWritten;
			bufPtr += numWritten;
		} while (numInBuf > 0);
	}
	
	HFree (buf);
	uio_close (src);
	uio_close (dst);
	errno = 0;
	return 0;
}

/*
 * Closes srcHandle if it's not -1.
 * Closes dstHandle if it's not -1.
 * Removes unlinkpath from the unlinkHandle dir if it's not NULL.
 * Frees 'buf' if not NULL.
 * Always returns -1.
 * errno is what was before the call.
 */
static int
copyError(uio_Handle *srcHandle, uio_Handle *dstHandle,
		uio_DirHandle *unlinkHandle, const char *unlinkPath, uint8 *buf)
{
	int savedErrno;

	savedErrno = errno;

	log_add (log_Debug, "Error while copying: %s", strerror (errno));

	if (srcHandle != NULL)
		uio_close (srcHandle);
	
	if (dstHandle != NULL)
		uio_close (dstHandle);
	
	if (unlinkPath != NULL)
		uio_unlink (unlinkHandle, unlinkPath);
	
	if (buf != NULL)
		HFree(buf);
	
	errno = savedErrno;
	return -1;
}