busybox/libbb/copyfd.c

/* vi: set sw=4 ts=4: */
/*
 * Utility routines.
 *
 * Copyright (C) 1999-2005 by Erik Andersen <andersen@codepoet.org>
 *
 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
 */

#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "libbb.h"


#if BUFSIZ < 4096
#undef BUFSIZ
#define BUFSIZ 4096
#endif


static off_t bb_full_fd_action(int src_fd, int dst_fd, off_t size)
{
	int status = -1;
	off_t total = 0;
	RESERVE_CONFIG_BUFFER(buffer,BUFSIZ);

	if (src_fd < 0) goto out;
	while (!size || total < size) {
		ssize_t wr, rd;

		rd = safe_read(src_fd, buffer,
				(!size || size - total > BUFSIZ) ? BUFSIZ : size - total);

		if (rd > 0) {
			/* A -1 dst_fd means we need to fake it... */
			wr = (dst_fd < 0) ? rd : full_write(dst_fd, buffer, rd);
			if (wr < rd) {
				bb_perror_msg(bb_msg_write_error);
				break;
			}
			total += wr;
			if (total == size) status = 0;
		} else if (rd < 0) {
			bb_perror_msg(bb_msg_read_error);
			break;
		} else if (rd == 0) {
			/* All done. */
			status = 0;
			break;
		}
	}

out:
	RELEASE_CONFIG_BUFFER(buffer);

	return status ? status : total;
}


off_t bb_copyfd_size(int fd1, int fd2, off_t size)
{
	if (size) {
		return bb_full_fd_action(fd1, fd2, size);
	}
	return 0;
}

off_t bb_copyfd_eof(int fd1, int fd2)
{
	return bb_full_fd_action(fd1, fd2, 0);
}