/*******************************************************************************

    Copyright(C) Jonas 'Sortie' Termansen 2011, 2013.

    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 <http://www.gnu.org/licenses/>.

    cp.cpp
    Copy files and directories.

*******************************************************************************/

#include <sys/stat.h>

#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <error.h>
#include <string.h>

const char* basename(const char* path)
{
	size_t len = strlen(path);
	while ( len-- ) { if ( path[len] == '/' ) { return path + len + 1; } }
	return path;
}

int main(int argc, char* argv[])
{
	if ( argc != 3 ) { printf("usage: %s <from> <to>\n", argv[0]); return 0; }

	const char* frompath = argv[1];
	const char* topath = argv[2];

	int fromfd = open(frompath, O_RDONLY);
	if ( fromfd < 0 ) { error(1, errno, "%s", frompath); return 1; }

	int tofd = open(topath, O_WRONLY | O_TRUNC | O_CREAT, 0777);
	if ( tofd < 0 )
		error(1, errno, "%s", topath);

	struct stat st;
	if ( fstat(tofd, &st) )
		error(1, errno, "stat: %s", topath);

	if ( S_ISDIR(st.st_mode) )
	{
		int dirfd = tofd;
		const char* name = basename(frompath);
		tofd = openat(dirfd, name, O_WRONLY | O_TRUNC | O_CREAT, 0777);
		close(dirfd);
		if ( tofd < 0 )
			error(1, errno, "%s/%s", topath, name);
	}

	while ( true )
	{
		const size_t BUFFER_SIZE = 4096;
		char buffer[BUFFER_SIZE];
		ssize_t bytesread = read(fromfd, buffer, BUFFER_SIZE);
		if ( bytesread < 0 ) { error(1, errno, "read: %s", frompath); return 1; }
		if ( bytesread == 0 ) { return 0; }
		if ( writeall(tofd, buffer, bytesread) < (size_t) bytesread )
		{
			error(1, errno, "write: %s", topath);
			return 1;
		}
	}
}