/*
 * The Qubes OS Project, http://www.qubes-os.org
 *
 * Copyright (C) 2010  Rafal Wojtczuk  <rafal@invisiblethingslab.com>
 *
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 */

#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <errno.h>

void perror_wrapper(const char * msg)
{
    int prev=errno;
    perror(msg);
    errno=prev;
}

void set_nonblock(int fd)
{
    int fl = fcntl(fd, F_GETFL, 0);
    if (fl & O_NONBLOCK)
        return;
    fcntl(fd, F_SETFL, fl | O_NONBLOCK);
}

void set_block(int fd)
{
    int fl = fcntl(fd, F_GETFL, 0);
    if (!(fl & O_NONBLOCK))
        return;
    fcntl(fd, F_SETFL, fl & ~O_NONBLOCK);
}

int write_all(int fd, const void *buf, int size)
{
    int written = 0;
    int ret;
    while (written < size) {
        ret = write(fd, (char *) buf + written, size - written);
        if (ret == -1 && errno == EINTR)
            continue;
        if (ret <= 0) {
            return 0;
        }
        written += ret;
    }
    //      fprintf(stderr, "sent %d bytes\n", size);
    return 1;
}

int read_all(int fd, void *buf, int size)
{
    int got_read = 0;
    int ret;
    while (got_read < size) {
        ret = read(fd, (char *) buf + got_read, size - got_read);
        if (ret == -1 && errno == EINTR)
            continue;
        if (ret == 0) {
            errno = 0;
            fprintf(stderr, "EOF\n");
            return 0;
        }
        if (ret < 0) {
            if (errno != EAGAIN)
                perror_wrapper("read");
            return 0;
        }
        if (got_read == 0) {
            // force blocking operation on further reads
            set_block(fd);
        }
        got_read += ret;
    }
    //      fprintf(stderr, "read %d bytes\n", size);
    return 1;
}

int copy_fd_all(int fdout, int fdin)
{
    int ret;
    char buf[4096];
    for (;;) {
        ret = read(fdin, buf, sizeof(buf));
        if (ret == -1 && errno == EINTR)
            continue;
        if (!ret)
            break;
        if (ret < 0) {
            perror_wrapper("read");
            return 0;
        }
        if (!write_all(fdout, buf, ret)) {
            perror_wrapper("write");
            return 0;
        }
    }
    return 1;
}