/*-
 * Copyright (c) 2003-2007 Tim Kientzle
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "archive_platform.h"
__FBSDID("$FreeBSD: src/lib/libarchive/archive_read_open_fd.c,v 1.13 2007/06/26 03:06:48 kientzle Exp $");

#ifdef HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif
#ifdef HAVE_ERRNO_H
#include <errno.h>
#endif
#ifdef HAVE_FCNTL_H
#include <fcntl.h>
#endif
#ifdef HAVE_IO_H
#include <io.h>
#endif
#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif
#ifdef HAVE_STRING_H
#include <string.h>
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

#include "archive.h"

struct read_fd_data {
    int  fd;
    size_t   block_size;
    char     can_skip;
    void    *buffer;
};

static int  file_close(struct archive *, void *);
static ssize_t  file_read(struct archive *, void *, const void **buff);
#if ARCHIVE_API_VERSION < 2
static ssize_t  file_skip(struct archive *, void *, size_t request);
#else
static off_t    file_skip(struct archive *, void *, off_t request);
#endif

int
archive_read_open_fd(struct archive *a, int fd, size_t block_size)
{
    struct stat st;
    struct read_fd_data *mine;
    void *b;

    archive_clear_error(a);
    if (fstat(fd, &st) != 0) {
        archive_set_error(a, errno, "Can't stat fd %d", fd);
        return (ARCHIVE_FATAL);
    }

    mine = (struct read_fd_data *)malloc(sizeof(*mine));
    b = malloc(block_size);
    if (mine == NULL || b == NULL) {
        archive_set_error(a, ENOMEM, "No memory");
        free(mine);
        free(b);
        return (ARCHIVE_FATAL);
    }
    mine->block_size = block_size;
    mine->buffer = b;
    mine->fd = fd;
    /*
     * Skip support is a performance optimization for anything
     * that supports lseek().  On FreeBSD, only regular files and
     * raw disk devices support lseek() and there's no portable
     * way to determine if a device is a raw disk device, so we
     * only enable this optimization for regular files.
     */
    if (S_ISREG(st.st_mode)) {
        archive_read_extract_set_skip_file(a, st.st_dev, st.st_ino);
        mine->can_skip = 1;
    } else
        mine->can_skip = 0;
#if defined(__CYGWIN__)
    setmode(mine->fd, O_BINARY);
#elif defined(_WIN32)
    _setmode(mine->fd, _O_BINARY);
#endif

    return (archive_read_open2(a, mine,
        NULL, file_read, file_skip, file_close));
}

static ssize_t
file_read(struct archive *a, void *client_data, const void **buff)
{
    struct read_fd_data *mine = (struct read_fd_data *)client_data;
    ssize_t bytes_read;

    *buff = mine->buffer;
    bytes_read = read(mine->fd, mine->buffer, mine->block_size);
    if (bytes_read < 0) {
        archive_set_error(a, errno, "Error reading fd %d", mine->fd);
    }
    return (bytes_read);
}

#if ARCHIVE_API_VERSION < 2
static ssize_t
file_skip(struct archive *a, void *client_data, size_t request)
#else
static off_t
file_skip(struct archive *a, void *client_data, off_t request)
#endif
{
    struct read_fd_data *mine = (struct read_fd_data *)client_data;
    off_t old_offset, new_offset;

    if (!mine->can_skip)
        return (0);

    /* Reduce request to the next smallest multiple of block_size */
    request = (request / mine->block_size) * mine->block_size;
    if (request == 0)
        return (0);

    /*
     * Hurray for lazy evaluation: if the first lseek fails, the second
     * one will not be executed.
     */
    if (((old_offset = lseek(mine->fd, 0, SEEK_CUR)) < 0) ||
        ((new_offset = lseek(mine->fd, request, SEEK_CUR)) < 0))
    {
        /* If seek failed once, it will probably fail again. */
        mine->can_skip = 0;

        if (errno == ESPIPE)
        {
            /*
             * Failure to lseek() can be caused by the file
             * descriptor pointing to a pipe, socket or FIFO.
             * Return 0 here, so the compression layer will use
             * read()s instead to advance the file descriptor.
             * It's slower of course, but works as well.
             */
            return (0);
        }
        /*
         * There's been an error other than ESPIPE. This is most
         * likely caused by a programmer error (too large request)
         * or a corrupted archive file.
         */
        archive_set_error(a, errno, "Error seeking");
        return (-1);
    }
    return (new_offset - old_offset);
}

static int
file_close(struct archive *a, void *client_data)
{
    struct read_fd_data *mine = (struct read_fd_data *)client_data;

    (void)a; /* UNUSED */
    free(mine->buffer);
    free(mine);
    return (ARCHIVE_OK);
}