libexplain/iocontrol/vidioc_dqbuf.c

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/*
 * libexplain - a library of system-call-specific strerror replacements
 * Copyright (C) 2011, 2013 Peter Miller
 * Written by Peter Miller <pmiller@opensource.org.au>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser 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 Lesser General Public
 * License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */

#include <libexplain/ac/errno.h>
#include <libexplain/ac/linux/videodev2.h>
#include <libexplain/ac/string.h>
#include <libexplain/ac/sys/ioctl.h>

#include <libexplain/buffer/efault.h>
#include <libexplain/buffer/einval.h>
#include <libexplain/buffer/enotsup.h>
#include <libexplain/buffer/is_the_null_pointer.h>
#include <libexplain/buffer/v4l2_buffer.h>
#include <libexplain/buffer/v4l2_buf_type.h>
#include <libexplain/iocontrol/generic.h>
#include <libexplain/iocontrol/vidioc_dqbuf.h>
#include <libexplain/is_efault.h>

#ifdef VIDIOC_DQBUF


static void
print_data(const explain_iocontrol_t *p, explain_string_buffer_t *sb,
    int errnum, int fildes, int request, const void *data)
{
    (void)p;
    (void)errnum;
    (void)fildes;
    (void)request;
    explain_buffer_v4l2_buffer(sb, data, 0);
}


static void
print_explanation(const explain_iocontrol_t *p, explain_string_buffer_t *sb,
    int errnum, int fildes, int request, const void *data)
{
    /*
     * Note: Linux:
     * drivers/media/video/stk-webcam.c can return EIO when it means ENODEV
     */
    switch (errnum)
    {
    case EINVAL:
        if (!data)
        {
            explain_buffer_is_the_null_pointer(sb, "data");
            return;
        }

        {
            const struct v4l2_buffer *arg = data;

            if (explain_is_efault_pointer(arg, sizeof(*arg)))
                goto generic;

            /*
             * Check the type (Linux kernel always does this first).
             */
            switch (explain_v4l2_buf_type_check(fildes, arg->type))
            {
            case explain_v4l2_buf_type_check_no_idea:
            default:
                break;

            case explain_v4l2_buf_type_check_notsup:
                explain_buffer_enotsup_device(sb, "data->type");
                return;

            case explain_v4l2_buf_type_check_nosuch:
                explain_buffer_einval_vague(sb, "data->type");
                return;

            case explain_v4l2_buf_type_check_ok:
                break;
            }

            /*
             * Check the frame index
             */
            {
                int             nframes;

                nframes = explain_v4l2_buffer_get_nframes(fildes, arg->type);
                if (nframes == 0)
                {
                    explain_string_buffer_puts
                    (
                        sb,
                        /* FIXME: i18n */
                        "no frames have been allocated yet"
                    );
                    return;
                }
                else if (nframes > 0 && arg->index >= (unsigned)nframes)
                {
                    explain_buffer_einval_out_of_range
                    (
                        sb,
                        "data->index",
                        0,
                        nframes - 1
                    );
                    return;
                }
            }
        }

        /* no idea */
        goto generic;

    case EIO:
        explain_string_buffer_puts
        (
            sb,
            /* FIXME: i18n */
            "timeout waiting for frame to become ready"
        );
        break;

    case EFAULT:
        {
            const struct v4l2_buffer *arg;

            arg = data;
            if (explain_is_efault_pointer(arg, sizeof*arg))
            {
                explain_buffer_efault(sb, "data");
                return;
            }

            switch (arg->memory)
            {
            case V4L2_MEMORY_MMAP:
            case V4L2_MEMORY_OVERLAY:
            default:
                break;

            case V4L2_MEMORY_USERPTR:
                {
                    struct v4l2_buffer b;

                    /*
                     * Interestingly, some Linux drivers use the userptr given
                     * to it in VIDIOC_QBUF, and ignore the one given to this
                     * ioctl... which makes sense if throughput is the goal.
                     */
                    memset(&b, 0, sizeof(b));
                    b.index = arg->index;
                    b.type = arg->type;
                    if (ioctl(fildes, VIDIOC_QUERYBUF, &b) >= 0)
                    {
                        const void *vp = (const void *)b.m.userptr;
                        if (explain_is_efault_pointer(vp, b.bytesused))
                        {
                            explain_buffer_efault(sb, "data->m.userptr");
                            return;
                        }
                    }
                }
                break;
            }
        }

        /* no idea */
        goto generic;

    default:
        generic:
        explain_iocontrol_generic_print_explanation
        (
            p,
            sb,
            errnum,
            fildes,
            request,
            data
        );
        break;
    }
}


static void
print_data_returned(const explain_iocontrol_t *p, explain_string_buffer_t *sb,
    int errnum, int fildes, int request, const void *data)
{
    (void)p;
    (void)errnum;
    (void)fildes;
    (void)request;
    explain_buffer_v4l2_buffer(sb, data, 1);
}


const explain_iocontrol_t explain_iocontrol_vidioc_dqbuf =
{
    "VIDIOC_DQBUF", /* name */
    VIDIOC_DQBUF, /* value */
    0, /* disambiguate */
    0, /* print_name */
    print_data,
    print_explanation,
    print_data_returned,
    sizeof(struct v4l2_buffer), /* data_size */
    "struct v4l2_buffer *", /* data_type */
    0, /* flags */
    __FILE__,
    __LINE__,
};

#else /* ndef VIDIOC_DQBUF */

const explain_iocontrol_t explain_iocontrol_vidioc_dqbuf =
{
    0, /* name */
    0, /* value */
    0, /* disambiguate */
    0, /* print_name */
    0, /* print_data */
    0, /* print_explanation */
    0, /* print_data_returned */
    0, /* data_size */
    0, /* data_type */
    0, /* flags */
    __FILE__,
    __LINE__,
};

#endif /* VIDIOC_DQBUF */

/* vim: set ts=8 sw=4 et : */