// SPDX-License-Identifier: GPL-2.0-only
/*
 * V4L2 JPEG header parser helpers.
 *
 * Copyright (C) 2019 Pengutronix, Philipp Zabel <kernel@pengutronix.de>
 *
 * For reference, see JPEG ITU-T.81 (ISO/IEC 10918-1) [1]
 *
 * [1] https://www.w3.org/Graphics/JPEG/itu-t81.pdf
 */

#include <linux/unaligned.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/types.h>
#include <media/v4l2-jpeg.h>

MODULE_DESCRIPTION("V4L2 JPEG header parser helpers");
MODULE_AUTHOR("Philipp Zabel <kernel@pengutronix.de>");
MODULE_LICENSE("GPL");

/* Table B.1 - Marker code assignments */
#define SOF0    0xffc0  /* start of frame */
#define SOF1    0xffc1
#define SOF2    0xffc2
#define SOF3    0xffc3
#define SOF5    0xffc5
#define SOF7    0xffc7
#define JPG     0xffc8  /* extensions */
#define SOF9    0xffc9
#define SOF11   0xffcb
#define SOF13   0xffcd
#define SOF15   0xffcf
#define DHT     0xffc4  /* huffman table */
#define DAC     0xffcc  /* arithmetic coding conditioning */
#define RST0    0xffd0  /* restart */
#define RST7    0xffd7
#define SOI     0xffd8  /* start of image */
#define EOI     0xffd9  /* end of image */
#define SOS     0xffda  /* start of stream */
#define DQT     0xffdb  /* quantization table */
#define DNL     0xffdc  /* number of lines */
#define DRI     0xffdd  /* restart interval */
#define DHP     0xffde  /* hierarchical progression */
#define EXP     0xffdf  /* expand reference */
#define APP0    0xffe0  /* application data */
#define APP14   0xffee  /* application data for colour encoding */
#define APP15   0xffef
#define JPG0    0xfff0  /* extensions */
#define JPG13   0xfffd
#define COM     0xfffe  /* comment */
#define TEM     0xff01  /* temporary */

/* Luma and chroma qp tables to achieve 50% compression quality
 * This is as per example in Annex K.1 of ITU-T.81
 */
const u8 v4l2_jpeg_ref_table_luma_qt[V4L2_JPEG_PIXELS_IN_BLOCK] = {
        16, 11, 10, 16, 24, 40, 51, 61,
        12, 12, 14, 19, 26, 58, 60, 55,
        14, 13, 16, 24, 40, 57, 69, 56,
        14, 17, 22, 29, 51, 87, 80, 62,
        18, 22, 37, 56, 68, 109, 103, 77,
        24, 35, 55, 64, 81, 104, 113, 92,
        49, 64, 78, 87, 103, 121, 120, 101,
        72, 92, 95, 98, 112, 100, 103, 99
};
EXPORT_SYMBOL_GPL(v4l2_jpeg_ref_table_luma_qt);

const u8 v4l2_jpeg_ref_table_chroma_qt[V4L2_JPEG_PIXELS_IN_BLOCK] = {
        17, 18, 24, 47, 99, 99, 99, 99,
        18, 21, 26, 66, 99, 99, 99, 99,
        24, 26, 56, 99, 99, 99, 99, 99,
        47, 66, 99, 99, 99, 99, 99, 99,
        99, 99, 99, 99, 99, 99, 99, 99,
        99, 99, 99, 99, 99, 99, 99, 99,
        99, 99, 99, 99, 99, 99, 99, 99,
        99, 99, 99, 99, 99, 99, 99, 99
};
EXPORT_SYMBOL_GPL(v4l2_jpeg_ref_table_chroma_qt);

/* Zigzag scan pattern indexes */
const u8 v4l2_jpeg_zigzag_scan_index[V4L2_JPEG_PIXELS_IN_BLOCK] = {
        0,   1,  8, 16,  9,  2,  3, 10,
        17, 24, 32, 25, 18, 11,  4,  5,
        12, 19, 26, 33, 40, 48, 41, 34,
        27, 20, 13,  6,  7, 14, 21, 28,
        35, 42, 49, 56, 57, 50, 43, 36,
        29, 22, 15, 23, 30, 37, 44, 51,
        58, 59, 52, 45, 38, 31, 39, 46,
        53, 60, 61, 54, 47, 55, 62, 63
};
EXPORT_SYMBOL_GPL(v4l2_jpeg_zigzag_scan_index);

/*
 * Contains the data that needs to be sent in the marker segment of an
 * interchange format JPEG stream or an abbreviated format table specification
 * data stream. Specifies the huffman table used for encoding the luminance DC
 * coefficient differences. The table represents Table K.3 of ITU-T.81
 */
const u8 v4l2_jpeg_ref_table_luma_dc_ht[V4L2_JPEG_REF_HT_DC_LEN] = {
        0x00, 0x01, 0x05, 0x01, 0x01, 0x01, 0x01, 0x01,
        0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 0x0B
};
EXPORT_SYMBOL_GPL(v4l2_jpeg_ref_table_luma_dc_ht);

/*
 * Contains the data that needs to be sent in the marker segment of an
 * interchange format JPEG stream or an abbreviated format table specification
 * data stream. Specifies the huffman table used for encoding the luminance AC
 * coefficients. The table represents Table K.5 of ITU-T.81
 */
const u8 v4l2_jpeg_ref_table_luma_ac_ht[V4L2_JPEG_REF_HT_AC_LEN] = {
        0x00, 0x02, 0x01, 0x03, 0x03, 0x02, 0x04, 0x03, 0x05, 0x05, 0x04, 0x04,
        0x00, 0x00, 0x01, 0x7D, 0x01, 0x02, 0x03, 0x00, 0x04, 0x11, 0x05, 0x12,
        0x21, 0x31, 0x41, 0x06, 0x13, 0x51, 0x61, 0x07, 0x22, 0x71, 0x14, 0x32,
        0x81, 0x91, 0xA1, 0x08, 0x23, 0x42, 0xB1, 0xC1, 0x15, 0x52, 0xD1, 0xF0,
        0x24, 0x33, 0x62, 0x72, 0x82, 0x09, 0x0A, 0x16, 0x17, 0x18, 0x19, 0x1A,
        0x25, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39,
        0x3A, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49, 0x4A, 0x53, 0x54, 0x55,
        0x56, 0x57, 0x58, 0x59, 0x5A, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69,
        0x6A, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7A, 0x83, 0x84, 0x85,
        0x86, 0x87, 0x88, 0x89, 0x8A, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98,
        0x99, 0x9A, 0xA2, 0xA3, 0xA4, 0xA5, 0xA6, 0xA7, 0xA8, 0xA9, 0xAA, 0xB2,
        0xB3, 0xB4, 0xB5, 0xB6, 0xB7, 0xB8, 0xB9, 0xBA, 0xC2, 0xC3, 0xC4, 0xC5,
        0xC6, 0xC7, 0xC8, 0xC9, 0xCA, 0xD2, 0xD3, 0xD4, 0xD5, 0xD6, 0xD7, 0xD8,
        0xD9, 0xDA, 0xE1, 0xE2, 0xE3, 0xE4, 0xE5, 0xE6, 0xE7, 0xE8, 0xE9, 0xEA,
        0xF1, 0xF2, 0xF3, 0xF4, 0xF5, 0xF6, 0xF7, 0xF8, 0xF9, 0xFA
};
EXPORT_SYMBOL_GPL(v4l2_jpeg_ref_table_luma_ac_ht);

/*
 * Contains the data that needs to be sent in the marker segment of an interchange format JPEG
 * stream or an abbreviated format table specification data stream.
 * Specifies the huffman table used for encoding the chrominance DC coefficient differences.
 * The table represents Table K.4 of ITU-T.81
 */
const u8 v4l2_jpeg_ref_table_chroma_dc_ht[V4L2_JPEG_REF_HT_DC_LEN] = {
        0x00, 0x03, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
        0x01, 0x01, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 0x0B
};
EXPORT_SYMBOL_GPL(v4l2_jpeg_ref_table_chroma_dc_ht);

/*
 * Contains the data that needs to be sent in the marker segment of an
 * interchange format JPEG stream or an abbreviated format table specification
 * data stream. Specifies the huffman table used for encoding the chrominance
 * AC coefficients. The table represents Table K.6 of ITU-T.81
 */
const u8 v4l2_jpeg_ref_table_chroma_ac_ht[V4L2_JPEG_REF_HT_AC_LEN] = {
        0x00, 0x02, 0x01, 0x02, 0x04, 0x04, 0x03, 0x04, 0x07, 0x05, 0x04, 0x04,
        0x00, 0x01, 0x02, 0x77, 0x00, 0x01, 0x02, 0x03, 0x11, 0x04, 0x05, 0x21,
        0x31, 0x06, 0x12, 0x41, 0x51, 0x07, 0x61, 0x71, 0x13, 0x22, 0x32, 0x81,
        0x08, 0x14, 0x42, 0x91, 0xA1, 0xB1, 0xC1, 0x09, 0x23, 0x33, 0x52, 0xF0,
        0x15, 0x62, 0x72, 0xD1, 0x0A, 0x16, 0x24, 0x34, 0xE1, 0x25, 0xF1, 0x17,
        0x18, 0x19, 0x1A, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x35, 0x36, 0x37, 0x38,
        0x39, 0x3A, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49, 0x4A, 0x53, 0x54,
        0x55, 0x56, 0x57, 0x58, 0x59, 0x5A, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68,
        0x69, 0x6A, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7A, 0x82, 0x83,
        0x84, 0x85, 0x86, 0x87, 0x88, 0x89, 0x8A, 0x92, 0x93, 0x94, 0x95, 0x96,
        0x97, 0x98, 0x99, 0x9A, 0xA2, 0xA3, 0xA4, 0xA5, 0xA6, 0xA7, 0xA8, 0xA9,
        0xAA, 0xB2, 0xB3, 0xB4, 0xB5, 0xB6, 0xB7, 0xB8, 0xB9, 0xBA, 0xC2, 0xC3,
        0xC4, 0xC5, 0xC6, 0xC7, 0xC8, 0xC9, 0xCA, 0xD2, 0xD3, 0xD4, 0xD5, 0xD6,
        0xD7, 0xD8, 0xD9, 0xDA, 0xE2, 0xE3, 0xE4, 0xE5, 0xE6, 0xE7, 0xE8, 0xE9,
        0xEA, 0xF2, 0xF3, 0xF4, 0xF5, 0xF6, 0xF7, 0xF8, 0xF9, 0xFA
};
EXPORT_SYMBOL_GPL(v4l2_jpeg_ref_table_chroma_ac_ht);

/**
 * struct jpeg_stream - JPEG byte stream
 * @curr: current position in stream
 * @end: end position, after last byte
 */
struct jpeg_stream {
        u8 *curr;
        u8 *end;
};

/* returns a value that fits into u8, or negative error */
static int jpeg_get_byte(struct jpeg_stream *stream)
{
        if (stream->curr >= stream->end)
                return -EINVAL;

        return *stream->curr++;
}

/* returns a value that fits into u16, or negative error */
static int jpeg_get_word_be(struct jpeg_stream *stream)
{
        u16 word;

        if (stream->curr + sizeof(__be16) > stream->end)
                return -EINVAL;

        word = get_unaligned_be16(stream->curr);
        stream->curr += sizeof(__be16);

        return word;
}

static int jpeg_skip(struct jpeg_stream *stream, size_t len)
{
        if (stream->curr + len > stream->end)
                return -EINVAL;

        stream->curr += len;

        return 0;
}

static int jpeg_next_marker(struct jpeg_stream *stream)
{
        int byte;
        u16 marker = 0;

        while ((byte = jpeg_get_byte(stream)) >= 0) {
                marker = (marker << 8) | byte;
                /* skip stuffing bytes and REServed markers */
                if (marker == TEM || (marker > 0xffbf && marker < 0xffff))
                        return marker;
        }

        return byte;
}

/* this does not advance the current position in the stream */
static int jpeg_reference_segment(struct jpeg_stream *stream,
                                  struct v4l2_jpeg_reference *segment)
{
        u16 len;

        if (stream->curr + sizeof(__be16) > stream->end)
                return -EINVAL;

        len = get_unaligned_be16(stream->curr);
        if (stream->curr + len > stream->end)
                return -EINVAL;

        segment->start = stream->curr;
        segment->length = len;

        return 0;
}

static int v4l2_jpeg_decode_subsampling(u8 nf, u8 h_v)
{
        if (nf == 1)
                return V4L2_JPEG_CHROMA_SUBSAMPLING_GRAY;

        /* no chroma subsampling for 4-component images */
        if (nf == 4 && h_v != 0x11)
                return -EINVAL;

        switch (h_v) {
        case 0x11:
                return V4L2_JPEG_CHROMA_SUBSAMPLING_444;
        case 0x21:
                return V4L2_JPEG_CHROMA_SUBSAMPLING_422;
        case 0x22:
                return V4L2_JPEG_CHROMA_SUBSAMPLING_420;
        case 0x41:
                return V4L2_JPEG_CHROMA_SUBSAMPLING_411;
        default:
                return -EINVAL;
        }
}

static int jpeg_parse_frame_header(struct jpeg_stream *stream, u16 sof_marker,
                                   struct v4l2_jpeg_frame_header *frame_header)
{
        int len = jpeg_get_word_be(stream);

        if (len < 0)
                return len;
        /* Lf = 8 + 3 * Nf, Nf >= 1 */
        if (len < 8 + 3)
                return -EINVAL;

        if (frame_header) {
                /* Table B.2 - Frame header parameter sizes and values */
                int p, y, x, nf;
                int i;

                p = jpeg_get_byte(stream);
                if (p < 0)
                        return p;
                /*
                 * Baseline DCT only supports 8-bit precision.
                 * Extended sequential DCT also supports 12-bit precision.
                 */
                if (p != 8 && (p != 12 || sof_marker != SOF1))
                        return -EINVAL;

                y = jpeg_get_word_be(stream);
                if (y < 0)
                        return y;
                if (y == 0)
                        return -EINVAL;

                x = jpeg_get_word_be(stream);
                if (x < 0)
                        return x;
                if (x == 0)
                        return -EINVAL;

                nf = jpeg_get_byte(stream);
                if (nf < 0)
                        return nf;
                /*
                 * The spec allows 1 <= Nf <= 255, but we only support up to 4
                 * components.
                 */
                if (nf < 1 || nf > V4L2_JPEG_MAX_COMPONENTS)
                        return -EINVAL;
                if (len != 8 + 3 * nf)
                        return -EINVAL;

                frame_header->precision = p;
                frame_header->height = y;
                frame_header->width = x;
                frame_header->num_components = nf;

                for (i = 0; i < nf; i++) {
                        struct v4l2_jpeg_frame_component_spec *component;
                        int c, h_v, tq;

                        c = jpeg_get_byte(stream);
                        if (c < 0)
                                return c;

                        h_v = jpeg_get_byte(stream);
                        if (h_v < 0)
                                return h_v;
                        if (i == 0) {
                                int subs;

                                subs = v4l2_jpeg_decode_subsampling(nf, h_v);
                                if (subs < 0)
                                        return subs;
                                frame_header->subsampling = subs;
                        } else if (h_v != 0x11) {
                                /* all chroma sampling factors must be 1 */
                                return -EINVAL;
                        }

                        tq = jpeg_get_byte(stream);
                        if (tq < 0)
                                return tq;

                        component = &frame_header->component[i];
                        component->component_identifier = c;
                        component->horizontal_sampling_factor =
                                (h_v >> 4) & 0xf;
                        component->vertical_sampling_factor = h_v & 0xf;
                        component->quantization_table_selector = tq;
                }
        } else {
                return jpeg_skip(stream, len - 2);
        }

        return 0;
}

static int jpeg_parse_scan_header(struct jpeg_stream *stream,
                                  struct v4l2_jpeg_scan_header *scan_header)
{
        size_t skip;
        int len = jpeg_get_word_be(stream);

        if (len < 0)
                return len;
        /* Ls = 8 + 3 * Ns, Ns >= 1 */
        if (len < 6 + 2)
                return -EINVAL;

        if (scan_header) {
                int ns;
                int i;

                ns = jpeg_get_byte(stream);
                if (ns < 0)
                        return ns;
                if (ns < 1 || ns > 4 || len != 6 + 2 * ns)
                        return -EINVAL;

                scan_header->num_components = ns;

                for (i = 0; i < ns; i++) {
                        struct v4l2_jpeg_scan_component_spec *component;
                        int cs, td_ta;

                        cs = jpeg_get_byte(stream);
                        if (cs < 0)
                                return cs;

                        td_ta = jpeg_get_byte(stream);
                        if (td_ta < 0)
                                return td_ta;

                        component = &scan_header->component[i];
                        component->component_selector = cs;
                        component->dc_entropy_coding_table_selector =
                                (td_ta >> 4) & 0xf;
                        component->ac_entropy_coding_table_selector =
                                td_ta & 0xf;
                }

                skip = 3; /* skip Ss, Se, Ah, and Al */
        } else {
                skip = len - 2;
        }

        return jpeg_skip(stream, skip);
}

/* B.2.4.1 Quantization table-specification syntax */
static int jpeg_parse_quantization_tables(struct jpeg_stream *stream,
                                          u8 precision,
                                          struct v4l2_jpeg_reference *tables)
{
        int len = jpeg_get_word_be(stream);

        if (len < 0)
                return len;
        /* Lq = 2 + n * 65 (for baseline DCT), n >= 1 */
        if (len < 2 + 65)
                return -EINVAL;

        len -= 2;
        while (len >= 65) {
                u8 pq, tq, *qk;
                int ret;
                int pq_tq = jpeg_get_byte(stream);

                if (pq_tq < 0)
                        return pq_tq;

                /* quantization table element precision */
                pq = (pq_tq >> 4) & 0xf;
                /*
                 * Only 8-bit Qk values for 8-bit sample precision. Extended
                 * sequential DCT with 12-bit sample precision also supports
                 * 16-bit Qk values.
                 */
                if (pq != 0 && (pq != 1 || precision != 12))
                        return -EINVAL;

                /* quantization table destination identifier */
                tq = pq_tq & 0xf;
                if (tq > 3)
                        return -EINVAL;

                /* quantization table element */
                qk = stream->curr;
                ret = jpeg_skip(stream, pq ? 128 : 64);
                if (ret < 0)
                        return -EINVAL;

                if (tables) {
                        tables[tq].start = qk;
                        tables[tq].length = pq ? 128 : 64;
                }

                len -= pq ? 129 : 65;
        }

        return 0;
}

/* B.2.4.2 Huffman table-specification syntax */
static int jpeg_parse_huffman_tables(struct jpeg_stream *stream,
                                     struct v4l2_jpeg_reference *tables)
{
        int mt;
        int len = jpeg_get_word_be(stream);

        if (len < 0)
                return len;
        /* Table B.5 - Huffman table specification parameter sizes and values */
        if (len < 2 + 17)
                return -EINVAL;

        for (len -= 2; len >= 17; len -= 17 + mt) {
                u8 tc, th, *table;
                int tc_th = jpeg_get_byte(stream);
                int i, ret;

                if (tc_th < 0)
                        return tc_th;

                /* table class - 0 = DC, 1 = AC */
                tc = (tc_th >> 4) & 0xf;
                if (tc > 1)
                        return -EINVAL;

                /* huffman table destination identifier */
                th = tc_th & 0xf;
                /* only two Huffman tables for baseline DCT */
                if (th > 1)
                        return -EINVAL;

                /* BITS - number of Huffman codes with length i */
                table = stream->curr;
                mt = 0;
                for (i = 0; i < 16; i++) {
                        int li;

                        li = jpeg_get_byte(stream);
                        if (li < 0)
                                return li;

                        mt += li;
                }
                /* HUFFVAL - values associated with each Huffman code */
                ret = jpeg_skip(stream, mt);
                if (ret < 0)
                        return ret;

                if (tables) {
                        tables[(tc << 1) | th].start = table;
                        tables[(tc << 1) | th].length = stream->curr - table;
                }
        }

        return jpeg_skip(stream, len - 2);
}

/* B.2.4.4 Restart interval definition syntax */
static int jpeg_parse_restart_interval(struct jpeg_stream *stream,
                                       u16 *restart_interval)
{
        int len = jpeg_get_word_be(stream);
        int ri;

        if (len < 0)
                return len;
        if (len != 4)
                return -EINVAL;

        ri = jpeg_get_word_be(stream);
        if (ri < 0)
                return ri;

        *restart_interval = ri;

        return 0;
}

static int jpeg_skip_segment(struct jpeg_stream *stream)
{
        int len = jpeg_get_word_be(stream);

        if (len < 0)
                return len;
        if (len < 2)
                return -EINVAL;

        return jpeg_skip(stream, len - 2);
}

/* Rec. ITU-T T.872 (06/2012) 6.5.3 */
static int jpeg_parse_app14_data(struct jpeg_stream *stream,
                                 enum v4l2_jpeg_app14_tf *tf)
{
        int ret;
        int lp;
        int skip;

        lp = jpeg_get_word_be(stream);
        if (lp < 0)
                return lp;

        /* Check for "Adobe\0" in Ap1..6 */
        if (stream->curr + 6 > stream->end ||
            strncmp(stream->curr, "Adobe\0", 6))
                return jpeg_skip(stream, lp - 2);

        /* get to Ap12 */
        ret = jpeg_skip(stream, 11);
        if (ret < 0)
                return ret;

        ret = jpeg_get_byte(stream);
        if (ret < 0)
                return ret;

        *tf = ret;

        /* skip the rest of the segment, this ensures at least it is complete */
        skip = lp - 2 - 11 - 1;
        return jpeg_skip(stream, skip);
}

/**
 * v4l2_jpeg_parse_header - locate marker segments and optionally parse headers
 * @buf: address of the JPEG buffer, should start with a SOI marker
 * @len: length of the JPEG buffer
 * @out: returns marker segment positions and optionally parsed headers
 *
 * The out->scan_header pointer must be initialized to NULL or point to a valid
 * v4l2_jpeg_scan_header structure. The out->huffman_tables and
 * out->quantization_tables pointers must be initialized to NULL or point to a
 * valid array of 4 v4l2_jpeg_reference structures each.
 *
 * Returns 0 or negative error if parsing failed.
 */
int v4l2_jpeg_parse_header(void *buf, size_t len, struct v4l2_jpeg_header *out)
{
        struct jpeg_stream stream;
        int marker;
        int ret = 0;

        stream.curr = buf;
        stream.end = stream.curr + len;

        out->num_dht = 0;
        out->num_dqt = 0;

        /* the first bytes must be SOI, B.2.1 High-level syntax */
        if (jpeg_get_word_be(&stream) != SOI)
                return -EINVAL;

        /* init value to signal if this marker is not present */
        out->app14_tf = V4L2_JPEG_APP14_TF_UNKNOWN;

        /* loop through marker segments */
        while ((marker = jpeg_next_marker(&stream)) >= 0) {
                switch (marker) {
                /* baseline DCT, extended sequential DCT */
                case SOF0 ... SOF1:
                        ret = jpeg_reference_segment(&stream, &out->sof);
                        if (ret < 0)
                                return ret;
                        ret = jpeg_parse_frame_header(&stream, marker,
                                                      &out->frame);
                        break;
                /* progressive, lossless */
                case SOF2 ... SOF3:
                /* differential coding */
                case SOF5 ... SOF7:
                /* arithmetic coding */
                case SOF9 ... SOF11:
                case SOF13 ... SOF15:
                case DAC:
                case TEM:
                        return -EINVAL;

                case DHT:
                        ret = jpeg_reference_segment(&stream,
                                        &out->dht[out->num_dht++ % 4]);
                        if (ret < 0)
                                return ret;
                        if (!out->huffman_tables) {
                                ret = jpeg_skip_segment(&stream);
                                break;
                        }
                        ret = jpeg_parse_huffman_tables(&stream,
                                                        out->huffman_tables);
                        break;
                case DQT:
                        ret = jpeg_reference_segment(&stream,
                                        &out->dqt[out->num_dqt++ % 4]);
                        if (ret < 0)
                                return ret;
                        if (!out->quantization_tables) {
                                ret = jpeg_skip_segment(&stream);
                                break;
                        }
                        ret = jpeg_parse_quantization_tables(&stream,
                                        out->frame.precision,
                                        out->quantization_tables);
                        break;
                case DRI:
                        ret = jpeg_parse_restart_interval(&stream,
                                                        &out->restart_interval);
                        break;
                case APP14:
                        ret = jpeg_parse_app14_data(&stream,
                                                    &out->app14_tf);
                        break;
                case SOS:
                        ret = jpeg_reference_segment(&stream, &out->sos);
                        if (ret < 0)
                                return ret;
                        ret = jpeg_parse_scan_header(&stream, out->scan);
                        /*
                         * stop parsing, the scan header marks the beginning of
                         * the entropy coded segment
                         */
                        out->ecs_offset = stream.curr - (u8 *)buf;
                        return ret;

                /* markers without parameters */
                case RST0 ... RST7: /* restart */
                case SOI: /* start of image */
                case EOI: /* end of image */
                        break;

                /* skip unknown or unsupported marker segments */
                default:
                        ret = jpeg_skip_segment(&stream);
                        break;
                }
                if (ret < 0)
                        return ret;
        }

        return marker;
}
EXPORT_SYMBOL_GPL(v4l2_jpeg_parse_header);