Re: [FFmpeg-devel] [PATCH v3 1/6] avutil/uuid: add utility library for manipulating UUIDs as specified in RFC 4122

[Andreas Rheinhardt <andreas.rheinhardt@outlook.com>]

pal@sandflow.com:
> From: Zane van Iperen <zane@zanevaniperen.com>
> 
> Addresses review comments including:
> 
> * simplifying av_uuid_parse_range()
> * removing avcodec/cbs_sei from this refactoring exercise
> 
> Co-authored-by: Pierre-Anthony Lemieux <pal@palemieux.com>
> Signed-off-by: Zane van Iperen <zane@zanevaniperen.com>
> ---
>  libavutil/Makefile |   2 +
>  libavutil/uuid.c   | 142 +++++++++++++++++++++++++++++++++++++++++++
>  libavutil/uuid.h   | 147 +++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 291 insertions(+)
>  create mode 100644 libavutil/uuid.c
>  create mode 100644 libavutil/uuid.h
> 
> diff --git a/libavutil/uuid.c b/libavutil/uuid.c
> new file mode 100644
> index 0000000000..8943212f30
> --- /dev/null
> +++ b/libavutil/uuid.c
> @@ -0,0 +1,142 @@
> +/*
> + * Copyright (c) 2022 Pierre-Anthony Lemieux <pal@palemieux.com>
> + *                    Zane van Iperen <zane@zanevaniperen.com>
> + *
> + * This file is part of FFmpeg.
> + *
> + * FFmpeg 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 2.1 of the License, or (at your option) any later version.
> + *
> + * FFmpeg 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 FFmpeg; if not, write to the Free Software
> + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
> + */
> +
> +/*
> + * Copyright (C) 1996, 1997 Theodore Ts'o.
> + *
> + * 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, and the entire permission notice in its entirety,
> + *    including the disclaimer of warranties.
> + * 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.
> + * 3. The name of the author may not be used to endorse or promote
> + *    products derived from this software without specific prior
> + *    written permission.
> + *
> + * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
> + * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
> + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF
> + * WHICH ARE HEREBY DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR 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 NOT ADVISED OF THE POSSIBILITY OF SUCH
> + * DAMAGE.
> + */
> +
> +/**
> + * @file
> + * UUID parsing and serialization utilities.
> + * The library treat the UUID as an opaque sequence of 16 unsigned bytes,
> + * i.e. ignoring the internal layout of the UUID, which depends on the type
> + * of the UUID.
> + *
> + * @author Pierre-Anthony Lemieux <pal@palemieux.com>
> + * @author Zane van Iperen <zane@zanevaniperen.com>
> + */
> +
> +#include "uuid.h"
> +#include "error.h"
> +#include "avstring.h"
> +#include <stdlib.h>

What is this used for?

> +
> +int av_uuid_parse(const char *in, AVUUID uu)
> +{
> +    if (strlen(in) != 36)
> +        return AVERROR(EINVAL);
> +
> +    return av_uuid_parse_range(in, in + 36, uu);
> +}
> +
> +static int xdigit_to_int(char c)
> +{
> +    c = av_tolower(c);
> +
> +    if (c >= 'a' && c <= 'f')
> +        return c - 'a' + 10;
> +
> +    if (c >= '0' && c <= '9')
> +        return c - '0';
> +
> +    return -1;
> +}
> +
> +int av_uuid_parse_range(const char *in_start, const char *in_end, AVUUID uu)
> +{
> +    int i;
> +    const char *cp;
> +
> +    if ((in_end - in_start) != 36)
> +        return AVERROR(EINVAL);
> +
> +    for (i = 0, cp = in_start; i < 16; i++) {
> +        int hi;
> +        int lo;
> +
> +        if (i == 4 || i == 6 || i == 8 || i == 10)
> +            cp++;
> +
> +        hi = xdigit_to_int(*cp++);
> +        lo = xdigit_to_int(*cp++);
> +
> +        if (hi == -1 || lo == -1)
> +            return AVERROR(EINVAL);
> +
> +        uu[i] = (hi << 4) + lo;
> +    }
> +
> +    return 0;
> +}
> +
> +static char const hexdigits_lower[16] = "0123456789abcdef";

Our typical order is "static const char"

> +
> +void av_uuid_unparse(const AVUUID uuid, char *out)
> +{
> +    char *p = out;
> +
> +    for (int i = 0; i < 16; i++) {
> +        uint8_t tmp;
> +
> +        if (i == 4 || i == 6 || i == 8 || i == 10)
> +            *p++ = '-';
> +
> +        tmp = uuid[i];
> +        *p++ = hexdigits_lower[tmp >> 4];
> +        *p++ = hexdigits_lower[tmp & 15];
> +    }
> +
> +    *p = '\0';
> +}
> +
> +int av_uuid_urn_parse(const char *in, AVUUID uu)
> +{
> +    if (av_stristr(in, "urn:uuid:") != in)
> +        return AVERROR(EINVAL);
> +
> +    return av_uuid_parse(in + 9, uu);
> +}

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