FFmpeg/libavcodec/avpacket.c

/*
 * AVPacket functions for libavcodec
 * Copyright (c) 2000, 2001, 2002 Fabrice Bellard
 *
 * This file is part of Libav.
 *
 * Libav 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.
 *
 * Libav 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 Libav; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include <string.h>

#include "libavutil/avassert.h"
#include "libavutil/mem.h"
#include "avcodec.h"

void av_destruct_packet(AVPacket *pkt)
{
    int i;

    av_free(pkt->data);
    pkt->data = NULL;
    pkt->size = 0;

    for (i = 0; i < pkt->side_data_elems; i++)
        av_free(pkt->side_data[i].data);
    av_freep(&pkt->side_data);
    pkt->side_data_elems = 0;
}

void av_init_packet(AVPacket *pkt)
{
    pkt->pts                  = AV_NOPTS_VALUE;
    pkt->dts                  = AV_NOPTS_VALUE;
    pkt->pos                  = -1;
    pkt->duration             = 0;
    pkt->convergence_duration = 0;
    pkt->flags                = 0;
    pkt->stream_index         = 0;
    pkt->destruct             = NULL;
    pkt->side_data            = NULL;
    pkt->side_data_elems      = 0;
}

int av_new_packet(AVPacket *pkt, int size)
{
    uint8_t *data = NULL;
    if ((unsigned)size < (unsigned)size + FF_INPUT_BUFFER_PADDING_SIZE)
        data = av_malloc(size + FF_INPUT_BUFFER_PADDING_SIZE);
    if (data) {
        memset(data + size, 0, FF_INPUT_BUFFER_PADDING_SIZE);
    } else
        size = 0;

    av_init_packet(pkt);
    pkt->data     = data;
    pkt->size     = size;
    pkt->destruct = av_destruct_packet;
    if (!data)
        return AVERROR(ENOMEM);
    return 0;
}

void av_shrink_packet(AVPacket *pkt, int size)
{
    if (pkt->size <= size)
        return;
    pkt->size = size;
    memset(pkt->data + size, 0, FF_INPUT_BUFFER_PADDING_SIZE);
}

int av_grow_packet(AVPacket *pkt, int grow_by)
{
    void *new_ptr;
    av_assert0((unsigned)pkt->size <= INT_MAX - FF_INPUT_BUFFER_PADDING_SIZE);
    if (!pkt->size)
        return av_new_packet(pkt, grow_by);
    if ((unsigned)grow_by >
        INT_MAX - (pkt->size + FF_INPUT_BUFFER_PADDING_SIZE))
        return -1;
    new_ptr = av_realloc(pkt->data,
                         pkt->size + grow_by + FF_INPUT_BUFFER_PADDING_SIZE);
    if (!new_ptr)
        return AVERROR(ENOMEM);
    pkt->data  = new_ptr;
    pkt->size += grow_by;
    memset(pkt->data + pkt->size, 0, FF_INPUT_BUFFER_PADDING_SIZE);
    return 0;
}

#define DUP_DATA(dst, src, size, padding)                               \
    do {                                                                \
        void *data;                                                     \
        if (padding) {                                                  \
            if ((unsigned)(size) >                                      \
                (unsigned)(size) + FF_INPUT_BUFFER_PADDING_SIZE)        \
                goto failed_alloc;                                      \
            data = av_malloc(size + FF_INPUT_BUFFER_PADDING_SIZE);      \
        } else {                                                        \
            data = av_malloc(size);                                     \
        }                                                               \
        if (!data)                                                      \
            goto failed_alloc;                                          \
        memcpy(data, src, size);                                        \
        if (padding)                                                    \
            memset((uint8_t *)data + size, 0,                           \
                   FF_INPUT_BUFFER_PADDING_SIZE);                       \
        dst = data;                                                     \
    } while (0)

int av_dup_packet(AVPacket *pkt)
{
    AVPacket tmp_pkt;

    if (pkt->destruct == NULL && pkt->data) {
        tmp_pkt = *pkt;

        pkt->data      = NULL;
        pkt->side_data = NULL;
        DUP_DATA(pkt->data, tmp_pkt.data, pkt->size, 1);
        pkt->destruct = av_destruct_packet;

        if (pkt->side_data_elems) {
            int i;

            DUP_DATA(pkt->side_data, tmp_pkt.side_data,
                     pkt->side_data_elems * sizeof(*pkt->side_data), 0);
            memset(pkt->side_data, 0,
                   pkt->side_data_elems * sizeof(*pkt->side_data));
            for (i = 0; i < pkt->side_data_elems; i++)
                DUP_DATA(pkt->side_data[i].data, tmp_pkt.side_data[i].data,
                         tmp_pkt.side_data[i].size, 1);
        }
    }
    return 0;

failed_alloc:
    av_destruct_packet(pkt);
    return AVERROR(ENOMEM);
}

void av_free_packet(AVPacket *pkt)
{
    if (pkt) {
        if (pkt->destruct)
            pkt->destruct(pkt);
        pkt->data            = NULL;
        pkt->size            = 0;
        pkt->side_data       = NULL;
        pkt->side_data_elems = 0;
    }
}

uint8_t *av_packet_new_side_data(AVPacket *pkt, enum AVPacketSideDataType type,
                                 int size)
{
    int elems = pkt->side_data_elems;

    if ((unsigned)elems + 1 > INT_MAX / sizeof(*pkt->side_data))
        return NULL;
    if ((unsigned)size > INT_MAX - FF_INPUT_BUFFER_PADDING_SIZE)
        return NULL;

    pkt->side_data = av_realloc(pkt->side_data,
                                (elems + 1) * sizeof(*pkt->side_data));
    if (!pkt->side_data)
        return NULL;

    pkt->side_data[elems].data = av_malloc(size + FF_INPUT_BUFFER_PADDING_SIZE);
    if (!pkt->side_data[elems].data)
        return NULL;
    pkt->side_data[elems].size = size;
    pkt->side_data[elems].type = type;
    pkt->side_data_elems++;

    return pkt->side_data[elems].data;
}

uint8_t *av_packet_get_side_data(AVPacket *pkt, enum AVPacketSideDataType type,
                                 int *size)
{
    int i;

    for (i = 0; i < pkt->side_data_elems; i++) {
        if (pkt->side_data[i].type == type) {
            if (size)
                *size = pkt->side_data[i].size;
            return pkt->side_data[i].data;
        }
    }
    return NULL;
}

int av_packet_shrink_side_data(AVPacket *pkt, enum AVPacketSideDataType type,
                               int size)
{
    int i;

    for (i = 0; i < pkt->side_data_elems; i++) {
        if (pkt->side_data[i].type == type) {
            if (size > pkt->side_data[i].size)
                return AVERROR(ENOMEM);
            pkt->side_data[i].size = size;
            return 0;
        }
    }
    return AVERROR(ENOENT);
}