/*

 * unbuffered I/O

 * Copyright (c) 2001 Fabrice Bellard

 *

 * 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

 */

#include "libavutil/avstring.h"

#include "libavutil/dict.h"

#include "libavutil/mem.h"

#include "libavutil/opt.h"

#include "libavutil/time.h"

#include "libavutil/avassert.h"

#include "avio_internal.h"

#include "os_support.h"

#include "internal.h"

#if CONFIG_NETWORK

#include "network.h"

#endif

#include "url.h"

#define IO_BUFFER_SIZE 32768

/** @name Logging context. */

/*@{*/

static const char *urlcontext_to_name(void *ptr)

{

    URLContext *h = (URLContext *)ptr;

    if (h->prot)

        return h->prot->name;

    else

        return "NULL";

}

static void *urlcontext_child_next(void *obj, void *prev)

{

    URLContext *h = obj;

    if (!prev && h->priv_data && h->prot->priv_data_class)

        return h->priv_data;

    return NULL;

}

#define OFFSET(x) offsetof(URLContext,x)

#define E AV_OPT_FLAG_ENCODING_PARAM

#define D AV_OPT_FLAG_DECODING_PARAM

static const AVOption options[] = {

    {"protocol_whitelist", "List of protocols that are allowed to be used", OFFSET(protocol_whitelist), AV_OPT_TYPE_STRING, { .str = NULL },  0, 0, D },

    {"protocol_blacklist", "List of protocols that are not allowed to be used", OFFSET(protocol_blacklist), AV_OPT_TYPE_STRING, { .str = NULL },  0, 0, D },

    {"rw_timeout", "Timeout for IO operations (in microseconds)", offsetof(URLContext, rw_timeout), AV_OPT_TYPE_INT64, { .i64 = 0 }, 0, INT64_MAX, AV_OPT_FLAG_ENCODING_PARAM | AV_OPT_FLAG_DECODING_PARAM },

    { NULL }

};

static const AVClass url_context_class = {

    .class_name       = "URLContext",

    .item_name        = urlcontext_to_name,

    .option           = options,

    .version          = LIBAVUTIL_VERSION_INT,

    .child_next       = urlcontext_child_next,

    .child_class_iterate = ff_urlcontext_child_class_iterate,

};

/*@}*/

static void *avio_child_next(void *obj, void *prev)

{

    AVIOContext *s = obj;

    return prev ? NULL : s->opaque;

}

static const AVClass *child_class_iterate(void **iter)

{

    const AVClass *c = *iter ? NULL : &url_context_class;

    *iter = (void*)(uintptr_t)c;

    return c;

}

#define AVIOOFFSET(x) offsetof(AVIOContext,x)

#define E AV_OPT_FLAG_ENCODING_PARAM

#define D AV_OPT_FLAG_DECODING_PARAM

static const AVOption avio_options[] = {

    {"protocol_whitelist", "List of protocols that are allowed to be used", AVIOOFFSET(protocol_whitelist), AV_OPT_TYPE_STRING, { .str = NULL },  0, 0, D },

    { NULL },

};

const AVClass ff_avio_class = {

    .class_name = "AVIOContext",

    .item_name  = av_default_item_name,

    .version    = LIBAVUTIL_VERSION_INT,

    .option     = avio_options,

    .child_next = avio_child_next,

    .child_class_iterate = child_class_iterate,

};

URLContext *ffio_geturlcontext(AVIOContext *s)

{

    if (!s)

        return NULL;

    if (s->opaque && s->read_packet == ffurl_read2)

        return s->opaque;

    else

        return NULL;

}

static int url_alloc_for_protocol(URLContext **puc, const URLProtocol *up,

                                  const char *filename, int flags,

                                  const AVIOInterruptCB *int_cb)

{

    URLContext *uc;

    int err;

#if CONFIG_NETWORK

    if (up->flags & URL_PROTOCOL_FLAG_NETWORK && !ff_network_init())

        return AVERROR(EIO);

#endif

    if ((flags & AVIO_FLAG_READ) && !up->url_read) {

        av_log(NULL, AV_LOG_ERROR,

               "Impossible to open the '%s' protocol for reading\n", up->name);

        return AVERROR(EIO);

    }

    if ((flags & AVIO_FLAG_WRITE) && !up->url_write) {

        av_log(NULL, AV_LOG_ERROR,

               "Impossible to open the '%s' protocol for writing\n", up->name);

        return AVERROR(EIO);

    }

    uc = av_mallocz(sizeof(URLContext) + strlen(filename) + 1);

    if (!uc) {

        err = AVERROR(ENOMEM);

        goto fail;

    }

    uc->av_class = &url_context_class;

    uc->filename = (char *)&uc[1];

    strcpy(uc->filename, filename);

    uc->prot            = up;

    uc->flags           = flags;

    uc->is_streamed     = 0; /* default = not streamed */

    uc->max_packet_size = 0; /* default: stream file */

    if (up->priv_data_size) {

        uc->priv_data = av_mallocz(up->priv_data_size);

        if (!uc->priv_data) {

            err = AVERROR(ENOMEM);

            goto fail;

        }

        if (up->priv_data_class) {

            char *start;

            *(const AVClass **)uc->priv_data = up->priv_data_class;

            av_opt_set_defaults(uc->priv_data);

            if (av_strstart(uc->filename, up->name, (const char**)&start) && *start == ',') {

                int ret= 0;

                char *p= start;

                char sep= *++p;

                char *key, *val;

                p++;

                if (strcmp(up->name, "subfile"))

                    ret = AVERROR(EINVAL);

                while(ret >= 0 && (key= strchr(p, sep)) && p<key && (val = strchr(key+1, sep))){

                    *val= *key= 0;

                    ret = av_opt_set(uc->priv_data, p, key+1, 0);

                    if (ret == AVERROR_OPTION_NOT_FOUND)

                        av_log(uc, AV_LOG_ERROR, "Key '%s' not found.\n", p);

                    *val= *key= sep;

                    p= val+1;

                }

                if(ret<0 || p!=key){

                    av_log(uc, AV_LOG_ERROR, "Error parsing options string %s\n", start);

                    err = AVERROR(EINVAL);

                    goto fail;

                }

                memmove(start, key+1, strlen(key));

            }

        }

    }

    if (int_cb)

        uc->interrupt_callback = *int_cb;

    *puc = uc;

    return 0;

fail:

    *puc = NULL;

    if (uc)

        av_freep(&uc->priv_data);

    av_freep(&uc);

#if CONFIG_NETWORK

    if (up->flags & URL_PROTOCOL_FLAG_NETWORK)

        ff_network_close();

#endif

    return err;

}

int ffurl_connect(URLContext *uc, AVDictionary **options)

{

    int err;

    AVDictionary *tmp_opts = NULL;

    AVDictionaryEntry *e;

    if (!options)

        options = &tmp_opts;

    // Check that URLContext was initialized correctly and lists are matching if set

    av_assert0(!(e=av_dict_get(*options, "protocol_whitelist", NULL, 0)) ||

               (uc->protocol_whitelist && !strcmp(uc->protocol_whitelist, e->value)));

    av_assert0(!(e=av_dict_get(*options, "protocol_blacklist", NULL, 0)) ||

               (uc->protocol_blacklist && !strcmp(uc->protocol_blacklist, e->value)));

    if (uc->protocol_whitelist && av_match_list(uc->prot->name, uc->protocol_whitelist, ',') <= 0) {

        av_log(uc, AV_LOG_ERROR, "Protocol '%s' not on whitelist '%s'!\n", uc->prot->name, uc->protocol_whitelist);

        return AVERROR(EINVAL);

    }

    if (uc->protocol_blacklist && av_match_list(uc->prot->name, uc->protocol_blacklist, ',') > 0) {

        av_log(uc, AV_LOG_ERROR, "Protocol '%s' on blacklist '%s'!\n", uc->prot->name, uc->protocol_blacklist);

        return AVERROR(EINVAL);

    }

    if (!uc->protocol_whitelist && uc->prot->default_whitelist) {

        av_log(uc, AV_LOG_DEBUG, "Setting default whitelist '%s'\n", uc->prot->default_whitelist);

        uc->protocol_whitelist = av_strdup(uc->prot->default_whitelist);

        if (!uc->protocol_whitelist) {

            return AVERROR(ENOMEM);

        }

    } else if (!uc->protocol_whitelist)

        av_log(uc, AV_LOG_DEBUG, "No default whitelist set\n"); // This should be an error once all declare a default whitelist

    if ((err = av_dict_set(options, "protocol_whitelist", uc->protocol_whitelist, 0)) < 0)

        return err;

    if ((err = av_dict_set(options, "protocol_blacklist", uc->protocol_blacklist, 0)) < 0)

        return err;

    err =

        uc->prot->url_open2 ? uc->prot->url_open2(uc,

                                                  uc->filename,

                                                  uc->flags,

                                                  options) :

        uc->prot->url_open(uc, uc->filename, uc->flags);

    av_dict_set(options, "protocol_whitelist", NULL, 0);

    av_dict_set(options, "protocol_blacklist", NULL, 0);

    if (err)

        return err;

    uc->is_connected = 1;

    /* We must be careful here as ffurl_seek() could be slow,

     * for example for http */

    if ((uc->flags & AVIO_FLAG_WRITE) || !strcmp(uc->prot->name, "file"))

        if (!uc->is_streamed && ffurl_seek(uc, 0, SEEK_SET) < 0)

            uc->is_streamed = 1;

    return 0;

}

int ffurl_accept(URLContext *s, URLContext **c)

{

    av_assert0(!*c);

    if (s->prot->url_accept)

        return s->prot->url_accept(s, c);

    return AVERROR(EBADF);

}

int avio_accept(AVIOContext *s, AVIOContext **c)

{

    int ret;

    URLContext *sc = s->opaque;

    URLContext *cc = NULL;

    ret = ffurl_accept(sc, &cc);

    if (ret < 0)

        return ret;

    return ffio_fdopen(c, cc);

}

int ffurl_handshake(URLContext *c)

{

    int ret;

    if (c->prot->url_handshake) {

        ret = c->prot->url_handshake(c);

        if (ret)

            return ret;

    }

    c->is_connected = 1;

    return 0;

}

int avio_handshake(AVIOContext *c)

{

    URLContext *cc = c->opaque;

    return ffurl_handshake(cc);

}

#define URL_SCHEME_CHARS                        \

    "abcdefghijklmnopqrstuvwxyz"                \

    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"                \

    "0123456789+-."

static const struct URLProtocol *url_find_protocol(const char *filename)

{

    const URLProtocol **protocols;

    char proto_str[128], proto_nested[128], *ptr;

    size_t proto_len = strspn(filename, URL_SCHEME_CHARS);

    int i;

    if (filename[proto_len] != ':' &&

        (strncmp(filename, "subfile,", 8) || !strchr(filename + proto_len + 1, ':')) ||

        is_dos_path(filename))

        strcpy(proto_str, "file");

    else

        av_strlcpy(proto_str, filename,

                   FFMIN(proto_len + 1, sizeof(proto_str)));

    av_strlcpy(proto_nested, proto_str, sizeof(proto_nested));

    if ((ptr = strchr(proto_nested, '+')))

        *ptr = '\0';

    protocols = ffurl_get_protocols(NULL, NULL);

    if (!protocols)

        return NULL;

    for (i = 0; protocols[i]; i++) {

            const URLProtocol *up = protocols[i];

        if (!strcmp(proto_str, up->name)) {

            av_freep(&protocols);

            return up;

        }

        if (up->flags & URL_PROTOCOL_FLAG_NESTED_SCHEME &&

            !strcmp(proto_nested, up->name)) {

            av_freep(&protocols);

            return up;

        }

    }

    av_freep(&protocols);

    if (av_strstart(filename, "https:", NULL) || av_strstart(filename, "tls:", NULL) ||

        av_strstart(filename, "dtls:", NULL))

        av_log(NULL, AV_LOG_WARNING, "https or dtls protocol not found, recompile FFmpeg with "

                                     "openssl, gnutls or securetransport enabled.\n");

    return NULL;

}

int ffurl_alloc(URLContext **puc, const char *filename, int flags,

                const AVIOInterruptCB *int_cb)

{

    const URLProtocol *p = NULL;

    p = url_find_protocol(filename);

    if (p)

       return url_alloc_for_protocol(puc, p, filename, flags, int_cb);

    *puc = NULL;

    return AVERROR_PROTOCOL_NOT_FOUND;

}

int ffurl_open_whitelist(URLContext **puc, const char *filename, int flags,

                         const AVIOInterruptCB *int_cb, AVDictionary **options,

                         const char *whitelist, const char* blacklist,

                         URLContext *parent)

{

    AVDictionary *tmp_opts = NULL;

    AVDictionaryEntry *e;

    int ret = ffurl_alloc(puc, filename, flags, int_cb);

    if (ret < 0)

        return ret;

    if (parent) {

        ret = av_opt_copy(*puc, parent);

        if (ret < 0)

            goto fail;

    }

    if (options &&

        (ret = av_opt_set_dict(*puc, options)) < 0)

        goto fail;

    if (options && (*puc)->prot->priv_data_class &&

        (ret = av_opt_set_dict((*puc)->priv_data, options)) < 0)

        goto fail;

    if (!options)

        options = &tmp_opts;

    av_assert0(!whitelist ||

               !(e=av_dict_get(*options, "protocol_whitelist", NULL, 0)) ||

               !strcmp(whitelist, e->value));

    av_assert0(!blacklist ||

               !(e=av_dict_get(*options, "protocol_blacklist", NULL, 0)) ||

               !strcmp(blacklist, e->value));

    if ((ret = av_dict_set(options, "protocol_whitelist", whitelist, 0)) < 0)

        goto fail;

    if ((ret = av_dict_set(options, "protocol_blacklist", blacklist, 0)) < 0)

        goto fail;

    if ((ret = av_opt_set_dict(*puc, options)) < 0)

        goto fail;

    ret = ffurl_connect(*puc, options);

    if (!ret)

        return 0;

fail:

    ffurl_closep(puc);

    return ret;

}

int ffio_fdopen(AVIOContext **sp, URLContext *h)

{

    AVIOContext *s;

    uint8_t *buffer = NULL;

    int buffer_size, max_packet_size;

    max_packet_size = h->max_packet_size;

    if (max_packet_size) {

        buffer_size = max_packet_size; /* no need to bufferize more than one packet */

    } else {

        buffer_size = IO_BUFFER_SIZE;

    }

    if (!(h->flags & AVIO_FLAG_WRITE) && h->is_streamed) {

        if (buffer_size > INT_MAX/2)

            return AVERROR(EINVAL);

        buffer_size *= 2;

    }

    buffer = av_malloc(buffer_size);

    if (!buffer)

        return AVERROR(ENOMEM);

    *sp = avio_alloc_context(buffer, buffer_size, h->flags & AVIO_FLAG_WRITE, h,

                             ffurl_read2, ffurl_write2, ffurl_seek2);

    if (!*sp) {

        av_freep(&buffer);

        return AVERROR(ENOMEM);

    }

    s = *sp;

    if (h->protocol_whitelist) {

        s->protocol_whitelist = av_strdup(h->protocol_whitelist);

        if (!s->protocol_whitelist) {

            avio_closep(sp);

            return AVERROR(ENOMEM);

        }

    }

    if (h->protocol_blacklist) {

        s->protocol_blacklist = av_strdup(h->protocol_blacklist);

        if (!s->protocol_blacklist) {

            avio_closep(sp);

            return AVERROR(ENOMEM);

        }

    }

    s->direct = h->flags & AVIO_FLAG_DIRECT;

    s->seekable = h->is_streamed ? 0 : AVIO_SEEKABLE_NORMAL;

    s->max_packet_size = max_packet_size;

    s->min_packet_size = h->min_packet_size;

    if(h->prot) {

        s->read_pause = h->prot->url_read_pause;

        s->read_seek  = h->prot->url_read_seek;

        if (h->prot->url_read_seek)

            s->seekable |= AVIO_SEEKABLE_TIME;

    }

    ((FFIOContext*)s)->short_seek_get = ffurl_get_short_seek;

    s->av_class = &ff_avio_class;

    return 0;

}

int ffio_open_whitelist(AVIOContext **s, const char *filename, int flags,

                        const AVIOInterruptCB *int_cb, AVDictionary **options,

                        const char *whitelist, const char *blacklist)

{

    URLContext *h;

    int err;

    *s = NULL;

    err = ffurl_open_whitelist(&h, filename, flags, int_cb, options, whitelist, blacklist, NULL);

    if (err < 0)

        return err;

    err = ffio_fdopen(s, h);

    if (err < 0) {

        ffurl_close(h);

        return err;

    }

    return 0;

}

int avio_open2(AVIOContext **s, const char *filename, int flags,

               const AVIOInterruptCB *int_cb, AVDictionary **options)

{

    return ffio_open_whitelist(s, filename, flags, int_cb, options, NULL, NULL);

}

int avio_open(AVIOContext **s, const char *filename, int flags)

{

    return avio_open2(s, filename, flags, NULL, NULL);

}

static inline int retry_transfer_wrapper(URLContext *h, uint8_t *buf,

                                         const uint8_t *cbuf,

                                         int size, int size_min,

                                         int read)

{

    int ret, len;

    int fast_retries = 5;

    int64_t wait_since = 0;

    len = 0;

    while (len < size_min) {

        if (ff_check_interrupt(&h->interrupt_callback))

            return AVERROR_EXIT;

        ret = read ? h->prot->url_read (h, buf + len, size - len):

                     h->prot->url_write(h, cbuf + len, size - len);

        if (ret == AVERROR(EINTR))

            continue;

        if (h->flags & AVIO_FLAG_NONBLOCK)

            return ret;

        if (ret == AVERROR(EAGAIN)) {

            ret = 0;

            if (fast_retries) {

                fast_retries--;

            } else {

                if (h->rw_timeout) {

                    if (!wait_since)

                        wait_since = av_gettime_relative();

                    else if (av_gettime_relative() > wait_since + h->rw_timeout)

                        return AVERROR(EIO);

                }

                av_usleep(1000);

            }

        } else if (ret == AVERROR_EOF)

            return (len > 0) ? len : AVERROR_EOF;

        else if (ret < 0)

            return ret;

        if (ret) {

            fast_retries = FFMAX(fast_retries, 2);

            wait_since = 0;

        }

        len += ret;

    }

    return len;

}

int ffurl_read2(void *urlcontext, uint8_t *buf, int size)

{

    URLContext *h = urlcontext;

    if (!(h->flags & AVIO_FLAG_READ))

        return AVERROR(EIO);

    return retry_transfer_wrapper(h, buf, NULL, size, 1, 1);

}

int ffurl_read_complete(URLContext *h, unsigned char *buf, int size)

{

    if (!(h->flags & AVIO_FLAG_READ))

        return AVERROR(EIO);

    return retry_transfer_wrapper(h, buf, NULL, size, size, 1);

}

int ffurl_write2(void *urlcontext, const uint8_t *buf, int size)

{

    URLContext *h = urlcontext;

    if (!(h->flags & AVIO_FLAG_WRITE))

        return AVERROR(EIO);

    /* avoid sending too big packets */

    if (h->max_packet_size && size > h->max_packet_size)

        return AVERROR(EIO);

    return retry_transfer_wrapper(h, NULL, buf, size, size, 0);

}

int64_t ffurl_seek2(void *urlcontext, int64_t pos, int whence)

{

    URLContext *h = urlcontext;

    int64_t ret;

    if (!h->prot->url_seek)

        return AVERROR(ENOSYS);

    ret = h->prot->url_seek(h, pos, whence & ~AVSEEK_FORCE);

    return ret;

}

int ffurl_closep(URLContext **hh)

{

    URLContext *h= *hh;

    int ret = 0;

    if (!h)

        return 0;     /* can happen when ffurl_open fails */

    if (h->is_connected && h->prot->url_close)

        ret = h->prot->url_close(h);

#if CONFIG_NETWORK

    if (h->prot->flags & URL_PROTOCOL_FLAG_NETWORK)

        ff_network_close();

#endif

    if (h->prot->priv_data_size) {

        if (h->prot->priv_data_class)

            av_opt_free(h->priv_data);

        av_freep(&h->priv_data);

    }

    av_opt_free(h);

    av_freep(hh);

    return ret;

}

int ffurl_close(URLContext *h)

{

    return ffurl_closep(&h);

}

int avio_close(AVIOContext *s)

{

    FFIOContext *const ctx = ffiocontext(s);

    URLContext *h;

    int ret, error;

    if (!s)

        return 0;

    avio_flush(s);

    h         = s->opaque;

    s->opaque = NULL;

    av_freep(&s->buffer);

    if (s->write_flag)

        av_log(s, AV_LOG_VERBOSE,

               "Statistics: %"PRId64" bytes written, %d seeks, %d writeouts\n",

               ctx->bytes_written, ctx->seek_count, ctx->writeout_count);

    else

        av_log(s, AV_LOG_VERBOSE, "Statistics: %"PRId64" bytes read, %d seeks\n",

               ctx->bytes_read, ctx->seek_count);

    av_opt_free(s);

    error = s->error;

    avio_context_free(&s);

    ret = ffurl_close(h);

    if (ret < 0)

        return ret;

    return error;

}

int avio_closep(AVIOContext **s)

{

    int ret = avio_close(*s);

    *s = NULL;

    return ret;

}

const char *avio_find_protocol_name(const char *url)

{

    const URLProtocol *p = url_find_protocol(url);

    return p ? p->name : NULL;

}

int avio_check(const char *url, int flags)

{

    URLContext *h;

    int ret = ffurl_alloc(&h, url, flags, NULL);

    if (ret < 0)

        return ret;

    if (h->prot->url_check) {

        ret = h->prot->url_check(h, flags);

    } else {

        ret = ffurl_connect(h, NULL);

        if (ret >= 0)

            ret = flags;

    }

    ffurl_close(h);

    return ret;

}

int ffurl_move(const char *url_src, const char *url_dst)

{

    URLContext *h_src, *h_dst;

    int ret = ffurl_alloc(&h_src, url_src, AVIO_FLAG_READ_WRITE, NULL);

    if (ret < 0)

        return ret;

    ret = ffurl_alloc(&h_dst, url_dst, AVIO_FLAG_WRITE, NULL);

    if (ret < 0) {

        ffurl_close(h_src);

        return ret;

    }

    if (h_src->prot == h_dst->prot && h_src->prot->url_move)

        ret = h_src->prot->url_move(h_src, h_dst);

    else

        ret = AVERROR(ENOSYS);

    ffurl_close(h_src);

    ffurl_close(h_dst);

    return ret;

}

int ffurl_delete(const char *url)

{

    URLContext *h;

    int ret = ffurl_alloc(&h, url, AVIO_FLAG_WRITE, NULL);

    if (ret < 0)

        return ret;

    if (h->prot->url_delete)

        ret = h->prot->url_delete(h);

    else

        ret = AVERROR(ENOSYS);

    ffurl_close(h);

    return ret;

}

struct AVIODirContext {

    struct URLContext *url_context;

};

int avio_open_dir(AVIODirContext **s, const char *url, AVDictionary **options)

{

    URLContext *h = NULL;

    AVIODirContext *ctx = NULL;

    int ret;

    av_assert0(s);

    ctx = av_mallocz(sizeof(*ctx));

    if (!ctx) {

        ret = AVERROR(ENOMEM);

        goto fail;

    }

    if ((ret = ffurl_alloc(&h, url, AVIO_FLAG_READ, NULL)) < 0)

        goto fail;

    if (h->prot->url_open_dir && h->prot->url_read_dir && h->prot->url_close_dir) {

        if (options && h->prot->priv_data_class &&

            (ret = av_opt_set_dict(h->priv_data, options)) < 0)

            goto fail;

        ret = h->prot->url_open_dir(h);

    } else

        ret = AVERROR(ENOSYS);

    if (ret < 0)

        goto fail;

    h->is_connected = 1;

    ctx->url_context = h;

    *s = ctx;

    return 0;

  fail:

    av_free(ctx);

    *s = NULL;

    ffurl_close(h);

    return ret;

}

int avio_read_dir(AVIODirContext *s, AVIODirEntry **next)

{

    URLContext *h;

    int ret;

    if (!s || !s->url_context)

        return AVERROR(EINVAL);

    h = s->url_context;

    if ((ret = h->prot->url_read_dir(h, next)) < 0)

        avio_free_directory_entry(next);

    return ret;

}

int avio_close_dir(AVIODirContext **s)

{

    URLContext *h;

    av_assert0(s);

    if (!(*s) || !(*s)->url_context)

        return AVERROR(EINVAL);

    h = (*s)->url_context;

    h->prot->url_close_dir(h);

    ffurl_close(h);

    av_freep(s);

    *s = NULL;

    return 0;

}

void avio_free_directory_entry(AVIODirEntry **entry)

{

    if (!entry || !*entry)

        return;

    av_free((*entry)->name);

    av_freep(entry);

}

int64_t ffurl_size(URLContext *h)

{

    int64_t pos, size;

    size = ffurl_seek(h, 0, AVSEEK_SIZE);

    if (size < 0) {

        pos = ffurl_seek(h, 0, SEEK_CUR);

        if ((size = ffurl_seek(h, -1, SEEK_END)) < 0)

            return size;

        size++;

        ffurl_seek(h, pos, SEEK_SET);

    }

    return size;

}

int ffurl_get_file_handle(URLContext *h)

{

    if (!h || !h->prot || !h->prot->url_get_file_handle)

        return -1;

    return h->prot->url_get_file_handle(h);

}

int ffurl_get_multi_file_handle(URLContext *h, int **handles, int *numhandles)

{

    if (!h || !h->prot)

        return AVERROR(ENOSYS);

    if (!h->prot->url_get_multi_file_handle) {

        if (!h->prot->url_get_file_handle)

            return AVERROR(ENOSYS);

        *handles = av_malloc(sizeof(**handles));

        if (!*handles)

            return AVERROR(ENOMEM);

        *numhandles = 1;

        *handles[0] = h->prot->url_get_file_handle(h);

        return 0;

    }

    return h->prot->url_get_multi_file_handle(h, handles, numhandles);

}

int ffurl_get_short_seek(void *urlcontext)

{

    URLContext *h = urlcontext;

    if (!h || !h->prot || !h->prot->url_get_short_seek)

        return AVERROR(ENOSYS);

    return h->prot->url_get_short_seek(h);

}

int ffurl_shutdown(URLContext *h, int flags)

{

    if (!h || !h->prot || !h->prot->url_shutdown)

        return AVERROR(ENOSYS);

    return h->prot->url_shutdown(h, flags);

}

int ff_check_interrupt(AVIOInterruptCB *cb)

{

    if (cb && cb->callback)