src/input/stream_extractor.c

/*****************************************************************************
 * stream_extractor.c
 *****************************************************************************
 * Copyright (C) 2016 VLC authors and VideoLAN
 *
 * 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 2.1 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, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
 *****************************************************************************/

#ifndef STREAM_EXTRACTOR_H
#define STREAM_EXTRACTOR_H

#ifdef HAVE_CONFIG_H
#  include "config.h"
#endif

#include <vlc_common.h>
#include <vlc_stream.h>
#include <vlc_stream_extractor.h>
#include <vlc_modules.h>
#include <vlc_url.h>
#include <vlc_memstream.h>
#include <libvlc.h>
#include <assert.h>

#include "stream.h"
#include "mrl_helpers.h"

/**
 * \defgroup stream_extractor_Internals Stream Extractor Internals
 * \ingroup stream_extractor
 * \internal
 * @{
 * \file
 **/

struct stream_extractor_private {
    union {
        stream_extractor_t extractor;
        stream_directory_t directory;
    };

    /**
     * Callback to handle initialization
     *
     * \ref pf_init will be called after successful module probing to initialize
     * the relevant members of the underlying stream-extractor object, as well
     * as the wrapping stream.
     **/
    int (*pf_init)( struct stream_extractor_private*, stream_t* );

    /**
     * Callback to handle clean-up
     *
     * \ref pf_clean, unless NULL, will be called when the stream-extractor is to
     * be destroyed, and shall be used to clean-up resources (acquired during
     * initialization, see \ref pf_init).
     */
    void (*pf_clean)( struct stream_extractor_private* );

    stream_t* wrapper; /**< the wrapping \ref stream_t used to access the
                            underlying stream-extractor */

    stream_t* source; /**< the source stream consumed by the stream-extractor */
    module_t* module; /**< the stream-extractor module */

    vlc_object_t* object; /**< the underlying stream-extractor object */
};

/**
 * Create an MRL for a specific sub-entry
 *
 * This internal function is used to create an MRL that refers to \subentry
 * within \ref base, see \ref mrl_helpers for further information.
 **/

static char*
StreamExtractorCreateMRL( char const* base, char const* subentry )
{
    struct vlc_memstream buffer;
    char* escaped;

    if( mrl_EscapeFragmentIdentifier( &escaped, subentry ) )
        return NULL;

    if( vlc_memstream_open( &buffer ) )
    {
        free( escaped );
        return NULL;
    }

    vlc_memstream_puts( &buffer, base );

    if( !strstr( base, "#" ) )
        vlc_memstream_putc( &buffer, '#' );

    vlc_memstream_printf( &buffer, "!/%s", escaped );

    free( escaped );
    return vlc_memstream_close( &buffer ) ? NULL : buffer.ptr;
}

/**
 * Release the private data associated with a stream-extractor
 * \param priv pointer to the private section
 */
static void se_Release( struct stream_extractor_private* priv )
{
    if( priv->pf_clean )
        priv->pf_clean( priv );

    if( priv->module )
    {
        module_unneed( priv->object, priv->module );

        if( priv->source )
            vlc_stream_Delete( priv->source );
    }

    vlc_object_release( priv->object );
}

/**
 * \name Callbacks to forward work to the underlying stream-extractor
 *
 * @{
 */

static void
se_StreamDelete( stream_t* stream )
{
    se_Release( stream->p_sys );
}

static ssize_t
se_StreamRead( stream_t* stream, void* buf, size_t len )
{
    struct stream_extractor_private* priv = stream->p_sys;
    return priv->extractor.pf_read( &priv->extractor, buf, len );
}

static block_t*
se_StreamBlock( stream_t* stream, bool* eof )
{
    struct stream_extractor_private* priv = stream->p_sys;
    return priv->extractor.pf_block( &priv->extractor, eof );
}

static int
se_StreamSeek( stream_t* stream, uint64_t offset )
{
    struct stream_extractor_private* priv = stream->p_sys;
    return priv->extractor.pf_seek( &priv->extractor, offset );
}

static int
se_ReadDir( stream_t* stream, input_item_node_t* node )
{
    struct stream_extractor_private* priv = stream->p_sys;
    return priv->directory.pf_readdir( &priv->directory, node );
}

static int
se_StreamControl( stream_t* stream, int req, va_list args )
{
    struct stream_extractor_private* priv = stream->p_sys;
    return priv->extractor.pf_control( &priv->extractor, req, args );
}

static int
se_DirControl( stream_t* stream, int req, va_list args )
{
    (void)stream;
    (void)args;

    if( req == STREAM_IS_DIRECTORY )
        return VLC_SUCCESS;

    return VLC_EGENERIC;
}

/**
 * @}
 **/

/**
 * \name stream-extractor resource handlers
 * \ingroup stream_extractor
 * @{
 */

static int
se_InitStream( struct stream_extractor_private* priv, stream_t* s )
{
    if( priv->extractor.pf_read ) s->pf_read = se_StreamRead;
    else                          s->pf_block = se_StreamBlock;

    s->pf_seek = se_StreamSeek;
    s->pf_control = se_StreamControl;
    s->psz_url = StreamExtractorCreateMRL( priv->extractor.source->psz_url,
                                           priv->extractor.identifier );
    if( unlikely( !s->psz_url ) )
        return VLC_ENOMEM;

    return VLC_SUCCESS;
}

static void
se_CleanStream( struct stream_extractor_private* priv )
{
    free( (char*)priv->extractor.identifier );
}

static int
se_InitDirectory( struct stream_extractor_private* priv, stream_t* s )
{
    stream_directory_t* directory = &priv->directory;

    s->pf_readdir = se_ReadDir;
    s->pf_control = se_DirControl;
    s->psz_url = strdup( directory->source->psz_url );

    if( unlikely( !s->psz_url ) )
        return VLC_EGENERIC;

    return VLC_SUCCESS;
}

/**
 * @}
 **/

/**
 * Create the public stream_t that wraps a stream-extractor
 *
 * This initializes the relevant data-members of the public stream_t which is
 * used to read from the underlying stream-extractor.
 *
 * \param priv the private section of the stream_extractor_t
 * \param source the source stream which the stream_extractor_t should
 *        will read from
 * \return VLC_SUCCESS on success, an error-code on failure.
 **/
static int
se_AttachWrapper( struct stream_extractor_private* priv, stream_t* source )
{
    stream_t* s = vlc_stream_CommonNew( source->obj.parent, se_StreamDelete );

    if( unlikely( !s ) )
        return VLC_ENOMEM;

    if( priv->pf_init( priv, s ) )
    {
        stream_CommonDelete( s );
        return VLC_EGENERIC;
    }

    priv->wrapper = s;
    priv->wrapper->p_input = source->p_input;
    priv->wrapper->p_sys = priv;

    priv->source = source;

    if( priv->wrapper->pf_read )
        priv->wrapper = stream_FilterChainNew( priv->wrapper, "cache_read" );
    else if( priv->wrapper->pf_block )
        priv->wrapper = stream_FilterChainNew( priv->wrapper, "cache_block" );

    return VLC_SUCCESS;
}

static int
StreamExtractorAttach( stream_t** source, char const* identifier,
    char const* module_name )
{
    const bool extractor = identifier != NULL;
    char const* capability = extractor ? "stream_extractor"
                                       : "stream_directory";

    struct stream_extractor_private* priv = vlc_custom_create(
        (*source)->obj.parent, sizeof( *priv ), capability );

    if( unlikely( !priv ) )
        return VLC_ENOMEM;

    if( extractor )
    {
        priv->object = VLC_OBJECT( &priv->extractor );

        priv->pf_init = se_InitStream;
        priv->pf_clean = se_CleanStream;

        priv->extractor.source = *source;
        priv->extractor.identifier = strdup( identifier );

        if( unlikely( !priv->extractor.identifier ) )
            goto error;
    }
    else
    {
        priv->object = VLC_OBJECT( &priv->directory );

        priv->pf_init = se_InitDirectory;
        priv->pf_clean = NULL;

        priv->directory.source = *source;
    }

    priv->module = module_need( priv->object, capability, module_name, true );

    if( !priv->module || se_AttachWrapper( priv, *source ) )
        goto error;

    *source = priv->wrapper;
    return VLC_SUCCESS;

error:
    se_Release( priv );
    return VLC_EGENERIC;
}

int
vlc_stream_directory_Attach( stream_t** source, char const* module_name )
{
    return StreamExtractorAttach( source, NULL, module_name );
}

int
vlc_stream_extractor_Attach( stream_t** source, char const* identifier,
                             char const* module_name )
{
    return StreamExtractorAttach( source, identifier, module_name );
}

int
stream_extractor_AttachParsed( stream_t** source, char const* data,
                               char const** out_extra )
{
    vlc_array_t identifiers;

    if( mrl_FragmentSplit( &identifiers, out_extra, data ) )
        return VLC_EGENERIC;

    size_t count = vlc_array_count( &identifiers );
    size_t idx = 0;

    while( idx < count )
    {
        char* id = vlc_array_item_at_index( &identifiers, idx );

        if( vlc_stream_extractor_Attach( source, id, NULL ) )
            break;

        ++idx;
    }

    for( size_t i = 0; i < count; ++i )
        free( vlc_array_item_at_index( &identifiers, i ) );
    vlc_array_clear( &identifiers );

    return idx == count ? VLC_SUCCESS : VLC_EGENERIC;
}

char*
vlc_stream_extractor_CreateMRL( stream_directory_t* directory,
                                char const* subentry )
{
    return StreamExtractorCreateMRL( directory->source->psz_url, subentry );
}

/**
 * @}
 **/

#endif /* include-guard */