modules/access/imem-access.c

   1 /*****************************************************************************
   2  * imem-access.c: In-memory bit stream input for VLC
   3  *****************************************************************************
   4  * Copyright (C) 2015 Rémi Denis-Courmont
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU Lesser General Public License as published by
   8  * the Free Software Foundation; either version 2.1 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  14  * GNU Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public License
  17  * along with this program; if not, write to the Free Software Foundation,
  18  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  19  *****************************************************************************/
  20
  21 #ifdef HAVE_CONFIG_H
  22 # include "config.h"
  23 #endif
  24 #include <assert.h>
  25 #include <stdint.h>
  26
  27 #include <vlc_common.h>
  28 #include <vlc_access.h>
  29 #include <vlc_plugin.h>
  30
  31 typedef struct
  32 {
  33     void *opaque;
  34     ssize_t (*read_cb)(void *, unsigned char *, size_t);
  35     int (*seek_cb)(void *, uint64_t);
  36     void (*close_cb)(void *);
  37     uint64_t size;
  38 } access_sys_t;
  39
  40 static ssize_t Read(stream_t *access, void *buf, size_t len)
  41 {
  42     access_sys_t *sys = access->p_sys;
  43
  44     ssize_t val = sys->read_cb(sys->opaque, buf, len);
  45
  46     if (val < 0) {
  47         msg_Err(access, "read error");
  48         val = 0;
  49     }
  50
  51     return val;
  52 }
  53
  54 static int Seek(stream_t *access, uint64_t offset)
  55 {
  56     access_sys_t *sys = access->p_sys;
  57
  58     assert(sys->seek_cb != NULL);
  59
  60     if (sys->seek_cb(sys->opaque, offset) != 0)
  61         return VLC_EGENERIC;
  62    return VLC_SUCCESS;
  63 }
  64
  65 static int Control(stream_t *access, int query, va_list args)
  66 {
  67     access_sys_t *sys = access->p_sys;
  68
  69     switch (query)
  70     {
  71         case STREAM_CAN_SEEK:
  72             *va_arg(args, bool *) = sys->seek_cb != NULL;
  73             break;
  74
  75         case STREAM_CAN_FASTSEEK:
  76             *va_arg(args, bool *) = false;
  77             break;
  78
  79         case STREAM_CAN_PAUSE:
  80         case STREAM_CAN_CONTROL_PACE:
  81             *va_arg(args, bool *) = sys->seek_cb != NULL;
  82             break;
  83
  84         case STREAM_GET_SIZE:
  85             if (sys->size == UINT64_MAX)
  86                 return VLC_EGENERIC;
  87             *va_arg(args, uint64_t *) = sys->size;
  88             break;
  89
  90         case STREAM_GET_PTS_DELAY:
  91             *va_arg(args, vlc_tick_t *) = DEFAULT_PTS_DELAY;
  92             break;
  93
  94         case STREAM_SET_PAUSE_STATE:
  95             break;
  96
  97         default:
  98             return VLC_EGENERIC;
  99     }
 100     (void) access;
 101     return VLC_SUCCESS;
 102 }
 103
 104 static int open_cb_default(void *opaque, void **datap, uint64_t *sizep)
 105 {
 106     *datap = opaque;
 107     (void) sizep;
 108     return 0;
 109 }
 110
 111 static int Open(vlc_object_t *object)
 112 {
 113     stream_t *access = (stream_t *)object;
 114
 115     access_sys_t *sys = vlc_obj_malloc(object, sizeof (*sys));
 116     if (unlikely(sys == NULL))
 117         return VLC_ENOMEM;
 118
 119     int (*open_cb)(void *, void **, uint64_t *);
 120     void *opaque;
 121
 122     opaque = var_InheritAddress(access, "imem-data");
 123     open_cb = var_InheritAddress(access, "imem-open");
 124     sys->opaque = NULL;
 125     sys->read_cb = var_InheritAddress(access, "imem-read");
 126     sys->seek_cb = var_InheritAddress(access, "imem-seek");
 127     sys->close_cb = var_InheritAddress(access, "imem-close");
 128     sys->size = UINT64_MAX;
 129
 130     if (open_cb == NULL)
 131         open_cb = open_cb_default;
 132     if (sys->read_cb == NULL)
 133         return VLC_EGENERIC;
 134
 135     if (open_cb(opaque, &sys->opaque, &sys->size)) {
 136         msg_Err(access, "open error");
 137         return VLC_EGENERIC;
 138     }
 139
 140     access->pf_read = Read;
 141     access->pf_block = NULL;
 142     access->pf_seek = (sys->seek_cb != NULL) ? Seek : NULL;
 143     access->pf_control = Control;
 144
 145     access->p_sys = sys;
 146     return VLC_SUCCESS;
 147 }
 148
 149 static void Close(vlc_object_t *object)
 150 {
 151     stream_t *access = (stream_t *)object;
 152     access_sys_t *sys = access->p_sys;
 153
 154     if (sys->close_cb != NULL)
 155         sys->close_cb(sys->opaque);
 156 }
 157
 158 vlc_module_begin()
 159     set_shortname(N_("Memory stream"))
 160     set_description(N_("In-memory stream input"))
 161     set_category(CAT_INPUT)
 162     set_subcategory(SUBCAT_INPUT_ACCESS)
 163
 164     add_shortcut("imem")
 165     set_capability("access", 0)
 166     set_callbacks(Open, Close)
 167 vlc_module_end()