modules/video_output/xcb/pictures.c

   1 /**
   2  * @file pictures.c
   3  * @brief Pictures management code for XCB video output plugins
   4  */
   5 /*****************************************************************************
   6  * Copyright © 2009-2013 Rémi Denis-Courmont
   7  *
   8  * This program is free software; you can redistribute it and/or modify it
   9  * under the terms of the GNU Lesser General Public License as published by
  10  * the Free Software Foundation; either version 2.1 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public License
  19  * along with this program; if not, write to the Free Software Foundation,
  20  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  21  *****************************************************************************/
  22
  23 #ifdef HAVE_CONFIG_H
  24 # include <config.h>
  25 #endif
  26
  27 #include <stdlib.h>
  28 #include <assert.h>
  29 #include <errno.h>
  30
  31 #include <sys/types.h>
  32 #ifdef HAVE_SYS_SHM_H
  33 # include <sys/shm.h>
  34 # include <sys/stat.h>
  35 #else
  36 # define shmdt(mem) free(mem)
  37 #endif
  38
  39 #include <xcb/xcb.h>
  40 #include <xcb/shm.h>
  41
  42 #include <vlc_common.h>
  43 #include <vlc_vout_display.h>
  44
  45 #include "pictures.h"
  46 #include "events.h"
  47
  48 /** Check MIT-SHM shared memory support */
  49 bool XCB_shm_Check (vlc_object_t *obj, xcb_connection_t *conn)
  50 {
  51 #ifdef HAVE_SYS_SHM_H
  52     xcb_shm_query_version_cookie_t ck;
  53     xcb_shm_query_version_reply_t *r;
  54
  55     ck = xcb_shm_query_version (conn);
  56     r = xcb_shm_query_version_reply (conn, ck, NULL);
  57     if (r != NULL)
  58     {
  59         free (r);
  60         return true;
  61     }
  62     msg_Err (obj, "shared memory (MIT-SHM) not available");
  63     msg_Warn (obj, "display will be slow");
  64 #else
  65     msg_Warn (obj, "shared memory (MIT-SHM) not implemented");
  66     (void) conn;
  67 #endif
  68     return false;
  69 }
  70
  71 /**
  72  * Release picture private data: detach the shared memory segment.
  73  */
  74 static void XCB_picture_Destroy (picture_t *pic)
  75 {
  76     shmdt (pic->p[0].p_pixels);
  77     free (pic);
  78 }
  79
  80 /**
  81  * Initialize a picture buffer as shared memory, according to the video output
  82  * format. If a attach is true, the segment is attached to
  83  * the X server (MIT-SHM extension).
  84  */
  85 int XCB_picture_Alloc (vout_display_t *vd, picture_resource_t *res,
  86                        size_t size, xcb_connection_t *conn,
  87                        xcb_shm_seg_t segment)
  88 {
  89 #ifdef HAVE_SYS_SHM_H
  90     /* Allocate shared memory segment */
  91     int id = shmget (IPC_PRIVATE, size, IPC_CREAT | S_IRWXU);
  92     if (id == -1)
  93     {
  94         msg_Err (vd, "shared memory allocation error: %s",
  95                  vlc_strerror_c(errno));
  96         return -1;
  97     }
  98
  99     /* Attach the segment to VLC */
 100     void *shm = shmat (id, NULL, 0 /* read/write */);
 101     if (-1 == (intptr_t)shm)
 102     {
 103         msg_Err (vd, "shared memory attachment error: %s",
 104                  vlc_strerror_c(errno));
 105         shmctl (id, IPC_RMID, 0);
 106         return -1;
 107     }
 108
 109     if (segment != 0)
 110     {   /* Attach the segment to X */
 111         xcb_void_cookie_t ck = xcb_shm_attach_checked (conn, segment, id, 1);
 112         switch (XCB_error_Check (vd, conn, "shared memory server-side error",
 113                                  ck))
 114         {
 115             case 0:
 116                 break;
 117
 118             case XCB_ACCESS:
 119             {
 120                 struct shmid_ds buf;
 121                 /* Retry with promiscuous permissions */
 122                 shmctl (id, IPC_STAT, &buf);
 123                 buf.shm_perm.mode |= S_IRGRP|S_IROTH;
 124                 shmctl (id, IPC_SET, &buf);
 125                 ck = xcb_shm_attach_checked (conn, segment, id, 1);
 126                 if (XCB_error_Check (vd, conn, "same error on retry", ck) == 0)
 127                     break;
 128                 /* fall through */
 129             }
 130
 131             default:
 132                 msg_Info (vd, "using buggy X11 server - SSH proxying?");
 133                 segment = 0;
 134         }
 135     }
 136
 137     shmctl (id, IPC_RMID, NULL);
 138 #else
 139     assert (segment == 0);
 140
 141     /* XXX: align on 32 bytes for VLC chroma filters */
 142     void *shm = malloc (size);
 143     if (unlikely(shm == NULL))
 144         return -1;
 145 #endif
 146     res->p_sys = (void *)(uintptr_t)segment;
 147     res->pf_destroy = XCB_picture_Destroy;
 148     res->p[0].p_pixels = shm;
 149     return 0;
 150 }
 151
 152 picture_t *XCB_picture_NewFromResource (const video_format_t *restrict fmt,
 153                                         const picture_resource_t *restrict res)
 154 {
 155     picture_t *pic = picture_NewFromResource (fmt, res);
 156     if (unlikely(pic == NULL))
 157         shmdt (res->p[0].p_pixels);
 158     return pic;
 159 }