src/egl/main/eglcontext.c

   1 /**************************************************************************
   2  *
   3  * Copyright 2008 VMware, Inc.
   4  * Copyright 2009-2010 Chia-I Wu <olvaffe@gmail.com>
   5  * Copyright 2010-2011 LunarG, Inc.
   6  * All Rights Reserved.
   7  *
   8  * Permission is hereby granted, free of charge, to any person obtaining a
   9  * copy of this software and associated documentation files (the
  10  * "Software"), to deal in the Software without restriction, including
  11  * without limitation the rights to use, copy, modify, merge, publish,
  12  * distribute, sub license, and/or sell copies of the Software, and to
  13  * permit persons to whom the Software is furnished to do so, subject to
  14  * the following conditions:
  15  *
  16  * The above copyright notice and this permission notice (including the
  17  * next paragraph) shall be included in all copies or substantial portions
  18  * of the Software.
  19  *
  20  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  21  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  23  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  24  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  25  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  26  * DEALINGS IN THE SOFTWARE.
  27  *
  28  **************************************************************************/
  29
  30
  31 #include <assert.h>
  32 #include <stdlib.h>
  33 #include <string.h>
  34 #include "eglconfig.h"
  35 #include "eglcontext.h"
  36 #include "egldisplay.h"
  37 #include "eglcurrent.h"
  38 #include "eglsurface.h"
  39 #include "egllog.h"
  40
  41
  42 /**
  43  * Return the API bit (one of EGL_xxx_BIT) of the context.
  44  */
  45 static EGLint
  46 _eglGetContextAPIBit(_EGLContext *ctx)
  47 {
  48    EGLint bit = 0;
  49
  50    switch (ctx->ClientAPI) {
  51    case EGL_OPENGL_ES_API:
  52       switch (ctx->ClientMajorVersion) {
  53       case 1:
  54          bit = EGL_OPENGL_ES_BIT;
  55          break;
  56       case 2:
  57          bit = EGL_OPENGL_ES2_BIT;
  58          break;
  59       case 3:
  60          bit = EGL_OPENGL_ES3_BIT_KHR;
  61          break;
  62       default:
  63          break;
  64       }
  65       break;
  66    case EGL_OPENVG_API:
  67       bit = EGL_OPENVG_BIT;
  68       break;
  69    case EGL_OPENGL_API:
  70       bit = EGL_OPENGL_BIT;
  71       break;
  72    default:
  73       break;
  74    }
  75
  76    return bit;
  77 }
  78
  79
  80 /**
  81  * Parse the list of context attributes and return the proper error code.
  82  */
  83 static EGLint
  84 _eglParseContextAttribList(_EGLContext *ctx, _EGLDisplay *dpy,
  85                            const EGLint *attrib_list)
  86 {
  87    EGLenum api = ctx->ClientAPI;
  88    EGLint i, err = EGL_SUCCESS;
  89
  90    if (!attrib_list)
  91       return EGL_SUCCESS;
  92
  93    if (api == EGL_OPENVG_API && attrib_list[0] != EGL_NONE) {
  94       _eglLog(_EGL_DEBUG, "bad context attribute 0x%04x", attrib_list[0]);
  95       return EGL_BAD_ATTRIBUTE;
  96    }
  97
  98    for (i = 0; attrib_list[i] != EGL_NONE; i++) {
  99       EGLint attr = attrib_list[i++];
 100       EGLint val = attrib_list[i];
 101
 102       switch (attr) {
 103       case EGL_CONTEXT_CLIENT_VERSION:
 104          /* The EGL 1.4 spec says:
 105           *
 106           *     "attribute EGL_CONTEXT_CLIENT_VERSION is only valid when the
 107           *      current rendering API is EGL_OPENGL_ES_API"
 108           *
 109           * The EGL_KHR_create_context spec says:
 110           *
 111           *     "EGL_CONTEXT_MAJOR_VERSION_KHR           0x3098
 112           *      (this token is an alias for EGL_CONTEXT_CLIENT_VERSION)"
 113           *
 114           *     "The values for attributes EGL_CONTEXT_MAJOR_VERSION_KHR and
 115           *      EGL_CONTEXT_MINOR_VERSION_KHR specify the requested client API
 116           *      version. They are only meaningful for OpenGL and OpenGL ES
 117           *      contexts, and specifying them for other types of contexts will
 118           *      generate an error."
 119           */
 120          if ((api != EGL_OPENGL_ES_API &&
 121              (!dpy->Extensions.KHR_create_context || api != EGL_OPENGL_API))) {
 122                err = EGL_BAD_ATTRIBUTE;
 123                break;
 124          }
 125
 126          ctx->ClientMajorVersion = val;
 127          break;
 128
 129       case EGL_CONTEXT_MINOR_VERSION_KHR:
 130          /* The EGL_KHR_create_context spec says:
 131           *
 132           *     "The values for attributes EGL_CONTEXT_MAJOR_VERSION_KHR and
 133           *      EGL_CONTEXT_MINOR_VERSION_KHR specify the requested client API
 134           *      version. They are only meaningful for OpenGL and OpenGL ES
 135           *      contexts, and specifying them for other types of contexts will
 136           *      generate an error."
 137           */
 138          if (!dpy->Extensions.KHR_create_context ||
 139              (api != EGL_OPENGL_ES_API && api != EGL_OPENGL_API)) {
 140             err = EGL_BAD_ATTRIBUTE;
 141             break;
 142          }
 143
 144          ctx->ClientMinorVersion = val;
 145          break;
 146
 147       case EGL_CONTEXT_FLAGS_KHR:
 148          if (!dpy->Extensions.KHR_create_context) {
 149             err = EGL_BAD_ATTRIBUTE;
 150             break;
 151          }
 152
 153          /* The EGL_KHR_create_context spec says:
 154           *
 155           *     "If the EGL_CONTEXT_OPENGL_DEBUG_BIT_KHR flag bit is set in
 156           *     EGL_CONTEXT_FLAGS_KHR, then a <debug context> will be created.
 157           *     [...]
 158           *     In some cases a debug context may be identical to a non-debug
 159           *     context. This bit is supported for OpenGL and OpenGL ES
 160           *     contexts."
 161           */
 162          if ((val & EGL_CONTEXT_OPENGL_DEBUG_BIT_KHR) &&
 163              (api != EGL_OPENGL_API && api != EGL_OPENGL_ES_API)) {
 164             err = EGL_BAD_ATTRIBUTE;
 165             break;
 166          }
 167
 168          /* The EGL_KHR_create_context spec says:
 169           *
 170           *     "If the EGL_CONTEXT_OPENGL_FORWARD_COMPATIBLE_BIT_KHR flag bit
 171           *     is set in EGL_CONTEXT_FLAGS_KHR, then a <forward-compatible>
 172           *     context will be created. Forward-compatible contexts are
 173           *     defined only for OpenGL versions 3.0 and later. They must not
 174           *     support functionality marked as <deprecated> by that version of
 175           *     the API, while a non-forward-compatible context must support
 176           *     all functionality in that version, deprecated or not. This bit
 177           *     is supported for OpenGL contexts, and requesting a
 178           *     forward-compatible context for OpenGL versions less than 3.0
 179           *     will generate an error."
 180           */
 181          if ((val & EGL_CONTEXT_OPENGL_FORWARD_COMPATIBLE_BIT_KHR) &&
 182              (api != EGL_OPENGL_API || ctx->ClientMajorVersion < 3)) {
 183             err = EGL_BAD_ATTRIBUTE;
 184             break;
 185          }
 186
 187          /* The EGL_KHR_create_context_spec says:
 188           *
 189           *     "If the EGL_CONTEXT_OPENGL_ROBUST_ACCESS_BIT_KHR bit is set in
 190           *     EGL_CONTEXT_FLAGS_KHR, then a context supporting <robust buffer
 191           *     access> will be created. Robust buffer access is defined in the
 192           *     GL_ARB_robustness extension specification, and the resulting
 193           *     context must also support either the GL_ARB_robustness
 194           *     extension, or a version of OpenGL incorporating equivalent
 195           *     functionality. This bit is supported for OpenGL contexts.
 196           */
 197          if ((val & EGL_CONTEXT_OPENGL_ROBUST_ACCESS_BIT_KHR) &&
 198              (api != EGL_OPENGL_API ||
 199               !dpy->Extensions.EXT_create_context_robustness)) {
 200             err = EGL_BAD_ATTRIBUTE;
 201             break;
 202          }
 203
 204          ctx->Flags |= val;
 205          break;
 206
 207       case EGL_CONTEXT_OPENGL_PROFILE_MASK_KHR:
 208          if (!dpy->Extensions.KHR_create_context) {
 209             err = EGL_BAD_ATTRIBUTE;
 210             break;
 211          }
 212
 213          /* The EGL_KHR_create_context spec says:
 214           *
 215           *     "[EGL_CONTEXT_OPENGL_PROFILE_MASK_KHR] is only meaningful for
 216           *     OpenGL contexts, and specifying it for other types of
 217           *     contexts, including OpenGL ES contexts, will generate an
 218           *     error."
 219           */
 220          if (api != EGL_OPENGL_API) {
 221             err = EGL_BAD_ATTRIBUTE;
 222             break;
 223          }
 224
 225          ctx->Profile = val;
 226          break;
 227
 228       case EGL_CONTEXT_OPENGL_RESET_NOTIFICATION_STRATEGY_KHR:
 229          /* The EGL_KHR_create_context spec says:
 230           *
 231           *     "[EGL_CONTEXT_OPENGL_RESET_NOTIFICATION_STRATEGY_KHR] is only
 232           *     meaningful for OpenGL contexts, and specifying it for other
 233           *     types of contexts, including OpenGL ES contexts, will generate
 234           *     an error."
 235           */
 236            if (!dpy->Extensions.KHR_create_context
 237                || api != EGL_OPENGL_API) {
 238             err = EGL_BAD_ATTRIBUTE;
 239             break;
 240          }
 241
 242          ctx->ResetNotificationStrategy = val;
 243          break;
 244
 245       case EGL_CONTEXT_OPENGL_RESET_NOTIFICATION_STRATEGY_EXT:
 246          /* The EGL_EXT_create_context_robustness spec says:
 247           *
 248           *     "[EGL_CONTEXT_OPENGL_RESET_NOTIFICATION_STRATEGY_EXT] is only
 249           *     meaningful for OpenGL ES contexts, and specifying it for other
 250           *     types of contexts will generate an EGL_BAD_ATTRIBUTE error."
 251           */
 252          if (!dpy->Extensions.EXT_create_context_robustness
 253              || api != EGL_OPENGL_ES_API) {
 254             err = EGL_BAD_ATTRIBUTE;
 255             break;
 256          }
 257
 258          ctx->ResetNotificationStrategy = val;
 259          break;
 260
 261       case EGL_CONTEXT_OPENGL_ROBUST_ACCESS_EXT:
 262          if (!dpy->Extensions.EXT_create_context_robustness) {
 263             err = EGL_BAD_ATTRIBUTE;
 264             break;
 265          }
 266
 267          if (val == EGL_TRUE)
 268             ctx->Flags |= EGL_CONTEXT_OPENGL_ROBUST_ACCESS_BIT_KHR;
 269          break;
 270
 271       case EGL_CONTEXT_OPENGL_ROBUST_ACCESS:
 272          if (dpy->Version < 15) {
 273             err = EGL_BAD_ATTRIBUTE;
 274             break;
 275          }
 276
 277          if (val == EGL_TRUE)
 278             ctx->Flags |= EGL_CONTEXT_OPENGL_ROBUST_ACCESS_BIT_KHR;
 279          break;
 280
 281       case EGL_CONTEXT_OPENGL_DEBUG:
 282          if (dpy->Version < 15) {
 283             err = EGL_BAD_ATTRIBUTE;
 284             break;
 285          }
 286
 287          if (val == EGL_TRUE)
 288             ctx->Flags |= EGL_CONTEXT_OPENGL_DEBUG_BIT_KHR;
 289          break;
 290
 291       case EGL_CONTEXT_OPENGL_FORWARD_COMPATIBLE:
 292          if (dpy->Version < 15) {
 293             err = EGL_BAD_ATTRIBUTE;
 294             break;
 295          }
 296
 297          if (val == EGL_TRUE)
 298             ctx->Flags |= EGL_CONTEXT_OPENGL_FORWARD_COMPATIBLE_BIT_KHR;
 299          break;
 300
 301       default:
 302          err = EGL_BAD_ATTRIBUTE;
 303          break;
 304       }
 305
 306       if (err != EGL_SUCCESS) {
 307          _eglLog(_EGL_DEBUG, "bad context attribute 0x%04x", attr);
 308          break;
 309       }
 310    }
 311
 312    if (api == EGL_OPENGL_API) {
 313       /* The EGL_KHR_create_context spec says:
 314        *
 315        *     "If the requested OpenGL version is less than 3.2,
 316        *     EGL_CONTEXT_OPENGL_PROFILE_MASK_KHR is ignored and the
 317        *     functionality of the context is determined solely by the
 318        *     requested version."
 319        *
 320        * Since the value is ignored, only validate the setting if the version
 321        * is >= 3.2.
 322        */
 323       if (ctx->ClientMajorVersion >= 4
 324           || (ctx->ClientMajorVersion == 3 && ctx->ClientMinorVersion >= 2)) {
 325          switch (ctx->Profile) {
 326          case EGL_CONTEXT_OPENGL_CORE_PROFILE_BIT_KHR:
 327          case EGL_CONTEXT_OPENGL_COMPATIBILITY_PROFILE_BIT_KHR:
 328             break;
 329
 330          default:
 331             /* The EGL_KHR_create_context spec says:
 332              *
 333              *     "* If an OpenGL context is requested, the requested version
 334              *        is greater than 3.2, and the value for attribute
 335              *        EGL_CONTEXT_OPENGL_PROFILE_MASK_KHR has no bits set; has
 336              *        any bits set other than EGL_CONTEXT_OPENGL_CORE_PROFILE_BIT_KHR
 337              *        and EGL_CONTEXT_OPENGL_COMPATIBILITY_PROFILE_BIT_KHR; has
 338              *        more than one of these bits set; or if the implementation does
 339              *        not support the requested profile, then an EGL_BAD_MATCH error
 340              *        is generated."
 341              */
 342             err = EGL_BAD_MATCH;
 343             break;
 344          }
 345       }
 346
 347       /* The EGL_KHR_create_context spec says:
 348        *
 349        *     "* If an OpenGL context is requested and the values for
 350        *        attributes EGL_CONTEXT_MAJOR_VERSION_KHR and
 351        *        EGL_CONTEXT_MINOR_VERSION_KHR, when considered together with
 352        *        the value for attribute
 353        *        EGL_CONTEXT_FORWARD_COMPATIBLE_BIT_KHR, specify an OpenGL
 354        *        version and feature set that are not defined, than an
 355        *        EGL_BAD_MATCH error is generated.
 356        *
 357        *        ... Thus, examples of invalid combinations of attributes
 358        *        include:
 359        *
 360        *          - Major version < 1 or > 4
 361        *          - Major version == 1 and minor version < 0 or > 5
 362        *          - Major version == 2 and minor version < 0 or > 1
 363        *          - Major version == 3 and minor version < 0 or > 2
 364        *          - Major version == 4 and minor version < 0 or > 2
 365        *          - Forward-compatible flag set and major version < 3"
 366        */
 367       if (ctx->ClientMajorVersion < 1 || ctx->ClientMinorVersion < 0)
 368          err = EGL_BAD_MATCH;
 369
 370       switch (ctx->ClientMajorVersion) {
 371       case 1:
 372          if (ctx->ClientMinorVersion > 5
 373              || (ctx->Flags & EGL_CONTEXT_OPENGL_FORWARD_COMPATIBLE_BIT_KHR) != 0)
 374             err = EGL_BAD_MATCH;
 375          break;
 376
 377       case 2:
 378          if (ctx->ClientMinorVersion > 1
 379              || (ctx->Flags & EGL_CONTEXT_OPENGL_FORWARD_COMPATIBLE_BIT_KHR) != 0)
 380             err = EGL_BAD_MATCH;
 381          break;
 382
 383       case 3:
 384          /* Note: The text above is incorrect.  There *is* an OpenGL 3.3!
 385           */
 386          if (ctx->ClientMinorVersion > 3)
 387             err = EGL_BAD_MATCH;
 388          break;
 389
 390       case 4:
 391       default:
 392          /* Don't put additional version checks here.  We don't know that
 393           * there won't be versions > 4.2.
 394           */
 395          break;
 396       }
 397    } else if (api == EGL_OPENGL_ES_API) {
 398       /* The EGL_KHR_create_context spec says:
 399        *
 400        *     "* If an OpenGL ES context is requested and the values for
 401        *        attributes EGL_CONTEXT_MAJOR_VERSION_KHR and
 402        *        EGL_CONTEXT_MINOR_VERSION_KHR specify an OpenGL ES version that
 403        *        is not defined, than an EGL_BAD_MATCH error is generated.
 404        *
 405        *        ... Examples of invalid combinations of attributes include:
 406        *
 407        *          - Major version < 1 or > 2
 408        *          - Major version == 1 and minor version < 0 or > 1
 409        *          - Major version == 2 and minor version != 0
 410        */
 411       if (ctx->ClientMajorVersion < 1 || ctx->ClientMinorVersion < 0)
 412          err = EGL_BAD_MATCH;
 413
 414       switch (ctx->ClientMajorVersion) {
 415       case 1:
 416          if (ctx->ClientMinorVersion > 1)
 417             err = EGL_BAD_MATCH;
 418          break;
 419
 420       case 2:
 421          if (ctx->ClientMinorVersion > 0)
 422             err = EGL_BAD_MATCH;
 423          break;
 424
 425       case 3:
 426          /* Don't put additional version checks here.  We don't know that
 427           * there won't be versions > 3.0.
 428           */
 429          break;
 430
 431       default:
 432          err = EGL_BAD_MATCH;
 433          break;
 434       }
 435    }
 436
 437    switch (ctx->ResetNotificationStrategy) {
 438    case EGL_NO_RESET_NOTIFICATION_KHR:
 439    case EGL_LOSE_CONTEXT_ON_RESET_KHR:
 440       break;
 441
 442    default:
 443       err = EGL_BAD_ATTRIBUTE;
 444       break;
 445    }
 446
 447    if ((ctx->Flags & ~(EGL_CONTEXT_OPENGL_DEBUG_BIT_KHR
 448                       | EGL_CONTEXT_OPENGL_FORWARD_COMPATIBLE_BIT_KHR
 449                       | EGL_CONTEXT_OPENGL_ROBUST_ACCESS_BIT_KHR)) != 0) {
 450       err = EGL_BAD_ATTRIBUTE;
 451    }
 452
 453    return err;
 454 }
 455
 456
 457 /**
 458  * Initialize the given _EGLContext object to defaults and/or the values
 459  * in the attrib_list.
 460  *
 461  * According to EGL 1.5 Section 3.7:
 462  *
 463  *      "EGL_OPENGL_API and EGL_OPENGL_ES_API are interchangeable for all
 464  *      purposes except eglCreateContext."
 465  *
 466  * And since we only support GL and GLES, this is the only place where the
 467  * bound API matters at all. We look up the current API from the current
 468  * thread, and stash that in the context we're initializing. Our caller is
 469  * responsible for determining whether that's an API it supports.
 470  */
 471 EGLBoolean
 472 _eglInitContext(_EGLContext *ctx, _EGLDisplay *dpy, _EGLConfig *conf,
 473                 const EGLint *attrib_list)
 474 {
 475    const EGLenum api = eglQueryAPI();
 476    EGLint err;
 477
 478    if (api == EGL_NONE) {
 479       _eglError(EGL_BAD_MATCH, "eglCreateContext(no client API)");
 480       return EGL_FALSE;
 481    }
 482
 483    _eglInitResource(&ctx->Resource, sizeof(*ctx), dpy);
 484    ctx->ClientAPI = api;
 485    ctx->Config = conf;
 486    ctx->WindowRenderBuffer = EGL_NONE;
 487    ctx->Profile = EGL_CONTEXT_OPENGL_CORE_PROFILE_BIT_KHR;
 488
 489    ctx->ClientMajorVersion = 1; /* the default, per EGL spec */
 490    ctx->ClientMinorVersion = 0;
 491    ctx->Flags = 0;
 492    ctx->Profile = EGL_CONTEXT_OPENGL_CORE_PROFILE_BIT_KHR;
 493    ctx->ResetNotificationStrategy = EGL_NO_RESET_NOTIFICATION_KHR;
 494
 495    err = _eglParseContextAttribList(ctx, dpy, attrib_list);
 496    if (err == EGL_SUCCESS && ctx->Config) {
 497       EGLint api_bit;
 498
 499       api_bit = _eglGetContextAPIBit(ctx);
 500       if (!(ctx->Config->RenderableType & api_bit)) {
 501          _eglLog(_EGL_DEBUG, "context api is 0x%x while config supports 0x%x",
 502                api_bit, ctx->Config->RenderableType);
 503          err = EGL_BAD_CONFIG;
 504       }
 505    }
 506    if (err != EGL_SUCCESS)
 507       return _eglError(err, "eglCreateContext");
 508
 509    return EGL_TRUE;
 510 }
 511
 512
 513 static EGLint
 514 _eglQueryContextRenderBuffer(_EGLContext *ctx)
 515 {
 516    _EGLSurface *surf = ctx->DrawSurface;
 517    EGLint rb;
 518
 519    if (!surf)
 520       return EGL_NONE;
 521    if (surf->Type == EGL_WINDOW_BIT && ctx->WindowRenderBuffer != EGL_NONE)
 522       rb = ctx->WindowRenderBuffer;
 523    else
 524       rb = surf->RenderBuffer;
 525    return rb;
 526 }
 527
 528
 529 EGLBoolean
 530 _eglQueryContext(_EGLDriver *drv, _EGLDisplay *dpy, _EGLContext *c,
 531                  EGLint attribute, EGLint *value)
 532 {
 533    (void) drv;
 534    (void) dpy;
 535
 536    if (!value)
 537       return _eglError(EGL_BAD_PARAMETER, "eglQueryContext");
 538
 539    switch (attribute) {
 540    case EGL_CONFIG_ID:
 541       /*
 542        * From EGL_KHR_no_config_context:
 543        *
 544        *    "Querying EGL_CONFIG_ID returns the ID of the EGLConfig with
 545        *     respect to which the context was created, or zero if created
 546        *     without respect to an EGLConfig."
 547        */
 548       *value = c->Config ? c->Config->ConfigID : 0;
 549       break;
 550    case EGL_CONTEXT_CLIENT_VERSION:
 551       *value = c->ClientMajorVersion;
 552       break;
 553    case EGL_CONTEXT_CLIENT_TYPE:
 554       *value = c->ClientAPI;
 555       break;
 556    case EGL_RENDER_BUFFER:
 557       *value = _eglQueryContextRenderBuffer(c);
 558       break;
 559    default:
 560       return _eglError(EGL_BAD_ATTRIBUTE, "eglQueryContext");
 561    }
 562
 563    return EGL_TRUE;
 564 }
 565
 566
 567 /**
 568  * Bind the context to the thread and return the previous context.
 569  *
 570  * Note that the context may be NULL.
 571  */
 572 static _EGLContext *
 573 _eglBindContextToThread(_EGLContext *ctx, _EGLThreadInfo *t)
 574 {
 575    _EGLContext *oldCtx;
 576
 577    oldCtx = t->CurrentContext;
 578    if (ctx != oldCtx) {
 579       if (oldCtx)
 580          oldCtx->Binding = NULL;
 581       if (ctx)
 582          ctx->Binding = t;
 583
 584       t->CurrentContext = ctx;
 585    }
 586
 587    return oldCtx;
 588 }
 589
 590
 591 /**
 592  * Return true if the given context and surfaces can be made current.
 593  */
 594 static EGLBoolean
 595 _eglCheckMakeCurrent(_EGLContext *ctx, _EGLSurface *draw, _EGLSurface *read)
 596 {
 597    _EGLThreadInfo *t = _eglGetCurrentThread();
 598    _EGLDisplay *dpy;
 599
 600    if (_eglIsCurrentThreadDummy())
 601       return _eglError(EGL_BAD_ALLOC, "eglMakeCurrent");
 602
 603    /* this is easy */
 604    if (!ctx) {
 605       if (draw || read)
 606          return _eglError(EGL_BAD_MATCH, "eglMakeCurrent");
 607       return EGL_TRUE;
 608    }
 609
 610    dpy = ctx->Resource.Display;
 611    if (!dpy->Extensions.KHR_surfaceless_context
 612        && (draw == NULL || read == NULL))
 613       return _eglError(EGL_BAD_MATCH, "eglMakeCurrent");
 614
 615    /*
 616     * The spec says
 617     *
 618     * "If ctx is current to some other thread, or if either draw or read are
 619     * bound to contexts in another thread, an EGL_BAD_ACCESS error is
 620     * generated."
 621     *
 622     * and
 623     *
 624     * "at most one context may be bound to a particular surface at a given
 625     * time"
 626     */
 627    if (ctx->Binding && ctx->Binding != t)
 628       return _eglError(EGL_BAD_ACCESS, "eglMakeCurrent");
 629    if (draw && draw->CurrentContext && draw->CurrentContext != ctx) {
 630       if (draw->CurrentContext->Binding != t)
 631          return _eglError(EGL_BAD_ACCESS, "eglMakeCurrent");
 632    }
 633    if (read && read->CurrentContext && read->CurrentContext != ctx) {
 634       if (read->CurrentContext->Binding != t)
 635          return _eglError(EGL_BAD_ACCESS, "eglMakeCurrent");
 636    }
 637
 638    /* If the context has a config then it must match that of the two
 639     * surfaces */
 640    if (ctx->Config) {
 641       if ((draw && draw->Config != ctx->Config) ||
 642           (read && read->Config != ctx->Config))
 643          return _eglError(EGL_BAD_MATCH, "eglMakeCurrent");
 644    } else {
 645       /* Otherwise we must be using the EGL_MESA_configless_context
 646        * extension */
 647       assert(dpy->Extensions.MESA_configless_context);
 648
 649       /* The extension doesn't permit binding draw and read buffers with
 650        * differing contexts */
 651       if (draw && read && draw->Config != read->Config)
 652          return _eglError(EGL_BAD_MATCH, "eglMakeCurrent");
 653    }
 654
 655    return EGL_TRUE;
 656 }
 657
 658
 659 /**
 660  * Bind the context to the current thread and given surfaces.  Return the
 661  * previous bound context and surfaces.  The caller should unreference the
 662  * returned context and surfaces.
 663  *
 664  * Making a second call with the resources returned by the first call
 665  * unsurprisingly undoes the first call, except for the resouce reference
 666  * counts.
 667  */
 668 EGLBoolean
 669 _eglBindContext(_EGLContext *ctx, _EGLSurface *draw, _EGLSurface *read,
 670                 _EGLContext **old_ctx,
 671                 _EGLSurface **old_draw, _EGLSurface **old_read)
 672 {
 673    _EGLThreadInfo *t = _eglGetCurrentThread();
 674    _EGLContext *prev_ctx;
 675    _EGLSurface *prev_draw, *prev_read;
 676
 677    if (!_eglCheckMakeCurrent(ctx, draw, read))
 678       return EGL_FALSE;
 679
 680    /* increment refcounts before binding */
 681    _eglGetContext(ctx);
 682    _eglGetSurface(draw);
 683    _eglGetSurface(read);
 684
 685    /* bind the new context */
 686    prev_ctx = _eglBindContextToThread(ctx, t);
 687
 688    /* break previous bindings */
 689    if (prev_ctx) {
 690       prev_draw = prev_ctx->DrawSurface;
 691       prev_read = prev_ctx->ReadSurface;
 692
 693       if (prev_draw)
 694          prev_draw->CurrentContext = NULL;
 695       if (prev_read)
 696          prev_read->CurrentContext = NULL;
 697
 698       prev_ctx->DrawSurface = NULL;
 699       prev_ctx->ReadSurface = NULL;
 700    }
 701    else {
 702       prev_draw = prev_read = NULL;
 703    }
 704
 705    /* establish new bindings */
 706    if (ctx) {
 707       if (draw)
 708          draw->CurrentContext = ctx;
 709       if (read)
 710          read->CurrentContext = ctx;
 711
 712       ctx->DrawSurface = draw;
 713       ctx->ReadSurface = read;
 714    }
 715
 716    assert(old_ctx && old_draw && old_read);
 717    *old_ctx = prev_ctx;
 718    *old_draw = prev_draw;
 719    *old_read = prev_read;
 720
 721    return EGL_TRUE;
 722 }