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1 /*
2  * SGI FREE SOFTWARE LICENSE B (Version 2.0, Sept. 18, 2008)
3  * Copyright (C) 1991-2000 Silicon Graphics, Inc. All Rights Reserved.
4  *
5  * Permission is hereby granted, free of charge, to any person obtaining a
6  * copy of this software and associated documentation files (the "Software"),
7  * to deal in the Software without restriction, including without limitation
8  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
9  * and/or sell copies of the Software, and to permit persons to whom the
10  * Software is furnished to do so, subject to the following conditions:
11  *
12  * The above copyright notice including the dates of first publication and
13  * either this permission notice or a reference to
14  * http://oss.sgi.com/projects/FreeB/
15  * shall be included in all copies or substantial portions of the Software.
16  *
17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
18  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
20  * SILICON GRAPHICS, INC. BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
21  * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF
22  * OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
23  * SOFTWARE.
24  *
25  * Except as contained in this notice, the name of Silicon Graphics, Inc.
26  * shall not be used in advertising or otherwise to promote the sale, use or
27  * other dealings in this Software without prior written authorization from
28  * Silicon Graphics, Inc.
29  */
30 
31 /**
32  * \file glxcurrent.c
33  * Client-side GLX interface for current context management.
34  */
35 
36 #include <pthread.h>
37 
38 #include "glxclient.h"
39 #include "glapi.h"
40 #include "glx_error.h"
41 
42 /*
43 ** We setup some dummy structures here so that the API can be used
44 ** even if no context is current.
45 */
46 
47 static GLubyte dummyBuffer[__GLX_BUFFER_LIMIT_SIZE];
48 static struct glx_context_vtable dummyVtable;
49 /*
50 ** Dummy context used by small commands when there is no current context.
51 ** All the
52 ** gl and glx entry points are designed to operate as nop's when using
53 ** the dummy context structure.
54 */
55 struct glx_context dummyContext = {
56    &dummyBuffer[0],
57    &dummyBuffer[0],
58    &dummyBuffer[0],
59    &dummyBuffer[__GLX_BUFFER_LIMIT_SIZE],
60    sizeof(dummyBuffer),
61    &dummyVtable
62 };
63 
64 /*
65  * Current context management and locking
66  */
67 
68 _X_HIDDEN pthread_mutex_t __glXmutex = PTHREAD_MUTEX_INITIALIZER;
69 
70 /**
71  * Per-thread GLX context pointer.
72  *
73  * \c __glXSetCurrentContext is written is such a way that this pointer can
74  * \b never be \c NULL.  This is important!  Because of this
75  * \c __glXGetCurrentContext can be implemented as trivial macro.
76  */
77 __THREAD_INITIAL_EXEC void *__glX_tls_Context = &dummyContext;
78 
79 _X_HIDDEN void
__glXSetCurrentContext(struct glx_context * c)80 __glXSetCurrentContext(struct glx_context * c)
81 {
82    __glX_tls_Context = (c != NULL) ? c : &dummyContext;
83 }
84 
85 _X_HIDDEN void
__glXSetCurrentContextNull(void)86 __glXSetCurrentContextNull(void)
87 {
88    __glXSetCurrentContext(&dummyContext);
89 #if defined(GLX_DIRECT_RENDERING)
90    _glapi_set_dispatch(NULL);   /* no-op functions */
91    _glapi_set_context(NULL);
92 #endif
93 }
94 
95 _GLX_PUBLIC GLXContext
glXGetCurrentContext(void)96 glXGetCurrentContext(void)
97 {
98    struct glx_context *cx = __glXGetCurrentContext();
99 
100    if (cx == &dummyContext) {
101       return NULL;
102    }
103    else {
104       return (GLXContext) cx;
105    }
106 }
107 
108 _GLX_PUBLIC GLXDrawable
glXGetCurrentDrawable(void)109 glXGetCurrentDrawable(void)
110 {
111    struct glx_context *gc = __glXGetCurrentContext();
112    return gc->currentDrawable;
113 }
114 
115 /**
116  * Make a particular context current.
117  *
118  * \note This is in this file so that it can access dummyContext.
119  */
120 static Bool
MakeContextCurrent(Display * dpy,GLXDrawable draw,GLXDrawable read,GLXContext gc_user,int opcode)121 MakeContextCurrent(Display * dpy, GLXDrawable draw,
122                    GLXDrawable read, GLXContext gc_user,
123                    int opcode)
124 {
125    struct glx_context *gc = (struct glx_context *) gc_user;
126    struct glx_context *oldGC = __glXGetCurrentContext();
127 
128    /* Make sure that the new context has a nonzero ID.  In the request,
129     * a zero context ID is used only to mean that we bind to no current
130     * context.
131     */
132    if ((gc != NULL) && (gc->xid == None)) {
133       return GL_FALSE;
134    }
135 
136    _glapi_check_multithread();
137 
138    __glXLock();
139    if (oldGC == gc &&
140        gc->currentDrawable == draw && gc->currentReadable == read) {
141       __glXUnlock();
142       return True;
143    }
144 
145    /* can't have only one be 0 */
146    if (!!draw != !!read) {
147       __glXUnlock();
148       __glXSendError(dpy, BadMatch, None, opcode, True);
149       return False;
150    }
151 
152    if (oldGC != &dummyContext) {
153       oldGC->vtable->unbind(oldGC, gc);
154       oldGC->currentDpy = NULL;
155    }
156 
157    if (gc) {
158       /* Attempt to bind the context.  We do this before mucking with
159        * gc and __glXSetCurrentContext to properly handle our state in
160        * case of an error.
161        *
162        * If an error occurs, set the Null context since we've already
163        * blown away our old context.  The caller is responsible for
164        * figuring out how to handle setting a valid context.
165        */
166       if (gc->vtable->bind(gc, oldGC, draw, read) != Success) {
167          __glXSetCurrentContextNull();
168          __glXUnlock();
169          __glXSendError(dpy, GLXBadContext, None, opcode, False);
170          return GL_FALSE;
171       }
172 
173       gc->currentDpy = dpy;
174       gc->currentDrawable = draw;
175       gc->currentReadable = read;
176       __glXSetCurrentContext(gc);
177    } else {
178       __glXSetCurrentContextNull();
179    }
180 
181    if (oldGC->currentDpy == NULL && oldGC != &dummyContext && oldGC->xid == None) {
182       /* We are switching away from a context that was
183        * previously destroyed, so we need to free the memory
184        * for the old handle. */
185       oldGC->vtable->destroy(oldGC);
186    }
187 
188    __glXUnlock();
189 
190    return GL_TRUE;
191 }
192 
193 _GLX_PUBLIC Bool
glXMakeCurrent(Display * dpy,GLXDrawable draw,GLXContext gc)194 glXMakeCurrent(Display * dpy, GLXDrawable draw, GLXContext gc)
195 {
196    return MakeContextCurrent(dpy, draw, draw, gc, X_GLXMakeCurrent);
197 }
198 
199 _GLX_PUBLIC Bool
glXMakeContextCurrent(Display * dpy,GLXDrawable d,GLXDrawable r,GLXContext ctx)200 glXMakeContextCurrent(Display *dpy, GLXDrawable d, GLXDrawable r,
201                       GLXContext ctx)
202 {
203    return MakeContextCurrent(dpy, d, r, ctx, X_GLXMakeContextCurrent);
204 }
205 
206 _GLX_PUBLIC Bool
glXMakeCurrentReadSGI(Display * dpy,GLXDrawable d,GLXDrawable r,GLXContext ctx)207 glXMakeCurrentReadSGI(Display *dpy, GLXDrawable d, GLXDrawable r,
208                       GLXContext ctx)
209 {
210    return MakeContextCurrent(dpy, d, r, ctx, X_GLXvop_MakeCurrentReadSGI);
211 }
212