Copy the GL2 extension string before destroying context

The pointer returned by glGetString is owned by the GL context, so
when the GL context is destroyed it may become invalid. This happens
on Mesa, for example. Make/manage our own copy of the extension string
to use after destroying the context.

Bug: 9627179
Change-Id: I605536151ee64f50403546d0d38c5b5f1f27dd73

1 files changed, 15 insertions, 8 deletions

diff --git a/emulator/opengl/host/libs/libOpenglRender/FrameBuffer.cpp b/emulator/opengl/host/libs/libOpenglRender/FrameBuffer.cpp
index 2c9e8c5..042d38a 100644
--- a/emulator/opengl/host/libs/libOpenglRender/FrameBuffer.cpp
+++ b/emulator/opengl/host/libs/libOpenglRender/FrameBuffer.cpp
@@ -13,6 +13,7 @@
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
+
 #include "FrameBuffer.h"
 #include "NativeSubWindow.h"
 #include "FBConfig.h"
@@ -20,14 +21,14 @@
 #include "GLDispatch.h"
 #include "GL2Dispatch.h"
 #include "ThreadInfo.h"
-#include <stdio.h>
 #include "TimeUtils.h"
+#include <stdio.h>
 
 FrameBuffer *FrameBuffer::s_theFrameBuffer = NULL;
 HandleType FrameBuffer::s_nextHandle = 0;
 
 #ifdef WITH_GLES2
-static const char *getGLES2ExtensionString(EGLDisplay p_dpy)
+static char* getGLES2ExtensionString(EGLDisplay p_dpy)
 {
     EGLConfig config;
     EGLSurface surface;
@@ -74,10 +75,9 @@ static const char *getGLES2ExtensionString(EGLDisplay p_dpy)
         return NULL;
     }
 
-    const char *extString = (const char *)s_gl2.glGetString(GL_EXTENSIONS);
-    if (!extString) {
-        extString = "";
-    }
+    // the string pointer may become invalid when the context is destroyed
+    const char* s = (const char*)s_gl2.glGetString(GL_EXTENSIONS);
+    char* extString = strdup(s ? s : "");
 
     s_egl.eglMakeCurrent(p_dpy, NULL, NULL, NULL);
     s_egl.eglDestroyContext(p_dpy, ctx);
@@ -153,7 +153,7 @@ bool FrameBuffer::initialize(int width, int height)
     // if GLES2 plugin has loaded - try to make GLES2 context and
     // get GLES2 extension string
     //
-    const char *gl2Extensions = NULL;
+    char* gl2Extensions = NULL;
 #ifdef WITH_GLES2
     if (fb->m_caps.hasGL2) {
         gl2Extensions = getGLES2ExtensionString(fb->m_eglDisplay);
@@ -187,6 +187,7 @@ bool FrameBuffer::initialize(int width, int height)
     if (!s_egl.eglChooseConfig(fb->m_eglDisplay, configAttribs,
                                &fb->m_eglConfig, 1, &n)) {
         ERR("Failed on eglChooseConfig\n");
+        free(gl2Extensions);
         delete fb;
         return false;
     }
@@ -201,6 +202,7 @@ bool FrameBuffer::initialize(int width, int height)
                                               glContextAttribs);
     if (fb->m_eglContext == EGL_NO_CONTEXT) {
         printf("Failed to create Context 0x%x\n", s_egl.eglGetError());
+        free(gl2Extensions);
         delete fb;
         return false;
     }
@@ -218,6 +220,7 @@ bool FrameBuffer::initialize(int width, int height)
                                                glContextAttribs);
     if (fb->m_pbufContext == EGL_NO_CONTEXT) {
         printf("Failed to create Pbuffer Context 0x%x\n", s_egl.eglGetError());
+        free(gl2Extensions);
         delete fb;
         return false;
     }
@@ -238,6 +241,7 @@ bool FrameBuffer::initialize(int width, int height)
                                                   pbufAttribs);
     if (fb->m_pbufSurface == EGL_NO_SURFACE) {
         printf("Failed to create pbuf surface for FB 0x%x\n", s_egl.eglGetError());
+        free(gl2Extensions);
         delete fb;
         return false;
     }
@@ -245,6 +249,7 @@ bool FrameBuffer::initialize(int width, int height)
     // Make the context current
     if (!fb->bind_locked()) {
         ERR("Failed to make current\n");
+        free(gl2Extensions);
         delete fb;
         return false;
     }
@@ -259,8 +264,10 @@ bool FrameBuffer::initialize(int width, int height)
     }
 
     if (fb->m_caps.hasGL2 && has_gl_oes_image) {
-        has_gl_oes_image &= (strstr(gl2Extensions, "GL_OES_EGL_image") != NULL);
+        has_gl_oes_image &= strstr(gl2Extensions, "GL_OES_EGL_image") != NULL;
     }
+    free(gl2Extensions);
+    gl2Extensions = NULL;
 
     const char *eglExtensions = s_egl.eglQueryString(fb->m_eglDisplay,
                                                      EGL_EXTENSIONS);