From 4c5472555a3a418c06fd5e6a18240862eebce047 Mon Sep 17 00:00:00 2001
From: Nigel Stewart <nigels@users.sourceforge.net>
Date: Wed, 27 Jan 2016 22:15:49 +1000
Subject: [PATCH] For EGL purpose avoid using linked glGetString, load it via
 eglGetProcAddress instead.

---
 auto/src/glew_init_egl.c |  2 +-
 auto/src/glew_init_gl.c  | 17 ++++++++++++++---
 auto/src/glewinfo_tail.c | 22 ++++++++++++++++++++++
 3 files changed, 37 insertions(+), 4 deletions(-)

diff --git a/auto/src/glew_init_egl.c b/auto/src/glew_init_egl.c
index 26bd4ae..784285f 100644
--- a/auto/src/glew_init_egl.c
+++ b/auto/src/glew_init_egl.c
@@ -5,7 +5,7 @@ GLboolean eglewGetExtension (const char* name)
   const GLubyte* start;
   const GLubyte* end;
 
-  start = (const GLubyte*) eglQueryString(eglGetDisplay(EGL_DEFAULT_DISPLAY), EGL_EXTENSIONS);
+  start = (const GLubyte*) eglQueryString(eglGetCurrentDisplay(), EGL_EXTENSIONS);
   if (0 == start) return GL_FALSE;
   end = start + _glewStrLen(start);
   return _glewSearchExtension(name, start, end);
diff --git a/auto/src/glew_init_gl.c b/auto/src/glew_init_gl.c
index 6fd86ce..38bb7c1 100644
--- a/auto/src/glew_init_gl.c
+++ b/auto/src/glew_init_gl.c
@@ -71,14 +71,22 @@ GLboolean GLEWAPIENTRY glewGetExtension (const char* name)
 
 /* ------------------------------------------------------------------------- */
 
+typedef const GLubyte* (GLAPIENTRY * PFNGLGETSTRINGPROC) (GLenum name);
+typedef void (GLAPIENTRY * PFNGLGETINTEGERVPROC) (GLenum pname, GLint *params);
+
 static GLenum GLEWAPIENTRY glewContextInit ()
 {
+  PFNGLGETSTRINGPROC getString;
   const GLubyte* s;
   GLuint dot;
   GLint major, minor;
 
   /* query opengl version */
-  s = glGetString(GL_VERSION);
+  getString = (PFNGLGETSTRINGPROC)  glewGetProcAddress((const GLubyte*)"glGetString");
+  if (!getString)
+    return GLEW_ERROR_NO_GL_VERSION;
+
+  s = getString(GL_VERSION);
   dot = _glewStrCLen(s, '.');
   if (dot == 0)
     return GLEW_ERROR_NO_GL_VERSION;
@@ -123,11 +131,14 @@ static GLenum GLEWAPIENTRY glewContextInit ()
   {
     GLint n = 0;
     GLint i;
+    PFNGLGETINTEGERVPROC getIntegerv;
     PFNGLGETSTRINGIPROC getStringi;
     const char *ext;
     GLboolean *enable;
 
-    glGetIntegerv(GL_NUM_EXTENSIONS, &n);
+    getIntegerv = (PFNGLGETINTEGERVPROC) glewGetProcAddress((const GLubyte*)"glGetIntegerv");
+    if (getIntegerv)
+      getIntegerv(GL_NUM_EXTENSIONS, &n);
 
     /* glGetStringi is OpenGL 3.0 */
     getStringi = (PFNGLGETSTRINGIPROC) glewGetProcAddress((const GLubyte*)"glGetStringi");
@@ -156,7 +167,7 @@ static GLenum GLEWAPIENTRY glewContextInit ()
     char ext[128];
     GLboolean *enable;
 
-    extensions = (const char *) glGetString(GL_EXTENSIONS);
+    extensions = (const char *) getString(GL_EXTENSIONS);
 
     if (extensions)
     {
diff --git a/auto/src/glewinfo_tail.c b/auto/src/glewinfo_tail.c
index ec895f8..1975286 100644
--- a/auto/src/glewinfo_tail.c
+++ b/auto/src/glewinfo_tail.c
@@ -23,6 +23,11 @@ int main (int argc, char** argv)
     0    /* flags */
   };
 
+#if defined(GLEW_EGL)
+  typedef const GLubyte* (GLAPIENTRY * PFNGLGETSTRINGPROC) (GLenum name);
+  PFNGLGETSTRINGPROC getString;
+#endif
+
   if (glewParseArgs(argc-1, argv+1, &params))
   {
     fprintf(stderr, "Usage: glewinfo "
@@ -55,6 +60,17 @@ int main (int argc, char** argv)
     glewDestroyContext();
     return 1;
   }
+
+#if defined(GLEW_EGL)
+  getString = (PFNGLGETSTRINGPROC) eglGetProcAddress("glGetString");
+  if (!getString)
+  {
+    fprintf(stderr, "Error: eglGetProcAddress failed to fetch glGetString\n");
+    glewDestroyContext();
+    return 1;
+  }
+#endif
+
 #if defined(_WIN32)
 #if defined(_MSC_VER) && (_MSC_VER >= 1400)
   if (fopen_s(&f, "glewinfo.txt", "w") != 0)
@@ -78,9 +94,15 @@ int main (int argc, char** argv)
   fprintf(f, "Reporting capabilities of display %s, visual 0x%x\n",
     params.display == NULL ? getenv("DISPLAY") : params.display, params.visual);
 #endif
+#if defined(GLEW_EGL)
+  fprintf(f, "Running on a %s from %s\n",
+    getString(GL_RENDERER), getString(GL_VENDOR));
+  fprintf(f, "OpenGL version %s is supported\n", getString(GL_VERSION));
+#else
   fprintf(f, "Running on a %s from %s\n",
     glGetString(GL_RENDERER), glGetString(GL_VENDOR));
   fprintf(f, "OpenGL version %s is supported\n", glGetString(GL_VERSION));
+#endif
   glewInfo();
 #if defined(GLEW_OSMESA)
 #elif defined(GLEW_EGL)