From 1b38b41837379649cc5f86b167b470be368c2a1d Mon Sep 17 00:00:00 2001
From: Nigel Stewart <nigels@sourceforge.net>
Date: Wed, 30 Mar 2011 11:38:25 -0500
Subject: [PATCH] Patch ID: 3260500 - Query extension string only once

---
 auto/bin/make_list.pl    |  2 +-
 auto/src/glew_head.c     | 20 ++++++++++++++++++++
 auto/src/glew_init_gl.c  | 35 ++++++++++++++++-------------------
 auto/src/glew_init_glx.c | 29 +++++++++++++++--------------
 auto/src/glew_init_wgl.c | 33 +++++++++++++++++++--------------
 5 files changed, 71 insertions(+), 48 deletions(-)

diff --git a/auto/bin/make_list.pl b/auto/bin/make_list.pl
index ceaa479..5571ea9 100755
--- a/auto/bin/make_list.pl
+++ b/auto/bin/make_list.pl
@@ -46,7 +46,7 @@ if (@ARGV)
 
                 if (length($extstring))
                 {
-		        print "  CONST_CAST(" . $extvar . ") = " . $extpre . "GetExtension(\"$extstring\");\n";
+		        print "  CONST_CAST(" . $extvar . ") = _glewSearchExtension(\"$extstring\", start, end);\n";
                 }
 
 		if (keys %$functions)
diff --git a/auto/src/glew_head.c b/auto/src/glew_head.c
index df16210..c6c50a7 100644
--- a/auto/src/glew_head.c
+++ b/auto/src/glew_head.c
@@ -217,3 +217,23 @@ static GLboolean _glewStrSame3 (GLubyte** a, GLuint* na, const GLubyte* b, GLuin
   }
   return GL_FALSE;
 }
+
+/*
+ * Search for name in the extensions string. Use of strstr()
+ * is not sufficient because extension names can be prefixes of
+ * other extension names. Could use strtok() but the constant
+ * string returned by glGetString might be in read-only memory.
+ */
+static GLboolean _glewSearchExtension (const char* name, const GLubyte *start, const GLubyte *end)
+{
+  const GLubyte* p;
+  GLuint len = _glewStrLen((const GLubyte*)name);
+  p = start;
+  while (p < end)
+  {
+    GLuint n = _glewStrCLen(p, ' ');
+    if (len == n && _glewStrSame((const GLubyte*)name, p, n)) return GL_TRUE;
+    p += n+1;
+  }
+  return GL_FALSE;
+}
diff --git a/auto/src/glew_init_gl.c b/auto/src/glew_init_gl.c
index 33bd85e..0779939 100644
--- a/auto/src/glew_init_gl.c
+++ b/auto/src/glew_init_gl.c
@@ -1,26 +1,14 @@
 /* ------------------------------------------------------------------------- */
 
-/* 
- * Search for name in the extensions string. Use of strstr()
- * is not sufficient because extension names can be prefixes of
- * other extension names. Could use strtok() but the constant
- * string returned by glGetString might be in read-only memory.
- */
 GLboolean glewGetExtension (const char* name)
 {    
-  GLubyte* p;
-  GLubyte* end;
-  GLuint len = _glewStrLen((const GLubyte*)name);
-  p = (GLubyte*)glGetString(GL_EXTENSIONS);
-  if (0 == p) return GL_FALSE;
-  end = p + _glewStrLen(p);
-  while (p < end)
-  {
-    GLuint n = _glewStrCLen(p, ' ');
-    if (len == n && _glewStrSame((const GLubyte*)name, p, n)) return GL_TRUE;
-    p += n+1;
-  }
-  return GL_FALSE;
+  const GLubyte* start;
+  const GLubyte* end;
+  start = (const GLubyte*)glGetString(GL_EXTENSIONS);
+  if (start == 0)
+    return GL_FALSE;
+  end = start + _glewStrLen(start);
+  return _glewSearchExtension(name, start, end);
 }
 
 /* ------------------------------------------------------------------------- */
@@ -33,6 +21,8 @@ GLenum glewContextInit (GLEW_CONTEXT_ARG_DEF_LIST)
   const GLubyte* s;
   GLuint dot;
   GLint major, minor;
+  const GLubyte* start;
+  const GLubyte* end;
   /* query opengl version */
   s = glGetString(GL_VERSION);
   dot = _glewStrCLen(s, '.');
@@ -69,4 +59,11 @@ GLenum glewContextInit (GLEW_CONTEXT_ARG_DEF_LIST)
     CONST_CAST(GLEW_VERSION_1_2)   = GLEW_VERSION_1_2_1 == GL_TRUE || ( major == 1 && minor >= 2 ) ? GL_TRUE : GL_FALSE;
     CONST_CAST(GLEW_VERSION_1_1)   = GLEW_VERSION_1_2   == GL_TRUE || ( major == 1 && minor >= 1 ) ? GL_TRUE : GL_FALSE;
   }
+
+  /* query opengl extensions string */
+  start = glGetString(GL_EXTENSIONS);
+  if (start == 0)
+    start = (const GLubyte*)"";
+  end = start + _glewStrLen(start);
+
   /* initialize extensions */
diff --git a/auto/src/glew_init_glx.c b/auto/src/glew_init_glx.c
index c66e24c..37bbee1 100644
--- a/auto/src/glew_init_glx.c
+++ b/auto/src/glew_init_glx.c
@@ -2,27 +2,21 @@
 
 GLboolean glxewGetExtension (const char* name)
 {    
-  GLubyte* p;
-  GLubyte* end;
-  GLuint len;
+  const GLubyte* start;
+  const GLubyte* end;
 
   if (glXGetCurrentDisplay == NULL) return GL_FALSE;
-  len = _glewStrLen((const GLubyte*)name);
-  p = (GLubyte*)glXGetClientString(glXGetCurrentDisplay(), GLX_EXTENSIONS);
-  if (0 == p) return GL_FALSE;
-  end = p + _glewStrLen(p);
-  while (p < end)
-  {
-    GLuint n = _glewStrCLen(p, ' ');
-    if (len == n && _glewStrSame((const GLubyte*)name, p, n)) return GL_TRUE;
-    p += n+1;
-  }
-  return GL_FALSE;
+  start = (const GLubyte*)glXGetClientString(glXGetCurrentDisplay(), GLX_EXTENSIONS);
+  if (0 == start) return GL_FALSE;
+  end = start + _glewStrLen(start);
+  return _glewSearchExtension(name, start, end);
 }
 
 GLenum glxewContextInit (GLXEW_CONTEXT_ARG_DEF_LIST)
 {
   int major, minor;
+  const GLubyte* start;
+  const GLubyte* end;
   /* initialize core GLX 1.2 */
   if (_glewInit_GLX_VERSION_1_2(GLEW_CONTEXT_ARG_VAR_INIT)) return GLEW_ERROR_GLX_VERSION_11_ONLY;
   /* initialize flags */
@@ -49,4 +43,11 @@ GLenum glxewContextInit (GLXEW_CONTEXT_ARG_DEF_LIST)
       break;
     }
   }
+  /* query GLX extension string */
+  start = 0;
+  if (glXGetCurrentDisplay != NULL)
+    start = (const GLubyte*)glXGetClientString(glXGetCurrentDisplay(), GLX_EXTENSIONS);
+  if (start == 0)
+    start = (const GLubyte *)"";
+  end = start + _glewStrLen(start);
   /* initialize extensions */
diff --git a/auto/src/glew_init_wgl.c b/auto/src/glew_init_wgl.c
index e66de42..c37e084 100644
--- a/auto/src/glew_init_wgl.c
+++ b/auto/src/glew_init_wgl.c
@@ -5,32 +5,37 @@ static PFNWGLGETEXTENSIONSSTRINGEXTPROC _wglewGetExtensionsStringEXT = NULL;
 
 GLboolean wglewGetExtension (const char* name)
 {    
-  GLubyte* p;
-  GLubyte* end;
-  GLuint len = _glewStrLen((const GLubyte*)name);
+  const GLubyte* start;
+  const GLubyte* end;
   if (_wglewGetExtensionsStringARB == NULL)
     if (_wglewGetExtensionsStringEXT == NULL)
       return GL_FALSE;
     else
-      p = (GLubyte*)_wglewGetExtensionsStringEXT();
+      start = (const GLubyte*)_wglewGetExtensionsStringEXT();
   else
-    p = (GLubyte*)_wglewGetExtensionsStringARB(wglGetCurrentDC());
-  if (0 == p) return GL_FALSE;
-  end = p + _glewStrLen(p);
-  while (p < end)
-  {
-    GLuint n = _glewStrCLen(p, ' ');
-    if (len == n && _glewStrSame((const GLubyte*)name, p, n)) return GL_TRUE;
-    p += n+1;
-  }
-  return GL_FALSE;
+    start = (const GLubyte*)_wglewGetExtensionsStringARB(wglGetCurrentDC());
+  if (start == 0)
+    return GL_FALSE;
+  end = start + _glewStrLen(start);
+  return _glewSearchExtension(name, start, end);
 }
 
 GLenum wglewContextInit (WGLEW_CONTEXT_ARG_DEF_LIST)
 {
   GLboolean crippled;
+  const GLubyte* start;
+  const GLubyte* end;
   /* find wgl extension string query functions */
   _wglewGetExtensionsStringARB = (PFNWGLGETEXTENSIONSSTRINGARBPROC)glewGetProcAddress((const GLubyte*)"wglGetExtensionsStringARB");
   _wglewGetExtensionsStringEXT = (PFNWGLGETEXTENSIONSSTRINGEXTPROC)glewGetProcAddress((const GLubyte*)"wglGetExtensionsStringEXT");
+  /* query wgl extension string */
+  if (_wglewGetExtensionsStringARB == NULL)
+    if (_wglewGetExtensionsStringEXT == NULL)
+      start = (const GLubyte*)"";
+    else
+      start = (const GLubyte*)_wglewGetExtensionsStringEXT();
+  else
+    start = (const GLubyte*)_wglewGetExtensionsStringARB(wglGetCurrentDC());
+  end = start + _glewStrLen(start);
   /* initialize extensions */
   crippled = _wglewGetExtensionsStringARB == NULL && _wglewGetExtensionsStringEXT == NULL;