Fix calling new entrypoints from within glBegin()/glEnd().

3 files changed, 124 insertions, 11 deletions

diff --git a/src/dispatch_common.c b/src/dispatch_common.c
index 6d27cb1..7b976a5 100644
--- a/src/dispatch_common.c
+++ b/src/dispatch_common.c
@@ -117,6 +117,20 @@ struct api {
 
     /** dlopen() return value for libGLESv2.so.2 */
     void *gles2_handle;
+
+    /**
+     * This value gets incremented when any thread is in
+     * glBegin()/glEnd() called through epoxy.
+     *
+     * We're not guaranteed to be called through our wrapper, so the
+     * conservative paths also try to handle the failure cases they'll
+     * see if begin_count didn't reflect reality.  It's also a bit of
+     * a bug that the conservative paths might return success because
+     * some other thread was in epoxy glBegin/glEnd while our thread
+     * is trying to resolve, but given that it's basically just for
+     * informative error messages, we shouldn't need to care.
+     */
+    int begin_count;
 };
 
 static struct api api = {
@@ -159,18 +173,34 @@ PUBLIC bool
 epoxy_is_desktop_gl(void)
 {
     const char *es_prefix = "OpenGL ES ";
-    const char *version = (const char *)glGetString(GL_VERSION);
+    const char *version;
+
+    if (api.begin_count)
+        return true;
+
+    version = (const char *)glGetString(GL_VERSION);
+
+    /* If we didn't get a version back, there are only two things that
+     * could have happened: either malloc failure (which basically
+     * doesn't exist), or we were called within a glBegin()/glEnd().
+     * Assume the second, which only exists for desktop GL.
+     */
+    if (!version)
+        return true;
 
     return strncmp(es_prefix, version, strlen(es_prefix));
 }
 
-PUBLIC int
-epoxy_gl_version(void)
+static int
+epoxy_internal_gl_version(int error_version)
 {
     const char *version = (const char *)glGetString(GL_VERSION);
     GLint major, minor;
     int scanf_count;
 
+    if (!version)
+        return error_version;
+
     /* skip to version number */
     while (!isdigit(*version) && *version != '\0')
         version++;
@@ -185,6 +215,21 @@ epoxy_gl_version(void)
     return 10 * major + minor;
 }
 
+PUBLIC int
+epoxy_gl_version(void)
+{
+    return epoxy_internal_gl_version(0);
+}
+
+PUBLIC int
+epoxy_conservative_gl_version(void)
+{
+    if (api.begin_count)
+        return 100;
+
+    return epoxy_internal_gl_version(100);
+}
+
 /**
  * If we can determine the GLX version from the current context, then
  * return that, otherwise return a version that will just send us on
@@ -268,16 +313,21 @@ epoxy_extension_in_string(const char *extension_list, const char *ext)
     return ptr != NULL;
 }
 
-PUBLIC bool
-epoxy_has_gl_extension(const char *ext)
+static bool
+epoxy_internal_has_gl_extension(const char *ext, bool invalid_op_mode)
 {
     if (epoxy_gl_version() < 30) {
-        return epoxy_extension_in_string((const char *)glGetString(GL_EXTENSIONS),
-                                         ext);
+        const char *exts = (const char *)glGetString(GL_EXTENSIONS);
+        if (!exts)
+            return invalid_op_mode;
+        return epoxy_extension_in_string(exts, ext);
     } else {
         int num_extensions;
 
         glGetIntegerv(GL_NUM_EXTENSIONS, &num_extensions);
+        if (num_extensions == 0)
+            return invalid_op_mode;
+
         for (int i = 0; i < num_extensions; i++) {
             const char *gl_ext = (const char *)glGetStringi(GL_EXTENSIONS, i);
             if (strcmp(ext, gl_ext) == 0)
@@ -288,6 +338,29 @@ epoxy_has_gl_extension(const char *ext)
     }
 }
 
+/**
+ * Returns true if the given GL extension is supported in the current context.
+ *
+ * Note that this function can't be called from within glBegin()/glEnd().
+ *
+ * \sa epoxy_has_egl_extension()
+ * \sa epoxy_has_glx_extension()
+ */
+PUBLIC bool
+epoxy_has_gl_extension(const char *ext)
+{
+    return epoxy_internal_has_gl_extension(ext, false);
+}
+
+bool
+epoxy_conservative_has_gl_extension(const char *ext)
+{
+    if (api.begin_count)
+        return true;
+
+    return epoxy_internal_has_gl_extension(ext, true);
+}
+
 bool
 epoxy_conservative_has_egl_extension(const char *ext)
 {
@@ -424,3 +497,23 @@ epoxy_print_failure_reasons(const char *name,
     for (i = 0; providers[i] != 0; i++)
         puts(provider_names[providers[i]]);
 }
+
+PUBLIC void
+epoxy_glBegin(GLenum primtype)
+{
+    pthread_mutex_lock(&api.mutex);
+    api.begin_count++;
+    pthread_mutex_unlock(&api.mutex);
+
+    epoxy_glBegin_unwrapped(primtype);
+}
+
+PUBLIC void
+epoxy_glEnd(void)
+{
+    epoxy_glEnd_unwrapped();
+
+    pthread_mutex_lock(&api.mutex);
+    api.begin_count--;
+    pthread_mutex_unlock(&api.mutex);
+}
diff --git a/src/dispatch_common.h b/src/dispatch_common.h
index 34163ec..f66f165 100644
--- a/src/dispatch_common.h
+++ b/src/dispatch_common.h
@@ -41,6 +41,8 @@ void *epoxy_gles1_dlsym(const char *name);
 void *epoxy_gles2_dlsym(const char *name);
 void *epoxy_get_proc_address(const char *name);
 
+int epoxy_conservative_gl_version(void);
+bool epoxy_conservative_has_gl_extension(const char *name);
 int epoxy_conservative_glx_version(void);
 bool epoxy_conservative_has_glx_extension(const char *name);
 int epoxy_conservative_egl_version(void);
@@ -48,3 +50,6 @@ bool epoxy_conservative_has_egl_extension(const char *name);
 void epoxy_print_failure_reasons(const char *name,
                                  const char **provider_names,
                                  const int *providers);
+
+void epoxy_glBegin_unwrapped(GLenum primtype);
+void epoxy_glEnd_unwrapped(void);
diff --git a/src/gen_dispatch.py b/src/gen_dispatch.py
index e2c5308..048785f 100755
--- a/src/gen_dispatch.py
+++ b/src/gen_dispatch.py
@@ -130,6 +130,14 @@ class Generator(object):
         # provided the name of the symbol to be requested.
         self.provider_loader = {}
 
+        # These are functions with hand-written wrapper code in
+        # dispatch_common.c.  Their dispatch stubs will be replaced
+        # with non-public symbols with a "_unwrapped" suffix.
+        self.wrapped_functions = {
+            'glBegin',
+            'glEnd'
+        }
+
     def all_text_until_element_name(self, element, element_name):
         text = ''
 
@@ -265,7 +273,7 @@ class Generator(object):
                     loader = 'epoxy_gl_dlsym({0})'
                 else:
                     loader = 'epoxy_get_proc_address({0})'
-                    condition += ' && epoxy_gl_version() >= {0}'.format(version)
+                    condition += ' && epoxy_conservative_gl_version() >= {0}'.format(version)
             elif api == 'gles2':
                 human_name = 'OpenGL ES {0}'.format(feature.get('number'))
                 condition = '!epoxy_is_desktop_gl() && epoxy_gl_version() >= {0}'.format(version)
@@ -319,7 +327,7 @@ class Generator(object):
                 self.process_require_statements(extension, condition, loader, human_name)
             if 'gl' in apis:
                 human_name = 'GL extension \\"{0}\\"'.format(extname)
-                condition = 'epoxy_has_gl_extension("{0}")'.format(extname)
+                condition = 'epoxy_conservative_has_gl_extension("{0}")'.format(extname)
                 loader = 'epoxy_get_proc_address({0})'
                 self.process_require_statements(extension, condition, loader, human_name)
 
@@ -460,8 +468,15 @@ class Generator(object):
 
         dispatch_table_entry = 'dispatch_table->p{0}'.format(alias_name)
 
-        self.outln('PUBLIC {0}'.format(func.ret_type))
-        self.outln('epoxy_{0}({1})'.format(func.name, func.args_decl))
+        if func.name in self.wrapped_functions:
+            function_name = func.name + '_unwrapped'
+            public = ''
+        else:
+            function_name = func.name
+            public = 'PUBLIC '
+
+        self.outln('{0}{1}'.format(public, func.ret_type))
+        self.outln('epoxy_{0}({1})'.format(function_name, func.args_decl))
         self.outln('{')
         self.outln('    if (!{0})'.format(dispatch_table_entry))
         self.outln('        {0} = epoxy_{1}_resolver();'.format(dispatch_table_entry,