dri: Change __DriverApiRec::CreateContext to take a struct for attribs

Previously the CreateContext method of __DriverApiRec took a set of
arguments to describe the attribute values from the window system API's
CreateContextAttribs function. As more attributes get added this could
quickly get unworkable and every new attribute needs a modification for
every driver.

To fix that, pass the attribute values in a struct instead.  The struct
has a bitmask to specify which members are used. The first three members
(two for the GL version and one for the flags) are always set. If the
bit is not set in the attribute mask then it can be assumed the
attribute has the default value. Drivers will error if unknown bits in
the mask are set.

Reviewed-by: Adam Jackson <[email protected]>
Reviewed-by: Nicolai Hähnle <[email protected]>
Reviewed-by: Emil Velikov <[email protected]>
Signed-off-by: Neil Roberts <[email protected]>

2 files changed, 66 insertions, 28 deletions

diff --git a/src/mesa/drivers/dri/common/dri_util.c b/src/mesa/drivers/dri/common/dri_util.c
index 1cff0ddb2de..dc5260ca5b9 100644
--- a/src/mesa/drivers/dri/common/dri_util.c
+++ b/src/mesa/drivers/dri/common/dri_util.c
@@ -302,11 +302,13 @@ driCreateContextAttribs(__DRIscreen *screen, int api,
     const struct gl_config *modes = (config != NULL) ? &config->modes : NULL;
     void *shareCtx = (shared != NULL) ? shared->driverPrivate : NULL;
     gl_api mesa_api;
-    unsigned major_version = 1;
-    unsigned minor_version = 0;
-    uint32_t flags = 0;
-    bool notify_reset = false;
-    unsigned priority = __DRI_CTX_PRIORITY_MEDIUM;
+    struct __DriverContextConfig ctx_config;
+
+    ctx_config.major_version = 1;
+    ctx_config.minor_version = 0;
+    ctx_config.flags = 0;
+    ctx_config.attribute_mask = 0;
+    ctx_config.priority = __DRI_CTX_PRIORITY_MEDIUM;
 
     assert((num_attribs == 0) || (attribs != NULL));
 
@@ -337,20 +339,27 @@ driCreateContextAttribs(__DRIscreen *screen, int api,
     for (unsigned i = 0; i < num_attribs; i++) {
 	switch (attribs[i * 2]) {
 	case __DRI_CTX_ATTRIB_MAJOR_VERSION:
-	    major_version = attribs[i * 2 + 1];
+            ctx_config.major_version = attribs[i * 2 + 1];
 	    break;
 	case __DRI_CTX_ATTRIB_MINOR_VERSION:
-	    minor_version = attribs[i * 2 + 1];
+	    ctx_config.minor_version = attribs[i * 2 + 1];
 	    break;
 	case __DRI_CTX_ATTRIB_FLAGS:
-	    flags = attribs[i * 2 + 1];
+	    ctx_config.flags = attribs[i * 2 + 1];
 	    break;
         case __DRI_CTX_ATTRIB_RESET_STRATEGY:
-            notify_reset = (attribs[i * 2 + 1]
-                            != __DRI_CTX_RESET_NO_NOTIFICATION);
+            if (attribs[i * 2 + 1] != __DRI_CTX_RESET_NO_NOTIFICATION) {
+                ctx_config.attribute_mask |=
+                    __DRIVER_CONTEXT_ATTRIB_RESET_STRATEGY;
+                ctx_config.reset_strategy = attribs[i * 2 + 1];
+            } else {
+                ctx_config.attribute_mask &=
+                    ~__DRIVER_CONTEXT_ATTRIB_RESET_STRATEGY;
+            }
             break;
 	case __DRI_CTX_ATTRIB_PRIORITY:
-	    priority = attribs[i * 2 + 1];
+            ctx_config.attribute_mask |= __DRIVER_CONTEXT_ATTRIB_PRIORITY;
+	    ctx_config.priority = attribs[i * 2 + 1];
 	    break;
 	default:
 	    /* We can't create a context that satisfies the requirements of an
@@ -366,12 +375,14 @@ driCreateContextAttribs(__DRIscreen *screen, int api,
      * compatibility profile.  This means that we treat a API_OPENGL_COMPAT 3.1 as
      * API_OPENGL_CORE and reject API_OPENGL_COMPAT 3.2+.
      */
-    if (mesa_api == API_OPENGL_COMPAT && major_version == 3 && minor_version == 1)
+    if (mesa_api == API_OPENGL_COMPAT &&
+        ctx_config.major_version == 3 && ctx_config.minor_version == 1)
        mesa_api = API_OPENGL_CORE;
 
     if (mesa_api == API_OPENGL_COMPAT
-        && ((major_version > 3)
-            || (major_version == 3 && minor_version >= 2))) {
+        && ((ctx_config.major_version > 3)
+            || (ctx_config.major_version == 3 &&
+                ctx_config.minor_version >= 2))) {
        *error = __DRI_CTX_ERROR_BAD_API;
        return NULL;
     }
@@ -406,9 +417,9 @@ driCreateContextAttribs(__DRIscreen *screen, int api,
      */
     if (mesa_api != API_OPENGL_COMPAT
         && mesa_api != API_OPENGL_CORE
-        && (flags & ~(__DRI_CTX_FLAG_DEBUG |
-	              __DRI_CTX_FLAG_ROBUST_BUFFER_ACCESS |
-	              __DRI_CTX_FLAG_NO_ERROR))) {
+        && (ctx_config.flags & ~(__DRI_CTX_FLAG_DEBUG |
+                                 __DRI_CTX_FLAG_ROBUST_BUFFER_ACCESS |
+                                 __DRI_CTX_FLAG_NO_ERROR))) {
 	*error = __DRI_CTX_ERROR_BAD_FLAG;
 	return NULL;
     }
@@ -424,7 +435,7 @@ driCreateContextAttribs(__DRIscreen *screen, int api,
      *
      * In Mesa, a debug context is the same as a regular context.
      */
-    if ((flags & __DRI_CTX_FLAG_FORWARD_COMPATIBLE) != 0) {
+    if ((ctx_config.flags & __DRI_CTX_FLAG_FORWARD_COMPATIBLE) != 0) {
        mesa_api = API_OPENGL_CORE;
     }
 
@@ -432,13 +443,15 @@ driCreateContextAttribs(__DRIscreen *screen, int api,
                                     | __DRI_CTX_FLAG_FORWARD_COMPATIBLE
                                     | __DRI_CTX_FLAG_ROBUST_BUFFER_ACCESS
                                     | __DRI_CTX_FLAG_NO_ERROR);
-    if (flags & ~allowed_flags) {
+    if (ctx_config.flags & ~allowed_flags) {
 	*error = __DRI_CTX_ERROR_UNKNOWN_FLAG;
 	return NULL;
     }
 
     if (!validate_context_version(screen, mesa_api,
-                                  major_version, minor_version, error))
+                                  ctx_config.major_version,
+                                  ctx_config.minor_version,
+                                  error))
        return NULL;
 
     context = calloc(1, sizeof *context);
@@ -454,9 +467,7 @@ driCreateContextAttribs(__DRIscreen *screen, int api,
     context->driReadablePriv = NULL;
 
     if (!screen->driver->CreateContext(mesa_api, modes, context,
-                                       major_version, minor_version,
-                                       flags, notify_reset, priority,
-                                       error, shareCtx)) {
+                                       &ctx_config, error, shareCtx)) {
         free(context);
         return NULL;
     }
diff --git a/src/mesa/drivers/dri/common/dri_util.h b/src/mesa/drivers/dri/common/dri_util.h
index ecc2a475073..13d07dd5130 100644
--- a/src/mesa/drivers/dri/common/dri_util.h
+++ b/src/mesa/drivers/dri/common/dri_util.h
@@ -67,6 +67,37 @@ extern const __DRIswrastExtension driSWRastExtension;
 extern const __DRIdri2Extension driDRI2Extension;
 extern const __DRI2configQueryExtension dri2ConfigQueryExtension;
 extern const __DRIcopySubBufferExtension driCopySubBufferExtension;
+
+/**
+ * Description of the attributes used to create a config.
+ *
+ * This is passed as the context_config parameter to CreateContext. The idea
+ * with this struct is that it can be extended without having to modify all of
+ * the drivers. The first three members (major/minor_version and flags) are
+ * always valid, but the remaining members are only valid if the corresponding
+ * flag is set for the attribute. If the flag is not set then the default
+ * value should be assumed. That way the driver can quickly check if any
+ * attributes were set that it doesn't understand and report an error.
+ */
+struct __DriverContextConfig {
+    /* These members are always valid */
+    unsigned major_version;
+    unsigned minor_version;
+    uint32_t flags;
+
+    /* Flags describing which of the remaining members are valid */
+    uint32_t attribute_mask;
+
+    /* Only valid if __DRIVER_CONTEXT_ATTRIB_RESET_STRATEGY is set */
+    int reset_strategy;
+
+    /* Only valid if __DRIVER_CONTEXT_PRIORITY is set */
+    unsigned priority;
+};
+
+#define __DRIVER_CONTEXT_ATTRIB_RESET_STRATEGY  (1 << 0)
+#define __DRIVER_CONTEXT_ATTRIB_PRIORITY        (1 << 1)
+
 /**
  * Driver callback functions.
  *
@@ -85,11 +116,7 @@ struct __DriverAPIRec {
     GLboolean (*CreateContext)(gl_api api,
                                const struct gl_config *glVis,
                                __DRIcontext *driContextPriv,
-                               unsigned major_version,
-                               unsigned minor_version,
-                               uint32_t flags,
-                               bool notify_reset,
-                               unsigned priority,
+                               const struct __DriverContextConfig *ctx_config,
                                unsigned *error,
                                void *sharedContextPrivate);