[Mesa-dev] [PATCH] mesa/extensions: Enable overriding permanently enabled extensions

[Brian Paul]

On 11/20/2015 05:15 PM, Nanley Chery wrote:
> From: Nanley Chery <nanley.g.chery at intel.com>
>
> Provide the ability to prevent any permanently enabled extension
> from appearing in the string returned by glGetString[i]().
>
> Signed-off-by: Nanley Chery <nanley.g.chery at intel.com>
> ---
>   src/mesa/main/extensions.c | 64 +++++++++++++++++-----------------------------
>   1 file changed, 24 insertions(+), 40 deletions(-)
>
> diff --git a/src/mesa/main/extensions.c b/src/mesa/main/extensions.c
> index 01cfdf1..fa50cb6 100644
> --- a/src/mesa/main/extensions.c
> +++ b/src/mesa/main/extensions.c
> @@ -40,7 +40,6 @@
>   struct gl_extensions _mesa_extension_override_enables;
>   struct gl_extensions _mesa_extension_override_disables;
>   static char *extra_extensions = NULL;
> -static char *cant_disable_extensions = NULL;
>
>
>   /**
> @@ -68,29 +67,30 @@ const struct mesa_extension _mesa_extension_table[] = {
>   #undef EXT
>   };
>
> +static bool disabled_extensions[ARRAY_SIZE(_mesa_extension_table)];
>
>   /**
>    * Given an extension name, lookup up the corresponding member of struct
> - * gl_extensions and return that member's offset (in bytes).  If the name is
> - * not found in the \c _mesa_extension_table, return 0.
> + * gl_extensions and return that member's index.  If the name is
> + * not found in the \c _mesa_extension_table, return -1.
>    *
>    * \param name Name of extension.
> - * \return Offset of member in struct gl_extensions.
> + * \return Index of member in struct gl_extensions.
>    */
> -static size_t
> -name_to_offset(const char* name)
> +static int
> +name_to_index(const char* name)
>   {
>      unsigned i;
>
>      if (name == 0)
> -      return 0;
> +      return -1;
>
>      for (i = 0; i < ARRAY_SIZE(_mesa_extension_table); ++i) {
>         if (strcmp(name, _mesa_extension_table[i].name) == 0)
> -	 return _mesa_extension_table[i].offset;
> +	 return i;
>      }
>
> -   return 0;
> +   return -1;
>   }
>
>   /**
> @@ -206,11 +206,11 @@ _mesa_enable_sw_extensions(struct gl_context *ctx)
>    * \return offset of extensions withint `ext' or 0 if extension is not known
>    */
>   static size_t
> -set_extension(struct gl_extensions *ext, const char *name, GLboolean state)
> +set_extension(struct gl_extensions *ext, int i, GLboolean state)
>   {
>      size_t offset;
>
> -   offset = name_to_offset(name);
> +   offset = i < 0 ? 0 : _mesa_extension_table[i].offset;
>      if (offset != 0 && (offset != o(dummy_true) || state != GL_FALSE)) {
>         ((GLboolean *) ext)[offset] = state;
>      }
> @@ -240,12 +240,6 @@ get_extension_override( struct gl_context *ctx )
>   {
>      override_extensions_in_context(ctx);
>
> -   if (cant_disable_extensions != NULL) {
> -      _mesa_problem(ctx,
> -                    "Trying to disable permanently enabled extensions: %s",
> -	            cant_disable_extensions);
> -   }
> -
>      if (extra_extensions == NULL) {
>         return calloc(1, sizeof(char));
>      } else {
> @@ -257,7 +251,7 @@ get_extension_override( struct gl_context *ctx )
>
>
>   /**
> - * \brief Free extra_extensions and cant_disable_extensions strings
> + * \brief Free extra_extensions string
>    *
>    * These strings are allocated early during the first context creation by
>    * _mesa_one_time_init_extension_overrides.
> @@ -266,7 +260,6 @@ static void
>   free_unknown_extensions_strings(void)
>   {
>      free(extra_extensions);
> -   free(cant_disable_extensions);
>   }
>
>
> @@ -295,22 +288,20 @@ _mesa_one_time_init_extension_overrides(void)
>
>      /* extra_exts: List of unrecognized extensions. */
>      extra_extensions = calloc(ALIGN(strlen(env_const) + 2, 4), sizeof(char));
> -   cant_disable_extensions = calloc(ALIGN(strlen(env_const) + 2, 4), sizeof(char));
>
>      /* Copy env_const because strtok() is destructive. */
>      env = strdup(env_const);
>
>      if (env == NULL ||
> -       extra_extensions == NULL ||
> -       cant_disable_extensions == NULL) {
> +       extra_extensions == NULL) {
>         free(env);
>         free(extra_extensions);
> -      free(cant_disable_extensions);
>         return;
>      }
>
>      for (ext = strtok(env, " "); ext != NULL; ext = strtok(NULL, " ")) {
>         int enable;
> +      int i;
>         bool recognized;
>         switch (ext[0]) {
>         case '+':
> @@ -326,7 +317,8 @@ _mesa_one_time_init_extension_overrides(void)
>            break;
>         }
>
> -      offset = set_extension(&_mesa_extension_override_enables, ext, enable);
> +      i = name_to_index(ext);
> +      offset = set_extension(&_mesa_extension_override_enables, i, enable);
>         if (offset != 0 && (offset != o(dummy_true) || enable != GL_FALSE)) {
>            ((GLboolean *) &_mesa_extension_override_disables)[offset] = !enable;
>            recognized = true;
> @@ -334,14 +326,12 @@ _mesa_one_time_init_extension_overrides(void)
>            recognized = false;
>         }
>
> -      if (!recognized) {
> -         if (enable) {
> -            strcat(extra_extensions, ext);
> -            strcat(extra_extensions, " ");
> -         } else if (offset == o(dummy_true)) {
> -            strcat(cant_disable_extensions, ext);
> -            strcat(cant_disable_extensions, " ");
> -         }
> +      if (i >= 0)
> +         disabled_extensions[i] = !enable;
> +
> +      if (!recognized && enable) {
> +         strcat(extra_extensions, ext);
> +         strcat(extra_extensions, " ");
>         }
>      }
>
> @@ -355,13 +345,6 @@ _mesa_one_time_init_extension_overrides(void)
>      } else if (extra_extensions[len - 1] == ' ') {
>         extra_extensions[len - 1] = '\0';
>      }
> -   len = strlen(cant_disable_extensions);
> -   if (len == 0) {
> -      free(cant_disable_extensions);
> -      cant_disable_extensions = NULL;
> -   } else if (cant_disable_extensions[len - 1] == ' ') {
> -      cant_disable_extensions[len - 1] = '\0';
> -   }
>   }
>
>
> @@ -402,7 +385,8 @@ _mesa_extension_supported(const struct gl_context *ctx, extension_index i)
>      const bool *base = (bool *) &ctx->Extensions;
>      const struct mesa_extension *ext = _mesa_extension_table + i;
>
> -   return (ctx->Version >= ext->version[ctx->API]) && base[ext->offset];
> +   return !disabled_extensions[i] &&
> +          (ctx->Version >= ext->version[ctx->API]) && base[ext->offset];
>   }
>
>   /**
>

Reviewed-by: Brian Paul <brianp at vmware.com>
Tested-by: Brian Paul <brianp at vmware.com>

Thanks, Nanley!