| // Copyright 2025 Google LLC |
| // |
| // Use of this source code is governed by a BSD-style license |
| // that can be found in the COPYING file in the root of the source |
| // tree. An additional intellectual property rights grant can be found |
| // in the file PATENTS. All contributing project authors may |
| // be found in the AUTHORS file in the root of the source tree. |
| // ----------------------------------------------------------------------------- |
| // |
| // Adds compatibility / portability macros to support usage of -fbounds-safety |
| |
| #ifndef WEBP_UTILS_BOUNDS_SAFETY_H_ |
| #define WEBP_UTILS_BOUNDS_SAFETY_H_ |
| |
| #ifdef WEBP_SUPPORT_FBOUNDS_SAFETY |
| |
| #include <ptrcheck.h> |
| // |
| // There's some inherent complexity here due to the way -fbounds-safety works. |
| // Some annotations (notably __indexable and __bidi_indexable) change the ABI |
| // of the function or struct, so we don't want those annotations to silently |
| // disappear if they're expected. |
| // |
| // In ptrcheck.h provided by the compiler, ABI changing annotations do not |
| // "vanish" under any build configuration. This is intentional. Consider the |
| // following example: |
| // |
| // == Safe.h, where Safe.c is always compiled with -fbounds-safety == |
| // Forward declare my_function, implemented in Safe.c |
| // void my_function(char *__bidi_indexable ptr); |
| // |
| // If we have a project that does not use -fbounds-safety, and we want to call |
| // my_function that was pre-built with -fbounds-safety, this annotation cannot |
| // vanish or there'll be an ABI mismatch, which may fail to compile or have |
| // worse behaviors at runtime. |
| // |
| // TODO: https://issues.webmproject.org/432511225 - In the future, we should |
| // have CMake append to a header file (like this one) that libwebp was built |
| // with -fbounds-safety, so that we know to never make annotations vanish. |
| |
| // The annotations below are ABI breaking as they turn normal pointers into |
| // "wide" pointers. Breaking them down: |
| // * __indexable is akin to { ptr_curr, ptr_end }, and can only be |
| // forward-indexed. |
| // * __bidi_indexable (bidirectional indexable) is |
| // { ptr_begin, ptr_curr, ptr_end } |
| // and can be both forward and backward indexed. |
| // See https://clang.llvm.org/docs/BoundsSafety.html for more comprehensive |
| // documentation |
| #define WEBP_INDEXABLE __indexable |
| #define WEBP_BIDI_INDEXABLE __bidi_indexable |
| |
| #else // WEBP_SUPPORT_FBOUNDS_SAFETY |
| |
| #define WEBP_INDEXABLE |
| #define WEBP_BIDI_INDEXABLE |
| |
| #endif // WEBP_SUPPORT_FBOUNDS_SAFETY |
| |
| #endif // WEBP_UTILS_BOUNDS_SAFETY_H_ |
